How, specifically, does the game engines friction work?

Friction belongs to the surface. When the object touches the surface the combined frictions result in a sliding force (both objects have materials).

Distance and Force belongs to force field. The force field is defined above the faces with that material. 'Above' means

+Z (global) when Align to Normal is unset
+Z (local) when Align to Normal is set

I can't tell about the formulas, nor if friction belongs to force field too.


The functionality that is missing would be to see one reference image on every perspective. And yes you can no longer hide the image when you leave the front ortho view.

The easiest possibility is to set up a separate camera in Front-Ortho view and add a background image to the specific camera. If you leave the camera view the image will no longer be visible

To approximate what you want to achieve with a reference image you have to insert the image in "Front" View so the normal is aligned with the y-axis.Looking at the settings shown in this answer:

You have to uncheck "Display Perspective" so it doesn't show up in perspective view, And make sure you have "Front" Selected in the "Side" selector so it is transparent from the back.

You will however always see the outline of the plane.


Selecting a specific cube in an array to change properties

This operator does not return a reference for the created object.,
bpy.ops.mesh.primitive_cube_add(size=1, location=(i*2, 0, 0)))

so change to the following.
bpy.ops.mesh.primitive_cube_add(size=1, location=(i*2, 0, 0))
cubes.append(bpy.context.active_object)


It's printed to the system console. If it's not opened, go to Window > Toggle System Console.
Note that this option is only available on Windows. On other OS, start Blender from a terminal.
See here: https://docs.blender.org/manual/en/latest/advanced/command_line/introduction.html
You may also use this script:
Is there anyway to make blender print errors in the UI?


A helix is described using the parametric equation:

$$
\vec{r} = \begin{bmatrix} \alpha t \\ r\cos{t} \\ r\sin{t} \end{bmatrix}
$$

Where $\alpha$ is some scalar controlling the "wavelength" of the helix and $r$ is the radius. Sampling some points and creating a spline from them, we get:

By driving the amount of samples based on time, we get:

We can see in the reference that the helix extends tangentially for some units. To compute the position of the point that creates that extension, we have to compute the tangent of the helix at the last point. So by differentiating the parametric equation we get:

$$
\vec{r}^{\, \prime} = \begin{bmatrix} \alpha \\ -r\sin{t} \\ r\cos{t} \end{bmatrix}
$$

The position of the new point is the position of the last point plus a scalar multiple of the tangent at it. So the node tree becomes:

Where the index $-1$ gets us the last point. Note that instead of computing the tangent from scratch, we used the similarity between the function and its derivative to compute the tangent.

We notice that the spline intersects the cylinder, to fix that, we add the radius of the spline to the radius of the helix:


You can add elements to the bmesh history. The last added element is automatically set as active element. Here is a small code example:

import bpy
import bmesh

me = bpy.context.edit_object.data

#get bmesh (Object needs to be in Edit mode)
bm=bmesh.from_edit_mesh(me)

bm.select_history.add(bm.verts[5])

#print active vert:
print(bm.select_history.active)


How do I split the edges on all objects in a scene with a script?

Using bmesh.ops.split_edges(..)

Test script, object mode, for all unique meshes of all mesh objects in the scene, load a bmesh, split all edges, rewrite to mesh.  Need only pass edges of the bmesh to the operator.

import bpy
import bmesh
context = bpy.context
scene = context.scene

bm = bmesh.new()
meshes = set(o.data for o in scene.objects if o.type == 'MESH')
for me in meshes:
    bm.from_mesh(me)
    bmesh.ops.split_edges(bm, edges=bm.edges)
    bm.to_mesh(me)
    bm.clear()

bm.free()

On smooth shading AFAIK it is set on a per face basis. Using the methods outlined here Using python to set object shading to 'smooth' could make a flag to check if any, or in this case all the faces have smooth shading.

# check if all faces in bmesh are smooth
is_smooth = all(f.smooth for f in bm.faces)

Some notes on question code:

when using operators its far better to iterate over context.scene.objects or if pre selected context.selected_objects.  The collection bpy.data.objects is all objects in the blend whether linked to context scene any scene or no scene.  As well as being selected you also want to set the object to active, and select all geom before calling operator

mesh_objects = [o for o in context.scene.objects if o.type == 'MESH']
meshes = set(o.data for o in mesh_objects)
for ob in mesh_objects:
    if not meshes:
        break
    elif ob.data not in meshes:
        continue
    context.scene.objects.active = ob
    ob.select = True
    bpy.ops.object.editmode_toggle()
    bpy.ops.mesh.select_all(action='SELECT')
    bpy.ops.mesh.edge_split()
    bpy.ops.object.editmode_toggle()
    meshes.remove(ob.data)

Note that 100 objects in a scene could share one mesh, hence the logic above to avoid calling the operator on the same mesh 100 times.

No biggy, but as a generality, i is used for integer iterators.


recalculating the number of subdivisions of a cylinders

Select one of the cross sections and separate it into a new object or inverse the selection and delete the rest of the object.

Use the Screw modifier to recreate your wheel with Steps set to 30. You might need to change the Axis depending on how your wheel is oriented. Also  check the Merge Vertices checkbox.

Click the Apply button to convert the wheel back to an editable mesh.


There is a soduku of issues here and I don't know what to address specifically, so I'm going to skim all of them.

The steps to model and rig a hand are:

1) Model the hand.  You seem to be running into a topology issue here.  When people talk about "Topology" in terms of 3d modeling, they are talking about the layout and organization of the vertices and edges.  The rule of thumb is that each vertex and edge should be describe something unique about the model.  I could probably dissolve about 2/3rds of the verts in that hand and it would look functionally the same.  Additionally, there is isn't really topology describing how the fingers would bend.

The following wouldn't be considered good topology or even a good hand, but it is functional as far as animating is concerned.  Notice that even without a texture, you can tell where the fingers will bend and that it is a monster-y hand.

It is also only 500 verts and faces, which is far less than your hand right now.

2) Make the armature.  Rigging is an entire profession, so to keep it short: create an armature and add bones until you are satisfied you have enough control points. You seem to have done that, though I will add you seem to have extra bones in the palm.

3)Bind the armature to the Mesh.  In Blender you do that with the Armature modifier on the mesh.  Add the modifier to the mesh, then specify the Armature you want to use in the modifier.

You can also click the mesh, than the armature while holding shift, then press ctrl+P and choose the Armature Deform option of your liking, this does the same thing.

4) Tweak bone weights.  Now you get to specify how each bone affects each vertex in the mesh.  You will need to turn off "lock edit modes" in Blender 2.8x, as it prevents being in pose mode while weight painting.

Now: select your armature, and change to pose mode.  Then, select your mesh, and go into weight paint mode.  From here, you should be able to click on a bone to select it.  Click and drag on the mesh to apply your current tool. You can change your current tool by pressing N to bring up the toolshelf, going to the "tool" tab, and clicking the picture to change what brush you are using.  Adding to the mesh increases the proportion of the influence exerted, and the color will change from dark blue (no influence) -> green -> yellow -> red (full influence).  You can try moving the selected bone by pressing  R to test how it is working out.

There are plenty of online resources that can describe this in detail, but that is the gist.

Update
It appears that there are so many influences on these vertices that weight paint is giving up.  Four is pushing it, but many of these vertices have at least 7.

Completely blanking these influences allows weight paint to work again, but honestly, deleting and re-making the offending geometry will probably be easier and cleaner.  You do not need this many verts.


Sqorus is a cube with a hole inside it.

Add Mesh -- Extra Objects -- Beam Builder
And apply the settings as shown below


using boolean modifiers and shape keys in animation

I think this would probably be a lot easier if you made a dummy object used as subtraction for the Boolean Operation.

Just model a pill-like cylinder object ending in a spherical cap, possibly starting from a UV sphere, then use that in the Boolean operation.

You can then hide it, make it unrenderable, possibly even parented to the real sphere, and use it instead as the Boolean operand, and it should easily simulate the desired effect.


How do I position a donut onto a cube with the corner hanging in between the donut hole?

Select the cube, enter edit mode and select a vertex on the corner.

Then perss Shift+S to activate the snap function and select "snap cursor to selected" (the 3d cursor will move to the selected vertex).

Exit edit mode

Select the torus object and do "snap selected to cursor".


Automatic weights don't seem to work properly on the mirrored side of my model

If your mesh is strictly symmetrical, there's one easy solution to this. Just delete one half, apply the weight-painting, then add the mirror modifier (and apply it, if needed). Now both halves are identical, weight painting included.


When i Import an obj it imports far away from the origin

Any model imported will have it's coordinates where they are in the file. There is nothing to fix here since the problem is not in Blender or importing, but in the file.

Imported objects are selected after importing, so just after importing you can set the origin to its center of geometry:

And then you can snap it to cursor that you can place anywhere you wish:


This is a little dated, but for anybody having this issue in the future, I finally found out how to fix this issue..

I have been trying to use the NLA Editor as a generic timeline to construct my animation, so I have a huge amount of actions and an endless amount of tracks in the NLA Editor. I finally found that in order to get each track to play simultaneously (sp?) no matter it's track position, you need to

1) Hop over to the "Active Strip" options (Press N, then go to the "Active Strip" area

2) In the "Extra" dropdown menu, select "Nothing"

3) In the "Blend" dropdown menu, select "Combine"

That's it! Just make sure to do this with each action strip and everything will work good.... Note: You have to select the Action Strip itself, not the Track


After extruding the face where i extruded from is missing

You have to hit SPACE and type "extrude only edges".
Or in edge select mode hit ALT+E and choose "only Edges"
This way it keeps the original face in place and extrudes the edges only.

If you want to select multiple faces, you have to switch to edge select mode and only select the outer rim of the faces.

Hit only E and extrude the edges:


Figured it out

Expand Overlays (top-right)
Tick Face Orientation

Now blue faces are one way (presume forward) and red are other (presume backwards)


How to get a lamp icon at the location of a lamp

The large circle you described is showing because you have Proportional Editing enabled . Click the icon or use O to disable it. As for the missing icons, make sure that you didn't hide them accidentally or that you didn't tick Only Render under Display.


How to increase visible area of a camera without side effects?

