Find location of a specific point on a UV texture on the 3D object

I figured out a way, although I am not sure if it's the simplest solution:

In order to locate the inner corner of the marker I need a vertex at that point. Therefore I seperated the marker into two faces and created a UV map like this:

Next, using a script (see related lines below) I select the marker and apply the shrinkwrap modifier (it is important to apply it so that the positions of the mesh/vertices are actually affected).

Since these markers only consist of now five vertices, it is fairly simple to select the one in the center of the marker and read out its local coordinates. Finally, with the object's world matrix I can calculate the inner corner's global position.

# make the active object the current marker
bpy.context.scene.objects.active = marker

# apply the shrinkwrap modifier to access the exact marker position
bpy.ops.object.modifier_apply (modifier='Shrinkwrap')

# get the local position of the inner corner of the marker
# (assuming the additional vertex in the center is at index 4)
local_inner_corner_pos = marker.data.vertices[4].co

# calculate marker position with respect to the global coordinate system
global_inner_corner_pos = marker.matrix_world * local_inner_corner_pos


I recommend you a free addon which I created, specifically for this situation:
Object Sequence (https://github.com/sacrish/Object-Sequence)
After installing the addon, first set up your scene with an hierarchy like this:

Basically put the objects which need to be switched in a separate collection (here I named it "objects"), meanwhile keep all other things like the table, camera, etc. in another collection.
Open Object Sequence panel from the "Misc" tab, select your collection of objects, and hit Sequentialize.

And you will notice in the timeline that the visibilities of the objects have been keyframed, with their object names labeled on corresponding frames.

Now hit Render Sequence in the Object Sequence panel, and the frames will be automatically rendered and saved. Save location is set in your Output panel, so make sure it's correct before hitting render.
I also have a Youtube video which demonstrates the workflow.


A quick easy way without scripting is to use the Outliner to disable render from cameras you do not wish to use.

If you specifically want to do it in script, you'll need to run through all objects of type 'camera' then set the value for those you wish to not to render.

bpy.data.scenes['Scene'].camera.hide_render=True

Render your scene then return the cameras.

Below seems to work fine but be sure to have your camera selected.

import bpy

list_of_all_scenes = bpy.data.scenes

if bpy.data.is_saved:
    for y in list_of_all_scenes:
        bpy.context.screen.scene = y
        selected = bpy.context.selected_objects
        objs = y.objects
        for x in objs:
            if x.type == 'CAMERA':
                x.hide_render = True
        objs.active.hide_render = False


Align an object to transform orientation with python


Something like this can split triangle into quads, just cut it with Knife tool K. But geometry will become densier in this place.

P.S. Also, I want to mention that if you are doubting how to subdivide something to quads - use Subsurf Modifier set to Simple mode (Simple - because we need to keep original curvature without smoothing). This is easy and absolutely non-destructive way to see how it can be done. So, add modifier and set viewport shading to wireframe Z and don't forget to enable Draw all edges in object settings.


Cycle Nodes problem. Have no idea where to put ColorRamp

The specular map that i had was way too powerful(went back to ShaderMap3 and inverted the value)
@Carlo made me realize that i should have put the output from the bump to the diffuse
I didn't needed of a ColorRamp, the specular map was at fault.

Thanks @Carlo


Scaling/Rezise in Blender 2.8 Python/Script not working on mesh

Another take on getting the result.

Rather than trying to debug what is happening with your question script here is another take to achieve what I believe is the desired result.

Test script, object mode, adds a cylinder, removes bottom face, scales top face.

Bottom and top faces have z component to their normals. This is how they are selected below.

Once selected, the bottom face is removed from the faces collection.

Scaling top face similar to  related question  Using python and bmesh to scale/resize a face in place , in this case,  using bmesh.ops.scale

Notice apart from adding the cylinder to test, there is no bpy.ops used.

import bpy
import bmesh
from mathutils import Matrix

scale_factor = 0.85

# add a cylinder to test

bpy.ops.mesh.primitive_cylinder_add()
ob = bpy.context.object
me = ob.data
bm = bmesh.new()
bm.from_mesh(me)

top_face = [f for f in bm.faces if f.normal.z > 0.5].pop()

bottom_face = [f for f in bm.faces if f.normal.z < 0.5].pop()

# remove bottom face

bm.faces.remove(bottom_face)

# scale top face

bmesh.ops.scale(bm,
        vec = (scale_factor,) * 3,
        space = Matrix.Translation(-top_face.calc_center_median()),
        verts = top_face.verts)

bm.to_mesh(me)
me.update()

Note bmesh.ops.create_cone(diameter1=1, diameter2=0.85) could be used to create the shape, removing the need to scale.

Suggestion, don't over comment code, and consider using if f.select: instead of if f.select == True:


How can put a mesh into a different position?

Align identical object by a twin tris
Let's suppose you have an object and another one, very similar to the first, and you want to overlay the two.
If they are not perfectlty identical, you should probably start an iterating computation that would progressively guess the function that best fit all the vertex positions...
...if instead they are identical (as in your case), but with different transformations applied such as in the picture below:

the problem is much more simple. If you'll get able to align one triangular face to the corrispective one, the whole mesh will be aligned. I would suggest to use the Precise Align add-on.
Basically you have to activate edit mode of both object (one at time), select the same triangular faces by selecting the vertices in the same ordere and than create a parented empty with the add-on command:

These two empty are now associated with the mesh. All you have to do is to match position and rotation of the empty object and the two jaws will follow their trasformation:

Overlapped!

Limit object's rotation
Easiest way to set up a moving jaw is to first of all add an empty that would represent the rotation pivot and than parent the upper jaw to it.

Now the jaw will follow empty's transfrormations.

Add a Limit Rotation constrain to the empty and assign min e max angles to limit the rotation of the jaw to a given range too.
Credits: jaw's model by lucasfalcao from Blendswap


Bodies linked with a Rigid Body Joint are detaching by itself in simulation

Ok, I found it. I had to set "No Sleeping" flag in the Physics properties for each of the rigid bodies.


The term standard is not used in the sense you think. It's not like an SI units standard or sRGB (literally meaning standard red green blue) standard. There is no definition for lowpoly, other than it needs to display in real-time. It depends on hardware.

By modern standards (standards in hadrware) it is safe to say that the dolphin can be rendered in real-time and so would be considered low poly.

By ancient standards (4bit computer the size of a room) you wouldn't be able to render that at 60fps, it would be considered high poly.


Trying to change modifier properties through script

You can get the list of existing modifiers from obj.modifiers.
You can access them by index or by name. For example, if the array modifier you want is the first in the stack and called "Array", you can get with either of these:

modifier = obj.modifiers[0]
modifier = obj.modifiers["Array"]

From there on you can set the properties as you see them in the Python tooltips or in the auto completion of the Python console (or the API reference).

One correct solution for the code of your example would be:

import bpy

obj =  bpy.context.object
modifier = obj.modifiers["Array"] # Get existing modifier with name "Array"
modifier.constant_offset_displace[0] = 1.6

Note that the user can change a modifier's name at any time, so you might want to use a more stable way of finding the modifier, but what's the best way to do that depends on your specific case.


How can I make the knife tool cut in a straight line between two vertices?

Knife tool works like that - it depends on the viewing angle how it cuts. If you want to join two vertices by the shortest path on surface between them, you can use 'Vertex Connect Path' function. It can be accessed from the vertex menu(Ctrl+v in edit mode) or simply by selecting two vertices and hitting j.


Donut tutorial: Condensation for coffee cup not adding

I tried your file, it works fine after I relinked the image from my local drive. Maybe the image link is broken? Did you assign the material in Edit Mode? there is my screenshot of all the windows.


Export OBJ with materials crashes Blender on import

Export the .obj out with no materials (unselect write materials on export). Import the obj into a brand new scene and recreate all the materials.


Check if a property is animated or has a driver

A keyframe check could be done like this:

import bpy

def has_keyframe(ob, attr):
    anim = ob.animation_data
    if anim is not None and anim.action is not None:
        for fcu in anim.action.fcurves:
            if fcu.data_path == attr:
                return len(fcu.keyframe_points) > 0
    return False

print(has_keyframe(bpy.context.object, "location"))

But don't think there is an easy way to test for drivers.


Blender Game Engine: Do something when an 'action' animation happens

You can add a property (float or int) and enter it into the Frame Property field (right lower corner of your image). Then you can check the property with a property sensor.

Be aware that frames are float. Therefore it is better to check against a range e.g. 0.5 ... 1.5 (Interval mode) rather than a concrete value, as it is not likely to match it.


Press A, then all you have to do is press I on frame one. That would set all the starting positions for the skeletons.


Generating object mask during rendering for data collection

If you are looking to create a black and white image of a portion of a mesh, make the portion you wish to capture a distinct material (top image).

Assign the material a material pass (see yellow arrow), and collect and output that pass in your render (See render stack):

Here's a step-by-step, if this is your desired output: How to put 2 parts of 1 object on different layers?

Hand by SuperDasil on BlendSwap: https://www.blendswap.com/blends/view/81285


Edit: true answer for your problem is point 2

1)

If you want to move your character along the X axis for example, you need to move the armature (in Object mode), not the object itself: The object is parented to the armature, so it will follow the armature. So delete the keyframes you've created for the object and create keyframes for the armature.

To see the keyframes of the selected object only, enable this button on the bottom of the Dopesheet window, otherwise you'll see all the keyframes of all the objects of your scene.

Now select the character object (not the armature) and delete the keyframes you've probably created.

2)

Now, my first answer didn't fix your problem but I've found the anomaly. I can't explain how it happened but this will fix the problem: Go into the Outliner, you'll see that the Animation is part of the object while it should not be the case, so ctrl right click over Animation and Clear Animation Data


So you are trying to make a tileset in unity3D, using blender?
I did just that. Mine is simple, like this:

Notice how the larger tile (to L-turn) is much larger than the others. Still, it is only one square texture for each of them. The trick is to UV-map it correctly.

Here is the UV-map for the L-turn. It wraps the texture twice.

Here is the UV-map for a simple tile. It wraps the texture once.

So for a long floor tile, you have two options.

