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How to assign verts to bones (2.79(
I want to assign this vert to this bone
When i try weight painting it just isnt as accurate

Assigning a vertex to a bone must be done by first assigning that vertex to a vertex group. This vertex group must have the same name as the bone which will influence the vertex you want affected. If your mesh doesn't already have a vertex group with the name of this bone, you will need to create one. With the mesh selected that contains the vertex you want controlled, go to the Object Data tab in the Properties Panel, and under the Vertex Groups section, click the plus sign to add a new vertex group and give it the same name as the bone you want to influence your vertex. Now, in Edit Mode, select the vertex you want controlled and in the Vertex Group section, press the Assign button. If your mesh already has an armature modifier on it, then moving the bone in Pose Mode should move the vertex.

If it happens that your mesh does already have a vertex group with the same name as the bone you want to influence this vertex, then don't create a new one. Instead, go into Edit Mode, select that vertex group in the Vertex Group section, select the vertex you want to add to this group, and click Assign.
Once assigned, the weight of this vertex can be tweaked if it is too low or high by rolling out the Properties Shelf (n key) and looking for the Vertex Weights section. Listed underneath will be all the vertex groups this single selected vertex belongs to, along with the weights, which can be edited here.


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Cannot export .dae with color
How do I export .dae models with color? When I export it, it ends up black and white.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


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Python script to randomize modifiers and their values applied to an object
I’m completely new to blender and python, only having marginal experience with C+. I have a personal project where I’d like to apply randomized generative modifiers, with their values themselves using random values. Is this reasonable? I have a general idea that python can access blenders list of modifiers, assign variables to them and randomly select and apply from that set. As for values, having the script recognize which modifier has been “selected” and determine which values can be randomized. To begin I’d like to just apply one modifier, and then rerun the script to abstract the form further. Is this reasonable? As a newcomer to python it seems very flexible but perhaps this is too specific (python can actually manipulate values in this way)? Some recommendations or even rough sketches of such a script would be greatly appreciated.

Adding modifiers or changing their parameters at random will likely not give you any useful output, constraining the allowed options is advisable. Nevertheless adding modifiers and adjusting the parameters is possible. https://blender.stackexchange.com/questions/71569/how-to-add-modifiers-using-python-script-and-set-parameters

Got it, if I wanted to continue regardless is it possible to randomize the selected modifier? And consequently it’s value like the ones mentioned in the link? Essentially type=randomModifier and as an example, octree.depth(n), n being a random value.

And sorry, what constraints would be reasonable? I get that your saying certain inputs would be redundant.

While you can do what you're describing, it has the potential to go very wrong. You should therefore limit yourself to a subset of modifiers and a subset of their configurable properties. Ensure that you assign values from a sensible range to the properties. Otherwise you may not only create visually unappealing results, but very likely crash Blender. For instancing adding a subdivision modifier and setting the number of subdivisions to 10 is possible, but it will likely to consume more memory than you have.

Of course, that makes a lot of sense. It’s more experimental so I am hoping for absurdities. Again I am quite illiterate as far writing it goes. Any further suggestions? About the randomizing the library of modifiers for example?

Create a list of the modifiers you want, import random and then pick a random item from the list using random.choice()

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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How to import reference images to specific XYZ positions
Dears,
Scientific question:
I have a bunch of images taken from a microscope.
All images have XYZ coordinates of their real world position.
How can I import them into Blender via a script to have them placed correctly?
I have placed five images manually as an example, but I will have 100+ images to process.
See below how my data is organized at the moment and what I am hoping to achieve.
Thanks in advance.

Place the data in a CSV file containing the coordinates and image names.
Loop over each line of the CSV file:

use Images as Planes to import each image
move the image to the location.

Although given that your Z values are identical, you may want to read only the X and Y coordinates.
Here's an example CSV reader that you would have to modify to handle the format of your file
import csv
with open(csvFilename, 'r') as csvFile:
    csvreader = csv.reader(csvFile, delimiter=',',
        quotechar='|',
        quoting=csv.QUOTE_NONNUMERIC)
    for row in csvreader:
        print(f"{int(row[0])} is ({row[1]}, {row[2]}, {row[3]})")

Once you've decided on your CSV format, replace the print statement with code to decode a row, use the importer, and move the resulting object.
Here's an example of how to import an image as a plane and move it.
from pathlib import Path

image_file = Path("c:\\tmp\\0001.png")
bpy.ops.import_image.to_plane(files=[{'name':str(image_file)}])

image = bpy.data.images[image_file.name]
image.location = (x, y, z)

So the entire loop looks like this:
import csv
from pathlib import Path

with open(csvFilename, 'r') as csvFile:
    csvreader = csv.reader(csvFile, delimiter=',',
        quotechar='|',
        quoting=csv.QUOTE_NONNUMERIC)
    for row in csvreader:
        # YOU need to place code here to convert the row entries
        # into a file name and set of coordinates

        bpy.ops.import_image.to_plane(files=[{'name':str(image_file)}])

        image = bpy.data.images[image_file.name]
        image.location = (x, y, z)


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how to remove a default menu in blender using python?
I'd like to remove some toolbar from the blender interface to simplify that for a potential customer, but I'm not able to do that using python.
I know that it can be set up as default saving all the settings in a startup.blender file, but it doesn't work in every PC.
For example, how to do the "Ctrl+space" over the "Layout" view with python?
My aim is illustrated in the following picture:

Are you looking for this: bpy.ops.screen.screen_full_area(use_hide_panels=True). Going to this link will help you in that case.

Thank you! But this command is not working in my code, I don't understand why.
Moreover, it could be better if there is a solution to completely remove some of the pannel and not only hide them.

Check out these links: removing panels and python api for panels

Thank you very much!
With bpy.ops.screen.screen_full_area(use_hide_panels=True all the pannels are hyde permanently and I'm not able to show some of them.
Meanwhile with bpy.utils.unregister_class(bpy_types.bpy_types.*** it is possible to remove some buttons, but it's not allowed to cycle through "bpy_types.bpy_types.*" and writing a line for each button of each panel that I would like to remove is really a lot.
Any idea?


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Why is the grass (hair particle) going into the mesh?
I have a simple scene (deleted almost everything from the blend to upload it), and for some reason the hair particles are going straight into the mesh. I tried playing with the transforms, the normals, the force fields I had going on, and literally every setting in particle settings.
I just don´t know where else to look, and I´m also on the clock cause I have to turn this in next week.

It's the Wind object that's blowing your hair down. The Strength setting of 200 is much too high. Maybe you cranked it up because you didn't see any effect. If this is the case, go into the Particle Settings and enable Regrow.
Then the checkbox Use For Growing Hair under Field Weights is enabled, this makes the hair get pulled down by gravity right from start.
Another thing might be, the plane is scaled very large to 46.8 which also has an effect on the hair. But maybe this is intentional, if not apply the scale by hitting Ctrl+A > Apply > Scale.


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Are weird shading artifacts normal with the subdivision modifier in edit mode?
TLDNR: Are the circled thingies in the picture normal with a subdivision modifier while in edit mode? (note: subdivision set display modifier in edit mode)
I've been trying to create a character that I might like to use for a game in the future. I'm pretty new to blender and these "artifacts" (unsure if that's what they are) are slowing me down.
This problem doesn't show itself when in object mode, only in edit.  I'm using the mirror modifier and the subdiv modifier.  I've applied the mirror mod before the sub mod, due to some strange separation of vertices at the origin of my character.  However, I went back and forth to check, and with the subdiv mod before the mirror mod, these odd "artifacts" don't seem to show. I can't use that arrangement thought, because of the weird tearing problem D:
Any experienced blenderers out there that think they might have the solution to my problem?
PS/Side question: Should I just go ahead and continue making the model of my character, no matter the mistakes/ngons there might be, and then just go over it afterwards with some nice retopology afterwards?

yes it is normal, just the shape that the subsurf modifier creates which is a bit different from the original mesh

It is completely normal that the subdivided surface crosses the original mesh's edges when they make a concave geometry, and this shouldn't be considered an issue with the mesh. This becomes evident in Edit Mode because, together with your subdivided mesh, you also see the un-subdivided wireframe:

That "artifact" is just the subdivided mesh "coming out" from the cage of the un-subdivided mesh. Nothing to worry about. This effect doesn't appear in Object Mode since, in that mode, you don't see the underlying un-subdivided geometry.
However, you have the option to see the effect of Subdivision Surface also on the Edit Mode's wireframe. There is a button () in the modifier panel for this:

Thank you so much! I feel that the amount of work I put in for this question was overkill haha.  Thanks again for your explanation, I appreciate it.