To increase the visible area of theh camera without actually moving the camera (which would change the view through the camera) you can simply adjust the Camera 'Sensor Size' in the camera properties. See related answer for Change camera from rectangle to square by center


It looks like blender has trouble performing boolean operation on meshes with large ngons. There is a very easy workaround for this problem.

Select the face that will hold the window

This single polygon has 8 vertices, more than 4 vertices is considered an ngon

Triangulate it by pressing Ctrl + T, this will make many triangles out of the big ngon
(optional step) With the polygons still selected, you can reduce the number of triangles by converting tris to quads by pressing Alt + J.

Final Result


Why does my water turn into a cube at the end of the simulation?

There can be several reasons to this.

If there is no fluid in the domain (possibly because of an outflow), it will display the domain mesh.
The simulation is not baked to the last frame of the scene. Once a simulation is baked (it uses the scenes start and end frame) it stops at that frame. Increasing the end frame would result in some unsimulated frames, the simulation has to be run again.
The fluid particles may be too small or too few in the domain. When the fluid falls below the minimum size (specified by the simulation resolution), it display the domain mesh. If you have many tiny drops, which you want to simulate, you need to increase the resolution.

The solution is to hide the domain in the viewport and in the render.
To hide the domain mesh from the last simulated frame onwards, animate the Restrict Render and Restrict Viewport visibility. This way, you can hide the domain mesh on certain frames.

Step 1: Go a frame where domain is still simulated. Hover over the Restrict Render property in the outliner and press I to set a keyframe. (Same with the Restrict Viewport visibility property.)

Step 2: Go to the first frame, from which on you want to hide the domain.  Disable Restrict Render and Restrict Viewport visibility and keyframe them again.


Weight-painting mesh containing only vertices

Yes you can. Weights are all stored per vertex and have nothing to do with edges or faces.

That said, without faces to shade, you will have trouble visualising what the weights are, so with 119,617 points, this is going to be very difficult to manage without just having a script set the correct values automatically.


Is there any way to fill the whole back of this mesh?

Hoo boy.
Ok so before I suggest something to solve this at this stage, id like to really reconsider your workflow in modeling: Fill first, extrude later. Also: do not intersect geometry (non-manifold meshes)

For this case i would say that maybe if you used the "Grid Fill" feature you could fill the faces to make sense on automatic (space -> search: "grid fill").
Otherwise theres always the soul-crushing way of doing it by hand: quad by quad (have fun)

At this stage id just trash what you did here, and restart the whole model with the elements already filled and then extrude them. It doesnt look like too much work.


EDIT: This answer is going to be pretty useless if we are talking about an SVG file (as the edit implies). In that case the comments explain the method of importing an SVG into blender, which would solve the problem.
This answer only applies to raster images such as PNGs or JPGs. I'll keep it around only in case someone else wants to do this with a raster image and might bump into this answer.

If your 2D image is a simple black and white representation, this should do the trick:

Open your image in a UV/Image editor.
Open a text editor window and paste the script below there.
Update the image name in line 15.
Update the image resolution in line 18.
Press "Run Script".

Code:

import bpy
import numpy as np

def make_mesh( context, name, verts ):
    mesh = bpy.data.meshes.new( name = name )

    o = bpy.data.objects.new(name, mesh)
    o.location = (0,0,0) # place at object origin
    context.scene.objects.link( o )

    mesh.from_pydata( verts, [], [] )

    return o

img = bpy.data.images['figure_1.png']  # Update name to the right one in your scene

pixels = np.array( img.pixels[:] )
pixels = pixels.reshape( ( 1024, 1024 ) )  # Update resolution to the one in your image

verts = []
for i in range( pixels.shape[0] ):
    for j in range( pixels.shape[1] ):
        if pixels[i,j] == 0.0:
            verts.append( [ i, j, 0 ] )

o = make_mesh( bpy.context, 'PointCloud', verts )


Does Blender consider each frame to be separate scenes, while rendering animation?

I can only answer the first question.

Each frame is NOT considered a different scene. Every scene has their own frames/timeline.

So "Scene 1" could have 250 frames, and "Scene 2" could have 150 frames. However, the first 150 frames in each of these scenes are different. Changing some animation in frame 50 in "Scene 1" does not affect frame 50 in "Scene 2" (unless you've specifically linked them).

At the top of Blender, you can see which scene you currently reside in:


The difference of subdivision surface modifier between 2.7x & 2.80?

Yes, 2.8 now uses Pixars OpenSubdiv. So there is a change on how they are computed and behave.

[EDIT]
I actually can't see why there should be a difference here from maya for instance. You may want to discuss this on devtalk.blender.org.


This is built into Blender.  Go to File -> User Preferences... -> Add-ons and type "FBX" into the search box at the top.  Put a checkmark on the FBX plugin to activate it.


How to achieve multiple emission color on one mesh..?

create different material slots and materials (emission shader) for the same mesh
go to edit mode, select some faces
select a material slot and press "assign" button
(this will assign the material only to selected faces)
(eevee/cycles)


How can I stop Blender from selecting vertices on backfaces?

The closest thing would be to select one vertex of a backface and select similar vertices Shift-G Normal adjust the threshold in the last operator panel (Left to the viewport if not visible toggle with T)

and hide the selection H, after editing unhide Alt-H.

Note: Hiding backfaces would only prevent Blender from filling them, all vertices,edges will still be selectable in Edit Mode:


Blender takes a long time syncing objects

This may not be a solution, but does help me speeding up the animation render.

In my case one object needs a lot of time to synchronize. While this is happening the computer is not really busy. To use these ressources I started a 2nd instance of blender (background render at the commandline) starting rendering the 2nd half of the animation. This increased the render time of both render instances just a little bit which in general accelerates the animation render almost by a factor of two.

I don't know how that is influenced by the specific scene and the hardware used. But for me it worked pretty well.


I think the best way to this is with only array modifier and object offset.
Create a empty at the center and rotate it (36°).
You can still edit the shell and maybe add solidify and subsurf modifier!


Combining two manifold objects creates a non-manifold with issues

Firstly I think you have your terminology backwards. non manifold is bad, manifold is good.
It looks to me that you are trying to attach a bolt head to a cylinder. The problem with using bridge edge loops to do this is that the cylinder has empty space on the inside while the nut does not. this means that you are asking the printer to print faces with 0 thickness, which is impossible so the slicer ignores it or bugs out.
In order to make that a manifold print I would recommend doing 2 things.
Firstly select the bottom face of your bolt and hit I to create an extra perimeter.

now that you have 2 perimeters you can bridge both the inside and outside of the cylinder.
make sure you remember to fill the hole that this creates in the bottom of the nut.

Finally go inside and delete any faces edges or vertices that you would consider to be inside the final 3d printed item.

That should give you a manifold model.


Enum Property Error: expected a string enum, not tuple

You are attempting to assign a property definition as a property value:

scn.pipe.asset_categories = bpy.props.EnumProperty(...)

Should be:

scn.pipe.asset_categories = 'new'

Or, if you actually want to change the definition, uou must manipulate the type instead of it's instance:

del bpy.types.Scene.pipe
bpy.types.Scene.pipe = bpy.props.EnumProperty(...)

Where ... are all the enum arguments


How do I stop a displacement modifier from breaking the edges of its mesh into many small parts?

With the displacement modifier, the edges are occluded by bumps created by the modifier and hence are no longer fully visible from the camera.  Freestyle identifies both visible and hidden lines, and by default draws only visible lines.  If you want to draw all lines no matter whether they are visible or hidden, then you need to turn off the selection by visibility (i.e., disable the "Visibility" toggle in the "Selection By" section of the Freestyle Line Set panel).

Update on May 12, 2017

Setting the mesh faces to the smooth shading and turning on the Face Smoothness option could improve the result as you expect.

That said, there seems a bug in Freestyle that prevents visible and hidden lines from getting chained into a single stroke.  For instance, the following render shows lines composed of visible and hidden parts.  Most lines are consistent in the sense that they start in red and end in green, while some lines are not.

The next image shows some of those inconsistent lines that are expected to be long continuous red-green strokes rather than being split into short pieces.

The render below shows the visibility of line segments in question (visible and hidden parts in red and green, respectively).

By comparing the last two renders, it is seen that in some cases visible and hidden line segments can be chained to form a consistent line, while not in some other cases.  I think this is a bug in Freestyle (to be fixed as soon as time permits).


How to rotate objects in array along path

An array modifier duplicates the object multiple times, the curve modifier can then control the direction of the duplications. The curve modifier uses the chosen axis of the object when it does the deform, the offset dimensions of the array modifier need to match the axis that the curve modifier is using.

Each point in a curve has a tilt property. You can use this to align the objects second axis to point the direction you want. You can use CtrlT to interactively alter the tilt in the viewport.


How can I render an edge only mesh as solid lines?

Note: This answer is for 2.79 only. For 2.8+ you will have to look at some of the other answers.

The simplest way to render an object that has no faces is to change the material type in the internal renderer to a 'Wire' material:

The mesh on the left, when rendered, looks like the image on the right:

I also changed it to be 'Shadeless' in the shading panel of the material so that it wouldn't be affected by shadows and would be lit equally.


How do I put an image texture on a material in Cycles?

Applying an Image Texture in Cycles

Select the object you want to put the image on
Give it a new material with an Image Texture Shader:
Object Properties window -> Materials tab -> click the New button
For the Color, click on the grey dot icon on the right side (  ) then select "Image Texture":

Select the image you want to use:

UV Unwrap your object and position the image as you'd like it:

Select your object and enter Edit mode (TAB)
Unwrap mesh (U) -> here, I use Smart UV project

NOTE: UV Unwrapping a mesh and positioning the image properly can be a very complex and involved process. So, I highly recommend you study some UV Mapping tutorials to get all the details; YouTube has quite a lot of excellent video tutorials for beginners on this subject.


Can a curve with a bevel profile have 2 materials

There is currently no way to have multiple materials using a single curve and a profile object.

You could have a single material containing 2 different shaders, but you would need a way to separate what material is for what part of the object. One way to do that would be to use a bevel object curve composed of two separate splines inside. You could flip the direction of one of the splines (w -> Switch Direction with the spline selected in edit mode) in order for the result to have one part of it with inverted normals.