Make a square floor tile with simple UV-map in blender and repeat it several times in unity (preferred).
Make a long tile with "long" uv-map in blender and use it once in unity.

No baking!

If you bake a tiling texture to a polygon UV-mapped as yours you are ruining your texture resolution. If your texture (512px) tiles four times it has an effective resolution of 2048px (4x512). If you bake that to 512 you have reduced your texture resolution 4 times. You could bake it to 2048 and keep the resolution but you would end up with very large textures.

It might also be so that unity downsamples your texture when building the game and you loos quality again. It is a matter of settings, target device and quality.

In any case, I advice against baking.

The reason that it works inside blender is that blender can use texture of odd resolutions and multiple textures per face.

You might be able to make a shader that combines two textures with different tiling in unity. But then how would you position it?


Yes, they are achieved through SCENES. Create a new Scene (which is like a giant collection of things) place everything in your settings, your render outputs, your render camera, your objects, duration (timeline) for each scene and thus creating SCENE 02, SCENE 03...etc..

For quick sketches and simple drawing you can use the grease pencil, that allows you to make markings in a 3 dimensional space.
Once you have set the timing, framing, layout of elements, etc..
CHANGE THE WORKSPACE TO VSE (Blender video EDITOR).
Hover the timelines and SHIFT+A (ADD A "SCENE" STRIP), and then choose the ones you have created.
THE VSE EDITOR MUST EXIST IN A NEW EXCLUSIVE SCENE (name it VSE SCENE) so that it can contain all other scenes.
The rest is up to you to edit, cut, trim SCENE clips, just like you would in an animated storyboard.


Volume Scatter in World makes the sky turn black

(Blatant Quote from the Blender Manual)

Volume World
A volume shader can also be applied to the entirely world, filling the entire space.
Currently, this is most useful for night time or other dark scenes, as the world surface shader or sun lamps will have no effect if a volume shader is used. This is because the world background is assumed to be infinitely far away, which is accurate enough for the sun for example. However, for modeling effects such as fog or atmospheric scattering, it is not a good assumption that the volume fills the entire space, as most of the distance between the sun and the earth is empty space. For such effects it is be better to create a volume object surrounding the scene. The size of this object will determine how much light is scattered or absorbed.

To illustrate this workaround: create a box around the scene (it will cat as a domain) and have that box use volume scatter:

Please note that the volume scatter is plugged to the volume socket of the material for the domain, the surface socket should not be used.


Eevee multicolor gradient by object location?

In order to achieve this you need to take account of both the X and Y location - your current example is only using X from the Separate XYZ node.
Something like the following should do the trick :

Here the X and Y are used to generate the Red and the Green channel of the resultant color and the Blue is generated using some maths to color from the opposite corner of the range (ie, subtract each of X and Y from 1 to invert the range and use the minumum to combined them). The two Value nodes are used to control the Range of the fade (the one on the Mapping node) and the spread of the colors (the ones connected to the Power nodes). The start location of the range any any rotation can be controlled via the Mapping node.
This produces the following result :

To get different mix of colors you can adjust the maths to something more complicated. You could potentially add a Color Ramp before each input of the Convert XYZ node to give you more visual control of the result (with each controlling the level of that channel via gray-scale values).


The red object is not a reflection of the green object, wherever you put the mirror. It's a rotation of it. You could get there via 2 reflections, bit the mirror modifier would generate excess objects on the way.
An array modifier can do it using an axis/origin Empty with a rotation in Z of 180, the translation will depend on the origin of your object and the relative position of the Empty ...


In the timeline, go to the first frame of the animation, rotate the object to the desired starting rotation (0 in Z axis). With the object still highlighted, hit "i" and select 'rotation' to set the keyframe.
Go to the last frame of the animation, rotate the object to the desired end rotation (360 in Z for a full rotation). With the object still highlighted, hit "i" and select 'rotation' to set the keyframe.
You have to set both keyframes, or else blender will reset the rotation and will not animate.


How to add a embossed/debossed logo to a curved surface?

If you don't need to have it in the topology, but just in the render, you can unwrap the bottle and use the logo image as a displacement texture in the material nodes (using Cycles).

If you want to actually emboss/deboss the topology, you could try to import the vector logo, extrude it, curve it (with curve modifier, put it around the bottle and apply the Boolean modifier (Union or difference, in order to emboss/deboss) to the bottle, using the logo as boolean object.


Please help me get started with modeling a solid surface fuel tank for a tractor

Have you tried scaling in the y axis only? Hit S then y so that it only scales that way.

You can also try using relative scaling. If you hit O then S to scale a circle comes up that you can make larger or smaller with the middle mouse button and it will only scale within that circle.


issue after changing the color of the UV image with photoshop

On your 3rd image you can see that on each polygon border on your UV layout the color are brighter, this probably happened in Photoshop for some reasons. This is what causing the wireframe pattern on your last image.

To do the same thing in the node editor you should use a Color Ramp node, which will convert your RGB image to a grayscale image. Then you can control your skin color with a RGB node.


How to properly scale image in uv editor

You don't need the eye in the whole eyeball, so select only the faces that you want the image on.
In the case of a UV sphere it's easier to do this in top orhto view.
Then do project from view (bounds).

Use that UV map to map thimage on a material for the iris,
then assign a different material for the rest of the eye.

Note that the second material would not be necessary if the original image had an alpha channel filling the image around the iris instead of just white, then you could use the alpha to have better control on the placement of the texture.


Select your text object and under it's data change the font to use:

Use a Unicode font file or a file that has all the symbols you need. On windows machine you can find fonts in:

/Windows/Fonts/        (Fonts folder may be hidden)

and on linux machine in:

/usr/share/fonts
/usr/local/share/fonts
/home/<username>/.fonts       (.fonts is a hidden folder)

There are also many font sources in internet. For example Dafont is a free one.

You can copy-paste the content into the text object, you don't have to use text editor for this.

There should be no problem with russian symbols:

Or any other symbols:


Calculating and exporting global rotation of faces created from splitting an isosphere

A script to do this

Shows origin and local orientation of one split off face

Adds an icosphere, edge splits, separates and returns to object mode
Selected objects are the result of separate modifier.
For each face object get its lone face and calculate the global center and normal.  See how far the normal is rotated from default quaternion.

Use this to create the global matrix aligned to normal, origin at center.  The object space inverse is applied to the mesh with transfrom (makes origin (0, 0, 0).

The global transform is given to the object by way of world matrix.

Script.

import bpy
from mathutils import Quaternion

context = bpy.context
bpy.ops.mesh.primitive_ico_sphere_add(enter_editmode=True)
bpy.ops.mesh.edge_split()
bpy.ops.mesh.separate(type='LOOSE')

bpy.ops.object.mode_set()
z = Quaternion()
for ob in context.selected_objects:
    print(ob)
    me = ob.data
    mw = ob.matrix_world
    mwi = mw.inverted()
    f = ob.data.polygons[0]
    c = mw @ f.center
    n = mw @ f.normal

    q = z.rotation_difference(n.to_track_quat())
    M =  q.to_matrix().to_4x4()
    M.translation = c
    me.transform(mwi @ M.inverted())
    ob.matrix_world = M

Related. Another example of making a matrix based on known orthogonals.

https://blender.stackexchange.com/a/177331/15543


How to shrink an image with the Video Sequence Editor

When import image into VSE, it is true that the original aspect will be changed to match the scene resolution. To fix this, you can simply add another Transform strip to first Transform (NOT the picture strip itself).

So, basically one for Uniform scale, and another one for aspect ratio correction.

P.S.: When setting the second Transform scale, be sure to set the longest side to 1.000, which is X in this case.


Fill the volume area of a bounding box with a grouping of individual meshes

How to use the particle emitter to create hexagonal fills.

Create a Cylinder with 6 sides as your Hexagon and define a Plane as the level shape. (I did try this with a 3D mesh but it is a bit more tricky to get everything lined up).

Add an Emitter and set the Object to be your Cylinder and the size to 0.5

Set the Emitter End to 1(so everything is done in frame 1) the Emit From to Faces and Grid, then you can check the box Hexagonal Grid. The Resolution needs to be tweaked here to get the fit of hexagons correct.

Then on the Modifiers panel click Convert to make the particles real.

and you can delete the original Plane and source Cylinder and manipulate the individual Cylinders.


Blender is not the right tool to do this. You can do almost everything in Blender, but sometimes coding and doing it yourself is required.

You cannot obtain the deep image directly, because there is no renderer (as my knowledge goes) that can output that (a volumetric output).

You get multi-channel output at most (beauty pass, z-depth, shadow pass,..) - and this is what most 3d apps will let you save:

Save all render passes to a single EXR image

Some will let you save this as deep image, for example MentalRay.

To get your image with deep pixels, you would have to create it from all the rendered images. To be able to do this inside Blender, you would have to use the OpenEXR source code and code it yourself and run it from Blender through python bindings. Some compositing applications offer creation of openEXR deep images, like Nuke for example.

A deep image is nothing else than volumetric data structure in camera space. You cannot 'render' such data in Blender, but you can create them (smoke, fire, ..) and export as Alembic (in global space). From there it might be easier to handle such data externally.

If you need to convert particles or geometry into volumetric data structures, Houdini is a good tool to do that.


How to animate proportional editing effect?

You could set up a grid, instance your cubes on its vertices, and then deform the grid using a Hook modifier...
The hook:

.. here, to an Empty. (Assignment of hooked vertices has to be done in Edit mode.)
This lets you keyframe the position of the hook, and the radius and strength of its influence. Much like Proportional Editing.
Here, one of the faces has been copied from the undistorted grid, and P separated to a new object. That has been parented to the grid, and instanced on each of its vertices by setting 'Vertices' in the grid's Object Properties tab > Instancing panel.


How can I export STL->OBJ without the coordinate system getting messed up?

In the obj exporter in blender 2.76 I have axis settings like that:


bpy.data.objects.remove(bpy.context.scene.objects[id], do_unlink = True)

This should remove unlink the object from every scene you have. After that, the creation of a new object should go without the namechange.


How can I move an object with a UV map to a DIFFERENT project?

From what i understand you want to move the image texture connected to the object's material to your new project file. There's two ways i know how to do that.