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Motion capture movement from 3d model animation
I have a set of animations of a model with a complex rig that I would like to copy to another model that is unrigged.The original model has more than 250 bones in total and it would take a really long time to convert the whole animation set.
I wonder if there is a way to motion capture the 3d animations and apply them on my model or another solution that wouldn't be so time consuming.

Try using a deform mesh modifier, this is similar to a lattice in that a mesh contained within the deform mesh will deform with it.


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Shader nodes: ignore scaling, keep rotation
I've successfully built a procedural wood texture, but I'm having problems with coordinate spaces.
By default, textures seem to follow the UV coordinates of the geometry. This is obviously useless; each object I apply the wood texture to gets its coordinates horribly mangled according to the UV map of that object (if it even has one). Most particularly, if you scale an object, the texture is also scaled.
Fortunately, using the "geometry" node, you can get actual, absolute coordinates in 3D space. This allows the wood texture to operate as a correct 3D texture, which different faces of the object showing different sides of the grain and so forth. It also means that every object in the scene has the same size grain.
There's a snag, however: The texture now correctly ignores scaling, but it also ignores translation and rotation. I understand why, but I don't know how to fix it. How can I make it so that rotating an object also rotates the wood grain? It would seem I need some way to read the object's rotation... but I don't see an input node for that. Can I get the local-to-world transformation matrix somehow?
The only other solution I can think of is to have a duplicate copy of the material for every single wooden object in the entire scene, each with the rotation factor manually set to match the object geometry. But that's a horrid, horrid idea! I do not want to have an entire separate material for every individual object! And having to manually update the material every time I rotate the geometry sounds awful. There's got to be a better way...

@RobinBetts That seems to fix it. If you make that an answer, I'll accept.

It sounds as if you should be using Texture Coordinate > Object space.
This is in Blender units, from the object's origin, and in the orientation of the object's axes.
Be aware, that space carries the object's scale transform as well; to make sense, the object's scale will have to be (1,1,1).. (i.e. applied).
There's an example of a procedural wood here

This way, whatever transformations I "apply" don't affect the texture, and whatever transformations I leave unapplied do affect the texture. Couldn't really be much more flexible than that...

Un-applied scale, especially non-uniform, is a notorious cause of unexpected results from modifiers, etc., so you just have to know it's there, in the object's transformation matrix.


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How to animate cuts between shots?
I'm having a surprising amount of difficulty finding an answer to a rather simple question...
I've worked out how to animate things in Blender. But I'm having trouble putting cuts into the animation.
Initially I had the camera just fly from place to place, but the repeated fairly fast camera movements come across as rather disorienting and confusing. Then I had the idea that maybe cutting from shot to shot might work better. But how do I do that, exactly?
My first though was that this would be trivial: If you put two keyframes on consecutive frames, the camera position will just instantly snap to the next keyframe. Well, it does, but it also screws up all the interpolation. (Presumably Blender is still trying to make the control spline smooth, so it's changing the animation I've already set up.) It's also really fiddly to set up this way.
I'm really struggling to find the right search terms to answer this simple question. Google returns lots of hits for how to existing cut video files (not what I'm asking), or how to animate a character jumping (nope), or how to animate cutting an object in half (still no).
I did find a few glimmers of relevant stuff, but I don't really understand it. One page off-handedly mentioned multiple cameras. (Wouldn't that be an error? How would that even work?) Another hinted at having multiple "scenes". (What's that?) But I couldn't find any in-depth explanations.
Basically, what is the "correct" way to cut between shots? Surely everybody does this constantly, all the time, so I'm confused as to why I can't find any information about it...

You can set markers in the animation time-line to set which camera is active at a given frame : https://blender.stackexchange.com/a/3503/86891

Here's the video. Hope this helps.
https://www.youtube.com/watch?v=i1idLrDgbE4

@Gorgious Is multiple cameras the best way to do this then?

Yes, else as you experienced, you risk having some motion blur or other artifacts between frames

As per the comments, I eventually went with the approach of using multiple cameras.
Basically this consists of:

Have more than one camera object in the file.
Add "markers" to the dope sheet on a specific frame number.
Select the marker you want, select the camera you want, and find the hidden menu item to "bind" one to the other.

Now the render output does a hard-cut from one camera to the other when that specific frame is reached.
Unfortunately, binding a camera to a marker deletes the label on the marker, so it's now useless for... you know... marking anything. But hey, it generates the right output frames...

Just put camera keyframes as close to each other as possible. Now camera has no time to slide and it will teleport instantly.
Hope it helps,
Kirill

As I explained, I already did that, and while the camera does teleport instantly, it also messes up the smoothing of the rest of the animation.

It does not mess up the rest of the animation. It is working as intended as the animation tries to interpolate all the way through your frames you have keyed.  Select the Camera in question.  Open a Graph Editor Window. (Bonus points for doing in the in Animation Layout!)

Open Properties with N key.  Select key for last frame of Shot A.  In Active Keyframe, change the Interpolation from Bezier to Constant.  This says, "do what the previous curve says until here; then change instantly to the next curve."   Repeat for any other keys set on the Camera.


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Mesh looks edgy in object mode and smooth in sculpt mode
I encounter a weird problem working with a mesh.While in object mode, the mesh looks edgy but when in sculpt mode the mesh looks smooth.The mesh has 2804 polygons.
I also tried to apply a multi resolution modifier but not even a single change took place.

What is the cause of this problem and how can i solve it ?Thanks.

These problems are tied with internal Blender settings for this certain project mesh is in. It could be e.g. AutoSmooth angle set too low so in Object mode it sharpens all the edges while in Sculpt mode Dyntopo is enabled which smoothens all the edges. Exporting and importing will kind of solve this while will be a workaround

I solved the problem by exporting the mesh in a Wavefront format (obj).When I exported it I checked Selection only and unchecked everything else.Then in a new project I imported the obj file and it seems to behave normal now.

While this may work it is not really a solution to the issue. You would lose all modifiers, materials and other data associated with that object.

I know that.I only wanted the mesh without any materials/texture/modifiers.


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How to add Fall-Off texture to every instance in geometry nodes individually and keep each instances color?
In Geo Nodes I have a setup that creates these colored circles on certain points. This circles are overlapping and thus not all colors are visible right.
I have a texture with a fade/fall-off. But I can't find a way to add this fade to each individual circles.
The mix-shader node only applies the fade over all the circles and not to each individually.
The color of the circle needs to stay the same just fade towards the edge of the circle.
Is there a way to add this texture to each instance and keep the color?

Probably need to UVUnwrap the circles and then use that vector data as an input into the ImageTexture node's vector input from the attribute node in the material.

Thanks to @Jakemoyo I was able to generate the shader I needed!
I had to use an object from the scene, the white circle, that I UV unwrapped and added a mix shader with a principled and a transparent shader.

Nicely done! Remember to mark your own answer as accepted whenever you can so that the question gets removed from the "Unanswered questions" queue.


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Unknown Object in my rendering
In my very first rendering I have an unknown object in my rendering image. its not found on any layer and I cant finde any unknown axis or objects on my rendered layers. Its a white circle behind a cup. could it have something to do with the light?

it would be helpful if you would upload the scene somewhere.
and no, i dont believe its a lighting artifact.

Alt+H has shown me the hidden circle.
Problem solved


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Dividing image radially
My goal is to go from subdivide the coastline of Antarctica as such:

And manipulate and animate the pieces to move into this shape:

I am not sure if an Array modifier is the way to go. The act is as if I am slicing a pizza, but keeping the crust intact and then unraveling the crust into a straight line. **(this line is technically a series of 36 arcs)

are all the pieces supposed to be separate when flat like it seems on your 2nd picture? Also, how is the animation supposed to happen?

The entire animation will be 2-dimensional. The animation will begin with image#1 above. The radial grid will be cut and separate from the radius representing 12 o'clock noon on a clock. The "crust" will layout along the ground. The crust is acting as a spine with all slices attached. The point representing 6 o'clock on a clock will never move throughout the animation. There are now 36 slices stretched out almost as in image#2. The final step is to cut each slice horizontally into three sections and separate to show image#2.

This isn't exactly procedural, but it's OK for a one-off, maybe.
Create a single segment.