You could then use Backfacing output of the Geometry node to mix your different shaders. Note that you will have the normals inverted so you will also have to take that into account in one of your shaders: for example you would have to invert the IOR value of the Fresnel node if you used one in the shader:


How can I emit smoke from just the outline of a model?

Use the mesh as emitter. Use vertex painting to paint the “silhouette” as a vertex group. Set vertex group in smoke. Set volume to 0.


How does the Vector Math Normalize node work?

For the normalize option the node will only normalize the first input vector (set the length to 1). You are right, a second vector isn't needed for this operation.

This example shows how it can be used to multiply a vector by a scalar:


Using a mapping node to disable tiling is streaching texture?

As mentioned by Róbert László Páli, this is an artifact of the way the mapping node works.

You can get around this using hjaarnio's technique:

Using this node setup that creates a map of where the image is:

Values in the 0-1 range are where the original image is, so if we use that as a mix factor:

It will use the Image texture only where the original image is mapped, and Base Color everywhere else.

Base Color can be a texture or even another shader as well:


Can you bake materials (not textures) in Blender?

You cannot bake the "node tree" itself to use it directly in the shader node editor of another program like Unity, Unreal engine or Substance painter.

But you can bake the resulting maps (albedo, roughness, metallic, alpha value...) and then apply them in another software as if they were regular textures.

See : for texture baking
How do I bake a texture using Cycles bake


How do I control the blurriness of light through frosted glass?

Use a mix of glass and translucent shaders. To control how blurry the light source behind the glass is, play with the factor values on the mix and the roughness of the glass shader.

Here's an example of an emitter object enclosed on a glass cube. The glass walls  have to have some thickness (you can use a solidfy modifier) so that it is not a solid glass cube.

An other factor that will have a great impact in the light effects you are after, is the color transform used in the color management settings. Being able to use a bright light source and a much larger dynamic range for the image, will help you have a more realistic result. Experiment using the filmic blender colour tranforms.

(Click on the images to enlarge)

Read also:

Render with a wider dynamic range in cycles to produce photorealistic looking images


You can use a particle grid to get back the ability to use a Voxel data texture.

Create a box with the proportions of the voxel data
add a particle system
set the emission to Volume and Grid
set the end emission frame to 1
set a low resolution at first (like 40)
add a texture to the particle system
set the texture to Voxel data
load your voxel data file
Enable Ramp to tweak the threshold
Set the influence to Density

If your volume doesn't appear, it's just because of a little bug that you can easily get around by switching to Blender Internal Render View mode and back to Cycles Solid mode, then refreshing the Voxel Data. The bug is reported here.

add a material
Replace the Diffuse by a Volume Scatter and plug it to Volume
Add a Point Density node and plug it to the density of the Volume scatter
Plug a multiply node inbetween to get a higher density
In the Point Density node, select the other box object and its particle system

tweak the resolution settings of both the particle grid and the point density. Note that the particle grid resolution is limited to 250. If you want a higher resolution you have to slice your voxel data in pieces of 250x250x250 (or any resolution below) and use multiple particle grids. I won't do that because my computer is a toaster but I think you get the idea.

You can then add a particle killer mesh to cut your MRI where you want :

This is ugly because the resolution is low but it can be as good as your computer allows it to be.

Here's a file you can open to test (provided you also put your MRI file in the same folder as the .blend) :


Can't try Blender 2.8 due graphic card and/or driver

Sorry guys, just found the solution. In my case, Blender runs just after a complete uninstall (disabling not enough) of Intel driver.


Mesh silhouette as a polygon or pixels surrounded by the silhouette on the rendered image?

You can use object index to identify to which object does the pixel belongs to, for this you have to :

assign unique object index to each object
enable the object index pass in the render layer

after that you can output this read the corresponding object for each point from this pass

in the following script we assign unique object index for each object and store this index and name in a dictionary :

import bpy

index = 0
obj_index = dict()

for obj in bpy.context.scene.objects :
    if obj.type == 'MESH' :
        index += 1
        obj.pass_index = index
        obj_index[obj.name] = index

print(obj_index)

this part is for extracting the object index pass from the node viewer image :

# division by 4 since we have RGBA
# object index is contained in any of R, G, B values
l = len(bpy.data.images['Viewer Node'].pixels)//4
table = [0 for x in range(l)]
pixels = bpy.data.images['Viewer Node'].pixels
for i in range(l):
    table[i] = int(pixels[i*4])

print(table[:])

to make this work you have to setup the composition nodes as this :


Can't get node editor to add volume scatter for smoke domain in 2.71

Select your smoke domain (not the sphere)

Open the Node editor and make sure you are on the shader node editor,
(the Sphere icon on the left). also click on the object material (The cube icon).
Enable Use Nodes


Is there way to control opacity of selection/active color in 3DView?

No, this feature isn't currently available. Workarounds can be found in following questions: Remove selection overlays when Editing UVs?


How can I group into one layer all similar items?

If i understood the question here the answer
If you have made the single sphere as a group ok

Select the 1st sphere and hold shift and select other spheres and group.

To find group go to outliner > drop down menu select group

Unlink group the old group (i.e. made before with 1 sphere). Right click on the old group and click unlink group


What's the difference between : Multiply, Add, etc

This is a different color blend modes like in 2D drawing programs like Gimp, Inkscape, Photoshop, Imagemagick, ets

For example, if you chose add, colors from first input will be add to second witch makes bright sum of both inputs.

Here is detailed explanation about blend modes in gimp manual


They can be either! although FK rigs are much easier on the game engine's animation player, they're usually not as flexible (i.e. your player doesn't look where the camera does.) I tend to use a combo of both:

To start with, give the player animations (FK) then, simply add the constraint you want (the fewer the better) and add a "armature" actuator. Now this is automatically set to "run armature" but the setting can be changed to "enable/disable" (for individual constraints) or "set influence" or even "set target" which, although is resource consuming for your computer, can bring you some awesome mechanics that just aren't available for FK rigs.
And don't be fooled, not just the IK constraint can be used with the armature actuator, track-to and the whole kebab can be integrated into your game just as easily (with a few exceptions, I’ll look them up).

Now, usually, to get my player to look where I want, he needs a vertical head bone. I next add a cube at the location of the head bone, set it to no-collision, and add an empty above it. Parent cube to player, empty to cube, give mouse look logic to the cube and set the IK target of the head-bone to the empty and you're gold!


How to get displacement working on a completed house?

You can create vertex groups in edit mode and attach them to the displacement modifier.

Select your wall's vertices.
Press space and search for add vertex group
Assign the vertex group to the modifier.


What is the best way of making an MP4 from an image sequence (PNG)

Maybe the given answer is not specific enough for you. If you want an MP4 with best quality I would suggest (since you don't care about file size) to choose the following settings:

File Format: FFmpeg video
Container: MPEG-4
Video Codec: H.264
Output Quality: Perceptually lossless (with 'Lossless' I once had playback issues, might be because MP4 cannot be completely lossless, I'm satisfied with using 'High quality')
Encoding Speed: Slowest (should give best quality, but I see no advantage over 'Good')

Normally this should produce quite good results, although MP4 is not a lossless format it usually provides high quality along with a good compression i.e. small filesize.


Blender 2.9 scripting, how to get the name of the driven property

Use f_curve.data_pathand f_curve.array_index to get the property index in case of vectorized properties (like location, scale, etc.)
import bpy

if bpy.context.active_object and bpy.context.active_object.animation_data:
    for d in bpy.context.active_object.animation_data.drivers:
        print(bpy.context.active_object)
        print(f"Driven property : {d.data_path}")
        print(f"Property index : {d.array_index}")

Example :


How can I edge slide a vertex to a specific coordinate, using Python?

The Vertex Slide doesn't have a feature (currently Dec 2015) to limit the extent of a slide for any given axis. This means that there's no script-able way to do it from the operator by simply passing a few parameters. This doesn't mean an alternative doesn't exist, or several. Some code will have to be written though, and to make it usable as a tool also some UI code.
Projecting a vertex of an edge towards a Face on the YZ plane would have the same effect as limiting a vertex's sliding till it reached a given axis limit. (ie x = 10)

We can find the intersection of a line on the infinite plane using a built-in geometry function mathutils.geometry.intersect_line_plane . We then use the plane_nol=(1,0,0) to show the plane extends only in the YZ axes, and plane_co=(your_x, 0, 0) to give the plane an origin (this is the axis constraint)
# alias it first, for convenience here
intersect_l_p = mathutils.geometry.intersect_line_plane
intersect_l_p(line_a, line_b, plane_co, plane_no, no_flip=False)

and then overwrite the vertex location with the intersection location.
Let's take the example above where I have a plane on the X axis at about 4.2 units. and the Vertex i want to move along the arrow till it hits the plane.
Non-UI version.
This example assumes we have a mesh object in edit-mode
import bpy
import bmesh
import mathutils

def extend_vertex(limit_axis='x', coordinate=4.2):

    obj = bpy.context.edit_object
    me = obj.data
    bm = bmesh.from_edit_mesh(me)
    verts = bm.verts
    try:
        v1, v2 = [v for v in bm.verts if v.select]
    except:
        print('need two vertices selected, or one edge')
        bm.free()
        return

    plane_idx = {'x': 0, 'y': 1, 'z': 2}.get(limit_axis)
    plane_co, plane_no = [0,0,0], [0,0,0]
    plane_no[plane_idx] = 1
    plane_co[plane_idx] = coordinate

    intersect_l_p = mathutils.geometry.intersect_line_plane
    new_co = intersect_l_p(v1.co, v2.co, plane_co, plane_no, False)

    # move closest of the two vertices
    A_len = (v1.co-new_co).length
    B_len = (v2.co-new_co).length
    if A_len < B_len:
        v1.co = new_co
    else:
        v2.co = new_co

    bmesh.update_edit_mesh(me, True)

extend_vertex(limit_axis='x', coordinate=4.2)

warning:
This doesn't take into account the object's unapplied Transforms (origin may not coincide with the world's (0,0,0), you may have scaling, rotation, translation), easy enough to fix - but it complicates the example code a little.
To take matrix_world into account, do something like this:
vertex_towards_plane.py


Only showing world texture, not allowing to add texture to other objects

For the blender internal:

You have to change the texture type. The button is in the texture panel of the properties window. It is highlighted in red in the image below. You will want it to me set to Material Textures, the second button. A object that can have a materiel must be selected. If everything is selected or nothing is selected that option will not be there.