You can go to your old project, open the UV/Image editor tab, select your image and click Image > Save As Image. You can then bring this image into your new project from the location where you saved it at.

Another option is to append the files from your old project into your new one. You can do this by pressing Shift+F1 or by going to File > Append. From there you must locate your old .blend and find the required files in the corresponding folders.

I hope this was useful to you. I'm sorry if i misread your question, feel free to correct me.


alpha over node is adding to the foreground artifact that is not in the background

I'm not really sure what you're trying to do, sorry.  This might help, might not: https://uvassociates.in/sites/default/files/resize/remote/c0631e46351ca76e7380488b072beb7f-400x312.png

It makes a mesh invisible and just renders the light from it.  It's an older version of Blender, so may not work.  GL


Is there any way i can place models down like blocks in games?

Drag a new window from the handle on the top left of the viewport. Make it a 3d view window and position it next to the other 3d view window. Then, build up a library of props and set them off to the side in the second window.

I would enable snapping just to make it more like Minecraft at this point. Now, just copy and past from one window to the other, and Alt+G to center the object in the middle of the construction area.


Blender Guru Anvil Tutorial Base Problem

You have several vertices overlaying at the same position, you can delete them quickly with A (Select All), then W > Remove Doubles


Is it possible to export specific components of a .blend file?

You can simply create one new "partial" file, and import into it only (eg) armatures, from your "complete" file and share that "partial" , of course.

Or create a copy of the "complete" file and delete everything except (eg) armatures. There is no "export only (eg) armatures" command.


Is it possibile to retain a glossy material when the object is made shadeless in cycles?

The solution is to make the hand cast no shadow. The other object cannot be shaded (glossy) and shadeless at the same time:

If you want to tone down the shadows you can make it partially transparent for lights and shaded for camera:

What is a shadow ray?

Instead of blue transparency input grey transparent shader (so it's not tinted), and instead of green diffuse input your hand material.


Any word on custom closures, or new ones?

This is, in my eyes, not even theoretically possible to implement in Cycles. The backside of an object cannot be influenced by a light source on the front, simply because Cycles works with samples from the camera over the surface towards the lamp. There is no way that a sample bouncing off the surface on the back could directly end up in the light on the other side as there is an object in-between.

However, I don't think this shader is necessary in Cycles. It was built to allow even light setups with very few lights to not look over-contrasted and harsh. With real global illumination, which you have in Cycles, light bouncing off of other objects around your object will automatically (at least with more than 0 diffuse-bounces) provide a smooth light distribution around your object from a single light source, which is exactly the effect the Half-Life developers tried to fake.


What is this dashed bounding box left where there is no geometry?

Those dashed lines normally represent the object's texture space when Texture Space is enabled in Properties > Object > Display:

You might have accidentally pressed ⇧ ShiftT at some point, which is used for translating the texture space. As a side effect it enables texture space display as in the screenshot above.

If you disable texture space display, then they should go away.


How to rotate a simple model if you have accelerator, gyroscope, magnetometer data?

I'm not exactly sure what you want to do with the Accelerometer and Magnetometer data, but the rotation can be done pretty easily with Animation Nodes.

After installing Animation Nodes (link above), create a text block in Blender with all of your Euler Rotation data. Make sure that there is only one space between each of the elements so it can be parsed easier:

In the Animation Nodes node editor add a Text Block Reader node (press Ctrl + A to search all nodes or Shift + A to view the node menu). Then add a Split Text node and split by Lines:

Next, we need to parse all of these strings into vectors. To do this, add an Expression node and create a new input from the Text List output of the previous node and name it t. Use the gear icon to set the output type to Euler List. Paste the following code into the text box:

[[float(e) for e in a.split(" ")] for a in t]

If your data is in degrees, you'll need to convert to radians:

[[(float(e)*pi/180) for e in a.split(" ")] for a in t]

The rest of it is just inserting and connecting nodes. Here's the completed NodeTree:

You can replace the Cube object with whatever yours is named.

Here is the result:


If you mean distortion around object's edge, change image extrapolation to Extend.
Displacement Modifier > Texture Properties > Mapping

... in case you use Subdivision Modifier > Adaptive Subdivision:


for 2.79 if you use an attribute node and put in flame or smoke you can add materials for flame and for smoke


How do I lengthen a cylinder that is tipped on it's axis?

You can always move a face along its normal by using the 'Normal' transform orientation.
If combined with the 'Individual Origins' pivot point, many face-islands can be GZ moved along their normals simultaneously:

(This is not scaling.. any selection of top or bottom faces could be moved just as easily.)


How can I make dynamic text in an animation?

Building off the answer in how to animate string properties, here's a solution.  You can insert the following code in the Text Editor and hit Run Script.

Example: display current frame

Assuming your text object is called 'Text', this will have it read the current frame:

import bpy

scene = bpy.context.scene
obj = scene.objects['Text']

def recalculate_text(scene):
    obj.data.body = 'Current frame: ' + str(scene.frame_current)

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

The last line just causes the recalculate_text function to be run each time the frame is changed (more on Application Handlers).

Example: distance travelled by object

To have a text showing the distance travelled by 'Cube':

import bpy

scene = bpy.context.scene
obj = scene.objects['Text']

def recalculate_text(scene):
    x = scene.objects['Cube'].location[0]
    obj.data.body = 'Distance in x-direction: {0:.1f} meters'.format(x)

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

where I've used Python's string formatting to make distance only display one decimal place.

Example: time elapsed

import bpy

scene = bpy.context.scene
obj = scene.objects['Text']

def recalculate_text(scene):
    fps = scene.render.fps / scene.render.fps_base  # actual framerate
    obj.data.body = 'Elapsed time: {0:.1f} seconds'.format(scene.frame_current/fps)

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

Demo video


How to make better looking lights/lightbulbs

Try to look, whre does the lightbulb really emit light and model this part, and make the outer part really out of glass. Try to do verything like it looks in a real lightbulb and then tweak your values until youre happy. Except they are in a far distance, then you might just use an light source in form of  bulb in purpose of shorter render times.


Ditch global lists and use selection
After calling the import operator any newly imported objects are selected and make up the context.selected_objects list.
I don't have any multi-object stl files to test theory against, but will go thru the motions with a single object file.
With no current selection.
>>> C.selected_objects
[]

Import stl
>>> bpy.ops.import_mesh.stl(filepath="/home/batfinger/Desktop/untitled.stl")
Import finished in 0.0156 sec.
{'FINISHED'}

Newly imported object(s) (Have no examples of multi object stls)
>>> C.selected_objects
[bpy.data.objects['Untitled']]

Remove that import
>>> old_import = C.selected_objects
>>> while old_import:
...     D.objects.remove(old_import.pop())
...
>>> C.selected_objects
[]

Import again
>>> bpy.ops.import_mesh.stl(filepath="/home/batfinger/Desktop/untitled.stl")
Import finished in 0.0140 sec.
{'FINISHED'}

>>> C.selected_objects
[bpy.data.objects['Untitled']]

Rename this time
>>> #and to rename
>>> for o in C.selected_objects:
...     o.name = "Foo"
...
>>> C.selected_objects
[bpy.data.objects['Foo']]

What's the file looking like
>>> D.objects[:]
[bpy.data.objects['Camera'], bpy.data.objects['Foo'], bpy.data.objects['Lamp']]

Notes.
Basically think the remove method in question code is "icky", as also is keeping some global list with object references ... just asking for a crash.
Notice the way the objects were removed in python console code above. They are unlinked (de-usered) by default.
To use a list like so recommend only using names, or just not doing it that way.
Putting this into a script
Have made a version of the script using a custom property tag to "mark" any imported STL. And to keep the new, remove, rename order also looked at the name.. one thinks remove, new, rename makes more sense.. anyhow
import bpy

tag = 'IMPORTED_STL_OBJECT'

def new_stl(filepath):
    #  import a STL file
    bpy.ops.import_mesh.stl(filepath=filepath)
    #  get new object list
    # ops use context silly not to use it.
    # could do set before / after here too.
    for o in bpy.context.selected_objects:
        o[tag] = 1
        o.data[tag] = 1

def delete_old_stl(name="NewSTL"):
    stls = [o for o in bpy.data.objects
            if (name and o.name.startswith(name))
            and tag in o.keys()]
    while stls:
        bpy.data.objects.remove(stls.pop())
    stl_meshes = [m for m in bpy.data.meshes
            if (name and m.name.startswith(name))
            and tag in m.keys()]
    while stl_meshes:
        bpy.data.meshes.remove(stl_meshes.pop())

def rename_stl(name="NewSTL"):
        stls = [o for o in bpy.data.objects
            if tag in o.keys()]
        for o in stls:
            o.name = name
            o.data.name = f"{name}_Mesh"

new_stl("/home/batfinger/Desktop/untitled.stl")
delete_old_stl()
rename_stl()


Use the Follow Active Quad UV unwrap option.

Click to select a segment of your track as the active face(s).
Tap A to select all other faces as well.
Press U to UV Unwrap and select Follow Active Quad

The track should be unwrapped properly with just a little adjustment needed.


I imported obj file but it seems it imported as single mesh?

Your .obj file likely doesn't separate objects using the o attribute followed by the object name or g attribute followed by the group name. Either one of those are needed to separate the scene into separate meshes. There seem to be several post in the Autodesk forums regarding the topic of exporting obj as separate meshes, you may find a solution there. Since I don't own a license of 3ds Max, I can't test whether one of them works.

In case 3ds Max doesn't provide a good option to accomplish this, perhaps another file format is better suited, e.g. .fbx, .dae, .ply, .gltf to name a few.


In Edit Mode, select the Bone and press W

You can switch the bone direction and others


You can be excused for being confused as it would seem logical to click the names of the object - rather you should click further down the bar and you will see the row colour change tone. You don't even need to hold down shift to select more items. Note that selecting items this way has nothing to do with the selection in the 3D window. Once selected you can just right click and select 'delete'.

Other keys that work here - A toggle (select all/ deselect all) note colour tone difference. Also B box select, and then middle box to remove select, work here.

Once you see how it works ...it is pretty efficient.


Blender has an ability inside edit mode to convert triangles to quads. Press ALT + J with everything selected, or by selecting everything, CTRL + F for Face Menu, then Tris to Quads.