Start with a whole 36-section circle, rotated, inset,and translated in Edit Mode as shown, so its origin is at the center of an edge, at World 0. We're working in XY, Z out of the screen.

Select out the bottom segment, V rip the internal edges, and P separate by loose parts into 3 objects. Parent the point to the midsection, and the midsection to the base.

Make hierarchies of left and right segments.
ShiftD duplicate all the parts of the segment in place, and place the origin of the duplicate in its bottom-left corner. In Object Mode, with Snap set to 'Vertex'  Shift D X duplicate it to the right, and snap the duplicate to the original, in one move.
Shift R repeat the move, until you have 18 segments, not counting the original, which you can delete.
Do the same on the left, this time with the origins of the objects at the bottom-right corner, stopping at 17 segments.
Now we have to parent the base of each segment to the next, working towards the center. This is tedious, so you can do it with this little script, having selected the (bases only)  of the right and left-hand groups in two batches, switching the reverse parameter in the script appropriately:
import bpy

obs = bpy.context.selected_objects

# set reverse = True for right (positive X) segments
obx  = sorted (obs, key=lambda ob: ob.location[0], reverse=False)

for i in range(len(obx)-1):
    obx[i].parent = obx[i+1]
    obx[i].matrix_parent_inverse = obx[i+1].matrix_world.inverted()

Now when you set the Pivot to 'Individual Origins' and rotate the bases in Z, a curl results:

.. and R Z10 closes the right half of the circle. This rotation is keyable. On the left, it's R Z-10
When all the segments are present and selected in the curled position, and all thrown into Edit Mode simultaneously, they can be UV mapped together with 'Project from View: Bounds'. Then they can all share the same material, and all acquire their own UV map into the image texture.
Then you're kitted up to animate the rotations, and later the translations of the segment-sections.


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Rendered Background video is B/W any ideas why?
I wanted to create a Muzzle Flare effect for a video of a friend (250 frames long)and managed to create the Flare effect using a Cylinder and some cloud deformation + emission. I´ve then set the video as a background video to the camera and placed my object at specific Keyframes making it appear for only for 1 keyframe (3 in total) but once  rendered,(Eevee) the video in the background appears in a kind of Black/White/Sepa-ish color. Video is sRGB though.
Any ideas how to get the original colors ?
I thought of maybe importing it as a plane and using it with Nodes.
Thank you in advance

Not into vers 2.8 but in earlier versions the background image/video feature would default to half opacity. It had to be wound up. You might have the same or similar happening there?

Thank you for your answer, I'm going to check this out :D


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Sculpting Symetry X Issue
I have started sculpting in Blender and Im not the biggest expert. I have a little issue now. When I started sculping Symetry X was on and it is still on. It worked all perfectly, it did mirror each side as it should. But now I started working on hands and as you can see in the pictures on one hand its fine but on the other hand at the finger tips there is "extra mass" and I do not know where it comes from. I did not turn off X Symetry or anything. I was just normally working. X Symetry still works at all but the fingers are an issue for that, and I do not know why. Please help me! Thx!
1: https://i.sstatic.net/ze1V9.jpg
[2: https://i.sstatic.net/ze1V9.jpg
[3: https://i.sstatic.net/643Xk.jpg

Try this, go into edit mode (where you can manipulate verts manually), you can try pressing tab to jump over. Tap 'A' should select all verts, then go to the Mesh menu, select symmetrize. Go back to sculpt mode, I think this should fix your issue.


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Natural movement to polygon Hair
I'm trying to make a polygon type hair, which moves as naturally as in the first gif, but it doesn't see like it and it doesn't stay in its place, (I used the softbody for the hair anyway) is there a way to get a more natural movement?

There is something wrong with how you weight painted the mesh. If I remember correctly, if you weight painted it at "the roots", the part of the mesh that is not weight painted should move. Or it could be the other way around. So just to be sure, here are some videos to help you out on the softbodies issue.
https://www.youtube.com/watch?v=j2tM_LS8jIA
https://www.youtube.com/watch?v=e1lHca7I3So
Hopefully, these videos can lead you into the right direction.

oh thanks, looks like these explain me better how softboies works, (I'm still new with animation and such)


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Sketchy look of geometry
How do I remove that small line extensions in EDIT mode that pop up from vertices and create that sketchy appearance in 2.8? I searched everywhere and cannot find option to turn that off. I like my geometry clean without those extra lines.
Thank You!


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How to define geometry from intersecting planes?
Is there a way to create a 3d shape by using intersecting planes? The image shows 6 planes that define an enclosed cuboid. I tried joining the planes, then using the knife tool with self-intersection, but the result did not generate vertices where three planes intersect. I know I could do it in steps by first joining the 4 vertical planes and using the knife tool, then join that to the horizontal planes and repeating, but that becomes tedious for more complex shapes.
This was done in 2.79, but I'm open to suggestions for 3.0 as well.

This comment is probably frustrating.. but Knife (Intersect) with 'Self-Intersect' checked, and set to 'Cut' works for me in 3.0 . Maybe  some tweaks necessary, where edges exactly coincide?

That's actually good to hear! I'll be using 3.0 tomorrow, so if it turns out to be just a version difference, I'll let you know so you can add a reply for me to accept, thanks!

I actually ended up just extruding the faces outwards, then used a boolean modifier (union) to define the verts and edges, then deleted the unwanted faces and welded the rest together. It's not a great solution though, so I'm not adding it as an answer.


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How to create rounded shape of the grill?
Hello and best regards to everyone viewing this post!
I am quite new to 3d art and blender in particular, so seeking for some help out here.
I am creating a 3d model of B&W 803 D3 speaker The problem is that I can't really create a rounded shape for the grill. I've created grill itself by using mirror modifier and a couple of arrays. Then I added lattice and bent it with proportional falloff. however disadvantage is corners of the grill which are sticking out of the body of twitter itself.
question is: is there any other way to bend it properly? or some other approaches?

Many thanks in advance!

That is how I would go about it. Another way would be to use the Shrinkwrap modifier and a target Sphere. Use the Project mode.

Shrinkwrap will stretch the holes in the mesh, which is unwanted. And the Lattice method is not precise. It needs to be bent. Look at morphing a plane into a sphere here. Then use Boolean modifier to cut only a section out of it.


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can i set the pivot of one object as that of another one?
I have a clock and a dial, and i want to set the pivot point of the dial as that of the clock, so i could rotate the dial freely and its center would stay at the same place. how can i do such a thing? right now the pivot point of the dial is a bit off ever so slightly and i want it exactly in the center.

Select the clock object in object mode.  Shift s (snap) -> snap cursor to selection.  Select the dial in object mode.  Shift ctrl alt c (set origin) -> set origin to cursor.  Done.

Thank you so much!


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Bend modifier not working?
Im trying to bend this plane into a hemisphere but its not bending correctly and i cant figure out why.
one half bends upwards and the other one bends downwards. what am i doing wrong?

Apply the rotation of your object or rotate it in Edit mode on the Z axis or change the modifier's Axis?

Thanks! That worked :)


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Transfer mesh to another rig
I'm new to blender and I have a rigging/skinning question
Here's my scenario: I have two rigs (Rig A and Rig B) which are identical in every way. And I also have two meshes (Mesh A and Mesh B) where Mesh A is skinned to Rig A and Mesh B is skinned to Rig B.
I would like to make Mesh B skinned to Rig A rather than Rig B... I don't want to alter the weights at all, I just want to make it so that when I move the bones of Rig A, Mesh A and Mesh B both move accordingly
How can I go about doing this?

Hey! welcome to blender stack exchange, correct me if I am wrong, so you have 2 individual rigged meshes and you wish to switch the rigs for either of them such that rig A although being in the mesh A but when moved, affects the movement of mesh B and same goes for the other rig. Is it the usecase you are talking about ?

Thanks for the reply. That’s kind of it, I’ll be more specific: I have two character rigs which are identical, the character meshes which belong to each rig are different. I would like to make it so that both meshes are skinned to the same skeleton so that I can export one rig (with both character meshes) to a game engine. Then, in the game engine I can toggle the meshes on/off to change the appearance of the character.
So I guess what I’m asking is how can I transfer the bone weight information (probably the wrong terminology) to another rig with identical structure?