For Cycles:

The texture must be added through the cycles material. The texture panel when using cycles behaves differently then in the blender internal. If there is a texture node in the selected materiel then the texture will display in the texture panel.


Is there a way to apply a transformation across preexisting keyframes?

Keyframes can be created, read, updated and deleted.
Descriptions can be accurate or inaccurate.
From your description it leads the reader to believe you can delete all the keyframes for one particular bone and then create a single new keyframe or transformation.  If there are no keyframes the current transformation is the one that dominates.


How would one paint a narrow circle around the edge of a circular object in blender

In general, it doesnt sound as useful to draw narrow circle in Vertex Paint. For such result you would need a lot of vertices or very specific vertices for this purpose. It would be better if you can closer describe what is your goal. Maybe you dont need to use a Vertex Paint for it.

Narrow circle you can achive by many ways ...
version 01 Material

create specific geometry and assign one material to object and create another one assigned to specific faces.

version 02 Texture

create material with Image texture

version 03 Vertex Paint

I dont know if there is a specific tool for it (Sculpt mode had some paint from curve). One way that lays on vertices position as well - you can create a Vertex Group by assigning vertices to a group ... (here displayed in Weight Paint mode)

... switch to Vertex Paint mode and use Vertex Color from Weight operator.

version 04 Paint Editor

in Image editor in 2.91 go to side panel (N) Tool - Stroke - Stroke Method - Curve, add a new and with Ctrl manually create a circle shape from curve, than press Draw


Can Blender take two video files and morph one into the other?

In short: you could do it manually by morphing tesselated plane with video in texture from one shape key to another. If sequences have no highly significant difference then it would look more or less acceptable.

This tutorial will help you:
http://www.blendernation.com/2014/01/06/morphing-photographs-with-blender/


How to calculate the cross-section area of an object?

One method is:

Enable the "3D Print Toolbox" (follow instructions here).
It can make it easier to move the object to be measured to the origin such that the axis for which you want the cross-section is aligned with a coordinate axis.
Create a cube.
Move the cube using the text entry feature to align with the axis of the object for which you want the cross-section.
For the axis perpendicular to the cross-section, scale this side of the cube to almost nothing (e.g. 0.000001 should be enough).
Scale the other two sides of the cube such that they are larger than the object cross-section to be measured.
Add a Boolean modifier to the cube with an Intersect Operation on the object. Apply the modifier.
Select the object and press H to hide it, so the cross-section profile can be selected.
Select the cross-section profile. Select 3D view > Tool shelf > 3D Printing tab, and select the Area button.
Divide the displayed area result by two (the area measured is the whole surface area of the intersecting object. Ignoring the insignificant side area, that leaves the front and back areas contributing to the total cross-section area).

This illustrates the process visually (unfortunately some recorded key presses were accidental):

Useful resource: Create Cross Sections and 2D planes in Blender


To adjust the size of the B-Bone display type in Blender, enter Edit mode and use CtrlAltS. It will scale while keeping it constrained. To scale on a specific axis, select the desired axis after triggering this with X, Y or X.


cut your mesh in QUADS

UNWRAP again

add the solidify modifier, and apply

after this do the following

Save you Blend
CTRL + A
Apply SCALE and ROTATION

to return the value of the scale to one

save your blend again to update all

separate PIECES !!

see the screencast key in the gif

Step 1

Step 2

Step 3
separate the pieces one by one until completing this

NOTE: it is very likely that you have to adjust your uv map of each of the pieces because you have separated them and you have added new faces, you can use the same texture just place the uv in the place where the part that should texture your texture is, worth phrase redundancy

Remember remove dobles before you separate the piece

Step 4
repeat the process in each piece until you complete everything

another way to separate the pieces

obtain this


Use a glare node in the compositor.
The glare node works using a "threshold", that will allow you to have the effect on pixels brighter than a certain value.
Read:
Any way to control light halos in the compositor based on emission level?


.FCStd is a native, software specific format. You can't import or export it within Blender. You can however use an exchange format. According to wikipedia FreeCAD can import and export .stl, .obj, and .dae (among others). Those three are ones that blender can also import and export.


Is there any way to make hair particles follow the z axis?

I don't think that perfectly vertical grow would seem "natural", but if you need that, you can set Z axis velocity, using advanced settings:

Otherwise, you could also use "particle edit" mode to "comb" your grass as you wish:

then you comb "hair"

to get this, for example:

If you manually edit particles, your particle system gets some what locked, after. You can always revert those edit, use the "free edit" button on the particle settings, then.

Finally, and otherwise, you could use "a curve guide": https://docs.blender.org/manual/en/dev/physics/force_fields/types/curve_guide.html

That needs another bezier object with force field "curve guide" set, and then activate a force field effect of the same type on your hair object. Like this:

Remember, you could also use more than one particle systems, so to get some variation, and each can be using different methods and settings...


Cycles renders alpha channel in black and grey instead of black and white

Edit: Found the solution. At some point I set my exposure to -6 which darkened everything in my scene. Located under Render Properties - Color Management - Exposure


Bend flat, circular object into half sphere

Use a Cast Modifier.

For some reason you will have to move all you circle vertex up in local Z axis for it to work for some reason, then have to eye-ball the value to reach an aproximate half sphere.

In my case, move the circle [2] units in local Z axis in edit mode, then add a Cast modifier set to Sphere. Adjust tge Factor value.

Alternatively use the Control Object option, set it to an empty object to control the deformation center and move it down in Z axis as necessary, if you don't want to move the circle object center.


Depending on what the rest of the code does (and whether it handles any exceptions) you could simply raise an exception with :

raise Exception(“I’ve just triggered termination of my script”)

If the code doesn’t specifically handle exceptions then this will terminate the processing and Blender will report the message raised in the exception.

Obviously, you can replace the text with your own, appropriate to the situation.


AFAIK the unwrap function always unwrap inside the 0-1 area no matter what.

If you want to unwrap again some parts of your UV without affecting the rest, you can pin what you want to keep before unwrapping.
Just select in the UV Editor, then click UVs → Pin or press P. Don't forget to unpin when you're finished with ⎇ AltP


How do I delete a shader node (From Script)?

You can do something like this:

import bpy

#Get the material you want (replace the name below)
mat = bpy.data.materials['Material']

#Get the node in its node tree (replace the name below)
node_to_delete =  mat.node_tree.nodes['Principled BSDF']

#Remove it
mat.node_tree.nodes.remove( node_to_delete )


how affect all children or parent of object?

I'm not sure if I understand you correctly, but you do not need separate code for each object that has the same behavior. You can use the same sensor/controller configuration at each of the objects.

When the enemies are all copies of the same object(s) you can assign them a group and add group instances to the scene.

This way you just configure the original in Blender and all instances receive the changes. This even works with add object when running the game.


How to wait for an operation - to another operator - to complete within an operator (import_scene)

Path of least resistance. this works but it's hardly programmatically sound. if anyone has nay other functioning solutions i'm all ears :)

sceneobjects = 0
currentobjects = 0

def modal(self, context, event):
    if self.currentobjects > self.sceneobjects:
        bpy.ops.object.select_all(action='DESELECT')
        print("finished")
        return {'FINISHED'}
    else:
        self.currentobjects = len(bpy.data.objects)
        print(context.window_manager)
        return {'PASS_THROUGH'}

def invoke(self, context, event):
    #save current number of objects on scene
    self.sceneobjects = len(bpy.data.objects)
    #start the import
    bpy.ops.import_scene.fbx("INVOKE_REGION_WIN")
    context.window_manager.modal_handler_add(self)
    return {'RUNNING_MODAL'}


What is the difference between an edge loop and an edge ring?

Edge Loop
An edge loop is a series of directly connected edges:

You can select an edge loop with AltRMB.
Edge Ring
An edge ring is a series of edges which are not directly connected, but share faces:

You can select an edge ring with CtrlAltRMB.

As a bonus, you can run the select edge loop or the select edge ring operator on every selected edge automatically by pressing Edge loop or Edge ring in 3D view > Header > Select.


Cycles Render not utilizing the GPU as it should

GPU usage is highly dependent on the scene complexity. With a very simple scene like the one you tested, it is hard to bog-down a modern GPU. But with a realistically complete scene, you can expect the GPU usage to be a lot higher.

Take a look at this Cycles rendering benchmark


How can I make the pink part of this texure glow?

Easy - Since the other "color" in your image is black, all you have to do is connect it to the Emission input of the Principled BSDF. You'll probably want to increase the strength a bit as well (underneath). Don't forget to turn on Bloom in the Render Properties tab to make it glow properly:


Viewport face colors are different on the same mesh

It sounds like you have a non-manifold topology.  If you can travel from the inside of the mesh to the outside of the mesh by stepping from face-to-face without flipping sides then that is the case.  First, please check out the suggestion by @MrZak. If the Recalculate Normals button on the Shading/UVs tab (Edit mode:A then CTRLN) doesn't work you could be correct in that Blender is getting confused about what's inside and what's outside.  This can sometimes happen when you have an edge that doesn't have two faces connected to it - the Recalculate Normals function is only likely to work when this is true although there are a few special cases where it will still fail.  In edit mode select everything and then Delete Duplicates, then repeat the Recalculate Normals step above.

If this still doesn't solve the problem then you have an issue with the mesh that will probably need to be fixed by hand.  In the viewport render the darker faces indicate that the surface normal is pointing away from you while the brighter faces have a surface normal pointing towards you.  With a clean topology all faces will point towards you.  You will probably need to zoom in and look at the vertices, edges and faces near the transition between the two types of face.  You probably have a twisted face somewhere, or possibly faces or vertices that have been scaled by a negative number - which would cause the face normals to be inverted.  Given the apparent symmetry in your screenshot I suspect that a scale in the X or Y axes of -1 will resolve the issue surrounding the flipped geometry.  The remaining issue is the join between the current correct geometry and the incorrect geometry this may require a manual deletion of the linking edges or faces and then a relinking with new edges and/or faces.