Edit: Something that might take you the rest of the way there is the Quadriflow Remesh tool. Its available in Blender 2.81+. As with all things unknown, I'd test it on a safe duplicate.


How to turn off constraint lines drawn using OpenGL render?

In properties panel, turn off Relationship Lines under Display (or better, select Only Render). Guess, OpenGL uses the same render engine used by material viewport shading.


How can I access the graph editor for keyframes on node values?

There is a filter setting, in the graph editor. Most likely, you need to turn off "only show selected", then you can choose the element types you want to see:


You could try a new version of Blender, in some ways it is more optimized and organised.

Anyway, these steps are similar in all versions

Change amount of samples to around 10-20.
Reduce resolution (size of the output)
Multiply viewport pixel size

This will make your render look really grainy and crappy. Just like you asked.


a problem with applying automatic weights

Just add a subsurf modifier to the mesh as shown below:

Then parent the mesh with the armature again and it will work as shown below:

Updated .blend file can be found here:


Make hair in Blender Internal, but render in Cycle, realistic skin in blender render?

Assuming you don't change any of the particle settings, then there would be no problem rendering the hair in cycles and blender internal. Note you will need two different materials, one for the internal, and one for cycles.
See this question for how to use materials in blender internal and cycles.


Smoke & fire simulation: Cycles material not showing fire

The problem isn't the material, it's that there are no visible flames in the simulation.

On the "Debris Emitter" object, the Flame Rate set set to .025 If you set it to something like .25, the material works fine:


How i can hide object from viewport and render at the same time?

You can just click and drag on the icons in the Outliner:


Is there a way to group or organise keyframes for a complex animation?

Short answer: Dope Sheet and NLA editor
Dope sheet shows you all keyframes categorized in objects, then axes or properties. You have a complete overview and you can set it up to either show all keyframes in the scene or just of the selected object (click on the little arrow on the navigation bar in the dope sheet window).
For detailed edits you might also want to use the graph editor, which isn't good for an organized overview but let's you edit the key curves in Detail.
The NLA editor can store "animation templates". So for example you can create an idle animation for a character and a running animation and save both as "actions" in the NLA editor. It's layer based and you can do tons of stuff there to make complicated animations easy to manage. You could for example loop an action or layer multiple on top of each other (idle + running for example).


It looks like Boolean doesn't work well because of overlapping faces. Maybe there's another to do it, but to merge 2 crossed Parallelepipeds, you could use the Tinycad addon:

Download the Tinycad addon: https://en.blender.org/index.php/Extensions:2.6/Py/Scripts/Modeling/mesh_tinyCAD
Enable it in your Preferences.
Select your whole mesh and press W > Tinycad > XALL/Intersect Selected Edges.
It has created some additional vertices on the crossing edges but it has also deleted faces.
Remove all the doubles with W > Remove Doubles.
Fill the faces with F.


Why are anti-aliased normals so rough on polygon faces?

Why do your smooth shaded normals look so funny on this shape?  Because of the triangulation of long trapezoids.
Here's how Blender determines your per-sample normals: A) It calculates face normals (from the average plane of the face, for a quad.)  B) It calculates vertex normals from the face normals.  C) Then, very importantly, it triangulates the mesh (this is why a wireframe shaders shows triangles on a quad mesh).  D) Finally, it interpolates your vertex normals across each face to find the normal of each particular sample.
But let's look at what happens when we triangulate your mesh (using fixed triangulation, which is Blender's default method):

So first, be aware that when I triangulate, I'm going to get slightly different normals, because then I'm doing C before A or B.  I've left a copy of the untriangulated mesh in the upper left corner of the matcap view so you can see that the normals of the original still display triangulation.
But look at the triangulation: I'm left with these long skinny triangles, of uneven size.  For each sample inside each of those faces, I'm only interpolating from the 3 vertex normals composing that face.  The vertex normals are smooth throughout the mesh, but the triangulated mesh is not smooth-- the faces are of uneven size.  And so the per-sample normals are not smooth.  As we move our gaze across the object, the normals change rapidly then slowly, rapidly then slowly.
And this will persist even as we do procedural subdivision-- even as we subdivide, we maintain long, trapezoidal faces.
This is why one of the rules of good topology is, evenly sized square quads-- square in aspect and angle.  Is that doable for interesting meshes?  No, but it can be approached.  (This is one of the lesser appreciated rules of good topology, and I'm grateful for this SE question because it gives the simplest demonstration of it that I've seen.)
Okay, so then the next question is, how can we fix this?  By making our faces more square.  We're kind of stuck with trapezoids if we want to make this dish shape-- we can't get rid of the trapezoids without turning it into a cylinder.  But we can make them more square in aspect by adding loop cuts:

Upper left has our original mesh with subdivision level 1.  Lower right has our original mesh with two loop cuts to make our faces more square, and subdivision level 1.  Looks a lot better to me!  Of course, if you look more closely, you'll see triangulation-- unfortunately, triangulation is a fact of life in 3D rendering, and the only fix is lots of vertices.
Note: the problem here is a problem with interpolation of vertex data.  If we want to normal map this mesh, we don't have to worry about its actual normals, vertex or interpolated, because we're going to be overriding them anyways with arbitrary, per-sample normals.  (Although we will want to explicitly triangulate our low-poly, or else make sure our ultimate rendering engine triangulates in the same way as Blender, since those normals are specified relative to the interpolated normals, and those interpolated normals depend on exactly which way we triangulate our mesh.)


I do not know python, however you can change the depth of field to make it bigger or smaller to make you able to see the object in it's entirety.

Go to the Properties Panel (N) -> View -> Clip and change the End distance to increase the field of view and allow the whole object to be seen when zooming out.

Be mindful that it may slow down your computer is the object in question is very big and complex.


The default importer is doing no such thing for me when I put it into Unity with the default (click + drag) importer.

I suspect that the issue is purely on Unity's side.  The version of Unity I am using is
2018.3.2f1.  You might want to try updating your Unity and Blender versions.


What is the technical difference between an Ngon and a bunch of Triangles?

Subsurf does not treat tri, quad and ngon differently:

In each case the result follows exactly the same pattern:

Every edge is subdivided into exactly two edges.
Every face is subdivided into n faces where n = original number of vertices. Every new face is a quad.
A new vertex is created at the centre of the face. Every new face shares this vertex.

The difference in topology of the two results you showed can be more easily seen if we use simple subsurf (which does not smooth) and then apply the modifiers and look at the wireframes:

The result from subdividing the triangle fan has the extra edges (selected.) These extra edges are the result of subdividing the radial edges which connect the central vertex to the outside edges.

This does not demonstrate any fundamental difference between tris and ngons, because we can produce the same result using only triangles:

On the left is a triangle fan composed of three triangles. On the right our equivalent "ngon" is simply a normal triangle. The result of subdivision is different and follows the same pattern we saw before with the cylinders. The same results would be seen with a triangle fan composed of four triangles and a quad.

In general it's much better to think of tris and quads as special cases of the ngon than to consider an ngon a "bunch of triangles" like a triangle fan or triangle strip.


New to sculpting. How do you add parts and connect them by sculpting?

If what you want to add is supposed to be a part of this object, it makes more sense to add it to this object itself in Sculpt mode, and not add a new object, because:

I don't think you can sculpt several objects at the same time for the moment.
If they are different objects it will be harder to make them look like they are one.

So for example if you want to add a neck to a head, use the Snake Hook brush (it allows you to easily deform the topology and add geometry):

If what you want to add is another object (like for example here a hat), you can choose to create a second object. I guess it also depends on your final purpose, you can sculpt everything within one object.


Mesh text individual letters change colors

Speaking from Vers 2.77 here but 2.8+ should be the same or very similar...
Once you've changed your text to mesh you should be able to do that at least two ways -
1:
In edit mode select only those faces on the word(s) you wish to re-colour.
Assign them a new material slot and change it's colour.
2:
In edit mode, select the vertices in only the word(s) you wish to re-colour,
Part them from the mesh with "P".
Return to Object mode and select the words as a separate mesh and give it a new material slot if it hasn't got one already.  Colour it as required.
Parent the new mesh to the main text body if it's to be moved.
Colours can be changed with keyframes as with any other animation.


This was the problem!
In shading, the tutorial was about adding a lot of stuff and I guess something went wrong with "Displacement". I still don't know why this only happenend in cycles...


Boolean + Subdivision modifier warped surface

Well, I figured it out myself. I just needed to delete the bottom face.


Animation doesn't work in blender with a rigged object

If there is an orange bar between two keyframes, this means that nothing changes between those keyframes. That's why you cannot see an animation because you animated "nothing" because both values for different times(keyframes) are the same.
If you want to keyframe the offset, you do this by hovering with the mouse over the offset value and press "I". Then change the keyframe and the offset value and press "I" again when the mouse is hovering over it.
It is something totally different if you press "I" in the 3D View. Then you can choose what you want to keyframe: Location, Rotation, Scale or combinations of these. Because you keyframed LocRotScale and then changed the offset and hit "I" again in 3D View - you keyframed the same location, rotation, scale again - which makes no sense.


Group materials together and make transparent?

Here are two solutions.
Make sure each material has a blend mode set to alpha Blend or Hashed (Or clip if you don't want the material to be semi transparent before going into full transparency). These settings will only appear if Eevee if set as your render engine.

First solution (with a driver)
Create a value node and put it into a node group with Node > Make Group (CTRL G).
Rename the group and plug it into the principled BSDF of each of your materials. (To add in a material, choose Add > Group > group name )

In your object properties, on the last foldout click "add" to add a new custom property.

Now for ease of use you can access it in the N panel on the right of the viewport.

Get back into your node group by clicking on the icon on its top right. Right click in the "prop" field and choose "Copy as new Driver". Right click in the "Value" node's field and choose "Paste Driver". The field should now be purple.

Tweak the new prop to change the opacity of all the materials at once.

Second method : With the object color
The method is the same as the previous one, but you have to replace the value node by an "Object info" node and plug its "Color" output into the group output.

Go into the object properties, viewport display, and adjust the value of its viewport color to modify the opacity.

