Blender loads scripts at startup. It seems it cannot find these. The most likely reason is that the path to it has some characters Blender can't read or a file is corrupt. Here is what you can try.

Reinstall and clear all user settings.

On Windows, the directory is located at  C:\Users\USER_NAME\AppData\Roaming\Blender Foundation\Blender\2.6x. Delete this folder and reinstall Blender. See this post for more information on how to locate this directory. This can work for both portable copies and installations.

OR

When uninstalling the program, tick Remove all files (second option) to make it delete the directory and then reinstall.

Try a portable version.
Still clear the old folder from the first point. Since portable builds use the files they ship with, it should work with the files it comes with or generate new ones as needed.


How do you set the "current image" as far as bpy is concerned?

Unlike 3d view where you can only have one active object no matter how many views are open, the image editor is not restricted to that. From a UI standpoint you could have multiple UV/ImageEditor windows open, and then the concept of 'current image' starts to require more context. This is the case even if you had one image window open, or none when running in background mode. Luckily we don't need to worry about current image, or loop through views.

Use the right API calls

instead of calling operators intended to be called by the UI, it's often more convenient to manipulate Image datablocks directly using the methods provided by the Image class. You can use:

import bpy

# make an alias to increase readability.
images = bpy.data.images

# if the image changes on disk, this should get the new pixels
images[image_name].reload()

# the same can be done using .load()
images.load("/home/zeffii/Desktop/some_image.png", check_existing=True)

As explained in your other question

Don't do this if you can avoid it

https://gist.github.com/zeffii/54410dcbff9b6aa4953d

import bpy

images = bpy.data.images

# say I know I have 2 images, and 2 IMAGE_EDITORS open
# currently none of the image editors are showing any image.
loaded_images = images[:]

AREA = 'IMAGE_EDITOR'

for window in bpy.context.window_manager.windows:
    for area in window.screen.areas:

        if not area.type == AREA:
            continue

        for s in area.spaces:
            if s.type == AREA:
                image_to_use = loaded_images.pop()
                # s.image is the property to set for each
                # IMAGE_EDITOR to tell it to display a certain
                # image by reference.
                s.image = image_to_use


In curves, the vertices cannot be linked to more than two segments, curves cannot be forked or bifurcated.

To create such shape you would need to add a new disconnected curve segment and place it on top of an existing one.


Mesh is warped when I add subdivision surface. No amount of loop cuts gets rid of it

After examining your file, I found 2 main problems - one easy to solve, and the other, a bit more time consuming, to say the least.
The first (easy to solve) issue seems to be that you have a good deal of duplicate vertices in your mesh (somewhere in the 400 area). To solve this, select the whole mesh in edit mode (A) and select mesh > clean up > merge by distance from the mesh menu at the top of the viewport.
The second (not so easily solved) issue has to do with the topology of the mesh. Specifically, your mesh has a good number of n-gon's (faces with more than 4 vertices) which is causing the majority of your issues. Blender favors quad-based topology, and though n-gon's or tri's are sometimes unavoidable, they are best kept towards the center of flat faces, otherwise they cause issues with any number of things, from Subdivision Surface Modifiers, to Shading.
The solution, then, is to do your best to re-topologize your mesh to contain primarily quad-based faces (especially near curved edges) . In the image below, I have begun this process by joining many of the vertices to make quad faces. (I did not finish, however, as it is a lot of work for an example), You can see that the areas that are made of quads behave better, and those that have more than 4 vertices do not. I was also able to better define the overall form of the shape by adding the edge loops I left highlighted.

It's better, but it still needs a lot of retopology work to be "perfect". You will need to spend some time adjusting it manually, I'm afraid. You can see from the image that there are still some artifacts where the the n-gons remain. Check YouTube for guides on topology if you need it.


A shadow catcher was added in blender 2.79.

There is no reason to use compositor tricks any longer to generate a shadow. You simply add an object (In my case a simple plane) and check the Shadow Catcher box.

Go to the Object tab of the Properties Editor. In 2.79 the Shadow Catcher option is in the Cycles Settings section. In 2.8 the Shadow Catcher option is in the Visibility section.

Here is what my rendered scene looks like so far.

Now to get just the shadow you need to disable the Camera visibility on all the other objects. This setting is in nearly the same place as the shadow catcher. Go to Object tab of the Properties Editor. In 2.79 it's under the Cycles Settings section. In 2.8 it is in the Ray Visibility subsection of the Visibility section.


How to see the mesh with subdivisions in wireframe mode in blender 2.83?

Turn off Optimal Display

Came across this as well, found that switching the subsurf modifiers optimal display property has the desired result.


Linux kernel crashes corrupt my Blender files

Have you tried using the File > Recover Last option? it automatically loads the latest blend file saved to the tmp folder.

By default Blender saves the scene every 2 minutes. You can change the Auto Save duration in User Preferences.


Reload Startup File Causes Blender to Stop Responding

use "file" -> "load factory settings", followed by "file" -> "save startup file".

the reason it's slow because you may have changed your startup file to a custom blend file that uses alot of memory.


How to create a plane that follows the dimensions of an object?

Instead of using the dimensions property, create your own bounding box.

Create a list of the vertex positions matmultiplied by the objects world matrix. This list will hold the coordinates of the vertices in world space.
Get the min and max of the x and y property of the coordinate list.

def createPlane(context):

    obj = context.object
    coordinates = [obj.matrix_world @ v.co for v in obj.data.vertices]

    x_list = [co.x for co in coordinates]
    y_list = [co.y for co in coordinates]

    x_min, x_max = min(x_list), max(x_list)
    y_min, y_max = min(y_list), max(y_list)

    verts = ((x_min, y_min, 0),(x_min, y_max, 0),
             (x_max, y_max, 0),(x_max, y_min,0))

    bm = bmesh.new()
    [bm.verts.new((v[0], v[1], v[2])) for v in verts]
    bm.faces.new(bm.verts)

    bm.normal_update()

    me = bpy.data.meshes.new("")
    bm.to_mesh(me)

    plane = bpy.data.objects.new("", me)
    bpy.context.scene.collection.objects.link(plane)


Why do convex curves with sharp edges automatically flatten?

This happens because the surface is pretty much undefined. The only guaranteed flat surface there is is between exactly three vertices. If you have more vertices without edges,  it's a guessing game for Blender, so it will come to different conclusions, depending on angle and other factors.

What you can try is using the subdivision surface modifier, simple, not cattmull-clark, in a high resolution. It will try to fill the face with edges.


Blender 2.8 Viewport Render Image is dark and different to actual viewport

I had a similar issue. Navigate to Properties editor ‣ Render ‣ Color Management - If you have changed the settings in there it will affect the render, but not the viewport view. Using the sub-option curves You can set the rendered picture to appear similar to the viewport. It helped in my case.Hope it helps you too.


The reason it's a big white dot is because the Point light size defaults to 10cm:

The only way to get "rid" of the dot is to make the point light smaller (which makes the dot smaller), but then you'll have to crank up the Strength to compensate.  If you crank it up too much you'll probably get a ton of fireflies.

The hard edges of the dot are because your glass has a roughness of 0.  If you set the roughness a little higher the edges of the dot will get softer.

What I would actually recommend is to model a light bulb (or candle flame) for your lamp, and set it to have an Emission texture.  I think that'll give you the best results in the end.


Can I use a Max model with V-ray materials in Blender without too much trouble?

You can use a model from other application if the the model's file is in OBJ, FBX,Dae or ABC. If the model is in 3DS Format, which is a 3Ds Max format you can't use it unless you find a way to change the format (OBJ, FBX,Dae or ABC).
For the Materials, you need to make everything again with Blender Materials. As far as i know.


Editing verts via script like in editmode: scale, rotate

Relevant sections of the api documentation:

bmesh
bmesh.ops
mathutils

# See Text Editor -> Templates -> Python -> Simple Bmesh Editmode
# This example assumes we have a mesh object in edit-mode

import bpy
import bmesh
import math
import mathutils

# Get the active mesh
obj = bpy.context.edit_object
me = obj.data

# Get a BMesh representation
bm = bmesh.from_edit_mesh(me)
face = bm.faces.active

# Modify the BMesh, can do anything here...

# Rotate - (global)
center = bpy.context.scene.cursor_location
rot = mathutils.Euler((math.radians(45), 0.0, 0.0)).to_matrix()
bmesh.ops.rotate(
            bm,
            cent=bpy.context.scene.cursor_location,
            matrix=rot,
            verts=face.verts,
            space=obj.matrix_world
            )

# Scale - (local) - no space matrix passed
scale = mathutils.Vector((2.0, 1.0, 1.0))
bmesh.ops.scale(
            bm,
            vec=scale,
            verts=face.verts
            )

# Show the updates in the viewport
# and recalculate n-gon tessellation.
bmesh.update_edit_mesh(me, True)


Deform Text Objects in Blender to fit into other object

You might try the Mesh deform modifier:

Add a cube around your text and subdivide so that there are vertices where you want control points  to be:

Add a mesh deform modifier to the text and specify the cube as the control object.

Click bind and deform the control object in edit mode:


Since you are asking about the "easiest way"...

In my opinion, the easiest way to deal with those situations is by not creating them in the first place (unfortunately minecraft and other apps seem to have created unnecessary problems when it comes to modeling, by thinking in boxes that get added and somehow have to be connected. You have to think outside the box...).

If you know that those parts have to be connected, create them as connected elements from the start.

In this case create a base mesh, scale, add a couple of loop cuts and extrude.

The shape of your object is the result of it's topology. Topology shouldn't be an afterthought


Particles are not being killed by collision object when interacting with sides of object

In my case, to solve I just put the emitter and the collider in the same layer, and close and open the Blender to make the bake of the particles again.


How to animate with random values in Freestyle Lines

The stroke and gap lengths can be keyframed. If you, for example, set keyframes at the beginning and end of the animation range, at value 1 for them all, then, in the graph editor, you can give their f-curves a Noise modifier:

I think you're still limited to a (spatially) repeating cycle of 3 dash-and-gap pairs, but it might still do?


How do you rotate the local axes of an object?

if you just want that the local axes points like the standard global orientation, you can just go in Object - Apply - rotation


Flatten option is not available in Blender 2.92

I am not sure about any flatten option but if you have mesh:looptools enabled in preferences you can select your faces and then right click->looptools->flatten to get the result it seems you are looking for.


Fake
In edit mode select side faces and assign material with Emision Shader.