For example

To create this I started with a UV sphere, deleted the bottom half, extruded the bottom and added the lip along the lower edge.  I then selected the upper part of the original sphere and separated it from the lower part using P , then I scaled it in X by -1.  Here is a slice through it:

You can see the blue lines showing the surface normals indicating that the lower part points outwards (correct) and the upper part point inwards (incorrect).  To fix this I select the faces in the upper part and scale in X by -1 to give this:

As an alternative I could have simply selected the incorrect faces and then clicked on the Flip Direction button to achieve a similar result.  (This has the disadvantage of preventing you from using Recalculate Normals for any future issues the geometry might have as doing so will undo your changes and you will have to flip the incorrect faces again).

You need to be extra careful around the point marked with the red circle because if the correct and incorrect faces are connected then fixing one problem will create another.  In this case, if it applies to your situation,  you will need to separate the incorrect geometry from the correct geometry before applying the above scale.  The once applied you can reconnect them two parts.


my menu material is different from most people's menus on the internet, how to replace it?

As @Lemon said,
change your RenderEngine to Cycles and in the MaterialTab tick "use nodes". Now you have the same menu as in the YouTubeTutorials.


How to make an rod to rotate with another rod both have pivoting point at the origin

There's no need for Animation Nodes, here, unless you have reasons. You can used a Locked Track constraint on the red arrow.
Here, an Empty has been parented to the tip of the green arrow, for the red arrow to follow. The red arrow has been given a Locked Track constraint as follows:

.. so it points its own X axis at the Empty, while constrained to the plane whose normal is its own Z. (Apologies for the axes not being the same as yours, you'll just have to swizzle them). The green arrow is free to rotate...

...the red arrow points in the direction of the green arrow's projection onto  the red arrow's XY plane.


How to bake displacement map to different object?

You have to have low an high poly mesh in the same position, enabled Selected to Active in Bake options and new image texture in each low poly mesh materials(if there is more then one) texture node. Then You select high poly mesh first and low poly second and hit Bake.If you would like to know more details, here is a good tutorial on this topic


Not sure this is exactly what you mean but you if you want a shader only approach, try something like this. Lights in Cycles are just Emission objects anyway.


On a side note, I would use the Background BSDF for the worlds background.

You can use the Texture Coordinates Window socket (which you are using already) to determine, wether a light ray is inside the cameras view or outside.

Separate the Window sockets output into its channels. This will result in X, Y and Z coordinates from the camera view window. We are interested in the X and Y values which are inbetween of [0, 1]. We can filter them out with the Greater than and Less than nodes.


How to make translucent glossy soap-like material?

This is closest I can get. It is kind a partial answer but it could be starting point for you.

I've used fot this Subsurf Scattering shader added to Translucent shader and then mixed with Glossy shader by Fresnel to give it fake PBR look.

Here is a node setup:

And .blend file:


Do you have 1-1 vertex correspondence? If so, with both meshes selected, you could try adding one mesh as a shape key on the other.:

Then, move the slider to apply the shape key at 50%:

If your meshes don't have the same number of vertices, you can use a use a shrinkwrap modifier to warp one mesh onto the other before the shape key. This will make it match the other as closely as possible (consider this 100%). Then, you can apply that shrinkwrap as a shape key and turn the shape key back to 0.5 (consider this %50). Rinse and repeat for additional versions of the mesh.


foreach_get/set a mesh vertex group data?

I'm not entirely sure if this already is possible in some way but I made a patch last year that hasn't been reviewed yet to read/write vertex weights in batches. It speeds it up by around a factor of 8x. If you really really need it (and only on your computer) you can download and compile yourself.
https://developer.blender.org/D6227


How do you remove a draw handler after it's been added?

Your method makes a new instance.  What you want to do is make some kind of global variable for dc.

Could declare a global variable, make a get set property on some blender class. Another way to do this is to use the driver_namespace

import bpy
import blf

class DrawingClass:
    def __init__(self, context, prop):
        self.prop = prop
        self.handle = bpy.types.SpaceView3D.draw_handler_add(
                   self.draw_text_callback,(context,),
                   'WINDOW', 'POST_PIXEL')

    def draw_text_callback(self, context):
        font_id = 0  # XXX, need to find out how best to get this.

        # draw some text
        blf.position(font_id, 15, 50, 0)
        blf.size(font_id, 20, 72)
        blf.draw(font_id, "%s %s" % (context.scene.name, self.prop))

    def remove_handle(self):
         bpy.types.SpaceView3D.draw_handler_remove(self.handle, 'WINDOW')

context = bpy.context
dns = bpy.app.driver_namespace
dns["dc"] = DrawingClass(context, "Draw This On Screen")

After running the above, can then remove handle from this class with (from py console)

>>> dns = bpy.app.driver_namespace
>>> dc = dns.get("dc")
>>> dc
<__main__.DrawingClass object at 0x7f04830967b8>

>>> dc.remove_handle(
remove_handle(self)
>>> dc.remove_handle()

And the class stops drawing to the screen.


Move Object on Path through physical properties

This is an interesting question, and there is probably a better way than what I'm going to suggest.  But in the absence of another answer, one way you could approach it is to actually just simulate everything, including the curve that needs to be followed.

Let's say you want your object to follow a curve object.  Make your curve into a tube - in the Curve tab, under Shape, set Fill to "Full"; under Geometry, set the Bevel depth and Resolution to values that give you the kind of tube you want.  It's going to have to be the kind of tube that, in the real world, a marble would roll down, i.e., it's going to have to start relatively high on the z axis and slope down overall, although there can be sections with upward slopes.

Convert your curve to a mesh.

Make a ball object (e.g. a round cube).  Scale it to fit comfortably within your tube.  Put it at the start point in the tube.

Enable rigid body physics for the ball and the tube.

Ball:in Physics tab, under Rigid Body, set Type to Active; under
Rigid Body Collisions, set Shape to "sphere"; set Friction and
Bounciness to zero; under Rigid Body Dynamics, set Damping to zero
for Translation and Rotation
Tube: in Physics tab, under Rigid Body, set Type to Passive; under
Rigid Body Collisions, set Shape to "Mesh"; set Friction and
Bounciness to zero.

If you set your simulation going, the ball should roll along the tube, obeying gravity and angular momentum.  However, I've found that even without friction and damping, the ball loses momentum over time and can't climb small hills it should be able to climb.  The ball kind of bounces around in the tube which is partly impacted by the tube geometry, I have not found a way to really eliminate the bounciness.  Adding geometry to the tube only seems to make things worse.

Now, parent whatever object you actually want to animate to the ball.  This object shouldn't have any physics on it.

I have tried playing around with acceleration points using empty objects with Wind force field physics, but this has been . . . well it's fiddly.  Getting the strength and falloff right seems to be quite difficult.

Alternatively there is a "Curve Guide" type of force field, which can be set only for curve objects.  However this force seems to affect only particles . . . which is fine, you can create a particle system with a single particle and it is affected by the curve guide field.  The bigger problem is getting the curve guide force to integrate with gravity and angular momentum, and that may be . . . well I haven't had any luck.


How to organize bookmarks in the file browser?

You must edit a file called bookmarks.txt with your favorite text editor (e.g. notepad).
This file appears on your configuration folder of blender, which varies in location depending on your OS. As bookmarks are user specific, it will be in the user configuration path for your operating system. See the wiki.
Windows:
For Windows it is usually in %appdata%\Blender Foundation\Blender\2.69\config where 2.69 is the version of blender which you are using, and %appdata% is the AppData directory of your user folder).
Linux:
It will be in ~/.config/blender/2.69/config/, where ~ is your home directory.
OSX:
According to the wiki page about file paths, it should be in /Users/{user}/Library/Application Support/Blender/2.69/config/
Portable:
If you create a directory called config inside the 2.69 directory (where 2.69 is your version) this file will appear there the next time you run blender and add a bookmark.


I cannot rotate objects with python script in animation

Adding a keyframe for the rotation part was missing.
Just add:
myobj.keyframe_insert(data_path="rotation_euler")


Not sure if it's meant to be that way, but I found a fix.
By adding this to the operator, there is no more problem.

bl_options = {'UNDO'}

I suppose the ring function requires it somehow.


How to change the pivot point of scaling to the center of selected vertices in Blender 2.8?

You just have bad transform pivot set up, you have to change it to the median point


3D Print Toolbox Intersection Check Problems

This is a real regression indeed, compared e.g. to version 2.83.4. I see you've also asked here: https://blenderartists.org/t/strange-results-using-3d-print-toolbox-to-check-intersections/1258126 (pasting to ensure others can find an answer if it's posted there).
The only solution for now is to keep the 2.8x version around and use it primarily for running the 3D analysis, then moving up to 2.90.1. I have no other solution for now.
Is the issue reported on the blender bug tracker? Given importance of 3D printing and such, I would think Blender can afford an auto test ensuring such regressions does not slip between stable versions.
Cheers.


I would try removing double vertices and recalculating the normals.


Cycles: Will fire and smoke on GPU be supported in 2.75?

No.

I found that if you want a fast facsimile is to use OpenGL render (not in the render menu, rather a the top of the interface).  I rendered 100 frames in about a minute on a black background then "add" layer composition to the GPU smokeless animation.  Looks really good.


Custom exporter and problems with matrix and rotation order

With ther help of batFINGER and the other post, here's the working code:

import bpy
import mathutils
import math
from bpy_extras.io_utils import axis_conversion

item = bpy.data.objects["Camera"]

wm_src = item.matrix_world.copy()

m = axis_conversion(from_forward='-Y',
        from_up='Z',
        to_forward='Z',
        to_up='Y').to_4x4()

wm = m @ wm_src

rot = wm.to_euler("XYZ")

rotx = math.degrees(rot.x)
roty = math.degrees(rot.y)
rotz = math.degrees(rot.z)

rot_fix = (rotx, roty, rotz)

print(rot_fix)


The box you are looking for is the file name box, where you input the file name for the undergoing operation. Those buttons allow to increment or decrement the file numbering automatically

If you open the File Browser as a regular editor, there is no "default file action", it just open for view and navigation purposes, and as such the file name box is unavailable because there is no active operation to preform.

To have the name box available and the increment/decrement visible, the file manager has to be invoked from a menu to preform some IO action, rather than a permanently open browser part of the workspace layout.

If you go to File > Import or File > Save as or any other file operation like linking, appending, exporting, or any other operation that requires specifying a file the name box will show, along with the buttons.