Conclusion
Use the first method if you want to control the opacity of your materials across several objects, use the second one if you want to control the opacity of your materials on a specific object.


How can I open or import FLT (OpenFlight) files in Blender (mac)?

In Blender version 2.42a - 2.46 there is an option to load OpenFlight FLT files. In later versions this addon has been removed (most likely due to the lack of support by the community).

Best way currently is to download blender version 2.46 and import the FLT file (File → Import → OpenFlight(.flt)). Save the blend file and open this blend file with the blender version of your liking.

Second option is to find a developer who will migrate and maintain the OpenFlight plugin.

More information of the plugin can be found at https://wiki.blender.org/index.php/Extensions:2.4/Py/Scripts/Import/Openflight_flt


Using 'Float Property Layers' value in Node Editor (similar to Vertex Color)

Using UV Layer

Example showing UVMap

Then use the UV Map node as input.

UV layers and vertex color layers are available to the attribute node by name. Not custom polygon float layers.  Be careful not to  name two layers of different type the same, (which you can) if you are going to use either or both as  node input.

Script that sets a float layer to randoms, then for each face sets the uv of each loop vert; u to the face layer value, and v to another random (or ...).

Can only have 8 UV Maps.

import bpy
from random import random
context = bpy.context

def get_mesh_layer(me, type, name="Float Layer"):
    layer = getattr(me, type)
    return layer.get(name) or layer.new(name=name)

#bpy.ops.object.mode_set()
ob = context.object
me = ob.data

rflayer = get_mesh_layer(me, "polygon_layers_float")
for f in me.polygons:
    rflayer.data[f.index].value = random()

uv_layer = get_mesh_layer(me, "uv_layers", "Random")

for f in me.polygons:
    u, v = rflayer.data[f.index].value, random()
    for l in f.loop_indices:
        uv_layer.data[l].uv = u, v
#bpy.ops.object.mode_set(mode='EDIT')

Note: needs to be run in object mode. Can be emulated in edit mode using bmesh. Simply wrapped it in change mode ops for screen shot above


How can I instant delete all of the actions ?

Every animation that is not used by any object and that is not F (fake user, which means that doesn't need to have any user to be saved) won't be saved when you'll close and reopen your file.

Now, to delete an action that is currently used, go in the Dopesheet / Action Editor mode, and press shift and the X on the right of the name of the animation. When you'll reopen the file the animation won't be here anymore.

To delete a F (fake user) animation, disable the F, and same thing: press shift and the X and reopen the file.

If an animation isn't assigned to any object anymore, you can go to the Outliner, select Orphan Data in the dropdown menu, you'll see all the orphan animations, select them all and right click > Delete. Even the F animations will be deleted.

If you only want to delete the visible animations, you can select all your objects, press the Spacebar and type "Remove Animation", You can also go into the Outliner, type "Animation" in the Search box, select all the animations and right click > Clear Animation Data.


After finishing using blender, I tried to render it but the render icon won't show up at the top left of my laptop screen. How do I fix it?

So what seems to have happened here is you switched out the main menu bar for another 3d view. If you look at the extreme top left of your screen, to the left of what you have in the screenshot there should be a little icon with two small arrows. Click on that and a menu will pop up showing all of the different editors in blender. To get the menu you had before  you will want to select the info editor (the one with the blue i icon third from the bottom). That should get you back to where you were before.


Did compositing in Cycles, went to eevee for the background, went back to cycles... and all my compositing had been deleted

Ok I solved it, I actually confounded the compositor tab with the shading tab. The pink color was because I had previously deleted the file of the surface of the planet. I put a newer version of the file I did on Photoshop inside the "Image texture" block in the shading tab and tadaa... the planet is no longer pink.


Hard time getting my coiled thread like 'painting' to look right

For those interested, I was able to accomplish this material with something like this.

Although it looks congested, the concept is rather simple - I used wave textures to mainly just compose a bunch of different small line maps of different widths and rotations and adding them together. I probably could have done this more efficiently, but I was just prototyping. I also made some small color lines as well, because it looks like the background is disturbed by some other colors in addition to the black. After that, it was just a matter of mixing them together.

To get a realistic thread look, I combined 2 more wave textures, one sharper and at an angle to the other to make a rope like shape.

I then mixed this pattern with the original horizontal lines to get that wrapped-thread look. Afterwards, I mixed this combo with another wave texture with a smaller scale, which I used to form the large stripes.

For the background, I simply used a gradient texture with aqua colors, but I also used a slightly distorted noise texture to add some yellow as well. I mixed these together using a diagonal gradient as a factor, because in the image you have it looks like the yellowish tinge is mostly in the top left corner areas.

Lastly I made some normal and height information from a black and white version of the small stripe mix. I kept the values very low to give a subtle effect. The final result looks like this:

I made 2 versions of the material - one of them is a simple version using an emission texture to make the colors pop (done entirely from object coordinates), whereas the other one I aimed for a complex, but realistic thread like art look which is more costly because of the displacement, but looks more realistic (done mostly with generated coordinates).
I'll also upload the .blend file. It is here -
Happy Shading!


You could enable Undo support for your operator. Below

bl_label = "Simple Object Operator"

add

bl_options = {'REGISTER', 'UNDO'}

But I wouldn't make the operator undo itself on errors, rather let the user do it if necessarily. However, your script shouldn't raise exceptions in the first place, but check in the operator's poll() classmethod, if all pre-conditions are met. Or let it return {'CANCELLED'} inside the execute() body before something is damaged.


My model has a strange line on it and the mesh seems seperated

Select all vertices and in the search bar, (F3 or space) search "remove doubles." This will connect the vertices.


Join Instances of Animation Nodes/ Make them seperate Objects

In the advanced node settings of the instancer node, you can use the Unlink Instance From Node operator to make the object independent of the node, then you can merge them and do whatever you like.


Make the viewport color match the color for the shader automatically

Not that I'm aware of. You could use the Material view to match the colors but that asks a lot more from your computer.
I did find a relevant script, but havent tested it myself. I just manually edit the colors :)
http://blendervisionpro.blogspot.be/2014/12/copy-cycles-color-to-viewport.html


View Last Frame Outline While On Current

When animating an armature you can use the ghost feature in the armature tab. The range value determines how many frames it will show at once.

And the result:

Update:

New result with your .blend:


Animating grouped meshes with shape keys

To make object change its shape while animating complex movings like trees it's better to use rigging with Armature modifier than the shape keys.

Shape keys are generally used as an additional geometry changer working together with armature, i.e. they aren't armature substitution. They aren't as flexible as rigging because they can be added to one object and thus edit only that object; also one has to define the final form of the object initially in order key to work.

To animate a tree moving it's a good idea to rig that tree. Create a skeleton for it, use any method to skin a tree and create some poses for the tree leaves and / or trunk.

Note: When creating tree with Sapling: Add Tree addon it's possible to add an armature for the tree:


Can Blender build proxy files with transparency?

I've found this solution:

Blender looks for jpeg files, but actually you can use PNG files with .jpg extension.

This is my workflow:

1. Create resized copies of the render images:

25% > 1920 x 1080 -> 480 x 270

2. Change all the extensions from .png to .jpg

Assuming that the render path was:

/User/render/def/barca/b.png

the Proxy Directory in the VSE Panel was

/User/render/proxy/

I've used ffmpeg to create a scaled copy of the render files.

Open terminal (I'm on Mac) and type:

cd /User/render/

ffmpeg -i def/barca/b-%04d.png -vf scale=480:-1 proxy/images/25/b-%04d.png_proxy.png

than rename all the files

cd proxy/images/25/
for old in *.png; do mv $old `basename $old .png`.jpg; done

(thanks: https://stackoverflow.com/questions/14887275/changing-file-extensions-for-all-files-in-a-directory-osx)

Here's a rough script that sets all the strips

import bpy
C = bpy.context
C.scene.sequence_editor.proxy_storage = 'PROJECT'

C.scene.sequence_editor.proxy_dir = '/path/for/proxy/'

seq = C.scene.sequence_editor.sequences_all
for s in seq:
    s.use_proxy = True
    s.proxy.use_overwrite = False

    # I ONLY NEED PROXY 25%
    s.proxy.build_25 = True


Click and drag on the corner with the grabber (same one for making a new window) and drag DIRECTLY over the neighboring panel that you want to make disappear (if you drag anywhere else, you'll make a new panel). This will make a grey arrow which shows you which panel will get put on top of the other. Release the mouse button when your cursor is over the panel you want to go away.
Two caveats:

when you click and drag, you must immediately cross the boundary between two panels, before dragging anywhere else. THEN it will make the grey arrow. If you click and drag into the same panel, you'll create a new panel.
you can only join two windows that share a COMPLETE edge. If you have one full window on the left, and two windows (one on top of the other) on the right, then you have to join the two windows on the right together before you can join the window on the left.

Now, using this knowledge, you have a bit of a puzzle to solve. You have to close each of the windows in the red square individually. So I'd start with the smallest one first. Join it with the one with which it shares a complete edge, and the go to the next-smallest.
This is exactly what you need: http://www.youtube.com/watch?v=AMBi1R7KB48


How can I add more animation to my existing animation?

In order for the changes you make to an object to be saved, you need to insert a keyframe on the property or whatever it is that you changed. To do this, in this case, mouse over the color field and press I.

Alternatively, you can open the graph editor, by selecting it from the dropdown that appears when you press thebutton on the bottom left corner of thewindow (in the default screen layout), and then edit the f-curves for the property you wish to change manually.


I think it goes like this:
If you set the Cycles settings of a material to 'Displacement' only, then EEVEE, not supporting Displacement shading,  will substitute Bump mapping for any Displacement input to the Material Output node, to make the Cycles and EEVEE renders to look as similar as possible.
Cycles can't depend on that substitution - if you want a normal or bump-map in Cycles, you have to ask for one explicitly:

Not necessarily in Object space, but you get the idea..


You need to select the mesh used as particles/hairs and go into edit mode.
Rotate and move the object (in edit mode) till the emitter emits the mesh correctly.