Realistic
This glass plate consists from three materials:

front/back side with Glass Shader
bottom side with Emission Shader
top/left/right side with Glass Shader but now with Roughness 1


How to cut with Knife Tool parallel to the other edge in Ortho\Persp view?

In this case Offset Edge Slide will suit the situation, although it will create additional geometry.
Select the edge you want the new one to be parallel to and run the tool from the left area of the viewport (depending on Blender version) or Shift+Ctrl+R.
The tool has the same properties as Knife which means you can make edge being created parallel to the edge you choose to. To make it parallel to the top one in this case enable Even in the tool options (press E while operator is running) and choose orientation by enabling Flipped (or with F) as desired.
Then select the other edge created on the other side of the main edge and dissolve it.

Note that with topology in question you might need to make a clean-up depending on the purpose of the model. For example, the shown topology isn't suitable for Subsurface modifier and might provide artifacts if bevelled.

Regarding the Knife tool for this case. It is not possible to cut with it as shown in your screenshot. Knife tool can only cut under certain angles (0, 45 and 90) and it can't use perspective as a guide for the straight cut.


I think I figured it out. when I add the childof constraint I was picking the armature object. But when I used the picker took and pointed it at the armature of the robot, it showed a different object; the proxy. Once I selected that, things worked as I expected.


how will you model a cityscape at night?

I'd recommend modeling the fence, vegetation and other props in the foreground.

Don't forget to get the grungy texturing right.

And the perspective, which can be done easy with this PLUGIN, If you don't like it or have any technical problems there are many alternatives, there was a good one mentioned by Andrew Price, can't seem to remember what it's called now.

Then, render it with alpha background, by ticking Transparent under Film settings.

After, choose the right background and just plug it in Photoshop or Gimp.
Here's one of the top results in google image search: BACKGROUND

Then it's just post processing: Desaturation (Black and white) with high contrast. I'd further recommend going to blenderartists "work in progress" and let your peer artists guide you through the rest to get a more accurate result.


"Make Cyclic F Modifier" is making my animation cycle go out of sync

I figured it out! Turns out not all of my bone's last keyframes were actually at the last keyframe. For example, my right foot ik's last keyframe was at 125 when it should've been at 130.


Replace Every instances of an object by a 2.79duppligroup / 2.8CollectionInstance?doing this trough python?

here'sa code that do that .. the api may change in the future
i tested on 300 instances of suzannes its working great

theres just a missing part at the end of the code, i need to hide "newcoll", my original object of every instances from displaying in render, because the obj need to stay in X=0 Y=0 Z=0

import bpy

#Copy and past for later move to newcoll code
context = bpy.context
scene = context.scene
debut = context.object

def find_collection(context, item):
    collections = item.users_collection
    if len(collections) > 0:
        return collections[0]
    return context.scene.collection

def make_collection(collection_name, parent_collection):
    if collection_name in bpy.data.collections:
        return bpy.data.collections[collection_name]
    else:
        new_collection = bpy.data.collections.new(collection_name)
        parent_collection.children.link(new_collection)
        return new_collection

#naming preference of created layer system
pref = "%s Instancer " % debut.name
name = "%s" % (pref)

#nomme first select asset as basic, dupplicate it, name new newcoll, reset loc,rot,sca on newcoll
basic = bpy.context.object
bpy.ops.object.duplicate_move_linked(OBJECT_OT_duplicate={"linked":True, "mode":'TRANSLATION'})
newcoll = bpy.context.object
newcoll.location[0] = 0
newcoll.location[1] = 0
newcoll.location[2] = 0
newcoll.rotation_euler[0] = 0
newcoll.rotation_euler[1] = 0
newcoll.rotation_euler[2] = 0
newcoll.scale[0] = 1
newcoll.scale[1] = 1
newcoll.scale[2] = 1

#move newcoll dans collection appart
newcoll_collection = find_collection(bpy.context, newcoll)
new_collection = make_collection(name , newcoll_collection)
new_collection.objects.link(newcoll)
newcoll_collection.objects.unlink(newcoll)

#create a temporary instance, first create empty...
bpy.ops.object.empty_add(type='PLAIN_AXES', view_align=False, location= cursor)
bpy.context.object.name = "%s Instance " % debut.name
bpy.context.object.instance_type = 'COLLECTION'
bpy.context.object.instance_collection = bpy.data.collections[name]

instance = bpy.context.selected_objects[0]
instance.select_set(state=False)
newcoll.select_set(state=False)
debut.select_set(state=True)
bpy.context.view_layer.objects.active = debut

#selectionne tout instances sauf temporary instance, and newcoll
bpy.ops.object.select_linked(type='OBDATA')
newcoll.select_set(state=False)
instance.select_set(state=False)

#for every obj in selection, create an empty, copy collection of obj,create instance collection, then delete obj to enterely replace selection by empty
for obj in bpy.context.selected_objects :
    bpy.ops.object.empty_add(type='PLAIN_AXES', view_align=False, location= obj.location, rotation = obj.rotation_euler)
    bpy.context.object.name = "%s Instance " % newcoll.name
    empty = bpy.context.view_layer.objects.active
    empty.select_set(state=False)
    obj.select_set(state=True)
    bpy.context.view_layer.objects.active = obj
    empty.select_set(state=True)
    bpy.ops.object.make_links_data(type='GROUPS')
    empty.scale = obj.scale
    empty.instance_type = 'COLLECTION'
    empty.instance_collection = instance.instance_collection
    bpy.context.object.show_instancer_for_viewport = False

    bpy.data.objects.remove(obj, do_unlink=True)

#Delete temporary instances
bpy.data.objects.remove(instance, do_unlink=True)


The reason why they don't show up is that the UV unwrap is not done properly.

If you select the eyes in Edit Mode, you can see that the vertices are all in the bottom right corner, where the texture is transparent (so there is no color data). To change that, just position the vertices on the eyes in the texture and you are all set!

This is what you have right now (the wrong way):

And this is the right way:


Please excuse my ignorance on Dupil Objects function. However, you could possibly create a bolt mesh and use the array modifier to get equal distance across the body, both vertically and also across the circumference with the same modifier set to an 'empty'. that's how I usually create bolts


Having a hole in an NGon is not a good idea. faces have to be filled. An NGon is made of invisible triangles but the link between vertices has to exist! Leaving a few edges makes is possible without crossing the hole.

Your face is smooth (flat would be more exact), unless you want to subdivide it, what you'd better not do with an NGon. Having more edges is not a problem, it's a solution! it won't cause any problem printing it. (it still needs thickness)

NGons are just supposed to make things easier and clearer, some sort of shortcuts, but knowing what is topology and why you sometimes need more is crucial for doing things that looks good.


How to harden edges using subsurface modifier on corners (Mandalorian helmet)

This topology gives a good result, it just needs a bit of adjustments at the end (like flatten on custom axis) to avoid pinching. I didn't try to fix the rest of the topology (but here is an answer that might help).


How would I curve this cushion around this chair's outline?

This is a very general, sketched approach, but maybe enough to get you unstuck.
The basic structure of the back cushion can be created by sweeping a curve profile around a curve path.

Select an appropriate edge loop of your chair, duplicate it, separate it to a new object,and convert it into a Curve. That's your path.
Make a profile curve to be swept round it, bearing in mind that its own Z-axis will be the one following the path,and its origin will lie on it.
Assign the profile curve as a Bevel object for the path. While it's still a swept curve, you can still edit the profile. The illustration shows the Data tab > Geometry panel for the path.

Convert back to a Mesh. Possibly working under a Mirror modifier..

Grid Fill the open ends of the sweep. you need an even number of vertices in the perimeter for this.. you may have to add or delete an edge-loop to get that, and use Proportional editing to puff the front of the arm out a bit, when it's filled.
Select a set of faces which can be duplicated to form the back and sides  of your base cushion, duplicate, and separate off to a new object

Bridge Edge Loops the front edges,of the base-cushion rim, choosing the number of cuts to give you an even number of vertices in the perimeter, so you can ..
Again, grid fill the top. Select a central vertex, and under Proportional Editing, pull it up to plump up the base cushion a bit.

See what it looks like under a Subdivision Surface modifier.
The whole thing would then need tweaking, loops removed or added, edges made crisper or reshaped, maybe seams put in, etc. But so long as the basic topology is good, and you don't have too much geometry, it should be a pleasant job.

If you need to weld the base and the arms together, you can bridge some of those edge-loops together easily enough - they started off as duplicates, so their topologies will match.
Supplement: Creating the profile curve.. with Transform Pivot set to 3D Cursor ...

Create a Curve > Circle. It's a Bezier curve, by default.
CtrlX dissolve the leftmost control point
Select the two points on the left, and V convert their type to Vector
Select the bottom left point, and ShiftS snap the cursor to selected.

You can move the handles about to adjust the curve with the usual constraint options, (GX, GY, etc.) snap them to the grid, use the cursor as pivot point for scaling, and so on...

When you're done, in Object Mode, ShiftAltX > Origin to 3DCursor. The origin will lie on the sweep path.

In the profile's Object Properties tab > Viewport Display panel, switch on 'Axis' to check that the object's Z will point along the path. If not, rotate the whole curve in Edit mode by 90 in whatever, until it will.
You can assign it as the Bevel object to the path curve in the path's Data tab > Geometry panel,as shown in the top illustration.


In Blender2.79 ,Grease pencil keyframes are shown in the Dopesheet ->Grease pencil Panel.
Hotkeys should be same for other Blender versions as well.

IMPORTANT - Mouse Cursor  should be in the Dopesheet Editor for Blender to recognise the scope of the Hotkey.

For moving inbetween keyframes, following Hotkeys are available

1.First/Last Timeline Frame - Shift Ctrl UpArrow /Shift Ctrl DownArrow
2.Next Keyframe - UpArrow
3.Previous Keyframe - DownArrow
4.Play/Stop Animation - Alt A/Shift Alt A (Version Blender2.79 and below) &
   Play/Stop Animation - Spacebar (Version Blender2.8 and above)


How can I combine work that I've done in the "video editing" and "2D Animation" tabs in the same project on a render?

In order to add a scene into the VSE with a scene strip, you'll have to make a new scene for the VSE contents, as shown in this gif(from this post: https://blender.stackexchange.com/a/184931/37272):

To render from the VSE you'll need to check this box:


Expand specular map across multiple disconnected faces

Gradient across object:

We can map a gradient to generated texture coordinates on the joined object to smoothly display a gradient on the surface of our mesh.