The print statement worked fine for me. My approach would be to collect the positions in a list and iterate at the last frame over the list to determine the length.

import bpy
from mathutils import *
from math import *

test = Vector((0,0,0))
locations = [] # list to hold all locations between start and end frame

def my_handler(scene):
    if scene.frame_current == scene.frame_start:
        locations.clear()
    if scene.frame_current == scene.frame_end:
        total_len = 0
        for i in range(len(locations)-1):
            d = locations[i] - locations[i+1]
            total_len += d.length
        print("length %f" % total_len )

    location = bpy.data.objects['cube1'].location
    locations.append(Vector(location))
    #print(location)
    #print(locations)

bpy.app.handlers.frame_change_post.clear()
bpy.app.handlers.frame_change_post.append(my_handler)


How to turn these voronoi texture stars white

You can for instance take the star from the Voronoi and use that to mix white with the current color output:


How to build a Shader for Anodized Aluminium

Here's what I have come up with.

The shader consists of a little bit of diffuse mixed into some fairly rough gloss, with a smoother Fresnel gloss mixed in at the end.  I also noticed that the gloss on you reference image has a very slight, yet distinct, variation in reflectance across the phone.  To simulate this I added a noise texture controlling the roughness of the two glossy shaders.

Here is my node layout:

Click to enlarge.

A few notes:

I am using Geometry > Position as mapping coordinates for the noise texture to get even scaling.  Using generated coordinates on an object with a non-cuboidal bounding box results in stretching.
I use an RGB Curves node to bump up the contrast.
All the math nodes just remap the [0,1] range of the texture to the desired ranges for the glossy roughnesses.
The colors in the above node layout are for the gold shader on the right of the render.  The silver one just uses grey in all 3 shaders (light grey for the glosses and slightly darker for the diffuse).


How can I smooth edges but keep faces untouched?

While the best would be to find a topological solution, Shade Flat and Shade Smooth can also be applied on a per face basis in edit mode.  This can produce some strange results sometimes.


That's actually not a glitch. As weird as it looks, the Snake Hook tool is behaving exactly like it should in your case.

To get the tool working as you want it too, your object needs more geometry (more faces/vertices). Sculpting by default only modifies the vertices that your object has. In order to get the tool to pull out a tentacle like shape (like what is shown on the tool icon) you need some way of adding more vertices to your mesh. Currently the brush only affect the dozen or so vertices that are under it when you click. This is not nearly enough to create the shape shown by the brush icon. There are 3 main ways to add more vertices:

Add more vertices manually: This is probably not what you want to do in your case, but one of the ways to add more vertices is to simply add them in edit mode. You could use the loop cut tool (Ctrl+R) or subdivide(W) or some other tool. The reason you dont want to do it this way in your case is because for your object one of the next two ways will be better.
Multiresolution Modifier: The multiresolution modifier works very similar to the subdivision surface modifier in that it subdivides each face (splits it into 4 smaller faces) and then smooths the result. The difference is that the small faces generated by the multires modifier are sculptable, where as they are not for the subsurf modifier. To add a multires modifier, select your object and navigate to the modifier tab in the properties panel (the little wrench in the row of icons near the top left of your screen. Click the add modifier button and select Multiresolution from the Generate column (about halfway down). Then in the modifier option click subdivide as many times as you need to get it as smooth as you want. Just be careful as this modifier can generate a lot of vertices and make blender run slower.
Dynamic Topology: This will probably be what you want to do to get the results you are looking for. In sculpt mode, in the toolbar on the left there will be a panel titled Dyntopo (short for Dynamic Topology). Checking this option will make the Snake Hook tool generate new vertices only where it need them. You may want to adjust the detail size to make it smoother if need be. I would recommend looking up a tutorial that explains sculpting as it will be more thorough than I am here.

If you are new to Blender you are probably going to run into a lot more problems like this, as Blender is sometimes a bit unconventional in how it goes about certain things. There are many good introductory tutorials that can get you up to speed. CG Cookie and BlenderGuru both have excellent introductory series that can help you get started.


Selecting the Texture in Texture Paint Mode

You are needing the Texture Slots tab in the Properties panel in the tool properties. Select the appropriate slot to determine where your paint will go. Here I am using two image textures set to box mapping and one black generated image as a UV mapped stencil between them.

I used an RGB Color Mix node to combine the two textures with Multiply mix mode, so that the rust adds to the original texture instead of replacing it.


EEVEE is showing screen space reflections in the viewport, but not in the final render

sorry if this dose not usefull for you because i used google translate.
so first you have to do...(like imagine)
before

after

second

and i hope this help you.


Compositor: How to crop an image into multiple versions?

This can't be done in Blender, because the image pixel dimensions will always be that of the Scene from which the Render button was pushed.

I used a File Output node to test this, saving rendered data from different Scenes, each with different render dimensions. Their dimensions were overridden by the dimensions of the main Scene.

I'll post the .blend for anyone curious. It's nothing special.

What this means is that even if you use nodes to get the scaling and cropping right, you will just end up with transparency around the image. (If scaling up your image will be clipped instead.)

This sort of task should be done with other software, such as imagemagick or Photoshop (using Actions). Here is how to do it with imagemagick using scripting.


Connecting NodeSockets of differing types

RGB(A) to Value

It is neither a weighted sum nor the max channel (as is the case for Value in HSV) - instead it's something I don't understand at all, something to do with the black magic of color management, but I'm happy to write it here anyway :)

In node_shader_valToTgb.c is the function node_shader_exec_rgbtobw, which calls IMB_colormanagement_get_luminance(col). Inside that function, we have dot_v3v3(luma_coefficients, rgb) - the dot product of the input color and some apparently random numbers at the top of that file: luma_coefficients[3] = { 0.2126f, 0.7152f, 0.0722f };

Recreating that as a node setup in blender gives the same result as you'd get from plugging the color into a Color Ramp node or RGB to BW node:

The cube render is black meaning the difference = 0

Shader nodes are always only RGB and never include an alpha channel. However, in the compositor they do. When converting RGBA to a Value in the compositor, the alpha channel is simply ignored - only the RGB values are used.

RGB(A) to Vector

The alpha channel is simply discarded - Red becomes X, Green becomes Y, Blue becomes Z.

We can prove this by plugging a render into a Vector Curves node, and plugging that into a Viewer node - notice that the background becomes black (as the RGB values in that space were all 0):

Vector to RGB(A)

It's simply the opposite of what's said above. X becomes Red, Y becomes Green, Z becomes Blue. The alpha is always assumed to be 1.0.

Anything to Shader

This is the one exception - nothing is ever automatically converted to a shader, the result is always simply black, no matter what color or value you plug into it.

Personally I think this design is silly - if you plug a color straight into the material output (without going through any shaders first), you're expecting the result to be shadeless. But alas, this is not the case.

Value to RGB(A)/Vector

This is pretty obvious I think, but just for completeness: Whatever the value is becomes the same for each channel/axis when converted to RGBA/Vector (though the alpha channel simply = 1)

Have I missed anything?


Before adding keyframes you need to apply the rotation using CtrlA.
You are experiencing a gimbal lock, which happens when two rotation axes coincide causing a loss of rotational freedom- in this case, the X and Z axes. This is because you have set the Y rotation value to 90, so applying it should solve the issue.
More on gimbal lock: https://en.wikipedia.org/wiki/Gimbal_lock


Make selected edges equidistant, like you can in Inkscape?

You may use Loop Tools specials to do it. Select one edge of your mesh (Alt+RMB), then press W-->Loop Tools-->Space.

You can enable the Loop Tools in User Preferences (Ctrl+Alt+U).


you have to use own.scene.convertBlenderObject(bpy_object) to wrap it in a KX_Object / convert its logic


Is it possible to select a face in the UV editor and find it in the 3D View?

In the header of the UV editor window there's a button named "keep UV and edit mode mesh selection in sync", an icon with an arrow pointing to a cube mesh.

That resolve your problem.
Consider that also in the UV window you can choose if to work with vertices, edges or faces!
Notealso: if this button is selected, you can't edit the UV islands.


Edit STL file and perform a very simple cut

Well, as you seem to have discovered, there is no shortage of possible ways to go about this.

Without going into too much detail, I would probably use a boolean modifier in this case. To do this:

Import your STL file (File > Import > STL)
Create an object roughly in the shape of the hole you'd like to create in the STL.
To do this:

Add a cube (⇧ ShiftA> Mesh > Cube)
Scale it on the X axis to make it thinner (S to scale, X to restrict the scaling solely to the X axis,  LMB or ⏎ Enter to confirm and exit the scale operator)
Grab (G), rotate (R) and scale (S) the cube into position such that it intersects the buckle object where the hole should go.

Add a boolean modifier.
To do this:

Select the buckle object (click on it with  RMB) and add a  boolean modifier in Properties > Modifiers
Set the object added in step 2 as the "Target" object in the boolean modifier
Set the boolean operation to "Difference"
(Optional) Set the cube's Maximum Draw Type to Wire in Properties > Object > Display, so you can see the result of the boolean operation better

Adjust the cube further if needed
Export the result. Either Apply the boolean modifier and delete the cube object before doing this, or enable Selection Only in the export options and ensure that the cube is not selected.


Go to Edit mode.

Select the vertices or faces of the part you want to separate and press 'P'.

This opens the 'Separate' menu, where you can choose 'Selection'.

That's all. Now you will have that part as a separate object.


You could put the materials into nodegroups, and switch between them.
This setup can switch between any number of groups by animating the value node.
(I'm sure this was answered somewhere before, just couldn't find it)


Color all of my models using one texture

Just create a new material and assign it to all faces.
Make it uses the desired texture as diffuse or whatever channel suits you.

Then part by part select the faces of your mesh and unwrap them using any simple method with U > Unwrap

In the UV/Image Editor scale down the islands so they fit totally inside one of the nine color cells.

Repeat until you are done. You can readjust them easily by moving each island individually over a desired color.


Switching resolution wipes rendered layers?

Maybe something that auto-saves every render, and won't overwrite previous, just append a number to the end? Someone wrote a script that I think does this - https://blenderartists.org/t/autosave-every-render/425838/9


Animate winding a ribbon/rope/cable around a cylinder?