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Is it possible to animate the opacity of a grease pencil layer?
I'm trying to have a grease pencil fade in and out over a number of frames. I'm able to get this behaviour in the blender viewport, but not when I render. I've created a minimal example which is available here:

The minimal example has a grey square, drawn in the default "Lines" layer of the default "Stroke" grease pencil. The opacity of this layer is set to transition from 1 at the start to around 0.1 at the end. When I play in the blender viewport, I see a smooth transition. When I hit "render animation", I see no change in opacity for different frames, and the rendered opacity matches whichever frame I have selected in the UI. "Render animation" will still correctly render motion, if I add location keyframes, but the opacity still behaves in the described manner.
Is there a way to make the render output respect the transition between opacity values?
Steps to create the minimal example:

Draw a square in a new 2D animation
Set end frame to 20 in the timeline
Create a keyframe for the opacity property of the "Lines" layer, at frame 0
Create another keyframe for the opacity property of the "Lines" layer, at frame 20
In the graph editor, drag the opacity at frame 20 down to around 0.1

This appears to have been a bug in blender 2.81. The example above behaves as expected in blender 2.82.

Possibly better suited to a comment on question.  Questions re bugs in blender are regarded as off-topic, and it is suggested they be reported to the official bug tracker. As mentioned it appears tho, this one has been fixed.

I initially wasn't sure if this was a bug, or a misunderstanding on my part about how rendering works. Do you know of a more appropriate forum for discussing issues when I'm not sure whether there's a bug in blender or a problem with my use of blender? I'd like to respect the rules and etiquette of this site! Thanks.

Wouldn't worry about it too much.  The "powers that be" (other users) will decide if it be closed or not. Seems to me worth marking as about a bug, since it appears to be fixed and you were spot on, on method.  (Hence the upvotes).  When not sure, I would err on a question here rather than an official bug report too.


text:
Forcing two cylinders to touch when modeling
As the title said: how do you force two cylinders to always touch while modeling. What I want to achieve is that I can move or rotate one of the cylinders during modeling, but with a constraint so they keep touching. The final result is static, so the cylinders do not have to be able to slide along each other with a rig or something.
For context: I'm planning to write an extension with some tools to quickly model pioneering constructions in blender. For example something like this:
Modeling these constructions becomes tedious quite quickly because the spars have to touch and when slightly moving spars not perpendicular to each other they tend to intersect or stop touching. That is why I ant to write such an extension.
But I was wondering what is the best way to implement something like this, or if I'm missing already existing tools that would be useful. I succeeded to force two spars to touch using bones as follows:

I added a bone to the first spar, along its length
I added a bone at the the tail of the first bone, constrained it's length to the sum of the radii of the two spars and constrained it's rotation to the be perpendicular to the first bone (90° around x-axis in XZY-Euler)
At the tail of the second bone I connected a third bone, with the same rotation constraint as the second has with respect to the first. The second spar is aligned with this bone

This setup succeeds to force two spars to touch, and I can move the joint by moving the second bone. But it is a bit buggy and requires manipulating bones to model the construction. Furthermore, this is approach is bound to become a mess of bones for larger constructions.
Because I'm writing an add-on, I also thought about defining an object representing the joint. When this joint is moved, it would update the positions and/or rotations of the spars that it connect accordingly. But I did not find any way to listen for changes to a certain type of object to trigger a script.
any help is highly appreciated!


text:
Limit bone animation velocity
I'm currently animating a robot arm. For this purpose, I created an armature with IK solver. I've constraint the bone (aka robot joint) transform to match the motion possible with the robot.
However, what I couldn't find, was a constraint to limit the animation velocity and acceleration of a bone. Is this even possible with Blender?

Since nobody answers, I found a temporary solution:
The iTaSC IK solver features some velocity constraints: https://docs.blender.org/manual/en/latest/rigging/armatures/posing/bone_constraints/inverse_kinematics/introduction.html


text:
Mute/unmute IK via Python API
I'm trying to mute/unmute an IK constraint via Python, but unfortunately the change is not applied.
def update_function(group, context):
    pose = bpy.data.objects["Armature"].pose
    pose.bones["Gripper Core Bone"].constraints["IK"].mute = not group.enable_ik
    context.scene.update()

Any ideas what's happening? The "eye" icon in the properties menu does update.
I'm using the Blender 2.80 beta.


text:
Quads acting like triangles?
I'm a complete beginner so I really don't know what is happening.

Welcome to the Blender SE! If you could rephrase your question by describing what you want to do and then describe what is actually happening it will help people trying to answer your question.

Thank you, I have found the answers. Just first time seeing how blender interpolates difficult polygons.

Basically, quads are low-key made of triangles.
Quads have no magical ability to stay "flat" so if you move a vertex out of its original plane, it can't be a "real" quad anymore and so blender shows you the ugly truth: a quad is two triangles stuck together.
Generally you want to build models so the quads don't get bent much, but they often will a little, and that's ok as long as the result doesn't look bad.

Yes but how do I make it look the same on all 4 sides instead of this half and half?

@klaudchaser, what you want is not clear, but it's clear that you can't get it the way you're trying, please show a drawing of the object you want to model

@moonboots Oh I just never had the crash course on polygons/triangles, but no worries, I have managed to find answers on posts and around. Basically what happened was that it was a first time I see how blender interpolates difficult polygons, and all I had to do was knife.


text:
Blackbody node is not in the node list?
I'm looking for a node called Blackbody. I already looked at this, and I am in cycles mode. The manual says it should be under converters but it isn't there.
I have version 2.66a, that ships with my distro. Is this a new feature only in newer versions, or do I have to enable this somehow? I didn't see it in addons either.

2.66a is from 2013, maybe it is time to move on

There's an up-to-date PPA here if you happen to be on ubuntu (or a closely related distro). Note that the main PPA is on 2.8 now, which has significant breaking changes from 2.7x and is still in beta. If you want 2.79, there appears to be a blender-legacy repo as well.

Does "breaking changes" mean if I start something in 2.7 it won't open in 2.8?

Probably not in a version that old. It's time to update!


text:
Can I use Space + LMB to pan?
Is it possible to set the space bar so when it's held down, you can pan by using LMB plus dragging? This is how panning works in a bunch of other programs.

Yes, this is possible.
Open up the File > User Preferences (see 2nd image) by pressing ⎈ Ctrl⎇ AltU and go the the Input section (the third rider on the top menu of the User Preferences window).
First, we have to remove/change the existing bindings for a  LMB as well as Space.

The functionality bound to  LMB click is called Set 3D Cursor. Search for 3D Cursor in the search window. Remove the item by pressing the X - button.

Find the Spacebar command by searching for Space via key-binding. Remove this item as well.

Now search for Rotate View. Click on the items shortcut, then perform a left click again to enter a Left Mouse value. To set the modifier key to space, click on the (currently empty) input box in the right of the third row and press the Space key. It is going to be used as a modifier key for the action.

You can now rotate the view using Space LMB
You have to unbind Set 3D Cursor otherwise the event will not be passed on.

You press Space.
You make a  LMB down click.
Set 3D Cursor is called and all other events are aborted.

You can however set Set 3D Cursor to a  LMB using either Click or Release as the mouse mode. The action will however only be called once you release the mouse.

Is it not possible to do this without unbinding LMB?  The idea of using space is that the space bar becomes a modifier key. So when space is pressed, LMB pans, when space is not pressed, LMB does whatever is bound to it without a modifier.

@Nick Added some info at the end.

@Nick Yes, it is possible to do this without unbinding LMB. The trick is in placing your "spacebar + LMB" hotkey in a category that "out-prioritizes" the LMB-only hotkeys (specifically: “Screen->Screen Editing”). Full info here: https://blenderartists.org/t/issues-with-spacebar-as-a-modifier-key/570346/4?u=venryx


text:
How can I get single "a" to deslect in 2.8?
I'm using the 1-25-19 version of 2.8 beta. You have to double tap "a" every time you want to deselect something which is very annoying. Is there a way to make "a" work the old way where "a" selects all if nothing is selected and "a" deselects all if something is selected? ie. no double tap and no alt?

Since Blender 2.8 is still beta, this option might still be moved around in the Options but right now it should be under "Menu - Edit - Preferences - Keymap" and there on the right side under "Preferences - Select All toggles".


text:
Is there a way to limit the number of CPU Cores used for physics baking?
Is there a way (in Blender) to limit the number of CPU Cores used for physics baking, like you can with rendering?