You may also choose to make a material that has the gradient mapped to the height of the object. This method allows for each lego brick to be an idividual object as long as the have the same origin. The drawback of this method is that when transformed(scaled, translated, or rotated) the gradient will remain the same and not move with the objects transformation.

Post on Auto-Smooth:

I believe the problem you're encountering is not a material or UV issue but rather a modeling issue. Blender is shading the whole object as if it was smooth not retaining sharp edges. This is what is adding this specular highlight in the middle of your faces. By either using custom normals, marking sharps, using auto-smooth, an edge-split modifier, or a combination of these techniques, you can define and preserve what you want as sharp edges.

One of the easiest and most convenient ways to achieve this is auto-smooth which the Blender manual describes as

  Auto Smooth:
  Edges where an angle between the faces is smaller than specified in the Angle button will be smoothed, when shading of these parts of the mesh is set to smooth. This is an easier way to combine smooth and sharp edges.

The edge-split modifier works very similar but it actually 'rips' the edges from one another according to given angle.


While it is possible to make a round peg fit a square hole in Blender, that's generally more difficult than it's worth.

If you search "Cutting round holes Blender," there are some good resources out there for how to make a round element match up with a square element.

However, it's usually much more convenient to just model the greeble separately. Unless you have some specific reason that it has to be attached, I'd highly recommend this method. Keep in mind that you don't need to model a whole screw. You don't even have to model the whole head of the screw. You only need to model the part that will be seen, which is a tiny sliver of a disk with a slit in it.

If you're wanting to model any part of the hole or dent that the screw goes into on the weapon, it might be enough to just subdivide that area and "push" it in a little. If you want something more than that, a Boolean modifier would be a great way to cut out the part of the hole that you're interested in seeing.

I'll try to upload some images later today, if that helps.


Is there a way to change the colour of displaced areas only?

Using nodes might be a bit faster.
Simply use the same Displacement texture as a mask for MixRGB node and select the colors.
You can also use MixShader node to mix different shaders.


Link to your fixed blend file
There were a lot of minor problems here that I have fixed for you, such as turning on rotation in the Ik Parameters to allow for greater control and easier animating of the flytrap. I also noticed that due to the weight painting on the stalk, when fully extended there were weird creases created. Rebaking the weight paints fixed this. I created extra bones to control the "jaws" of the flytrap, disconnected them and the teeth from the rest of the mesh, then weight painted them onto the bones. I also noticed you somehow had over 200 bone vertex weight groups. Most of them having zero effect on anything, so I made sure to delete those too. I also remeshed and retopologized quite a bit of the mesh since it had a lot of holes and unnecessary geometry. I even added a small test animation as well, good luck with your project.


You have to separate it to work properly.

You could only rotate it in opposite directions in edit mode and be using shape keys to animate it, but it will mess the topology.

The easier way to do it is: delete the upper or down portion in edit mode and, in object mode, duplicate that object for further rotations or whatever.

I suggest you enter: https://blender.stackexchange.com/

Thare you will find a lot of people to help you better.


I don't think I understood your question. What is the reason use such deformed UV? What is your base mesh? And what is your final shape?
Until someone (who understood better) ... here is a tip.

I guess your mesh is always square, just stretched is some direction. So what about ...

Select all faces Unwrap > Reset.
With all selected and one face selected as Active (bright one) Unwrap > Follow Active Quad

Like that you can get even distribution again for your texture.

Also it is still square when view from top, so you can go to Top View (7) and Unwrap > From View


The issue is that your mask is not the correct size for your image, and you need to change the Mix Node settings from "Color" to "Mix".
You need to change the settings for your mask node to "Fixed" instead of "Scene Size."  Then, type in the x/y dimensions of your image.  I also changed the mix node to "Mix" instead of "Color."

If you don't know how to find the dimension of your image, open it on Windows Explorer, right-click on it, and press "Properties."  You can find the dimensions under the "Details" tab.
Hope that fixes your problem!  Let me know if you have any other issues.


Reducing internal faces generated by extensive curve extrusion?

There are a few things you can do:

1 Reduce curve resolution - Both in your curves and in your section defining objects

2 Eliminate unnecessary vertex - In straight line segments you don't need all that useless points adding additional geometry

3 Turn Handles to Vector - In straight segments change your handles type to Vector, so no additional subdivisions are created without need.

4 Clean up your sections Eliminate segments for parts that are never seen or end up inside the geometry

5 Use Bezier handles in curved parts wherever possible You can then take advantage of dynamically and easily adjustable resolution using the Resolution setting as shown in the first step, for sections curves too.

6 Use a mirror modifier Use a mirror modifier whenever possible. This will not necessarily reduce polygon count, but it will save you time, guarantee symmetry and save cleanup work (you only need to do half)

As for the self intersecting parts, it's probably more trouble than its worth. You may try using Booleans to intersect them, but you will have to destructively convert to mesh, and the resulting intersections (if they can even be made easily) will likely create more geometry and complexity then they solve.


weight painting copying to other side of mesh

You probably have weight paint X mirror on, someone else already had a problem similar to your own. Answer If you go down to the first answer it shows you how to turn x mirror mode off.

Also it might save you some time if you do a general search for the tool causing your problem, I just searched "weight painting symmetry tool" and the first result was the problem your having now.

Hope this helps!


this happens because either :

have edited the mash after unwrapping
have scaled the object after unwrapping

to resolve this :

apply scale :  Ctrl+A and select scale
unwrap the mesh again


How to show Point Density data in 3D viewport the same way a smoke simulation is visualised?

Smoke visualization in the viewport is based on a 3D texture, which gets mapped on a stack of coplanar planes facing the camera and using alpha-blending. You can access the raw values for density, color, etc. from the smoke domain, but i doubt this is of much use for visualization.

The point density texture works differently. In cycles it is implemented in the same way as smoke, using a 3D volumetric texture. However, it's internal data (you cannot access Cycles' own data anyway) is in the form of a kd-tree. This data structure is not accessible from the texture directly, but you could construct an equivalent tree through the bpy.mathutils.kdtree module, depending on the texture settings.


If I understand correctly, here is what you can do:

Create you gun, keep it aligned on the global Z axis, animate a 180° rotation on the global Z axis.
shiftE on the Dopesheet to create a Linear Extrapolation.
Create an empty on its bottom.
Parent the gun to the empty.
Tilt the empty the way you want (15° if the angle between the 2 guns is 30°).
Now your gun rotates on the empty angle.
Duplicate the gun + the empty to create you second gun, tilt them 30° in Front Ortho view (or 180° on the Z axis). You now have your two guns.


The invoke method of the operator is called which shows the menu.

You might set the operator's context using UILayout.operator_context to EXEC_DEFAULT to directly call the operators execute method with the argument given:

pie.operator_context = 'EXEC_DEFAULT'
pie.operator("transform.select_orientation", text="Local").orientation='LOCAL'

You can also use the generic wm.context_set_enum operator to change the transform orientation:

op_props = pie.operator("wm.context_set_enum")
op_props.data_path = "space_data.transform_orientation"
op_props.value = 'LOCAL'


Here is the Add-On: https://github.com/benkl/pixeler

  I will try to make it a plugin but for now this should help you. Open
  the source image in blender and replace the "test_file =" image
  variable (then run with open system console to see the progress). It
  will create a set of planes colored with the pixel values. You can
  then switch to edit mode and "Remove Doubles" to make it a consistent
  mesh (or seperate by loose/materials). It will slow down with bigger
  images (64*64 is quite fast - 1000*1000 takes a while). As a bonus
  pixels with alpha 0 will be skipped - so you can recreate icons eg (i
  tested single frame jpg and png). I am a designer and code is probably
  terrible - but it works  (feel free to improve it).

#pixeler v0.1 by BK for Blender 2.79 21/01/2018

import bpy

# Set Data Path
D = bpy.data

# Set File Name
test_file = 'blender.png'

# Set img
img = D.images[test_file]

# Get and set image width and height
w = img.size[0]
h = img.size[1]
tfac = img.pixels[:]

# Set basemesh
bpy.ops.mesh.primitive_plane_add(location=(-2.0, -2.0, 0.0))
basemesh = bpy.context.object
dmat = bpy.data.materials.new(name="origin")
basemesh.data.materials.append(dmat)

#Create Grid from Image
z = 0
y = 0
for index in range(0,h):
    x = 0
    for index in range(0,w):
        x = x+1

        # Get pixel position in flat array
        colar = (x+(y*w))*4

        # Set color values at current Pixel
        r = tfac[colar-4]
        g = tfac[colar-3]
        b = tfac[colar-2]

        # Alpha Check
        if tfac[colar-1]>0:

            # Add object at Pixel Location
            # bpy.ops.mesh.primitive_plane_add(location=(x*2, y*2, z))
            basemeshi = basemesh.copy()
            basemeshi.data = basemesh.data.copy()
            basemeshi.location.x = x*2
            basemeshi.location.y = y*2
            bpy.context.scene.objects.link(basemeshi)

            # Get material
            matname = "Mat" + str(r) + str(g) + str(b)
            mat = bpy.data.materials.get(matname)
            if mat is None:

                # create material
                mat = bpy.data.materials.new(name=matname)
                mat.use_nodes = True
                prinode = mat.node_tree.nodes.new(type = "ShaderNodeBsdfPrincipled")
                dif = mat.node_tree.nodes["Diffuse BSDF"]
                outshad = mat.node_tree.nodes["Material Output"]
                mat.node_tree.nodes.remove(dif)
                mat.node_tree.links.new(prinode.outputs[0], outshad.inputs[0])
                #rgb = mat.node_tree.nodes.new(type = "ShaderNodeRGB")

                # PBR Color
                prin = mat.node_tree.nodes["Principled BSDF"]
                prin.inputs[0].default_value = [r, g, b, 1]
                prin.inputs[7].default_value = 0.6

                # Set editor color from pixel value
                bpy.data.materials[matname].diffuse_color = (r, g, b)

            # assign to 1st material slot
            basemeshi.data.materials[0] = mat

            # Join newly creatd meshes
            basemeshi.select = True
            bpy.context.scene.objects.active = basemeshi
            basemesh.select = False

            # Print Pixel placement confirmation
            print("Placed object @ x " + str(x) + " y " + str(y))

    # Join line
    bpy.ops.object.join()

    # Incerement y last
    y = y+1
    #bpy.ops.object.select_all(action='DESELECT')

bpy.context.scene.update()
print("pixels to planes is done")


Parenting Objects to Animation Node Object Instances

The Object Instancer node dynamically add and remove objects on demand. So anything you do on the object is not persistent. The obvious solution here is create the the parent objects manually and do the parenting as you did. Then add those parents to a collection, get the collection's objects, get their transformation matrices, and offset them based on the target falloff just as you did.