The strip follows the cone using this principle:

The cylinder turns due its parent, an empty which rotates
The strip object turns too, with the same empty as parent
The cone orientation (-Z axis) and location are used to ray cast on the cylinder: this gives a new position on the cylinder to complete the strip

All that is done using Animation Nodes.

More detailed steps:

Calculate the cone location and -Z orientation in world coordinates
Raycast on the cylinder from these previous parameters
This raycast gives a position on the cylinder and the normal of the hit face
Calculate the new strip part position from this previous data, extending it along the cone X axis and shifting it a bit along the face normal
This calculation replaces the last two strip vertices
Add new two vertices to the strip and place them at the cone position
Make a new face for these last 4 vertices
Input back all these vertices and polygons in the strip geometry

The overall cartography:

1/ Calculate the ray cast and new strip part's position

2/ Give a width to the strip

3/ Extract strip's current geometry

4/ Calculate last 2 previous vertices index

5/ Injects updated and new vertices in the strip data

6/ Make a new face from the last 4 vertices

7/ Put all back to the strip data

Note:

To make it work, the strip have to include at least an edge at the beginning of the animation.
This node setup is "constructive", at each frame it creates new vertices, and this is not rolled back at the end of the animation. So, to replay it, edit the strip and delete all its vertices except the two first ones.

To do list:

Constraint the cone -Z axis to always point to the cylinder, as if not the raycast will fail
Raycast on the strip itself too so that it superimposes on both the cylinder and on itself
Not only raycast one (middle) point, but the two extremities of the newly created strip's vertices

Another example, following the comment:


How to separate the object to smaller units to give different materials to the different parts?

Materials are assigned on a per-face basis. You can think of assignment to an object as a convenience function: 'Assign to all faces in the object's mesh'.
Assign to individual faces in Edit Mode. Add slots using the '+' sign next to the material slots panel. Select or create materials to occupy the slots.

Select the slot. Select the faces. Hit 'Assign'.


How to create a kinetic depth effect illusion?

At its simplest, something like this?

Create an environment-sphere, and put the camera and target object inside it.

Give the sphere your desired star-field texture in its object space, something like this:

Give the target a copy of the material: you will change its texture-scale manually to match the background as closely as possible.
Give the camera a reasonably long focal length. (Here, 100mm.) The more closely the camera approaches orthographic, and the more distant the target from the camera, the less apparent variation in texture-scale there will be between the near and far points of the target, but you sacrifice some perspectival visual cues.

For this sort of result:

I guess you could automate the scale of the texture according to the distance of the shading-point from the camera, but I'm not sure the resultant 'swimming' of the object through the texture would help.. I haven't tried it.


How do you make a cluster of cubes explode?

Add Active Rigid Body Physics to your cubes.
(I created the cubes with 3 array modifiers applied, then separated By Loose Parts, and finally moved the origins to the geometry.)
Add a force field in the middle of the stack of the cubes.
Increase the strength of the force field.
Press play or AltA and watch the explosion.

Quick gif showing the whole process.

Final result


How do I get rid of unwanted corners inside a bent tube?

I think this is a great question, because it applies to real-life engineering too. Before getting rid of that troubled geometry it helps to understand why it happens in the first place.

Problem

The reason for the overlapping geometry is that the radius of those bends is smaller than the radius of the tube minus the thickness.

Radius of tube exceeds bend radius:

Resolution

Either make the bends bigger or the radius of the tube smaller. If you want a tight corner tweak them so that the bend radius is about the same as the tube radius (plus or minus the tube thickness). Then use the solidify modifier in the offset direction which allows you to give it thickness (either offset towards the inside, or outside)

See: just about right

Whether you use bezier or spun geometry, is really down to personal taste. The bezier approach allows you to quickly edit your path, and while it will not give perfect arc bends mathematically, that might not matter for your purposes. If you are to simulate real tubing, that too is almost never perfect arc.

If you need to make a lot of tubing here's a blend that uses the sverchok  parametric addon, it lets you adjust the tube radius and bend radius on the fly till you get it right.


boolean modifier leaves cutting edge on face

If you want to convert that Ngon into quads delete it and use Ctrl+E > Bridge Edge Loops; it should work nicely if amount of vertices is the same.

However you can use more convenient way in order to construct cylinder like on your screenshot.

Start with simple cylinder, select its top and bottom faces (Ngons) and  inset them. Press I and drag the mouse to change effect.
With both Ngons still selected use Bridge Edge Loops.


What is causing this model to be "shiny" in Object mode?

Smooth Shading W -> Shade Smoth (in Edit Mode)

Most objects are represented by polygons and truly curved objects are often approximated by polygon meshes. When rendering images, you may notice that these polygons appear as a series of small, flat faces.

Smooth Shading tries to interpolate surface of model so you can't see faces.   Usually we want our objects to look nice and smooth,  but sometimes this makes this ugly artifacts than it tries to smooth too large angles between faces. Like in your case - 90 degrees.

So, turn off smooth shading, or, if you want to use it, set auto smooth option:


What are the Images in the UV editor for and how to prevent them affecting OBJ export?

I think I've found a workable answer. My fragment of python for setting these images to None was almost there, there's a more in depth version in this answer:
How to unlink material from a mesh, with python script?
I keep my materials, but the answer also covers this UV tex_face property that is the problem.

The whole tex_face feature is going away in 2.8 (which is a good thing as it's old and really well hidden and rarely used):
https://developer.blender.org/T51382

However there is one more crucial step which is to drop out of edit mode, otherwise none of the changes to the uv_texture images take effect before the export goes out, see the gotchas here:
https://docs.blender.org/api/2.79/info_gotcha.html#modes-and-mesh-access

So my final code fragment is as follows:

bpy.ops.object.mode_set(mode='OBJECT')

# Strip all the tex_face data, otherwise the obj export will use it
# We want it to use the material textures.
for mesh in bpy.data.meshes:
    if mesh.uv_textures.active is not None:
        for tf in mesh.uv_textures.active.data:
            tf.image = None

for mesh in bpy.data.meshes:
    for texlay in mesh.uv_textures:
        for tf in texlay.data:
            tf.image = None

Now my export seems to be behaving itself.


You cannot create faces or vertices that are shared across different objects. All vertices, edges and faces need to be part of the same object.

Select all of the circles, join them into a single object (shift select the objects to be joinede and press Ctrl+J). Once all vertices belong to a single object then you can use the bridge edge loops tool.


Set parent with automatic weight for selected bones only

Select the vertices in Edit mode, remove them from all vertex groups named like a bone, and add them to this one group that has the same name as the bone you want to parent the vertices to.
Blender creates a vertex group for each bone if you parent the armature With Automatic Weights, With Empty Groups or With Envelope Weights. The weight assigned to the vertices in the group controls the influence of the bone on the mesh.
If you move the hips and the arm moves as well then you need to remove the arm vertices from the hips vertex group. You can do this visually in Weight Paint mode (paint with WP=0), or in Edit mode with plain numbers by editing the values in the N-panel (Item > Vertex Weights) or assigning/removing vertices from the group (Object Properties > Vertex Groups).
If you remove the weight of the hip bone from the arm you should add it to the arm bone (keyword normalize weights).


How to make my prop search show the objects in my scene?

When using property search, you need to specify the collection of objects you want to search through in the 3rd and 4th parameters (in our case the list of objects in the active scene):

layout.prop_search(
    scene.ignit_panel,  # Object with your custom property
    "screen_selector",  # Your custom property
    context.scene,      # Object that contains the collection you want to search through
    "objects"           # The collection property
)


How do I get a python reference to the viewport camera?

If you use 'PRE_VIEW' or 'POST_VIEW' as draw handler type, you will be in world space and can draw straight ahead. If you want to draw on top of everything ("X-Ray"), then calculate the 2d region coordinates and use 'POST_PIXEL' - there is a utility function for the conversion:

from bpy_extras.view3d_utils import location_3d_to_region_2d

Here is a quick example that draws a line between 3D cursor and active object origin, using 'POST_VIEW', which will consider depth of other objects ('PRE_VIEW' would draw under everything else):

import bpy
import bgl
import blf

def draw_callback_px(self, context):

    ob = context.object
    if ob is None:
        return

    font_id = 0  # XXX, need to find out how best to get this.

    # draw some text
    blf.position(font_id, 15, 30, 0)
    blf.size(font_id, 20, 72)
    blf.draw(font_id, ob.name)

    # 50% alpha, 2 pixel width line
    bgl.glEnable(bgl.GL_BLEND)
    bgl.glColor4f(1.0, 1.0, 1.0, 0.5)
    bgl.glLineWidth(2)

    bgl.glBegin(bgl.GL_LINE_STRIP)
    bgl.glVertex3f(*ob.matrix_world.translation)
    bgl.glVertex3f(*context.scene.cursor_location)
    bgl.glEnd()

    # restore opengl defaults
    bgl.glLineWidth(1)
    bgl.glDisable(bgl.GL_BLEND)
    bgl.glColor4f(0.0, 0.0, 0.0, 1.0)

class ModalDrawOperator(bpy.types.Operator):
    """Draw a line with the mouse"""
    bl_idname = "view3d.modal_operator"
    bl_label = "Simple Modal View3D Operator"

    def modal(self, context, event):
        context.area.tag_redraw()

        if event.type in {'RIGHTMOUSE', 'ESC'}:
            bpy.types.SpaceView3D.draw_handler_remove(self._handle, 'WINDOW')
            return {'CANCELLED'}

        return {'PASS_THROUGH'}

    def invoke(self, context, event):
        if context.area.type == 'VIEW_3D':
            # the arguments we pass the the callback
            args = (self, context)
            # Add the region OpenGL drawing callback
            # draw in view space with 'POST_VIEW' and 'PRE_VIEW'
            self._handle = bpy.types.SpaceView3D.draw_handler_add(draw_callback_px, args, 'WINDOW', 'POST_VIEW')

            self.mouse_path = []

            context.window_manager.modal_handler_add(self)
            return {'RUNNING_MODAL'}
        else:
            self.report({'WARNING'}, "View3D not found, cannot run operator")
            return {'CANCELLED'}

def register():
    bpy.utils.register_class(ModalDrawOperator)

def unregister():
    bpy.utils.unregister_class(ModalDrawOperator)

if __name__ == "__main__":
    register()

    for area in bpy.context.screen.areas:
        if area.type == 'VIEW_3D':
            bpy.ops.view3d.modal_operator({'area': area}, 'INVOKE_DEFAULT')
            break


If you are using Rigid Bodies, you can just decrease Speed in Rigid Body World settings under Scene tab:

You can also increase Step Per Second and Solver Itarations to get smoother and more detailed simulations.