When I do follow path, the object is not followed with SHP-Root

As I can see in your screenshot, all location, rotation and scale channels of your SHP-Root are locked. Unlock them clicking on their lock icon on the "N" properties panel.
Changing version of Blender doesn't matter at all.


using cycles render engine ->
Set up the mirror object. GO to material-> Select a Glossy Shader
using internal render engine->
simply use the mirror option in materials


Blender - Subsurface Modifier causing extreme pinching in L-shaped corner

You have ngons in your mesh.

As I only now see that Christopher explains in his comment above, your pinching is a consequence of using Subdivision Surfaces with non-quad based topology. SubDs only want quads.


Moving vertices of two objects away from each other

Probably a nice balance between easy to implement and reasonably efficient would be to create a BVHTree for the mesh of one object, and query that with all the vertices of the other mesh using find_nearest_range(...).

Moving the vertices away is probably easiest if you mark the entire mesh as smooth first. That will casue the vertex normals to be in the opposite direction you want to move the vertices in. Then, for each vertex v that you want to move, you can do v.co -= f * v.normal, where f is a smoothing factor. The value of f depends on how quickly you want the vertices to move. You can use a fixed value like 0.01 to move them by 1/100th unit, or you could use a dynamic value that depends on the distance between the two meshes at that point.


It looks like, for some reason, the vertices at the bottom of the top cap and the top of the bottom cap have been duplicated -- so there's a "hidden" set of faces in the middle, which you're exposing when you bend the other set out of the way.

If I'm right, fixing it will be easy. There are two options:

If you can still undo the "extrusion": in Edit Mode, select all of the vertices with A. Then hit Alt-M, and click "By Distance". This will automatically merge all vertices that are within a certain very small threshold from one another, removing duplicates. After you've done that, you should find that the loop cut step works as expected.
If you've already committed to the "extrusion": Select the extra faces (the ones that weren't affected by your loop cut) and delete them with X. Then do the same as I described above to merge the extra vertices.


Enabled add-ons can be enabled permanently by saving the user settings.

Otherwise they are enabled only on the current session, but will not be loaded next time you open Blender.


How to create this curved 90-degree-angle quickly

First method:

This one will work only for external Edge Loop and will give ugly ngon, so it's just for the pure knowledge. Better skip to second one.

Select corner vertex, press CTRL+SHIFT+B, move mouse to get desired angle, use scroll to get more vertices. You can tweak it as well in in Tools Panel.

Second method:

This is with proper/clean/nice looking topology.

Make two Loop Cuts trough the surrounding faces - CTRL+R.
Delete corner face.
Select both Edges.
CTRL+E > Bridge Edge Loops.
Set values in Tools Panel or hit F6.

Edit:

I don't know math so maybe someone could elaborate more about what makes smooth corner perfectly 90 degrees. Below some doodling over result by Bridge Edge Loops method.


How do I generate pixel-art friendly UV maps?

Well I cannot promise this is the ideal technique, take it for what it's worth.

Edit: here's a more pixel art like render:

I decided to unwrap the model in the traditional way by marking seams.  This allows contiguous regions to be kept together on the UV map which makes the pixel editing more intuitive.

Unwrap with U-->Unwrap.

Next you will need to organize your texture space.  Your model has some non-straight edges, so I straightened them in the UV layout by selecting the points to be aligned and typing S-->X (or Y, as appropriate)-->0 (zero).  I moved the islands around to pack the texture into more or less a square, but I didn't scale any islands individually.  I decided to move the two side panels on top of one another to save texture space.  When everything was reasonably packed, I scaled the entire UV (i.e., all islands selected together) so it came to the edges of the UV space as much as possible.

I then exported this UV layout in SVG format.  Then, in GIMP, I created a new 64x64 bitmap, and imported the SVG as a path.  I chose "Merge imported paths" and "Scale imported paths to fit image" so I had a nice vector overlay for my texture editing.

I then painted my texture under the overlay.  I tried to fit the pixel boundaries of my texture to the UV grid overlay as well as reasonably possible, but exact alignment is not possible at this stage.  We'll fix the boundaries in the next step.

I exported the GIMP texture to a PNG.  Back in Blender, I imported the image to the model.  Then, in the UV/Image editor, I turned on "Snap to Pixels" (UVs-->Snap to Pixels) and moved individual vertices of the UV (corners, generally) manually to snap exactly to the pixels of my texture.  I did not attempt to snap the triangles of the "screen" area to exact pixels, the texture space isn't big enough; I just made sure the "screen" island as a whole fit over the appropriate area of the texture.

This is how the model looks with the texture:

Anyway, I hope at least some of those techniques meet your needs!

Edit: I thought you might like to see some pixel detail like in the image in your question.  Note that you should turn off "Interpolation" under "Image Sampling" in the Texture tab of the Properties window in order to see relatively sharp pixel edges.  Also I have found that changing the Filter to "Box" instead of "EWA" in the same tab/area also makes the edges crisper.

Another edit: it's not a fancy job, but I created a more arcade cabinet like pixel texture, the source for the animation at the top of this answer:


How to avoid switching layers and import an object directly into a specific layer?

When a new object is added to a scene, it is always placed on the active layer. It should be easy enough to modify an import script to work around this.

When creating an object by script, that is when not using bpy.ops, you create the mesh data, create a new object that uses the mesh data and then link the object to the scene. It is possible to set the objects layer visibility after linking it to the scene and before updating the scene so that it should not show briefly in the render. Worst case would mean setting the objects data to None, linking it to the scene, placing it on a layer and then setting the data property back.

For the obj importer, line 1297 is where it links the object to the scene. The following addition of one line (base.layers=) seems to work with importing new objects into layer twenty, I haven't tested during rendering or with multiprocessing to check if it might show.

# Create new obj
for obj in new_objects:
    base = scene.objects.link(obj)
    base.layers = [x in [19] for x in range(20)]
    base.select = True

Note that Collada and Alembic support is compiled into blender so would need some more work and a custom build of blender to make this adjustment.


add-ons in a linux installation of blender

Avoid using distro packages since they don't usually work well. Grab the binary from the website unzip it and double click on the executable to run it.


how can I cut a sphere by selecting all the faces that intersect a plane?

Go into front view 1 on numpad, go into wireframe mode tab and press B. Then you can select all of the faces you want. With the faces selected, press P and Separate by selection.


How can I achieve a crystalline glaze material procedurally?

A favorite trick of mine is to mix a bit of noise into the coordinate vector.

You can use object coordinates here, it's not really important as long as you can make the masks you need.
What I ended up doing is generating several noise masks, some of them share the same nodes, I'm just using a Color Ramp to isolate different parts:

And used Math nodes to add and subtract them rather randomly:

And then I used a Math node set to Greater Than and played with the value until I found something I liked.

Using this as the factor input for a Mix Shader you can create the top and bottom materials to your liking.
My favorite detail of handmade objects like this is that they are rarely perfect.  We often model these objects to (float) precision, perfect all the way around.  So to add an almost imperceptible bit of realism I take a very lumpy Noise Texture and do just a tad of displacement.

Here is a render using these methods.  HDRI environment is Cayley Interior from HDRIHaven.  I'm using only Noise Textures for the base color layers.


Why does this model unwrap despite having no seams marked on it?

All primitive objects in Blender are unwrapped by default. So when you add your own seams and try to unwrap it, Blender discards the default UV and tries to unwrap UV according to your defined seams.
In your example, it looks like someone already unwrapped it and exported it as obj. So when you import it, you get the UVs but not the seams.


Can blender render on multiple graphics cards?

Yes.
Blender's Cycles can use multiple CPUs and GPUs for rendering. You can use both CPU and GPU devices at the same time as well.


Rigid Body Mesh Collisions: Objects falling through each other

As @m.ardito and @Rich Sedman pointed out, the solution is to remove doubles: Edit mode, select all, Remove Doubles.

The simulation now runs fine


Circular Light Source Causing Speckles in Cycles

I figured out the problem: I needed to turn up "Clamp Indirect." The Article Here has a bunch of solutions, and the only one that worked for me was the 6th option.


Why is one bone distorting my mesh? Only one vertex group?

I assume the OP has already done manually what the OP needs to do.
You might consider deleting all groups and parent again ... to Single Bone which was previously selected.  Consult a Tutorial Video, one or more.  I am trying to avoid writing a tutorial.

We assume rigid mechanical motion .. so only one bone should have influence.  What follows is a short explanation.  Edit Mode Show Weights is selected.  The bones are outside the mesh only for visibility and discussion purposes. Bones are typically near the mesh.

Below preparing to delete mistake groups.

When deleting you can delete one by one. You can also lock (the lock symbol in vertex groups) and then delete  all unlocked groups from the menu. Tutorial Slippery Slop ... I mean Slope.

Image Below a mistake needs to be corrected,

Correct bone group appears.  Mistake bone groups were deleted.

Image below.
All vertices were selected in edit and the weight 1.0 assigned in the Vertex Groups Panel by clicking the button [Assign]

There are videos on famous video websites that show many of the bone weighting features.  It serves you best to see those because its more entertaining for you and the features are quite numerous so video may be the best format.  There are multiple ways to get something done in Blender.  Single Bone Parent is possible.  Please consult a video. Scripts were not discussed.


Maximum that you can import - textures with the materials slot and UE can make simple material with this textures for you.

but complicated material with masks, additional color and math you should create in UE by null )


Subdivision Surface and Knife Project. Blender 2.8

Ok, the problem you mentioned in the comments is because of these little straggler vertices that aren't connected to the mesh like the others.

So to fix that you can start by deleting this ring of faces:

Next, you create a new circle, place it where you want the hole, select the circle and the rim of the guitar created by the deleting of faces, hit ctrl-E, and select "bridge Edge loops".

And here is the result:

It's definitely not as pretty, but there doesn't seem to be any intersections or anything, and it does get the problem fixed.  Hope that helps.


How do i toggle off this weird cursor tracer when in texture paint mode? (Blender 2.8 LS)

This is the stroke stabilizer, to smooth out strokes.