How to do AddonPreferences using extensions_framework?

No (as of 2.68), the Python extensions_framework directory has no references to AddonPreferences.

You could contact Doug Hammond about this or check on adding support yourself.


Mesh with particles not rendering after append from 2.79 to 2.80

OK, so after a couple of hours trying to figure this out and just after posting this question I have found the answer. Emitter has to be checked in particles Render settings.


Can Blender do mathematical reservoir simulation for petroleum engineer?

No. Blender is not designed to run scientific simulations. You will need to find another tool for the job. There are no tools designed for that in Blender and if you wanted to script them in Python using Blender's Python API you should also consider that Blender mostly stores data as 32 bit floats that might not be ideal for any scientific applications where precise calculations are important.


Material appears different after being assigned to the same object

Try go into Edit Mode when the floor object is selected. Select all the faces by pressing A . Then unwrap it again by selecting Cube Projection from the UV menu.


What are the best ways of designing sword topology?

https://youtu.be/i7LlZQyryek
I ended up using a mirror merge and it seems to turn out okay. a point at the end can be done through merging a few faces together. Triangles are generally avoided because subsurface doesn't work as well on them. My exploration used a few at the tip, but they were not a problem for me.
You probably need to have higher poly count for your mesh to describe it.


The answer to my question is simple. After some soulsearching in blender 2.8 I found the checkbox in a new place. The 'Weight Table' is also there like in 2.7. So all is well and good in blenderland. Here a gif for another adventurer to not have to search as I had to.


Why is my 2minute animation taking 5 days to render

Why?
It is normal that rendering takes a long time. You should expect that. This is the reason why animations are usually rendered on render farms using many powerful computers. If you are rendering 2 minutes in 4K at 30 frames per second for example, you have 2 x 60 x 30 = 3600 pictures to render and each of them has 3840 x 2160 = 8 294 400 pixels so that's a lot of pixels to compute. So say you are rendering with Cycles and use 2000 samples. Every one of those 8 294 400 pixels is checked 2000 times for every one of those 3600 pictures so that's really a lot of computation and will take a very long time on a single computer. It is often not practical to render on a single computer because it would take many years and there is no other option but to use tens or even hundreds of computers to render.
What can you do
Obviously you may not afford to build a render farm yourself or to buy commercial render farm services since that is expensive, but you can look into SheepIt for your hobby or even freelance projects. It is free in terms of money, but you still have to render projects for other people to collect points. This way you can render for the farm when you are not using your PC(at night for example) while you work on your animation and when the time comes, you can use the farm to render your project quickly. It has disadvantages compared to commercial solutions obviously like for example it is not that hard for other people to access your files, because they need to be sent for rendering and the farm is not that stable, it may experience technical issues more often than other solutions and there is a file size limit, it doesn't support some features like render passes and so on, but it can make certain things possible that wouln't be without it, so it's great.


The mesh object has quite a bit of double vertices shown in the example below. They will prevent modifier from working properly as if extruded they will create even more intersections leading to z-fighting even without solidifying.

Selecting all and removing doubles in Edit mode solves that as they are intersecting with each other. Then extrusion should be done to have faces Solidify to work with. After extruding by default Blender orients half of normals to one side and half - to another.

Blue lines show normals orientation. According to that modifier will orient half of faces to one side and half to another one leading to intersections. Select all and recalculate normals in Edit mode.

Lastly object scale is uneven. It doesn't prevent Solidify from working but it does give unexpected result, on the image below left is before scale applied, right one is after. To apply scale in Object mode press Ctrl+A.


blender 2.8 renders png with transparency inverted

OK.  So after poking at this for a while, I come up with the node ordering going into the mix shader affects the transparency.  I had built an alpha channel png, and I was able to get it to work, and when I inverted the mix shader inputs the result was identical to my original post.

So I went back to my original file, swapped the mix shader inputs, and the scene now works as I expect!

Thx


How do you execture the subdivide function on the multiresolution modifier in python?

as you see in API

  bpy.ops.object.multires_subdivide(modifier="") Add a new level of
  subdivision

you can test this:

bpy.ops.object.modifier_add(type='MULTIRES')
bpy.context.object.modifiers["Multires"].name = "A"
bpy.context.object.modifiers["A"].subdivision_type = 'CATMULL_CLARK'
bpy.ops.object.multires_subdivide(modifier="A")


Is there a way to turn an obj into a partial shrink wrap for another obj to deform into?

Shrinkwrap contains a vertex group field. Just assign the needed vertices in a group, and specify this group in the shrinkwrap modifier.


With mouse cursor over your Timeline press Home on your keyboard or go to View > Frame All:
.
Same trick applies for Dope Sheet (and pretty much any other view in Blender).


If the purpose of doing a model is learning, start from scratch. Plan your topology carefully. Add detail where is needed and keep it simple where is supposed to be simple. Try as much as possible to keep your topology as
 quads. You will spend less time in a carefully planned model than trying to fix something that is poorly put together.

Adding to what @DuarteFarrajotaRamos said, topology should not be an afterthought or some form of wrapper, but the model itself.


Connecting the center of a polyhedron to its corners

Finally figured out how to do this! Not sure if it is the most efficient way but it worked for me. Here are the steps.
(a) Go to Edit>Preferences, and click on the Add-ons tab. Enable the Add Mesh: Extra Objects feature.
(b) Delete the default cube if you have it and add Mesh>Math function>Regular Solid. A tetrahedron should come up automatically. If not go to the Source pull down menu of the dialog box that came up when you first added the Regular Solid and change to Tetrahedron.
(c) The tetrahedron will be centered around the 3D cursor. Be sure not to move that cursor. Now add Mesh>Single Vert>Add Single Vert to add an a single isolated vertex at the 3D cursor.
(d) When you add the single vertex you will automatically be put in the Edit mode. So Tab back to the Object mode.
(e) Select the tetrahedron and the single vertex (in either order) and hit Ctrl J to join the two objects.
(f) Tab into edit mode, and select the wire frame view. Select the central vertex and one of the tetrahedron's vertices (in either order) and hit F. This should create an edge between the two vertices. Repeat the process three more times to connect the center of the tetrahedron to the other three corners.
(g) Select and delete the original edges of the tetrahedron. This should now leave four edges (lines) connecting the center of 3D cursor to the four vertices of the tetrahedron.
(h) Tab into Object mode, select the object and, from the Object pull down menu select Convert to > Curve from Mesh/Text.
(i) Click on the Object data properties tab and, under Geometry, adjust the bevel depth to the desired thickness.
(j) This gives the basic structure. Pull down the object menu and Convert to> Mesh from Curve/Meta/Surf/Text/. If you prefer you could add a Subdivision Surface modifier but in that case be sure to change from Catmull-Clark (default option) to Simple in order to retain the shape.


Use Duplicate Strips. You'll find it in the Strip menu:

If you can't select a strip, then it may be too small and you can use the horizontal scrollbar handles to zoom in. After that, you just select it and drag it to where you want it.

To make sure you only render the part with a strip, use this function to limit the render range:


Sound can be added in the video sequence editor. Go to the video sequence editor, press Shift + A, click sound, and select the sound file you want to add.
Remember to change the audio codec, found under the Encoding scroll in the Render tab, from "none" to one of the other options.


I came up with two scripts, one which "brutally" instantiates verts and edges, then converts it to a curve in order to add thickness.

import bpy

mesh = bpy.data.meshes.new('Mesh_Grid')
obj = bpy.data.objects.new('Obj_Grid', mesh)

rows, columns, levels = 10, 10, 10
wire_thickness = 0.02

verts, edges = [], []

i = 0
for l in range(levels):
    for r in range(rows):
        for c in range(columns):
            verts.append((c, r, l))
            if c < columns - 1:
                edges.append((i, i + 1))
            if r < rows - 1:
                edges.append((i, i + columns))
            if l < levels - 1:
                edges.append((i, i + (rows * columns)))
            i += 1

mesh.from_pydata(verts, edges , [])

bpy.context.scene.collection.objects.link(obj)

obj.select_set(True)
bpy.context.view_layer.objects.active = obj

bpy.ops.object.convert(target='CURVE')

obj.data.bevel_depth = wire_thickness

Result :

And the other one which is the same as @Vega_KH's answer, but as a script. I just added a weld modifier in order to avoid duplicate geometry. (Need Blender 2.82+) :

import bpy

dimensions = (10,10,10)
wf_thickness = 0.1

bpy.ops.mesh.primitive_cube_add(enter_editmode=False, location=(0, 0, 0))
cube = bpy.context.selected_objects[0]

for i in range(3):
    mod = cube.modifiers.new('Array_' + str(i), 'ARRAY')
    mod.relative_offset_displace[0] = 0
    mod.relative_offset_displace[i] = 1
    mod.count = dimensions[i]

cube.modifiers.new('WD', 'WELD')
wf = cube.modifiers.new('WF', 'WIREFRAME')
wf.thickness = wf_thickness

Result :


unexpected result from boolean difference

This is one of the most common mistakes new users of Boolean modifiers make, so I'll give a detailed example.
Add a cylinder to a scene with the default cube.  Scale the cylinder by .5 and move it +1 on the Z axis.  The result looks like this:

Select the cube. Add a Boolean modifier and set the modifier object to the cylinder.

Nothing seems to have changed in the scene:

The Boolean modifier has worked, as you can see from the wire frame below, but the cylinder is still in the scene, so in solid mode it doesn't look like it worked:

By convention, when a object is used like the cylinder, it's referred to as a cutter.  The workflow for cutters has a few more steps usually:

Parent the cutter to the object it cuts.  This allows you to move the cutter around, but if you move the object the cutter moves with it.

Remove the cutter from the render.  If you leave the cutter in the render, then it will show up.  One way to remove it from the render is to put it into a separate collection and disable that collection.

Change the way the cutter looks in the viewport.  You can go the the cutter's object properties; open the Viewport Display panel and change Display As to Wire Frame


When texture painting, black line is pixelated when viewed up close

I would suggest giving the area where you need detail more real estate on the UV map. If that isn't enough, increase the size of the image. You can always bake down to a smaller image and a different UV map later.