How to do i disable a row.operator in my custom panel by detecting if there is a specific modifier type and name is present or not?

It is not the panel's job to decide if a button is enabled/disabled, the operator is responsible for deciding if it is able to be run with the current selection. The poll method of the operator class is used to determine if the operator can be run, if the poll method returns False then it's button will be disabled in your panel.

class myOperator(bpy.types.Operator):
    bl_idname = 'object.testing'
    bl_label = 'Simple test setup'

    @classmethod
    def poll(cls, context):
        mod_types = set()
        for o in context.selected_objects:
            for m in o.modifiers:
                mod_types.add(m.type)
        return 'ARRAY' in mod_types

    def execute(self, context):
        # do stuff
        return {'FINISHED'}

A panel can look through the context and adjust it's content based on the current selection, note that it is altering it's content and not disabling an item.

class samplePanel(bpy.types.Panel):
    bl_idname = "OBJECT_PT_example"
    bl_label = "Dynamic content"
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'

    def draw(self, context):
        mod_types = set()
        for o in context.selected_objects:
            for m in o.modifiers:
                mod_types.add(m.type)
        row = self.layout.row()
        if 'ARRAY' in mod_types:
            row.label(text='there is an array modifier')
        else:
            row.label(text='No object using an array')


Your background image is limiting the size of your render. If you look closely, you will notice that the render image that is not black is exactly the same size and color of the texture. The rest of the camera view is filled with the default black, or if you check Film > Transparent with a transparent alpha value.

You will either need to change the size of your image, or do some work in your compositor.

One way to do this is to add a Scale node after your image texture like this:

(Shift+A > Distort > Scale)

The result now looks like this:


How can I scale something with actual measurements in meter,cm,etc?

As mentioned, Scale is unitless, it's just a multiplier for the actual Dimensions.

The only solution is to divide the Final Dimension by the Current Dimension (FD/CD). You can type that directly into the scale value, Blender calculates it for you. So in your case type .335 / .285 which will result in a Scale of 1,17544 and your loop will have the correct dimension.


The cache limit in the user preferences only limits how much memory can be used by clip editor and the sequencer to preload frames for faster playback.
Fluid simulations are not limited by that value.

You can bake the simulation from the command line without loading blender's interface.


You have to check these squares in to allow screen space reflections:


What happens when I press F while selecting two faces?

What happens for real is a mega-super-wonky N-gon is created using all the vertices that are selected. F activates the fill tool, it appears to be vertex driven, that means it does recognize when a face is selected, just that there are four more vertices; hitting F forces blender to try to create a new face with all the vertices you selected as its extremities.

Lets assume that you were using nice, clean mesh, only quads. After selecting two faces, filling them

destroys the old faces
form a new 6-8 vertex face (depending on whether or not the faces were adjacent)
places the origin of the new face at the average of the vertices.

Now, I guess, this is essentially merging the two faces, but its bad form because it causes those dreaded N-gons, and you can see here what the results will be like when the faces aren't flush:


Why am I missing nodes in the 'Add node' menu?

There are three possible causes;

1- The render engine might set to Blender Render (also known as Blender Internal) instead of Cycles. Materials work very differently in each of the render engines, and are not interchangeable.

Blender internal does not use shaders, Cycles does.

To learn more about the difference between render engines read:How is Cycles different from Blender Internal? and Cycles vs internal vs game engine
2- The node editor might be set to a different mode.

There are three different modes for the node editor and they use different kinds of nodes.

By default the node editor is configured for compositing .

Change to the Material node editor (and make sure that the Use Nodes box is enabled).

:

More info:

https://www.blender.org/manual/editors/node_editor/introduction.html#node-tree-types

https://www.blender.org/manual/editors/node_editor/editor.html
3- If Cycles is not available in the render engine list, then it needs to be enabled in the System Preferences>Addon List (Access the system Preferences window by pressing CtrlAltU)

Look for the Cycles Addon in the render section, enable it using the check box and then save the user settings to enable cycles permanently.


how do you change material during animation

If you're using Nodes, you could use a Mixshader and animate the Value to change the material: 0 for one material and 1 for the other.


Why do fireflies increase with number of samples when using a hdri light source?

Fireflies is just the name that we give to the bright, isolated, pixel that seems to create a color discontinuity with the pixel in the neigborhood.

It is said they are resulting

  ...from numerical instabilities in solving the rendering equation.

So, talking about the rendering algorithm

  there is no guarantee that it would converge to the correct solution

Despite this, I think that in your case (and most of the times) the method is able to give a good solution, it's just a matter of iterations number.

Below you can see a few steps of the rendering process and an ending comparison with the result achievable by enabling Multiple Importance samples (see Commonly Ignored Features #1 from the author of the HDRI)

So "fireflies" from this point of view, can be considered as just the earliest stage of the rendering process, as they are when rendering caustics. We consider them bad because compared with other parts of the scene the area where they appears is always behind in terms of convergence.

Stop killing the wonderful fireflies! :)


In Edit mode, you need to bend the knees a bit so that Blender knows in what direction it is supposed to bend:


Volume is rendering through objects in foreground

The belt geometry is criss-crossing itself (exaggerated here for demonstration purposes):

To fix, delete and one side and re-extrude, this time being sure that it does not self-intersect.

↹ Tab into edit mode, ⌦ Delete
E to extrude, then drag the mouse around. If the extrusion does not already appear to be locked along the object's local Z axis (there should be a line indicating this), press Z twice. Then press 1 to extrude exactly one blender unit (or whatever value you desire), precisely along the blue line.

Another alternative is to use the solidify modifier.

Also note that your clipping settings are causing lots of artifacts in the viewport. Generally you want to keep the clipping range as small as you can. I found .1 . . . 1000 to work fairly well in this scene.


Vertices that seems to be aligned, are not?

i had problems like that as well. I ended up just starting from new and being very careful. Blender sometimes just creates some weird slightly invisible vertecies out if nothing. and if u don't ctrl + z them, I don't find any way to get rid of them


Unfortunately my answer got ignored, but I think i did it.

I've found out that i can adjust the skeleton. But there is the need to do a few steps:
1. Apply Armature modifier.
2. Select rig, go to edit mode and adjust all you need to adjust.
3. In pose mode apply current pose as rest pose.
4. Set Armature back.

It works for me. Yeah, i still didn't get the best result, but i'm trying. Maybe i'll add more information.


Create a collection and set the wanted objects in it (upper right part of the image above).

Then use a "Collection Info" node in the node setting and use the collection as input.


why do game textures that shouldn't be transparent have an alpha channel?

This channel can be interpreted by the game engine as grayscale data and used for any purpose like a subsurface scattering map, which may be what is happening here.  This is called Channel Packing.
Reference: http://wiki.polycount.com/wiki/ChannelPacking


Select the seven verts of the corner. Select the lower right vertex last so it becomes the active (white) vertex.

Extrude the selection with EESCAPE. That way the newly created verts stay in their places. Set the pivot point to 'Active Object' and scale the selection to 0 on the Y axis SY0RETURN. This will set all vertices to the y value of the active vertex, putting them in the back. Depending on how your object is oriented, you might need to pick a different axis.

Select everything with AA, remove doubles with WR and recalculate normals with CTRL-N


Given a float list representing the parameters of the points we want to split at. We can compute a list with the last element removed and a list with the first element removed and use those lists as the start and end list of a trim node respectively as follows:


How do you adjust and/or mute the audio of a video?

Actually, I think I know the answer. I've found it and it works! It's at the bottom left; click playback. Near the top of the dropdown menu, it says mute audio. Click that, and it'll be muted! Works for 2.82! Thanks still, to the community, for viewing/trying to answer this question!


How to apply stripe texture along a curved mesh?

Try using a wave generator set to use the Z axis of the object to power your color ramp.
I was able to get the following result by creating a curve, converting it to a mesh, and using the following node setup:

I've also used a Vector Math node to offset the pattern start, else the pink takes up more than it's fair share. Try adjusting the OFFSET input, as well as the Wave texture scale attribute.


How can I animate a mesh to be transparent without hiding the smoke that it emits also?

If I understand the question correctly... I think you are on the right track.
Simply disable the render-ability of the emitter object like so:

Then duplicate the emitter object and apply to it the shader which animates from opaque to transparent. (As described in this thread -> How can I animate an opaque material to being fully transparent in Cycles?)


Yes. Blender 2.75a works in Windows 10.

But I had some trouble making it work. After the upgrade from W8.1 to W10 it didn't work, but it was a problem of the new windows not having the correct drivers.

I didn't have to spend much time working it out. Windows 10 did, after some time and a few reboots, offer to install the correct drivers. That fixed most of the problems, including the usual trouble with hardware controls in laptops.

So, if you are upgrading to Windows 10, you might have some problems, but Blender will work well once your computer has Windows properly installed. At least it does with my Hardware.


Blender VSE - background color of video from imported image sequence

It now appears that I was wrong in suspecting this was something going wrong in the stage of rendering from image sequence to video. That is, it doesn't seem to be a Blender problem.

Timeline of my efforts:
I had viewed the rendered video with Windows Media Player, with Firefox, and with VLC player, same background color in each. With these three players giving the same result the error seemed to be in the video file itself.

For comparison I downloaded and installed Openshot video editor. Rendered a video (displayed with the same wrong background in the three players), then re-imported that video in Openshot. Then in the Openshot preview display the background color was correct: White.

Next I transfered a Blender rendered video to another computer, played it with VLC player, took a screnshot of a still and checked the background color, came back as RGB(255,255,254).

All of this indicates that the root of the problem is some misconfiguration of my graphics card.  Somehow display of the video goes wrong for each of the players that I used : Windows Media Player, Firefox, and VLC player.

While I don't know how to address the misconfiguration problem, it's pretty clear now that it never was a Blender problem.