Well the easy way would be to use a try-except catch

This would skip the meshes where errors happen
print their names and reselect them after deleting the rest:

import bpy
wm = bpy.context.window_manager
act_obj = bpy.context.active_object
union_list = []
passed = []
for sel_obj in bpy.context.selected_objects:
    if sel_obj.type == 'MESH':
        if sel_obj != act_obj:
            try:
                bpy.ops.object.modifier_add(type="BOOLEAN")
                union_list.append(sel_obj)
            except:
                print("\n"+sel_obj.name)
                passed.append(sel_obj)
                sel_obj.select = False

k=0
union_list_len = len(union_list)
wm.progress_begin(0, union_list_len)

for mod in act_obj.modifiers:
    if mod.type == "BOOLEAN":
        print(k,union_list_len,union_list[k].name)
        wm.progress_update(k)
        mod.operation = "UNION"
        mod.object = union_list[k]
        try:
            bpy.ops.object.modifier_apply(modifier=mod.name)
        except:
            print("\n"+sel_obj.name)
            passed.append(sel_obj)
            sel_obj.select = False
        k=k+1
act_obj.select = False
bpy.ops.object.delete()
wm.progress_end()
for obj in passed: obj.select = True

hope it helps, Teck-Freak


How to use some special symbols like ™ ,♟, ⚘, ✿,  etc in blender?

Try the font Segoe UI Emoji Standard, you can find it under the filename seguiemj.ttf in the Windows Fonts directory.


Gradient control on instanced objects from collection

To make a deep copy of the meshes for each instance, get the meshes from the objects and write them to the instances using the Mesh Object Output node as follows:


Save every other pixel of an image at half res

In your case where you are looking for exactly ½ resolution there is a very simple solution, just use the scale node in the compositor.

This is a 20x20px image; enlarged 16 times (to show detail). Here is the original if you want to try it.

Now after going through the scale node, you can see that every other pixel from the original is in the scaled image (again scaled up 16 times).

All you have to do is set up the compositor nodes: Image, Scale, and Composite nodes.

However if you need every other pixel starting with the second row or column of pixels you can add in a translate node to move the image before you scale it. Then after the scale node move the image back to the center.

This node setup will give you every other pixel starting with the second column. (Use the Y axis for the rows).

Last set the render size to ½ the resolution of the input image. So for a 10 megapixel image you could type 3872/2 in the resolution X field. In the render tab of the properties window.


Can I edit an armature's size through its bounding box?

An armature object doesn't provide it's bounding box size. However the mesh object of your character does. You can scale your mesh object until the height is to your liking (the dimensions are visible in the properties sidebar). By selecting your armature, then shift selecting your mesh, the mesh object is active and will display it's dimensions as both objects get scaled together.

If your character is made of several items you will only see the size of the active object, a trick there is to add a cube and size it to the height you want, then use it as a reference and resize your character to fit.


This is done uder the Image tab in the Side Bar of the Render View / Image Editor


How can I activate an actuator if A is false and B is true?

Assumptions
You have two AddObjectActuators?
You activate both randomly?
You want that only one at the time gets activated?
Analysis
It seams you have two independent random results that both decide when a certain object gets created.

Possible solution
How about changing the decisions? One random result decides when an object gets created and a second random result decides what object gets created.
How to decide what object to create?
You have two (or more actuators to activate) so you need a random result that represents one of the possible actuators. The simplest representation is you number them:

Actuator A
Actuator B

This way you can use the random actuator to generate a random number between 1 and you maximum (2) to be placed in a property. With the random actuator you can decide the likelihood what actuator to activate (e.g. you want 50:50 so you use "Int Uniform"

How to decide when to activate the actuator?
You already did that with the random sensor. It acts as "Bool Uniform" which means 50:50 chance.

How to connect both aspects?
This example just show how to randomly generate a random object number:

Now you add the actuators dependent on the previous choice:

You check what actuator to activate either 1 or 2 and activate the actuators. Only one condition can be positive at the same time.
We do this after the random actuator completed (actuator sensor). Otherwise there can be another object after a one frame delay, which looks like it created a second object at the same time.

Another Possible solution
You decide the what as above. You decide the when the same way. The benefit is that you get better control how to generate the wait time.
Now you get two properties:

one with the actuator number (actuatorNumber) and
one with the time to wait (waittime).

The timer property counts upwards so we generate negative wait times. When the wait time gets positive it is time to generate a new actuator number, new wait time and activate one of the actuators.
Interestingly the activation logic is the same as in the above solution. So I do not repeat it here.
I hope it helps
PS: I forgot to mention:
When deciding what to activate you can add "unmapped" numbers. This way it decides to activate nothing (e.g. 0=nothing, 1=Actuator A, 2=Actuator B).


turning the black to alpha in texture node

To the best of my knowledge the only thing you can do in a shader is to use the texture as input to the alpha input of a shader node that supports alpha input, like the principled shader node.  Here's an example of a red ball behind a brick wall:

Here's the simple shader for this.  Note that I inverted the color of the brick mask before feeding to the alpha input of the principled shader.  Otherwise, the mortar would have been black and the bricks transparent:

Note that if you are going to render this with EEVEE you need to go to the material settings and change the Blend Mode to Alpha Blend:


Create a base object with the shape of the mesh.

Then use a couple of array modifiers to extend it as much as you need.


I need help to smooth a part with a bevel

You have some duplicated loops overlapping other ones.

Select them using Select Edge Loops and dissolve them.

Image below:


UV unwrapping seems to be unwrapping my object twice

Seems like you accidentally duplicated parts of your mesh.
In this case you have to merge the vertices that are on the same location.
The easiest way to do this is to use the Remove Doubles operator:
Select All (A-key) > Press W-Key for Specials Menu > Remove Doubles
After removing the duplicate vertices you have to unwrap the mesh again.


How can I get Infinit Reflections on Cylces

You need to increase the number of Light Bounces.
It cannot be infinite, but it doesn't need to be.

head to Render Tab > Light Paths > Max Bounces
adjust both the Glossy value and the Total value to your liking
to look infinite, the latest reflection needs to be of 1px size

How many Suzannes do you see...?


Textures turn black in material and render mode

You need to use a newer version of blender.

You can't use the Principled BSDF shader in versions previous to 2.79
.


How to smooth a curve from an already existing model?

You can create brand new curves in blender, and then convert them to those tubes with needed resolution. How to do it, there is a lot of tutorials on youtube. Try to search something like "create pipes with curves in blender".
As for your existing meshes, you can convert them to curves. But segments you would have to handle anyway.
If you want to go this way, you have to get the single edge loop from your tube: Select your tube; go to Edit mode (Tab); switch to edge select mode (Ctrl+Tab, 2). Then select one entire longitudal edge (Alt + RMB on that longitudinal edge); and kill all others (Ctr+I - invert selection; X - delete Edges).
It will give you the wire-like mesh one vertex wide. Here it's good to switch to vertex selection mode (Ctrl+Tab, 1). You can use proportional editing (O) to edit it, use Smooth (Ctrl+V, Smooth), (W, Loop tools / Space), (W, Subdivide smooth) and any other tools you find useful. When you done with the mesh, return to the Object mode (Tab), and convert the mesh to curve (Alt + C, mesh to curve). And how to deal with curves you already know from the tutorials about pipes, that I suggested before :-)


yellow dotted wireframe appears when I mistakenly press Shift-t instead of Ctrl-t

Shift+T does indeed turn on the 'Texture Space' display mode.

To disable it go to Object> Display> Texture Space and untick the checkbox:


Is there a way to disable self-cast shadows on grass (particles,) but still have grass receive shadows from other objects?

I have an "okay" solution for your problem (in cycles) and it is only working with gras meshes (not billboards) so far. I know exactly what you are struggeling with, because I asked a similar question a while back but without an answer.
Recently I tried something that works best:
you need to render your scene 2 times.
First time:
Everything + the shadeless grass.
second time:
Check "shadow catcher" for the grass meshes + Instead of the Emissionshader give the grass a Diffuseshader. For everything else check "Holdout" (both checks are in the Object Properties). And under Render Properties -> Film -> Check Transperent (for a transperent background).
now you can combine both images in the compositor or in a programm like photoshop.
here is a quick example:
[
but i hope aswell we will get a better solution in the future, it must be possible because EEVEE is using the same technology as Game engines, and this is a well used and very common style in (indie)games (dauntless, the witness, zelda: botw, fortnite).


The Shading_View_Problem.blend file that you uploaded is not showing the problem for me.

The only way I can reproduce what you have is if I enable the Scene World lighting in the Shading drop down menu then in the Shader Editor I switch from Object to World and then disconnect the Background node from the Worlds Output node. This sometimes results in what you are experiencing but not always. The 3D view remains with the Black cube etc until I move the cursor back to the 3d Editor again, then the scene seems to update and turn the whole view black.

I have no idea if this is a bug or something to do with the graphics card (mine is a 1080 ti with updated drivers) or something else completely.

All I can suggest is that you download 2.80 again, sorry.


Getting a Bleach Bypass Look in the Compositor

The "bleach bypass look" can be replicated in its most simplest way by reducing saturation and increasing contrast of the image using bright/contrast node.

But instead to get a more detailed look what I would suggest is to:

have the image de-saturated slightly
have a copy of the original image de-saturated completely and boost
the contrast of this layer by carefully using an RGB curves node
the monochrome layer should be mixed with the first image using
"overlay" blending mode.

To adjust the contrast effect you would adjust the curve as desired and also the factor/strength of the mix/overlay node.

Full Size

In your example image the artist appears to have also used some sort of sharpening or detail enhancement to make details pop out more.


How to drive a node group in Geo Nodes Blender 2.9.3a?

It's not possible to instantiate geometry that's not tied to another object in the Point Instance node at the moment, but it is planned for a future version. It is a known limitation right now.
As a workaround you can use a collection with pre-generated objects and uncheck "Whole Collection". Tweak the node seed to randomize instances. Each element of the collection should have equal chances to be instantiated. I think weights similar to the particle system settings are planned.


How do I fix the loop cut eror "loop cut does not work well on deformed edit mesh display"?

It's not really an error, what you see is  just a warning that your mesh won't look like you want after a loop cut in a different pose since it's influenced by an armature.
you can delete the armature modifier temporarily and add it again after you do the cut to avoid seeing that message.


How to make object bend like a hair strand (particle system) - 2.77a?