If you don't want to go to the expense of simulation, a rig can get you quite close:

Prepare a copy of the plate's top surface, its rim (E,right-click, S) extended, as a Shrinkwrap target.

Make a triangular face from some vertices of your toast,ShiftD duplicated, and P separated to a new object. This will be the root object, and control the gross orientation and location of the toast.

Additionally, create a flat Lattice, (1 segment in Z) which will bend the toast.

With the toast and triangle selected, triangle active and in Edit Mode with all verts selected, CtrlP parent the toast to the triangle's vertices
in Object Mode, CtrlP parent the Lattice to the triangle.
Assign Shrinkwrap modifiers projected in Z, to both the triangle and the lattice, aimed at your newly created Srinkwrap target.
Assign a Lattice modifier to the toast, targeted on  the Lattice.

Now when you move the triangle, the toast will more-or-less conform to the plate. You can tune the resolution of the Lattice and influence of the Lattice modifier to make the toast more or less soggy, and the offset in the Shrinkwrap modifiers to control the proximity of the toast to the plate.

EDIT: A duff version of the blend replaced: 1400 GMT 19 March.


What is the max length of names in Blender?

A test suggests that the longest name that an object can have is sixty one characters. I determined this by using the default cube, and giving it the name

  howlongof_anamecant_hiscubeob_jecthavea_nywayaques_tionerasks_a

A material name has the same parameters, leading me to suspect that the same name length is the default for any internal name.

Although you did not ask it, I believe that the total path name of a Blender file is OS dependent, and in Window 7 Professonal 64 bit, is about 256 characters.


Blender 2.8 I can't see vertices, edges or faces in edit mode

The problem is that OVERLAYS is turned off, this feature is added in Blender 2.8, press the icon that looks like two intersecting circles next to Overlays.

In your image, it appears at the bottom of the 3D Viewport, by default it's at the top.


If you only want to scale the texture, you can use a MixRGB node set to Multiply instead of the Mapping node, as in this example:


Number of verts doubles after using symmetrize tool in Sculpt Mode

Never mind, just used "remove doubles" and its back to 250.000, and it no longer doubles verts


rendering 3D video/image for google cardboard

Found it!

Once you have set up your animation or single frame:

In your Scene tab enable Views and select Stero 3D

Select the Camera on the scene and go to the Camera tab. Sort out the interocular disctance this should be 0.06 = 6cm, the distance between your eyes. Set Lens to Panoramic

Go to the Render tab, change the Dimensions -> Resolution to be the resolution for a single eye (this will depend on the android phone you are using)

Again, in the Render tab scroll down to the Output and change the Views Format to be Stereo 3D. Set the Stereo Mode to be Side-by-Side.

Press Render or Animation depending on whether you are creating a single image or a video, and you should be done!

Check an example output here: https://youtu.be/fEFmGVymbUg (Which annoyingly youtube currently seems to be converting to different 3D formats!)

To render for VR, see this: http://b3d101.org/en/vr/


How can I project text around a sphere using shrinkwrap modifier?

Check this Blend file:

For the Shwinkwrap modifier to generate a smooth result in a situation like this, more geometry is needed. You need to subdivide the Text Object first to provide the necessary detail. Luckily, this can be done dynamically using modifiers:

Setup a Subsurf Modifier on the Text object. Set its mode to Simple instead of Catmull-Clark to avoid distorting your Text object. Subdivide as many times as needed, but try to stay on the lower end (I chose 2 for Display and render):

Now, to use Projected as a mode, you'll need to setup the Axis correctly as well as which direction Blender is supposed to look for the other object to wrap on: I chose my sphere as a Target, then set the Axis using the check boxes (note that for the modifier the LOCAL Axis of the object counts. In the first screenshot you can see that the blue arrow correlates with the direction I want to go in, so that's the Z direction). The direction field now lets you choose the direction in which Blender looks for the Sphere. Again, look at the first screenshot: the Blue Arrow points AWAY from the sphere. That means, to make the Text wrap towards it, the Direction needs to be set to 'negative'.


Changing location of a walk cycle keyframe

So I guess you must have keyframed the armature's location itself. What you need to do is open the Graph Editor, unfold the Object Transforms tracks, select the track that you need to change (probably X or Y Location), press ShiftH to hide all the other tracks (AltH to bring them back later) and move the curve on the Graph Editor X or Y axis. It will only work if the duplicated action is a simple copy and not a linked duplication, in that case you need to click on New Action in the Dope Sheet.


Editing object created from bezier curve

Use the knife tool with K and press C to constrain your cut at 45 degree (or straight or vertically) If you need to cut both side of your mesh hit Z. when you are done press enter.


well i just created a new rig for the head and connected it to the alredy generated rigify rig.


How to make a fold while following a circle edge?

If I understood the question. I have found 2 answers for it.

Answer 1

Add a circle and go in edit mode and press F to fill
faces.
Add a plane and go in edit mode and press W and subdivide once.
Delete 5 vertices and just have a square shape below.
Select the square and circle and press Ctrl+J (Join).
Go to edit mode and select the corner of the plane and press Ctrl+Shift+B (Bevel) and with the mouse wheel scroll to get segments.

Cleanup Geometry

Go to edit mode and select the verts of the curve and remove doubles and then Press F to fill faces.

Answer 2

Add a plane select to edges and Mean crease in the Properties panel (N) in edit mode.
Add Subsurf modifier view 6.
Add a cloth simulation with default value.

Smooth shading
Add a base cup shape and in physics panel add collision to it.
Play and stop the animation at a point where your satisfied.


Is it possible to continue baking Rigid Body Physics

What you should be able to do is 'Free Bake' but leave the baked frames in the memory cache (the frames in the timeline should switch to being marked in lighter orange instead of dark orange). Then play your animation (without changing anything about the objects which were previously baked) and Blender should play the 'cached' frames and then continue the animation from the point where the baked frames stopped. Once Blender has completed the simulation up to the new end point then click Current Cache to Bake to convert the cached frames back to a baked animation - without re-simulating.

Note, however, that you have to be very careful not to change anything about the animated objects - otherwise Blender will discard the cache and start afresh when you 'play' the animation, losing your bake. You should ensure that everything about your project (including the baked cache files) is backed up before you try this so as to not risk losing your previous bake if something goes wrong.


You can use a lot of translucent particles

(But you may prefer a more fuzzy (i.e. volumetric) solution)

The result:

This is my setup:

a planet (diffuse white sphere),
an atmosphere (bigger sphere with a "Volume Scatter" material),
a distant area lamp representing the Sun,
a monkey shaped probe
a randomly subdivided plane with a white "Translucent Shader" as material

The planet has a Particle System emitting 1000 particles, with a "Child" duplication set to 200 (but higher numbers will give you fuzzier plumes, and longer renders).

The particles are emitted slowly along the Normal (0.100) and have a fair amount of Brownian force (0.360). They are not affected by the scene gravity  (Gravity Field weight = 0). They are rendered as "Object" using the subdivided plane as the Duplication object.

You can play a lot with the settings to make it look right. These are my settings:

This can also be used in animation: the plumes are dynamic -- even if maybe too fast with my settings.

I attach my blend file if you want to have a look at how it works.


How do I make two objects collide? (Not referring to rigid body or collision physics)

The Follow Path constraint comes close to what you want to achieve.

Advanced Follow Path Setup

We need a path (curve object) to follow. If you have a mesh, you need to convert it. Go into edit mode (Tab) and select an edge loop with Alt+Click, which you want the object to follow.
Duplicate it the edges. Shift+D
Separate the duplicated edges. P > Selection
Go into object mode and select the separated edge loop.
Convert it to a curve. Alt+C This will generate a Poly curve.
[Optional] is probably a better approximation of the needed path if the curve is a bezier with automatic handles. Go into edit mode of the curve. From the Tools menu, click on Set Spline Type > BezierSelect all vertices (A) and set their Handles to Auto in the Tools menu.
In case the origin of our object is in the center and has to be offset from the ground, we will use a simple rig of empties. Create two empties and parent one (circle) to the other (cube). Ctrl+P
Select the parent empty (cube) and add a Follow Path ** constraint.Set the **Target property to the created curve. Check Fixed Position. The empty snaps to the start of the curve. By changing the Offset property, we can slide the empty along the path. Animate the Offset property, from 0 to 1 over the duration of the scene.
Position the mesh correctly above the ground at the starting position. Snap the cursor to the mesh's center. Then snap the child empty to the cursor. Add a Copy Location constraint from the child empty (circle) to the mesh.The rotation of the mesh can be easily animated.


Cycles Viewport Render not updating while Texture Painting

My answer to this question explains most of the issue.

The key points to make texture painting work while Cycles is set as the render engine are -

The 3DView shading mode should be set to Texture
The object needs to have a UV Map
The object needs to have a material that has an image node set to the desired image

When the material has multiple image nodes the selected image node defines the active image being drawn to. The image node does not need to be connected to any other nodes.

The UV Map selected in the UV Map list is the one being used to display the image selected. Any UV Maps linked into the image node are ignored with the 3DView set to Texture shading.

While you can switch the render engine to Blender Render while you do texture painting, the only real difference is that Cycles chooses the image from an image node were Blender Render links the image in the UV Image Editor to a UV Map while in edit mode.


So it looks like disabling the axis lock got rid of the odd bumps happening on the smooth brush. I can't yet tell you why but I disabled it and the behavior went away.


Blender does not set the alpha channel correctly

This issue stems from the way Blender currently performs color management. HDR color management is a complicated subject, so I recommend some related reading first if you are unfamiliar:

Color Management in the Blender documentation
How to get accurate colors with Filmic Blender
Render with a wider dynamic range in cycles to produce photorealistic looking images
Blender 2.8 image texture node and color space

The problems of using color as alpha
The Blender compositor always works on scene-referred values in the Linear color space; this cannot be changed. This means that the RGB values of the rendered image are not in the range [0.0, 1.0], but rather [0.0, +∞), and they have not yet been mapped into the display color space (usually sRGB).
After compositing has finished, Blender applies the selected View Transform, which maps the scene-referred values into the display color space. The exact way this is done is outside the scope of this answer, but you can read the above links for more details.
Alpha makes the already-complicated color management story significantly more complicated. Importantly, the alpha channel is not affected by the view transform; alpha is always linear information stored in the [0.0, 1.0] range. Blender uses associated alpha (aka “premultiplied” alpha), so the meaning of these values is simply the amount that the background is occluded when using Alpha Over compositing.
This is a problem for your compositing setup, since you are trying to use color data directly as an alpha channel:

The color-to-scalar transformation is relatively well-defined—Blender just takes the luminance—but interpreting the result as alpha is more fraught. You are using a scene-referred value in the range [0.0, +∞) where a value in the range [0.0, 1.0] is expected. This has two problems:

Most obviously, the values above 1.0 are simply clipped.