There isn't really a straight forward answer for this, it will depend on what simulation you want to bake and what OS you are using.
To use multiple cpus, some parts of blender use openmp and others use pthreads.
For simulations using openMP, setting the OMP_NUM_THREADS environment variable should limit the cpus used.
For simulations using pthreads, adjusting system limits should be able to limit the cpus or cpu time used. The way to do this varies between most operating systems, for linux there are /proc/... settings or the bash builtin ulimit command.
Another approach available on most *nix systems is the nice and renice commands to adjust the cpu priority so that other procs are given cpu time before blender.

On Windows you can press CTRL+SHIFT+ESC, find blender process in Details tab, right-click and choose Affinity. I think those settings reset every time, but you can use a program like WinAFC to automate changing affinity.


text:
What is the key combination in 2.8 that brings up the cursor moving pie menu?
I saw it in some tutorial but I don't remember what it is called or where I found it and I can't find it again.
It was a pie menu that opens with a combination of hotkeys that has a bunch of options like "cursor to selection", "move to cursor" or similar. There might have been origin stuff in there too.
What is the key combination in 2.8 that brings up that cursor moving pie menu?

It's called the "Snap" menu, opened with Shift+S.

If you're using the "industry compatible" shortcuts it's Shift + X


text:
cant access my user preferences in 2.82
I just downloaded Blender 2.82 (because Ctrl Z kept crashing the program on 2.81) and I cant figure out how to access my old user preferences which took me hours to set up. I copied startup.blend and userpref.blend into the same subdirectory as the .exe file  and into the config subdirectory under user/appdata/roaming/app data/Blender Foundation/blender 2.82/config but it still doesn't open with my old settings. What shall I do?

Hello :). This thread should hep: https://blender.stackexchange.com/q/78. There are some differences when using ZIP vs installer. In the worst case reinstall 2.82 and click Copy Previous Settings.

https://blender.stackexchange.com/questions/166953/is-losing-my-settings-upon-updating-a-problem-with-the-steam-version-of-blender

I tried reinstalling but saw no place on the splash screen to Copy Previous Settings.


text:
Modifier is disabled skipping apply messsage
I am very new to Blender, so I apologize if this seems trivial. Trying to apply a Boolean union transformation to two selected objects and I get this message. I've done other Boolean without a problem, so I am confused.
I see they are selected in the side listing, but at the moment things aren't turning orange when I select them, so is this the cause, and why does the orange effect go away sometimes?

You only need a boolean modifier on one of the objects for it to work.

You are probably in "edit mode." You can't apply modifiers in edit mode, and the orange selection outline goes away in edit mode.
Blender organizes "meshes" into "objects". An "object" is a container that contains a "mesh". You can edit the mesh or the object, but not both at the same time. When you're dragging individual points around, you're editing the mesh (in edit mode). When you have the orange selection outline and you're dragging whole objects around, you're in object mode (and you can't drag individual points).
To toggle back and forth between edit (mesh) mode and object mode, press tab.
To apply your Boolean modifier tab until you're in object mode, then select the object that has the modifier you want to apply, and the "apply" button should now be available.
Like Nate said, you only need a Boolean modifier on one of the objects, but experimenting with it is the best way to figure out how that works.

Matt is correct, though, to be fair, the wording of the error message is unnecessarily cryptic. It would save a lot of beginners a lot of grief if it simply said: "Can't apply modifers in Edit Mode." No one would misunderstand what was happening.


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Icon colors are difficult to see
I changed a lot of items individually in the Edit>Preferences>Themes options to make it easier for my deteriorating vision. Somehow these changes made the icons for the toolbars on the right funny colors, vary pale with turquoise accent colors.
Nothing I set under the Icons section has that turquoise color, so the shading and color come from something else apparently. I have been reading that the icons are supposed to hard wired into the program and monochromatic, but something has changed them, somehow. Since I don't know what changed them and I can't find that turquoise color on any other items I set.
I did find I could set the background of the icon to black and then I could see them, but my vision does better seeing black items on white backgrounds so if there is any way to adapt these icons on the toolbar, I would like to know.

If you are talking about these icons:

You need to change the Themes>User Interface>Tab Inner, Selected and Outline colors.
Edit: OK, you mean these:

Unfortunately, those are built from source. See this link if you are interested in trying to modify them.
You can change the background and border though by going to User Preferences>Themes>User Interface>Tool and changing the Outline and Inner Options.

I mean the ones on the toolbar which defaults to the left on the Object mode and Edit Mode of the 3D Viewport. (I am not sure how to add pictures to this Blender.stackexchange, but I have one if you will tell me how to.) I can change the background of these icons, but I have to leave it black because the icons are whitish. I have low vision and do best with high contrast (or bright color) things when they are small, so I was hoping to find a way to make them black on white which is the easiest for my vision. I'm making do with white on black, but if there is way to reverse it, I 'd like  that.

Please see edited answer.

Thank you! Not quite brave enough to try recompiling it, though. I'll have to make do and hope there are changes later.

Funny you should say that. The Blender live stream today showed that in 2.83, the toolbar icons will automatically switch from dark to light based on the background color. It's going to be a little while, but it's coming.


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Select Box in 3d View edit mode brings up the move tool, not a select box
Suddenly, when I click on the Select Box Tool in 3D Viewpoint with and item selected and in Edit mode, the Move tool (3 colored gimbal circles)comes up instead. In fact, it is happening in every variation of the select tool, so that I cannot select aything.

Hello :). It's not really clear what's happening, would you mind adding a screenshot of the issue? Without that, it's just guessing.

This can happen when you enable Object Gizmos in your viewport.
The gizmos are then visible even without selecting any transform tool.

I hve discovered the problem is specific to this file. Also on ethe information bar at t e very bottom I see that in the file with a problem is shows a mouse with a LMB darkened marked Select and then a similar mouse button with little curves on the upper right side marked Move. In another file, which is not malfunctioning that second mouse, is marked Box Select. So somehow I must have redefined that mouse key unintentionally. (I did not mess with any mouse settings on purpose.) Does this help?

Well, if it only affects one file, you can share it and I'll take a look :)

I unchecked the rotate option under Object Gizmos and the problem went away. I had Local selected ( I don't yet really understand what those sections mean) and I noticed that when I selected Default there, I could check the Rotate box without that happening. So I have a solution, even though I do not understand why it works that way. Thank you!

Correction: It is not different under Default.

If you want to learn more about the gizmos, it's covered here in the Blender Manual

Make sure you're not in Pose Mode. That turned out to be my problem


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3d View layout closer
Is there any way to move some of the top items in the 3D View to the left? On my laptop they are covered when I have a layout including side views (Outliner on left and Properties on right.)
I usually have  to minimize one or the other to get the shaders selectors and the options drop down there to be visible. I have the Blenderkit "Find Models" in  the middle which I rarely use (but do want to keep) and wonder if I can move that elswehere, and would it move the shaders more leftwise if I could??

See that little rounded corner where edges meet?
Hover over it, then click-and-drag it in whatever direction you want to create a new tab.

To remove a tab, right-click on that tiny darkened line that separates the tabs and select 'Join Areas'


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AVI Composite Export
I wanted to increase the brightness/contrast of an AVI video I have.
What I did was go to the compositer, load the video file in the Movie Clip node, fixed what I wanted to fix but:

The quality of the video seems to have dropped, looks more pixellated.
I have no idea how to export the video file.

Does anybody know how to export a composited AVI file as an AVI or MP4 file?
Thank you.

Hard to know why the video quality dropped without more information from you. Do you have screenshots of your setup and what you're seeing. To render out of the compositor you'll have to render the animation the same way you would for a 3d scene. Setup output dimensions/file format/etc in the Scene panel and Render->Render Animation.
You might consider using the Video Sequence Editor instead?
https://docs.blender.org/manual/en/dev/video_editing/introduction.html

I tried to render it but it says there is no camera (I dont need one as Im compositing a loaded video.) And if I add a camera it just renders whats on the 3d viewer :/

Add a file output node in the compositor linked to your color corrected movie. https://docs.blender.org/manual/en/latest/compositing/types/output/file.html

REMOVE the Render Layer node, as otherwise Blender will try to render the scene, which is not needed and will waste your time.
There is no need for a File Output node AND a Composite at the same time, they will both output a file in such setup.
The composite node will output a file according to your scene's output settings in the Properties Editor → Output tab.
Whereas the file output node acts basically as its own independent output in addition to the composite.
Thing is, the compositing is done with the scene's output settings (specifically the resolution), so will have to adjust your scene's output no matter what. In other words: if you don't need an extra file output, just use the Composite node, as all the compositing is done with the scene's output settings anyway.