I will demonstrate only on the trunk, the branches are the same idea.
At first add the cloth simulation and turn on the pinning, then assign the bottom vertices of the trunk to a groop and in the cloth simulation panel under the pinning set to the groop u just made, then use this picture values as a basis to make it suit u own purpose


You need to look at zooming in closer to your paint surface, or maybe switch to the Fill tool since you are using Face Select Masking it might be easier to drop the color in that way.

The main reason is that 3d painting uses projection, and being far from the target can cause it miss. Smaller brush sometimes helps also.


Formula (According to Blender) to create an Enneper Order 3

From the formula here:

If a stands for n (so 3 in our case) and b for 2n-1 (so 5), then:
x = u*cos(v)-(u**b * cos(b*v) / b)

y = u*sin(v)+(u**b * sin(b*v) / b)

z = 2 * (u**a) * cos(a*v)/a

with:
0 < u < 1.2
-pi < v < pi

And:
a = 3
b = 2 * a - 1

Which is:

Then:

If you want to push u to its limits, set it between:
0 < u < sqrt(2)

And you can change the order setting a and b differently (b = 2 * a - 1), for instance:

If useful, here is the preset file "enneper_n.py" that can be stored into the preset directory (on Windows):
C:\Users\userName\AppData\Roaming\Blender Foundation\Blender\2.90\scripts\presets\operator\mesh.primitive_xyz_function_surface

Its content is:
import bpy
op = bpy.context.active_operator

op.x_eq = 'u*cos(v)-(u**b * cos(b*v) / b)'
op.y_eq = 'u*sin(v)+(u**b * sin(b*v) / b)'
op.z_eq = '2 * (u**a) * cos(a*v)/a'
op.range_u_min = 0.0
op.range_u_max = 1.2000000476837158
op.range_u_step = 32
op.wrap_u = False
op.range_v_min = -3.1415927410125732
op.range_v_max = 3.1415927410125732
op.range_v_step = 128
op.wrap_v = False
op.close_v = False
op.n_eq = 1
op.a_eq = '3'
op.b_eq = '2*a-1'
op.c_eq = '0'
op.f_eq = '0'
op.g_eq = '0'
op.h_eq = '0'
op.show_wire = True
op.edit_mode = False


Thats actually not a reflection but indirect light.
you can use a light path node (more info on the node here) to control the color of your cube before and after light hits it.
Here is a basic node setup for your cube material:

the upper color of the mix color node controls the color of the light after it bounces off of the cube. the other color is the color of your cube itself.
Before

After


Making a necklace with the curve modifier

Shrinkwrap modifier generates from curve tmp mesh. What you can see on your second image is original shape of your curve (shape without shrink-wrap modifier) I guess. It means your Curve modifier used by Torus still follows the original curve shape. What you see on your first image with shrinkwrap is actually a mesh :)
You have to convert curve to mesh (to get desired shape) than convert mesh back to curve.
Ensure if origins of Curve and Torus are at the same location.
Error message is probably referring to my first note - circle is still constructed from four points therefor applying modifier can't result in a shape presented by modifier that operates on mesh level. ... just my theory :)


How to keep all the islands facing the right direction (UV)?

In 3D-View-Window press N for opening Properties.

Under "Mesh Display" you find "NORMALS:" press the "Face" Symbol. If you now go with your mesh to the Edit-Mode you see little lines coming out of the center of each face (These lines show the Normal direction). With "Size" in Properties-Panel you can change the Length of the these lines.

Now choose all your faces and open Tool-Shelf by pressing "T". Under "Shading" you find "Recalculate". All Faces should now look in the same Direction. If any of your faces should not, select these faces manually and press "Flip Direction".

"Recalculate" could not work perfectly when your faces are not connected (Island-faces?????)


How to Make Smooth Bevel Curve Without Extra Crease?

Maybe put an additional edge loop close to it, it should attenuate the problem:

If you ever want an alternative that works (but the whole profile is different so it may not be what you want):
Create your pipe with a series of vertices, when you want to curve an angle, bevel the vertex:

Convert to curve, go in the Properties panel > Object Data > Geometry, and bevel:


Is there a way to project field of view lines outward to look for camera overlap?

Sounds like you simply need to increase the Camera Size property.

It will virtually extend a camera's view frustum taking into account FOV, offsets and any other properties.


how to create an object in real time by extruding

You can't. The BGE does not support mesh creation.

You can modify the positions of vertexes (= mesh deformation). The vertices needs to exist already.


Rendering Translucent Materals through Glass in Cycles

Excuse my technically incorrect explanation. I'm stating this from an artists perspective and don't know all the math behind all of it. :P

Glass uses a lot of processing power, and there's really not a way to render faster. I can however suggest a few things that will make the glass look better.

More Light!

This is probably the biggest issue I see when glass looks dark and yucky. Glass refracts/reflects light all over the place. Glass doesn't really hold much color itself. It's mainly just a light-bender. That's what gives it a realistic look.

Use an Environment Map

As stated before, glass just bends light. The more types of light it has to work with the better. Environment maps are one of the easiest ways to make glass look realistic. And it's not too much work to put one in the scene.

Set the color to White

Setting the color of the material will tint the glass with that color, so if you leave it with the default "almost white" grey, your glass will be darker. Set it to full white to have the maximum transparency.

You do need caustics

I don't know exactly what they do, but I know it has something to do with light bounces. You need caustics if you want the light to go through the glass.

From Wikipedia:

  In optics, a caustic or caustic network is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface.


What is the proper way to make this robot arm?

Less is more ...
Add Circle 8 sides
(Rotate R 22.5, Extrude E, Scale S, Copy Shift+D, move and scale down, select 4 vertices press F ...

Add Subdivision Surface Modifier
Select edges you want keep as Sharp Edges Shift+E press 1

... here topology version for Quad Evangelists :)

Add thickness - you can simply select all and Extrude or use Solidify Mofifier. For more natural look of edges try Bevel Modifier

Note:
in some cases you can also use Bezier Curve with very similar workflow of creation - start from circle, duplicate, scale, extrude or connect points. You dont even have to manipulate with handles, you just select few of them and switch handle type V to Vector that automatically switch direction to point of a next control point.

For extrusion and bevelling edge use Properties Editor > Object Data > Geometry > Extrude and Bevel > Depth.
But keep in mind model can't be unwrapped, but it doen't has to be a deal in some cases with pointiness and other procedural material nodes.


Why are material animations not responding?

First, change the options in the tab, Material - Options - Object
Color and deactivate Use Mist.
Then, go to Timeline and place your marker in FRAME 1, go back to
the Object tab change the Object - Options - Object Color tab (you
will cmbios).
Change color or alpha according to your needs and insert a KEYFRAME
(place the mouse over the LMB level controls and select insert 1
keyframe).
Now, go to Timeline and place the marker in the frame you need in
this case, use FRAME 2.
Return to the Object tab and see options color object, again you
have the color or transparency adjustment you need and insert a new
keyframe.

Now try placing the mouse in Timeline or give play to your animation, it should work correctly.

  Follow the gif that I made this complete step by step:


how to make a text object have underlined text

There are two ways to change the formatting, first is using operators to replicate the steps you would do by hand.

bpy.ops.object.mode_set(mode='EDIT')
bpy.ops.font.move(type='LINE_BEGIN')
bpy.ops.font.move_select(type='NEXT_WORD')
bpy.ops.font.style_set(style='UNDERLINE', clear=false)
bpy.ops.object.mode_set(mode='OBJECT')

That should look obvious - move to the beginning of the line, move and select to the next word, then apply a style to the selected text.

The other way is to adjust the data that stores the formatting. A font object uses a TextCurve to store it's object data, the body and body_format properties are what you are interested in. body is the text string and body_format is a list of TextCharacterFormat which includes use_underline for each character in the body.

So to underline the first 6 characters of the active object -

for c in range(6):
    bpy.context.object.data.body_format[c].use_underline = True


How to export object with transparency from Blender Internal?

I think if you are going to export to .fbx, you should only use Principled BSDF. In that case you cannot use mirror shader, or something like this on your scene. You have to use alpha channel...
If someone have a better solution, plz tell us!


did you try to render a still image? If there is no problem with that I would suggest to always render animations just using still images, that has different advantages.

First, you can pause the render and continue at any point.
Second there are just less possible problems, in my opinion.
Third and most importantly, if something goes horribly wrong, for example your PC crashes, you do not have to start the render all over.

The most preffered format for many is png, since it has a good balance between data size and quality loss, due to compression.

Please comment, if this method is helpful, or not. :)


Can't move any character in blender even when in pose mode

after digging up in 2.82 I’ve solved it by clicking move in object gizmos (which was turned off by default)I have uploaded an image of what i am referring to for anyone who has or had this issue of the character not being able to move or pose at all. Enable the move checkbox ☑ in order for your move and pose your character


Blender Fluid Simulation Inflow From Particle System With Liquid Simulation

The workaround for this could be the use of dupliverts, which gives 99,99% of the particle system effect. The difference can be found in the Blender manual. And if you want to model a shower you can punch holes in a cylinder's bottom, make it an obstacle and put the inflow inside.


Is it possible to disable the mouse wheel?

It should be doable by removing (or changing) the Key Bindings in Blender. Go to File -> User Preferences -> Input and look for any Key Binding which is connected to the Wheel of the mouse. Like this:

In the example I'm deleting the binding for the Zoom in 3D View only. So in 2D Editors, you could still use it if you like. Otherwise, you'd need to remove it section by section.

To get it back, use the Restore button that shows up after you change or delete a binding (it will stay there as long as your keymap is different to the Defaults). If you want to keep your Blender Prefs this way, click Save User Settings


How do I use Proxies when compositing strips?

In the original approach, Offset and Crop were applied to the strip.  This approach did not work.
However, it does work when Offset and Crop are applied to a transform.  Click on the strip, then in the menu, choose Add -> Effect Strip -> Transform.   This then creates a green transform block for the strip (in the next channel).  By applying the Offset and Crop to the transform and then regenerate the proxies, everything worked as expected.


How to stop and save during a 'Progressive Refine' render in progress?

To stop a render in process, be it progressive or not simply press Esc.

You can also click the x next to the progress bar in the Info header to do the same thing.

To save the image, press F3 with your mouse in the UV/Image Editor window with the Render Result or output from the compositor Viewer Node displayed.