More subtly, even inputs that are in the [0.0, 1.0] range will not be mapped to display-referred values.

The second point is tricky to understand, but its implications are severe. Scene-referred values don’t have any useful absolute interpretation, only a relative one, which means the set of values that fall into the [0.0, 1.0] range is largely arbitrary. In other words, the value you’ve ended up with is largely meaningless, and it only looks close to correct by sheer coincidence.
Imagining a better solution
The previous section outlines why using scene-referred color values as alpha is fundamentally the wrong approach, but what could a better one look like? The answer to that question is different depending on what you’re actually trying to do. Let’s address each of those in turn.
Rendering an image for further compositing
If the goal here is to generate an output image that is subsequently composited on top of another scene, converting to straight alpha at this point isn’t what you want, anyway. Instead, you should save your render in the OpenEXR format, which will save the raw scene-referred values using associated alpha.
This allows you to do your compositing in the scene-referred Linear color space, then convert to a display-referred format only as a final step. This sidesteps all of the problems that make color management of images with alpha channels so awkward to deal with, and it ensures you’ll get the highest-quality result.
Rendering an image for display
If you want your semi-transparent output to be the final render result, intended for direct display, things are more complicated. Converting from associated to straight alpha is not, in general, a lossless process, and doing it properly depends on what background the image will eventually be displayed against.
However, in this particular case, one reasonable interpretation would be to simply assume the image will be displayed upon a solid black background and calculate the appropriate straight alpha values from there. To do that, you would need to do calculations in the display-referred color space, since you care about which absolute color values are eventually produced.
Unfortunately, Blender currently does not currently provide any mechanism for converting from scene- to display-referred data in the compositor. Providing this functionality in a proper way would likely be tricky (since applying a view transform is a whole-image operation that depends on the overall light intensity of the image), but it isn’t in principle impossible. That said, that doesn’t help you much, since there’s no way to do it right now.
If you really want a straight alpha PNG that best captures the visual characteristics of your render, your best bet is probably to render to OpenEXR and use an external tool to “digitally expose” the image in a way that handles alpha more satisfactorily. I unfortunately do not know of such a tool to recommend, but maybe someone else can chime in if they do.
Sorry.


Bmesh script

Result of running script on grid above, each separated object is represented with a different colour  Will notice some quad faces are "bent".  Suggest Triangulating first
Find the average normal.  Remember for objects like the cube this could be a zero vector.  Could also consider using an arbitrary vector eg z axis rather than average normal
Since want to separate into surfaces have used face normals.
Then run thru the script and look at the tangent (grade) of the face normal to the average face normal.
Test script.  Splits the current edit mesh into chunks with 0.05 grade intervals from the average normal.
When the script has run will still be in edit mode with a faceless mesh, all having been moved to separate objects.
import bpy
import bmesh
from mathutils import Vector
from math import tan
grade = 0.05

context = bpy.context
ob = context.object
me = ob.data
bm = bmesh.from_edit_mesh(me)

# use the average of all face normals
norm = sum((f.normal for f in bm.faces), Vector()) / len(bm.faces)

# use the local Z axis
#norm = (0, 0, 1)

# use the global z axis
#norm = ob.matrix_world.inverted() @ Vector((0, 0, 1))

# use the active element (will error if edge or none)
#norm = bm.select_history.active.normal

while bm.faces:
    for f in bm.faces:
        f.select = tan(f.normal.angle(norm)) < grade
    if any(f.select for f in bm.faces):
        bpy.ops.mesh.separate()
    grade += grade

# pop out of edit mode remove original


Damped Track constraint issues. Bone twists at a certain point

Use IK constraint with chain lenght of 1, instead of damped track constraint. When selecting the Ikeyed bone, in its IK properties panel lock the axes in which you don't want any rotation.


Constraints- My circle is not following the selected path in my follow path constraint

If you change your Forward axis (to 'X') it should work.  Have your Forward and Up axis be perpendicular, never the same.   X/Z, Z/X, etc...
Example:


Cycles
You can use parameter Random per Island
"A random value for each connected component (island) of the mesh. It is useful to add variations to meshes composed of separated units like tree leaves, wood planks, or curves of multiple splines."

BTW For "rainbow" ColorRamp you can set just a two colors (Red-Blue) with HSL > Clockwise.
Or for your full ring - Red-Cyan-Red. https://imgur.com/XUFqIju


How to run Blender through RDP on Windows Server 2008 R2 - opengl error

To run Blender on a machine without OpenGl support, you would need to:

Download the opengl32.dll or opengl64.dll from this
link: http://download.blender.org/ftp/sergey/softwaregl/
Copy and paste the dll next to your blender.exe (the directory
would typically be: C:\Program Files\Blender Foundation\Blender)
Run Blender

This enables Blender to open with software opengl legacy mode.


Cycles lamps have no effect and light disappears if ambient occlusion is turned off

To get some light through glass you need to modify the default glass shader as it will not let direct light go through (see this answer)

Change the glass material to something like this:

Then the sunlight will go through the glass:

Then you have at least one light that is outside of the object. Move it so that the light is not obstructed by the object.


The default settings are "capping" the framerate to 60, but it seems you can "unlock" the cap by deselecting the "use frame rate" checkbox under render > system properties tab:


Gravity simulation doesn't work (Cloth Simulation)

I'm a little new to Blender, so I don't know if this will help, but you can also try checking the Gravity in the Scene Properties tab.  According to the Blender documentation, the default setting should be -9.810 to simulate Earth's gravity.
Good Luck!
Source:
https://docs.blender.org/manual/en/latest/physics/forces/gravity.html


The problem is solved, set the value "simplify" from 1 to 0.1 in FBX export settings.


How do I rotate an object along it's own axis (windmill)

Actually, as your wheel is not aligned with the global axis anymore, Blender will mess up with the rotation interpolation (Quaternion mode will work better than Euler but it's not perfect either). Also, the animation won’t take your 3D View Pivot Center setting into account, it will use the object's origin.
The easiest way to do it is to keep your wheel aligned with the global axis, parent it to an empty, tilt the empty the way you want, and animate the wheel. The empty parent will somehow be the new world landmark of your object and this time it will work fine.
About the rotation value: you should choose 180°, then, in the Graph Editor, shift E Linear Extrapolation so that it understands that it needs to go indefinitely with a constant speed.


It is a comparison issue.
col.data[l_ix].color == color

You can:
from mathutils import Vector

color = Vector((0, 1, 0, 0))

Then compare with:
color == Vector(col.data[l_ix].color)

Alternatively, to avoid rounding issues, define an epsilon and compare using:
(color - Vector(col.data[l_ix].color)).length_squared < some_epsilon


How can to do the inverse of explode modifier in Blender

You may do it using the Video Sequence Editor.

Go to the Video Sequence Editor window (Sequencer) and add the scene animation strip to it (Shift+A-->Scene-->Scene). Check the Backwards checkbox in the Filter panel of the properties shelf (press N being in the Video Sequence Editor window).

Press the Image Preview button to see the preview of your animation. Render animation with F12.


Changing Size from small to big in array or duplication

Yes you can do this using modifiers. You need an array and curve modifier.

Create a curve
Add a sphere
Add an empty (plain axis)
Select Sphere and add an array modifier

turn off Relative Offset
enable Object Offset and chose the empty

move the empty along a axis (possibly the positive x-axis)
scale the empty down a bit, you should see the spheres get smaller towards the end

Select the sphere and add a curve modifier to it. Choose your curve
Depending on the orientation of the curve and the translation of the empty the array may look wrong. In this case move the empty along the other axis. You can also apply the transforms of the sphere and the curve using Ctrl A


Probable cause of your problem is your display ICC color profile or using wide-gamut monitor. You can check what profile you are using in your OS settings (I won't go into specifics because it's system dependant).
Blender does not respect your monitor profile, nor profiles embedded in image files. When you prepare image in Blender viewport you look at it in your display color space but Blender saves it with regular sRGB. It also happens when you use wide-gamut monitor which can display more colors than sRGB color space has. For example (not factual) 0.8 srgb red might look like 1.0 srgb red on such screen, so when you open it in a program that can actually handle profiles it will look like 0.8 srgb and not Blender's over-saturated red.
If you use wide-gamut monitor with default sRGB profile you may want to at least find the profile delivered by its manufacturer, though propper color calibration is the best.
When you know the path to your ICC/ICM profile, you can embed it into your image so other programs will know that your 0.8 red should be displayed as 1.0 red. You can also convert it to the sRGB space, though you'll loose colors displayable with wide-gamut screen.
You can use other graphical packages to manage color profiles (like Photoshop, probably Krita and Gimp, though I didn't have much luck...), ImageMagick or a Python script with PIL (PNG and JPEG only).
In Python it is fairly easy.
To attach profile:
from PIL import Image, ImageCms
img = Image.open(image_filepath)
display_profile = ImageCms.getOpenProfile(display_profile_path)
img.save(filepath, icc_profile=display_profile.tobytes())

To convert:
img = Image.open(image_filepath)
display_profile = ImageCms.getOpenProfile(display_profile_path)
srgb_profile = ImageCms.getOpenProfile(rgb_profile_path)
ImageCms.profileToProfile(img, display_profile, srgb_profile, inPlace=True)
img.save(filepath, icc_profile=display_profile.tobytes())

If you want Blender to handle it all for convenience sake, use Styriam ICC Image Compressor addon. It can embed/convert profiles in stills and animation frames.


What can the Alpha sliders in cycles be used for?

I think it's safe to say that it does nothing at all. It's only present there because all shaders use the standard RGBA selector even though an RGB selector would be sufficient.

In some other areas where only RGB-values make sense, however, RGB-selectors are in use, so it's not great user communication to not use them there I guess.