For the quality drop:
Don't fully trust the preview you get in the compositor: these are quick and dirty previews.
The only thing you should look at for quality is your actual output file.
Now there are a few things that you need to set up beforehand:

start/end frames
resolution
frame rate

You can get those info from your file browser, but you can also open your file in the movie clip editor to see the info you need:

Then in the encoding panel, set it to FFMPEG Video. FFMPEG is an encoding software and it offers quite a lot of possibilities.
For your case, since you want AVI, you can set the container to AVI, but you will still need to chose codecs for both the video and audio streams.
You can go two ways here: if you need to further edit this footage later, you may want a high quality encoding at the cost of encoding time and bigger file size. Or in the contrary this is your final result you want to ship on the internet or a client, then you want an encoding that will lose quality but will remain decent while having a lighter file size.
Now, for a good production quality encoding, usually i would like to use DNxHD, but that's bugged at the moment so we will need to use something else in the meantime.
But for reference, here's the parameters for a 1920x1080px 30fps DNxHD:

Note: DNxHD requires to use specific profiles in order to work, particularly bitrates. Here's a reference list.
But we can replace it with HuffYUV at the moment:

Using PCM as audio output.
Now, for a shipping video file, the gold standard right now is h264 contained in MP4, but it works with the AVI container too :

Note that this one uses abstract "output quality" settings. You can easily change them to whatever you want or set it to "constant bitrate" to manually choose the bitrates yourself.
In any case: I highly recommend you to first try woring on a little 1 second long portion with different parameters, and see what works for you. Each video is different, what works for one can be horrible for another one.
With Blender's limited controls, what you should spend time playing with are bit rates. The bigger it is, the more quality you get but also bigger files.

As mentioned in the comment, use a file output node or connect your output to the composite node. It's important to make sure that you're telling Blender to use nodes, in the compositor windows make sure "use nodes" is checked.


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Using rotation_difference to recover a quaternion
I'm trying to do something I think should be simple with Quaternions: Use a quaternion to rotate a vector; then use the difference between the original and new vectors to recover the quaternion. But I can't get it to work like I think it should.
bv = Vector((1,0,0))
q = Quaternion((1,1,1), radians(30)) # is our magic rotation
bvr = bv.copy()
bvr.rotate(q)
qq = bv.rotation_difference(bvr) # rotation difference must be our magic rotation, surely

qprint(qq.rotation_difference(q)) # Nope, that's not null
qprint(qq.inverted() @ q) # not this either

Results in the following (qprint is just a pretty printer for quaternions):
(<Vector (1.0000, -0.0000, -0.0000)>), 17.59
(<Vector (1.0000, -0.0000, -0.0000)>), 17.59

What am I mucking up? I woulda thought that qq would be the same rotation as q, since it is exactly the quaternion that turns bv into bvr. But that doesn't seem to be the case.

You cannot recover a quaternion by knowing where it sends a single vector (imagine if bv is the axis of rotation for example). You can recover it if you know where it sends two linearly independent vectors though, do you need to know how?

Yes, but howabout if I know the twist? to_swing_twist will return the angle of rotation around the vector. I just checked the twist on the above example and it's 17.59, suggesting that if I subtract that from the angle of my recovered vector, I'll get what I want.

I sorta have an answer, but I'd like to know if it's working by chance or not. I extended my code to capture the twist and then use it in the reverse operation. Because I'm using the to_swing_twist() operator the initial vector is constrained to lie on an axis, but that's okay for my application.
(What I'm doing, btw, is an import/export tool for nif files. On import, if I apply a bone's transform to the unit vector I get a good representation for the bone in the Blender armature. But then I want to reverse the operation to recover the transform for export. In truth, as long as the transform is equivalent it doesn't have to be numerically identical, but for testing it's much more convenient if it is.)
from mathutils import Quaternion, Vector, Matrix
from math import radians, degrees

bone_vectors = {'X': Vector((1,0,0)), 'Z': Vector((0,0,1))}

def qtobone(boneq:Quaternion, axis:str):
    """ Taxes a rotation and axis and applies the rotation to a unit vector
    on that axis. Returns resulting vector and twist. """
    s, t = boneq.to_swing_twist(axis)
    v = bone_vectors[axis].copy()
    v.rotate(boneq)
    return v, t

def bonetoq(vec:Vector, roll:float, axis:str):
    """ Takes a vector, roll angle, and axis and returns a quaternion that
    rotates the unit vector on the axis to the input vector, with the roll."""

    bv = bone_vectors[axis].copy()
    q = bv.rotation_difference(vec)
    rollq = Quaternion(bv, roll)
    return q @ rollq

def qtest(q):
    b1, r1 = qtobone(q, 'X')
    qq = bonetoq(b1, r1, 'X')
    print(f"Result \n{q}\n{qq}")

This works in every case I've tested:
qtest(Quaternion((1,0,0), radians(90)))
qtest(Quaternion((0,1,0), radians(90)))
qtest(Quaternion((0,0,1), radians(90)))
qtest(Quaternion((0,0,1), radians(45)))
qtest(Quaternion((1,1,1), radians(30)))
qtest(Quaternion((1,2,3), radians(40)))
qtest(Quaternion((1,2,3), radians(-40)))
qtest(Quaternion((1,2,3), radians(128)))

Output:
Result
<Quaternion (w=0.7071, x=0.7071, y=0.0000, z=0.0000)>
<Quaternion (w=0.7071, x=0.7071, y=0.0000, z=0.0000)>
Result
<Quaternion (w=0.7071, x=0.0000, y=0.7071, z=0.0000)>
<Quaternion (w=0.7071, x=0.0000, y=0.7071, z=0.0000)>
Result
<Quaternion (w=0.7071, x=0.0000, y=0.0000, z=0.7071)>
<Quaternion (w=0.7071, x=0.0000, y=0.0000, z=0.7071)>
Result
<Quaternion (w=0.9239, x=0.0000, y=0.0000, z=0.3827)>
<Quaternion (w=0.9239, x=0.0000, y=0.0000, z=0.3827)>
Result
<Quaternion (w=0.9659, x=0.1494, y=0.1494, z=0.1494)>
<Quaternion (w=0.9659, x=0.1494, y=0.1494, z=0.1494)>
Result
<Quaternion (w=0.9397, x=0.0914, y=0.1828, z=0.2742)>
<Quaternion (w=0.9397, x=0.0914, y=0.1828, z=0.2742)>
Result
<Quaternion (w=0.9397, x=-0.0914, y=-0.1828, z=-0.2742)>
<Quaternion (w=0.9397, x=-0.0914, y=-0.1828, z=-0.2742)>
Result
<Quaternion (w=0.4384, x=0.2402, y=0.4804, z=0.7206)>
<Quaternion (w=0.4384, x=0.2402, y=0.4804, z=0.7206)>

You can't.  Here's an image of your vectors:

Technically, rotation by quaternion is a many-to-one function.  Given a single vector there are many different quaternions that can result in the same rotation.  Since the difference function doesn't take the original rotation axis as an argument, it's free to pick any that will produce the difference.
You can also see this in your code, if you add
bvx = bv.copy()
bvx.rotate(qq)
bvx - bvr
from pprint import pprint
pprint(bvx-bvr)

you'll get console output like
Vector((-5.960464477539063e-08, 0.0, 0.0))

The X value isn't 0 because of floating point roundoff, but the result of rotating by either quaternion is the same.
For the curious, the display was produced by adding this code after the calculations:
mesh = bpy.data.meshes.new("mesh")
object = bpy.data.objects.new("mesh", mesh)
bpy.data.collections['Collection'].objects.link(object)

verts = [(0, 0, 0), bv, bvr, q.axis, qq.axis]
edges = [(0, 1), (0, 2), (2, 3), (0, 3), (0,4)]
faces = [(0, 1, 2), (0, 1, 3), (0, 2, 3), (1, 2, 3)]

mesh.from_pydata(verts, edges, faces)
mesh.update()

and removing the faces and extra edges from this output: (because I was too lazy to modify the edges and faces arrays when I realized what edges I really wanted.)

You say 'many different' quaternions would work, but isn't it a limited set? If I have bv and bvr doesn't any quaternion that turns bv into bvr have to have an axis normal to the plane defined by bv and bvr? So really, there's just two if the axis has unit length and the angle is constrained within -360 and +360 deg, and just one if the angle has to be positive. (Thanks for the very complete answer btw, and for the cool representation.)