Go to File->User Preferences...->Editing
and check "Allow Negative Frames"


Normals messed up after applying transform

The problem can also be caused by manifold meshes that have other issues, such as non-uniform normals. I ran into this issue just yesterday. I extruded a single plane into a prism, without realizing that the plane had preexisting issues with its normals.

As an aside: faces don't actually have normals. Each vert has a normal and a face's normal is calculated from its associated verts. One of my verts must have been upside-down, making the plane's normal... weird. As odd as that is to consider, it can happen.

The tricky part was that the resulting prism looked perfectly fine. The problem manifested in OTHER parts of the same object (as invisible faces), but that were not connected to the prism, even though there was nothing actually wrong with the part of the mesh where the issues manifested. It took me FOREVER to figure out, because I thought it was a non-manifold edge somewhere. Once I recalculated the normals on that prism, (because I'd tried EVERYTHING else) everything was fine.

All of which is to say, the problem may actually be in a part of your mesh that looks totally fine.


The Material

A material is set up for the object, coloring an emission shader with an image in the object's UV space, through a Mapping node:

Unwrapping

If you're following a method something like this one, then you're just unwrapping flat surfaces, before they are modified:

There is a seam down every longitudinal edge, so it's just U unwrap, followed by rotating/scaling in the UV Editor.
Although the UV space has been set up to allow different text on every face, in this case the UV islands have been snapped over one another, so they all refer to the same region of the image.

Modifiers

After Twist and Bend modifiers are assigned as shown in the linked answer ..

Animation

Now the Location: X field of the Mapping node in the material can be keyframed between 0 and 1 to loop the translation of the UV texture space (trim the last  frame, where X = 1 = 0, to get a seamless loop):

Here, the loop is shown without the animated twist: only the text is being animated across its surface.

Here, with the twist as well..


How to divide a circle into a square grid?

This is how I do it:

Create a circle and put it a little over the grid plane;
In Object mode select the circle first, then add the plane to the selection, by pressing ⇧ Shift RMB (the order is important);
Go to top view (Numpad 7) in Orthographic View (toggle with Numpad 5);
Go in Edit mode with ↹ Tab;
Be sure to have all the meshes selected (hit A);
In the T panel (or just by searching with Space) find Knife project and click it.
Invert the selection with Ctrl+I
Delete the selected mesh parts with X.

Like LukeD said in another answer, this causes your mesh to have a mix of ngons, quads and tris, but that's what you asked for in your question. :-)


Purge unused data (e.g. particle system, or groups) by script

To permanently delete curve data blocks that have no users  without reloading the project file (which can be bit problematic at times), you can use this python code:

import bpy
from bpy import data as D

for block in D.curves:
    if block.users == 0:
        D.curves.remove(block)

It'll iterate through all data blocks of type "Curve" and delete them if they have no users.


cycles through everything while trying to select one thing

Yes, this is normal. This is the way Blender handles selectable objects that are coincident, or very close to each other. If it can't tell which one you want, it will cycle through each possible option until you stop on the one you want.

If you want to avoid this behavior, there are a few options.

You may be able to move some objects to other layers.
A little known tool is "Local View." Press numpad / in object mode to view only the selected object. Do what you want to it, and then press / again to see everything else again.
Use h to hide selected objects
Use shift to hide UNselected objects
Use the Outliner to turn off selectability for certain objects


Can screen layouts or workspaces be locked?

Blender uses different layout screens or workspaces, all of them customizable.
While there are a number of built-in presets, those might not fit your workflow. So create different ones depending on your needs and get into the habit of using keyboard shortcuts to switch between them instead of resizing/splitting/changing modes and making a mess of the interface.
For 2.79 the shortcuts are:
CtrlLeft and CtrlRight Arrow
In 2.8 use:
CtrlPage Up and CtrlPage Down
Or use the menu:

To make your custom layout screens permanent:
Start blender.
On blender 2.79
Make new layout screens by pressing on the + sign:

Name them as something that make sense to you and re-arrange the windows to suit your needs.

Now save all of this as your startup file using CtrlU.
For 2.8
Create a new workspace by clicking on the plus sign next to the existing workspaces and select Duplicate Current.

You can rename the workspace by double clicking on the tab and typing a name that makes sense to you.

Arrange the workspace to fit your needs, then save the current project as the startup file.

From then on, every time you open blender your custom layouts will be loaded.
Alternatively, if you don't want to make permanent layout screens, just create a duplicate of your default layout and work on that one. That way you can go back to the original when you need.
If you moved things around and don't have a default layout screen to go back to, you can save your file, quit blender and re-open it making sure you don't load the User Interface (un-check the Load UI box). The file will then open using the default startup file's layout.


Could be you have disabled Display Overlays..........

Or in the Overlays menu you have unchecked the Outline Selected option.


It's not a bug, it's a feature! It's called "Limit Selection to visible", and it limits selection to the visible faces. To enable the Limiting, you have to click this button.


This is normal. As long as there is no image file being used for texturing, you will not see results in other modes than rendered.


Blender exported to UE4 Gun Animation Skeletal Mesh is Twisted

The model I was using did not have a frame bone attached I reimported a model with the frame bone attached which is also the root bone. This solved my problem, I guess this is what happens when you import to unreal engine 4 without a root bone attached to the skeleton.


Which graphics card would permit eGPU rendering in Cycles with iMac?

Blender has stopped OpenCL (the API AMD uses) support for Mac because the compiler on macOS is very buggy. Apple also hasn't shown any effort to fix it, and instead favored their own API called Metal (which Blender does not support).
Blender does, however, support CUDA on MacOS meaning that if you have an Nvidia GPU that is CUDA capable and has a compute capability of 3.0+, you would be able to render with that card. However, recent macs do not use Nvidia cards anymore, so the only way would be to use an eGPU with an Nvidia card installed. You can also install Windows on your mac and just use the AMD card you have as window's OpenCL compiler has no big issues and is supported by Blender.


How would I merge these 3 pipes with this corner?

Edit: Probably much easier since 2.8 with the new Mirror "Bisect" option
Former answer:
I've found an answer for a basic 3 cylinders shape, but it looks like it's not exactly what you're looking for. That said, I'm not sure your drawing means anything in 3D. Anyway, perhaps my solution will help?

Create a cylinder with Cap Fill Type > Ngon.
In Edit mode, rotate it and move its cap to the origin with the Snap to Grid option (or put the 3D Cursor on the center of the scene, choose the 3D Cursor as Pivot, and S Y 0).
In Object mode duplicate the cylinder once and presse Enter.
Rotate the duplication 120° on the Z axis.
Duplicate and rotate again. Now you have a 3 branches star.
Join the 3 cylinders with 2 Booleans modifiers / Union mode.
Apply the Booleans.
Select all and W > Remove Doubles.
Delete the inner edges.
Delete the useless vertices.
If you want to extend the cylinders length, you can select all the caps and use alt E > Individual Faces, or select each cap and move it on its normal axis.


It's probably a normal problem, the normals must be flipped, you can check this with the Display Overlays panel > Geometry > Face Orientation, to fix this press ShiftN, it will recalculate outside.


Directly after you add an Empty press F6 to get the Add Empty Operator parameters.

The Radius parameter will set the visual size of the current Empty and all new Empties that you add afterwards during that session.

Unfortunately there isn't a configuration option to set the default radius permanently.


What is the difference between using emission and bloom effect?

Bloom and emission are two completely different things.  Let's talk about Eevee, since that's what you're probably using (since implementing bloom in Cycles requires the use of compositing, with behavior that depends on the precise way that you implement the bloom.)
Emission just says, write this color to the screen.  That's all.  It doesn't get lighted/shadowed.  It doesn't care about the surface normals.
Now, what happens to the color you tell it to write to the screen depends on your color management settings (and a few other things.)  Let's say you're using a raw color transform.  What happens when you write a color like 2.0, 1.0, 1.0?  Your monitor is designed to only handle colors in the 0,1 range.  So it clamps the output, and even though 2,1,1 is a pink hue, you still get white output.  Because once you clamp the output, you just have 1,1,1 white.
Except, you're unlikely to be using a raw color transform.  Standard, filmic, etc are designed to tone map colors outside of the 0,1 range into colors inside the 0,1 range.  (This comes at the cost of some color fidelity.)  So you're going to see a reduced impact of clamping overbright pixels.  Still some loss of hue.
What's the point of having both emission and base color on a Principled BSDF?  You're just adding the effect of the Principled, a combination of diffuse and specular on default settings, using the base color as the diffuse and the base color's value as the specular, to the effect of emission.  Is that something you should ever do?  You risk losing energy conservation, although that's not an issue with Eevee.  Otherwise, sure.  Think about a very dim lightbulb next to a very bright lightbulb.  The dim light bulb may both be emitting light and reflecting light from its brighter neighbor.
Okay, so then what's bloom?  It's clear that using plain emission, especially given the limits of our monitors, isn't enough to give us the perception of very bright light.  Bloom is designed to give us that perception.  It does it by first drawing the screen, subtracting a grayscale value from each pixel (the "threshold"), then blurring the output, and finally adding that darkened, blurred output back into the original screen.  (Finally, of course, it runs the whole thing through the color transform, in order to get it back into the 0,1 range.)
This creates an aura around bright objects.  Notice also how it interacts with the clamping of colors.  2,1,1 gets clamped to white.  But if it's on a black background, some nearby pixel might get half that color from the blur: 1,0.5,0.5.  So although the emitter gets clamped to white, the nearby pixels appear pink nearby.
It's not necessary to run bloom on your basic screen output, although that's how Eevee was designed to do it.  A common alternative is to render an emission render layer and only bloom emission.  This would make more sense to you once you start implementing bloom using compositing nodes instead of Eevee's out-of-the-box bloom.


Removing light source on a reflective surface

Instead of Mesh light object use Point or Sun that generate much smaller light source ...

... to hide from render entirely change Size under Light  Properties to zero.


I see a lot of noise and fireflies with Glass BSDF Shader

Glass is something that causes a lot of noise in a cycles. While the proper solution is lots of samples, there are some options to get quicker acceptable results.

The first option added to 2.79 is Denoising

2.81 adds a new denoise composite node that uses Intels Open Image Denoise. CGCookie has a look and comparison.

There are also third party addons such as D-Noise.


Why does my river change itself into a big, flat (with some bumps) square when i use the ocean modifier?

By default, the Ocean modifier is set to generate its own geometry and discard whatever you're applying it on.