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Blending normals at edge of mesh and accessing result with python
I have this problem: Copying Vertex Normals
I have a head and a body that need to be separate objects, but they need to join seamlessly. Viewing them in object mode, I see the seam.
I can use the Data Transfer modifier or operation to copy "Custom Normals" from the body to the head with a max distance set so only normals near the seam are affected. Visually, that works fine. The seam is gone in the view.
But I need to export and when I go into the data model, the normal vectors haven't changed at all, even when I use the data transfer operator or apply the modifier. That is, bpy.object.data.vertices[1793].normal doesn't change before and after the operation (where 1793 is on the seam). So what is the view using to show the transferred normal? And how can I get at that normal through the data model so I can export it properly?

So it seems that data transfer for custom normals works opposite to other data transfers. The object you select first receives the normals from the active object.
The operator works by adding custom normals to the target, not by changing the regular normals.
The custom normals appear to be oriented backwards to the regular normals, and backwards to what you see on the display. If I make the standard cube and select face 0, its normal is (-1,0,0) but the custom normal on one of the verts in its loops is (1,0,0). That seems wrong to me, but I don't know how else to interpret the data.
I'm still not sure how to access these normals. Making a bmesh and using calc_normal on a loop isn't given the results I expect. On the cube the custom normals are still pointing along the axes even when the visuals say the cube is smoothed.
Edit: When I look at my object's mesh's loops and access the normal property of each loop, I see what I expect: The normal points in the direction I expect and it matches what's shown visually. But the bmesh is not picking them up in a way that's obvious to me.


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Blender armature edit_bones changes aren't kept after switch to object mode
I have some code that needs to add bones to an armature. I'm in edit mode. I add the bones using the_armature.data.edit_bones.new(). But when I leave edit mode the new bones I've added aren't there.
    bpy.ops.object.mode_set(mode='EDIT', toggle=False)

    <add my bones>

    print(f"***All armature edit bones: " + str(list(arm_ob.data.edit_bones.keys())))
    bpy.ops.object.mode_set(mode='OBJECT', toggle=False)
    print(f"***All armature '{arm_ob.name}' bones: " + str(list(arm_ob.data.bones.keys())))

The first print statement shows the bones I've added. The second, I think, should always produce the same list as the first, but it doesn't. Here's the output:
***All armature edit bones: ['Arm_ForeArm3_skin.R', 'Arm_Collarbone_skin.L', 'RibHelper.R', 'Spine1_skin', 'Arm_ShoulderFat_skin.R', 'Arm_UpperFat_skin.R', 'Leg_Calf_skin.L', 'Belly_skin', 'ButtFat_skin.R', 'Arm_UpperTwist2_skin.L', 'ButtFat_skin.L', 'Arm_ForeArm2_skin.R', 'Leg_Thigh_skin.L', 'Arm_UpperFat_skin.L', 'Breast_skin.R', 'Breast_skin.L', 'Neck_Low_skin', 'Leg_Calf_Low_skin.L', 'Spine1_Rear_skin', 'Spine2_skin', 'Leg_Thigh_Fat_skin.R', 'Chest', 'UpperBelly_skin', 'Leg_Calf_skin.R', 'Chest_Upper_skin', 'Arm_Hand.L', 'Pelvis_Rear_skin', 'Chest_skin', 'Leg_Toe1.R', 'Leg_Toe1.L', 'Leg_Thigh_Low_skin.R', 'Arm_UpperArm_skin.L', 'Arm_UpperTwist2_skin.R', 'Arm_ShoulderFat_skin.L', 'Arm_UpperArm_skin.R', 'Leg_Thigh_skin.R', 'Arm_Collarbone.R', 'Neck_skin', 'Pelvis_skin', 'Arm_ForeArm1_skin.R', 'SPINE2', 'LArm_UpperTwist1_skin', 'Arm_ForeArm1_skin.L', 'Arm_Collarbone_skin.R', 'Arm_Collarbone.L', 'Arm_ForeArm2_skin.L', 'RibHelper.L', 'RArm_UpperTwist1_skin', 'Leg_Calf_Low_skin.R', 'Leg_Thigh_Low_skin.L', 'Chest_Rear_Skin', 'SPINE1', 'Spine2_Rear_skin', 'Leg_Foot.R', 'Leg_Foot.L', 'Arm_Hand.R', 'Arm_ForeArm3_skin.L', 'Leg_Thigh_Fat_skin.L', 'Arm_ForeArm3.R', 'Arm_UpperTwist2.R', 'Leg_Calf.L', 'Pelvis', 'Arm_UpperTwist2.L', 'Arm_ForeArm2.R', 'Leg_Thigh.L', 'Leg_Thigh.R', 'Leg_Calf.R', 'Arm_ForeArm3.L', 'Arm_UpperArm.L', 'Arm_UpperArm.R', 'Neck', 'Arm_ForeArm1.R', 'Arm_UpperTwist1.L', 'Arm_ForeArm1.L', 'Arm_ForeArm2.L', 'Arm_UpperTwist1.R', 'COM']
***All armature 'BASE meshes\Actors\Character\CharacterAssets\MaleBody.nif' bones: ['Leg_Calf_skin.L', 'ButtFat_skin.R', 'ButtFat_skin.L', 'Leg_Thigh_skin.L', 'Leg_Calf_Low_skin.L', 'Leg_Thigh_Fat_skin.R', 'Leg_Calf_skin.R', 'Pelvis_Rear_skin', 'Leg_Thigh_Low_skin.R', 'Leg_Thigh_skin.R', 'Pelvis_skin', 'Leg_Calf_Low_skin.R', 'Leg_Thigh_Low_skin.L', 'SPINE1', 'Spine1_skin', 'Belly_skin', 'Spine1_Rear_skin', 'SPINE2', 'Spine2_skin', 'Chest', 'RibHelper.R', 'Breast_skin.R', 'Breast_skin.L', 'Neck_Low_skin', 'Chest_Upper_skin', 'Chest_skin', 'Arm_Collarbone.R', 'Arm_ForeArm3_skin.R', 'Arm_ShoulderFat_skin.R', 'Arm_UpperFat_skin.R', 'Arm_ForeArm2_skin.R', 'Arm_UpperTwist2_skin.R', 'Arm_UpperArm_skin.R', 'Arm_ForeArm1_skin.R', 'Arm_Collarbone_skin.R', 'RArm_UpperTwist1_skin', 'Arm_Hand.R', 'Neck_skin', 'Arm_Collarbone.L', 'Arm_Collarbone_skin.L', 'Arm_UpperTwist2_skin.L', 'Arm_UpperFat_skin.L', 'Arm_Hand.L', 'Arm_UpperArm_skin.L', 'Arm_ShoulderFat_skin.L', 'LArm_UpperTwist1_skin', 'Arm_ForeArm1_skin.L', 'Arm_ForeArm2_skin.L', 'Arm_ForeArm3_skin.L', 'RibHelper.L', 'Chest_Rear_Skin', 'UpperBelly_skin', 'Spine2_Rear_skin', 'Leg_Foot.R', 'Leg_Toe1.R', 'Leg_Foot.L', 'Leg_Toe1.L', 'Leg_Thigh_Fat_skin.L']

How is this even possible?

Oops, might be a dup of: https://blender.stackexchange.com/questions/6040/armature-bones-created-in-python-disappear-after-exiting-edit-mode?rq=1

Yes, it's a dup. I'm not sure how to delete or mark this one.


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Is there a way to create an animation trail within blender without post-video editing?
Im a begginer and I am looking to achieve this trail effect ( Example ) without doing post-video editing, is it possible to achieve within blender itself? Thank you.

Is this in 3D or 2D, so you have much experience with animation?

If you're working 3D then I think you're going to be working with smears and duplicated limbs, with the duplicates having a flat shade-less shader. Check out this link for a decent explanationhttps://www.youtube.com/watch?v=xNiUO6BwtTc&ab_channel=SirWadeNeistadt In the end animation just takes practice and perseverence

@James apologies I forgot to specify, I'm working with 3D models, similar to the example, no grease pencil animation nor planes with 2D animation on them, I will be checking the video you linked.