To have it use your existing geometry, just Generate to Displace:


If you want to animate it rotating, you move your time to specific frame.
Press I to set a key frame, select rotation from the pop-up window.
Move to another frame (15 frames after the previous frame), rotate the object around it's axis, press I again to set another key frame (select rotation again).

This will cause it to 'spin' for 15 frames.  Without more details regarding your goal, this is the simplest way to animate.


How to cut into an object that has a sub surface modifer with out changing the overall shape

Select these vertices and delete them, it will make 2 holes:

Select the border edge loop:

Extrude and scale down, press AltShiftS to round the selection, then give it the shape of the eyes:


Any way to hide an object while keeping its form?

Mix with transparency on the basis of light paths/is shadow ray, and you can make the wall invisible to the camera, but visible to your lights:


To clarify, you don't unwrap a texture, you unwrap a mesh. UV unwrapping is a way of defining the translation between a spot on a 3D object to a spot on a 2D image.

You can create multiple UV maps for an object and choose a specific UV map to use for a texture image. When you want to use more than one image for an object you don't have to use the same UV map for each image.

When UV unwrapping, the UV layout shown in the UV/Image Editor is the data associated with the UV map highlighted in the UV Map list. The UV map with a little camera next to it is the default layout that will be used if no specific UV map is chosen.

When using Blender Internal you choose the UV map to use in the Mapping panel of the texture settings.

For cycles instead of using a Texture Coordinate node, you add a UV map node and choose the UV map.


Importing PNG files into Blender Grease Pencil

In short... You can't.
PNG images are only images. You can't animate them in any program without previously rigging or doing most of the work by yourself.
There is an addon called Import Images as Planes that allows to import PNG images to blender as a plane in a 3D space. I could see a little animation made this way.
But png to grease pencil is pretty much impossible without transferring this manually to curves or redrawing it yourself.

Hope this helped.


Text in my image file doesn't display properly in final render

Fixed! The model came from an AutoCAD software, not sure what happened but it looks like it duplicated the geometry and made it as one piece.  Hard to notice in the viewport. In the UV editor, I was able to isolate the appropriate faces and delete them. Thank you LukeD for the speedy response.


My texture doesn't apply on a surface but does on an other

Thanks @lemon ! You're right, there is no UV map for the bad plane. Question solved. Thanks again for you very fast help !!


Make a backup of the file and apply scale and rotation on both the armature and the mesh.


Scripting: Displacement modifier visual update required

There is a handy from_pydata method (doc) when you have relatively simple mesh data. When I used this, I didn't have this disconnect after setting the modifiers.
By the way you are setting attributes to the screw modifier which are already default like the Zaxis or the 360° and the merge threshold distance.
Updated code :
import bpy
import bmesh

mesh = bpy.data.meshes.new("mesh")
obj = bpy.data.objects.new("object", mesh)
scene = bpy.context.scene
bpy.context.collection.objects.link(obj)

# 2: Generate Mesh - Verticies, Edges, and Faces
verts = [(0,0,0),(1,0,0)] #add a line
obj.data.from_pydata(verts, ((0,1),), [])

# 3: Create modifiers for object.
# length of the line object
radius_mod = obj.modifiers.new(name='length', type='DISPLACE')
radius_mod.show_in_editmode = True
radius_mod.show_on_cage = True
radius_mod.strength = -1
radius_mod.mid_level= 0.2
# create a circle
screw_mod = obj.modifiers.new(name="screw", type='SCREW')
screw_mod.use_merge_vertices = True


This code will animate (cycle) through all materials based on current frame value. Run this in Text editor, select some object (it works on active object), set frame range from 0 to number_of_materials-1 and render the animation as images.

import bpy

def my_handler(scene):
    if bpy.data.materials:
        ob = bpy.context.active_object
        mat = bpy.data.materials[min(len(bpy.data.materials)-1, scene.frame_current)]
        if len(ob.data.materials):
            ob.data.materials[0] = mat
        else:
            ob.data.materials.append(mat)

bpy.app.handlers.frame_change_pre.append(my_handler)


3d manipulator not on object, stuck in scene center

I assume the Pivot Point for rotation and scaling is set to 3D Cursor. In this mode the 3D manipulator, i.e. the movement arrows, is also placed at the 3D Cursor.

Setting the pivot point to something like Active Element will also move the 3D manipulator to the origin of the active object.

Alternatively, depending on your intentions, you can move the 3D cursor, for example to the active object by pressing Shift+S and selecting Snap Cursor to Active.


One way is to bevel by percentage of edge length.

Set Width Type > Percent
Uncheck Clamp Overlap
Add loops and slide them to control the angle


how can i select all objects by type using python

Blender 2.7x
import bpy

objects = bpy.context.scene.objects

for obj in objects:
    obj.select = obj.type == "EMPTY"

Blender 2.8x
import bpy

objects = bpy.context.scene.objects

for obj in objects:
    obj.select_set(obj.type == "EMPTY")

See this answer for more info.


Where is the Displacement node in Blender?

The Displacement node is an upcoming feature - this is an example of the documentation being ahead of the official Blender release.

You’ll note that in the example image from the documentation the Material Output Displacement socket is a Vector type (it’s blue). At all ‘current’ releases of Blender the Displacement socket is a Scalar value (grey) and would act as displacement along the surface normal.

The Displacement node effectively allows you to generate the Vector displacement from a Scalar value to effectively mimic the displacement available at 2.79 of Blender. The new Vector displacement will be an exciting new feature (for me, at least) and should hopefully be a point where the experimental ‘true’ displacement becomes standard supported functionality (rather than ‘experimental’ and subject to change - as it has here!).


To align the viewport to a specific axis you can use the Numpad:

Y axis - Numpad 1
X axis - Numpad 3
Z axis - Numpad 7

You can use the Ctrl key in conjunction with these keys to invert the direction you are looking along the axis. To move along a certain axis while preserving your viewport orientation:

To move along the Z axis - hold Shift while scrolling.
To move along the X or Y axis - hold Ctrl while scrolling.
To zoom along the X or Y axis - scroll.


I think you want to go to the node editor and plug the texture into the color of the emission shader of your material.

You can control the strength of the emission shader in the node editor.

If you want the emission shader to light other objects, in Eevee the emission shader doesn't light other objects unless you add an irradiance volume (shift + A -> Light probe -> irradiance volume) and wrap the scene you want with it and then bake the indirect lighting in the render tab.


How does one align texture maps of Multiple sizes and resolutions on same sphere?

It sounds like your images have some blank space once you've reduced the resolution. If you simply get rid of that space and make the whole image smaller blender should automatically scale the UVs relative to the image size.

What I mean by this is that if your UVs on the full resolution textures go right up to the bounds of the image, if you have a texture at half that resolution and size the UVs should just be scaled down and still go right up to the bounds of the image.

You can see how I mean if you take a lower resolution image that has no empty space and replace a high res image with it.


How can I erase part of an image to show another image under it?

There are two and a half options.

1) If your support bricks are in the EXACT same location in every single frame, you can create a mask in the compositor, and use the VSE to render out the result. The mask could be used to composite in something else, or just make the masked area transparent. It depends on what you need.

2) If your bricks are NOT in the same place, but are a different color from every other thing in you scene, you can use a chroma key to create a mask of everything that's a particular color.

3) This is the half-option. If your bricks are NOT in the same location, and they're NOT the right color for a chroma key... you might be out of luck. However, if you're SUPER lucky and the tracking is good, and you're SUPER good at video editing in Blender, you could make a mask that tracks the edges of the brick, and use that mask to make the bricks transparent, or white, or whatever you need.

Any one of these would make a HUGE answer. Detailing all three of them is far beyond the scope of this answer. BUT there are good resources out there.

Some good searches are

blender alpha mask video
blender chroma key
blender camera tracking mask

Searches are often difficult when you don't know what TERMS to use. Other times, Google is just overly specific. These searches seem to give good results.

I hope that helps!


Adaptive sampling is now an integration added to the 2.8x series, and you can enable this by going to the render properties panel (the camera icon), and checking the box for "Adaptive sampling" underneath the Sampling tab.


save avi files in blender using python script

bpy.context.scene.render.filepath contains the filename that the render will be saved to, you can change this and then use bpy.ops.render.render(animation=True) to render the animation to the specified file.

import bpy
bpy.context.active_object.material_slots[0].material = bpy.data.materials['Red']
bpy.context.scene.render.filepath = '//red.avi'
bpy.ops.render.render(animation=True)

bpy.context.active_object.material_slots[0].material = bpy.data.materials['Blue']
bpy.context.scene.render.filepath = '//blue.avi'
bpy.ops.render.render(animation=True)

The // at the beginning of the filename puts the file in the same folder as the blend file.


How do you control the number of loops on a bevel of a path?

It is in the resolution of the host path, not of the target bevel path.


To model a hole you will have to engineer a vertex by having an edge perpendicular to the edge shown. There are other options such as a bool. The main issue I can see here is that the surrounding topology could be better and any cuts would distort what you have due to the curves in the object.

Here is an option if you have a vert and I have shown it on a simple plane. You can take the process and do the same on yours but will need that edge crossing to create a vert.

Select the vertex

Ctrl + shift + b to bevel the vertex with 2 segments

Roughly get the shape of a circle.

Select the faces and right click to get your loop tools. If you do not have loop tools then get them via preferences add on (they come with Blender). Very useful to have if they are not already there.

With loop tools select circle and that will make your shape more circular

select i for inset and make a small inset to create a supporting edge for your circle and then delete the inner faces. Add the edge cuts (knife) to create quads.

With a sub surface modifier x 2 you get

Your issue here is getting that vertex. You could try this but I suspect it will distort at the bottom of the shape. Maybe it is worth a go but most options from here will probably distort a bit due to the existing topology.


Unfortunately, I don't know how to unlink it from the Archimesh tools. But it is worth noting that if you make a change by accident, undoing the change will get you back your custom modifications.


Control an object's specularity with distance (CYCLES)

Managed to figure it out and not entirely sure how I missed it! Here it is for those who might want to know how. I used the same set up highlighted in red and plugged them into the Glossy BSDF shader. I had to reverse Subtract, Multiply in the setup nodes as the specularity would fade out upon closing in on the Earth and not moving away.

I also fixed up the cloud map as missed something out. Looks nice a populated with them now.


When using turbulance to create a grass animation, the effect of the turbulance eventually fades out

I didn't get this process to work, still don't know why. But then I simply animated my force field to go from one position to another and that seems to do the job.