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Trouble using Mix Shader node to make a texture read alpha properly?
So I'm having trouble, I am novice when it comes to nodes, I want to have a material that already has a transparent texture also read a different set of nodes, I know how to set-up the texture nodes to make blender read the transparency/alpha, and I was also following a tutorial for "holo glitter" effects, the problem is that I dont know how to make both group of nodes match perfectly
The group of nodes I added
And the group of nodes I already had for the normal textures
The problem is that by setting them up that way, the original texture is no longer transparent as it should be, but the holo glitter effect from the second group of nodes is visible
example without the holo glitter node group

How it looks when I tie both group nodes onto a mix shader node

My goal is to have the holo glitter effect on top of the texture but without losing any of the transparency/with the alpha not being affected, is there a way to do that?
Thank you for your time.

Hello :). Well, the first nodegroup is fully opaque, so when you mix it with alpha channel, the alpha transparency is affected.

I see, what should I do to make the first nodegroup not fully opaque in that case? I tried adding another mix shader node linking a transparent node + the miix shader that groups both nodegroups together but I had no luck , Im pretty novice regarding nodes so Im pretty lost, any help or guidance with this problem would so appreciated! Thank you @JachymMichal


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How to render an animation in EEVEE with Anti Aliasing off?
Yo, I'm somewhat new to blender, but i've been practicing with the EEVEE engine and  making low poly models, but I'd like to render model turntables without anti-aliasing if that makes any sense, here's an example of what i'd like to achieve https://i.sstatic.net/HqB8I.jpg
I've looked at some tutorials but I couldn't find anything as specific as what I want to achieve, and since im new to this I just assume that type of render has to do with anti-aliasing
Thank you for your time

You can disable sample from nearby pixel to turn off anti-aliasing effect in EEVEE. The detail can be found in here.
Properties Panel: Scene → Film → Filter Size: 0.00 px

Once you disable the anti-aliasing, you can now scale up the final render to emphasis on that jagged part.
Compositing method:

Or using a value to change it for ease:

Thanks! This is super helpful, its helping me getting close to what I want to achieve, granted I think I'm doing something wrong, here are some test results https://imgur.com/a/BHcie50 basically if use 0.050 and 20.000, it comes out in the size I want but way too pixelated, and if I mess up with those settings I get results where the character is way too small or super close to the camera

@2Fleur2 You can use a math node to do with that value, see the update answer


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Boolean modifier applying, making holes in one object to connect it later to another /3d printing/
I have a problem with a Boolean modifier. I’m making a board game asset – stables in Blender v.2.82.

The building is made by two parts – fundament

And roof

Initially there was one only one object. I found a company to print it, but there were some problems and they suggested me to separate it and print two objects which can be connect after that.
I did’t comply that the object enter into each other.

I made some projects so far and when I wanted to connect some objects /or made holes/ used Boolean modifier.
After made the fundament object active went to modifiers chose Boolean.

On operation menu choose “Diffrence”, on object menu choose the other element /roof/, hit the apply button and then everything brokes.

Don’t know how to fix it.  I just want to make holes in the roof, so when the two parts are printed I can connect them and make one building. Before using the Boolean modifier recalculated normals, scaled the object. I don’t know what to do. Please help.

Download newer version of blender with new boolean solved "Exact" it might helps https://docs.blender.org/manual/en/latest/modeling/modifiers/generate/booleans.html or just search for Flat Shading in object mode if the only one issue is weird shading.


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Dynamically change size of image overlay in video editor
I am trying to add a logo (over a video) that grows during the video at a steady rate. I am able to position and overlay the video where I need it with the Transform tool but I can't find a method to animate the change in the tools that are available. I wonder if anyone knows a way to reach this goal. Thanks in advance.

Move the mouse cursor above the slider, what you adjust and hit I to insert a keyframe.

I don't understand what this means. Can you elaborate?

This tutorial explains well. https://youtu.be/u_m4X6Gyph0


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Set light color from python script
I would like to specify the color of a light that I add using a python script launched from the command line:
blender --python script.py

The script:
import bpy

bpy.ops.object.light_add(type='AREA')
light_obj             = bpy.data.objects['Area']
light_obj.data.energy = 500
light_obj.color       = [1.0, 0.0, 0.0, 1.0]

The light power is correctly set to 500, but the light color remains at its default white color, instead of being red.
Should I do something more to set the color of the light?
Note that I am using Blender 2.80 with Debian 10.
I noted a few weird thing:
The current online documentation of blender python api says here that the color of a light is a "float array of 3 items", but I get en error if I don't give 4 values. This post also talk about 3 values. Anyway, it proposes something similar to what I am trying to do: l.color = [r, g, b].
Is it en error in the documentation? Is their a bug?

Try light_obj.data.color = (1, 0, 0)

Test code out in the console.
Even if you are going to use a script from command line always (IMO) a good idea to test it out in the python console. (D = bpy.data, C = bpy.context)
When adding an object via operator, the new object added is the  context.object  Notice the name below is not "Area" as there are already other area lights in the scene.  Using light_ob = bpy.data.objects["Area"] will only work as expected if there are no other lights of that name in the blend file.
>>> bpy.ops.object.light_add(type='AREA')
{'FINISHED'}

>>> C.object #  the new object
bpy.data.objects['Area.002']

At any time can hit the autocomplete to see the available options.  The light is the data part of the light object.  (In the UI Properties panel it is under the Data tab.)
>>> light_ob = C.object
>>> light = light_ob.data
>>> light
bpy.data.lights['Area.002']

It's of type AreaLight which per documentation link posted in question is a subclass which inherits properties of bpy.types.Light
>> type(light)
<class 'bpy.types.AreaLight'>

>>> light.energy = 500

All objects have an rgba color property. For a lamp as commented above to set the lamp color set it on the data part.
>>> light.color = (1, 0, 0)
>>>

The script.
import bpy

bpy.ops.object.light_add(type='AREA')
light_ob = bpy.context.object
light = light_ob.data
light.energy = 500
light.color = (1, 0, 0)


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How to rotate the camera around an object and then zoom?
I followed this approach for animating the camera around an object.
Once the rotation is done, how to zoom or translate the camera toward another location on the scene ?
I did not find any easy way since the camera is linked to the empty frame.
Is it possible to change its relations and constraints using key-frames ?
Maybe it is better to create another camera, but I don't know how to place it with the exact same position and rotation as the first one (at the end of its rotation)...

May find this of some help https://blender.stackexchange.com/a/176762/15543   Try running the scripts on the default file.

you can either parent the camera to an empty and move the empty, or give the camera a Track To constraint and change the Influence values of the constraint?


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read_factory_settings makes all other operators call fail in a python script ran at startup
I want to read a ply mesh at blender startup using a python script given in the command line:
blender --python load_ply.py.
My script load_ply.py basically looks like this:
import bpy

# This line is the issue:
# bpy.ops.wm.read_factory_settings(use_empty=True)

bpy.ops.import_mesh.ply(filepath='mesh.ply')

It works fine until I use bpy.ops.wm.read_factory_settings(use_empty=True) to clear the scene before the import, which gives the following error:
Python: Traceback (most recent call last):
  File "/path/to/blender/blender-2.92.0-linux64/2.92/scripts/addons/io_mesh_ply/__init__.py", line 87, in execute
    context.window.cursor_set('WAIT')
AttributeError: 'NoneType' object has no attribute 'cursor_set'

location: /path/to/blender/blender-2.92.0-linux64/2.92/scripts/modules/bpy/ops.py:132
Error: Python: Traceback (most recent call last):
  File "/path/to/blender/blender-2.92.0-linux64/2.92/scripts/addons/io_mesh_ply/__init__.py", line 87, in execute
    context.window.cursor_set('WAIT')
AttributeError: 'NoneType' object has no attribute 'cursor_set'

location: /path/to/blender/blender-2.92.0-linux64/2.92/scripts/modules/bpy/ops.py:132

Traceback (most recent call last):
  File "/path/to/my/script/load_ply.py", line 5, in <module>
    bpy.ops.import_mesh.ply(filepath='mesh.ply')
  File "/path/to/blender/blender-2.92.0-linux64/2.92/scripts/modules/bpy/ops.py", line 132, in __call__
    ret = _op_call(self.idname_py(), None, kw)
RuntimeError: Error: Python: Traceback (most recent call last):
  File "/path/to/blender/blender-2.92.0-linux64/2.92/scripts/addons/io_mesh_ply/__init__.py", line 87, in execute
    context.window.cursor_set('WAIT')
AttributeError: 'NoneType' object has no attribute 'cursor_set'

location: /path/to/blender/blender-2.92.0-linux64/2.92/scripts/modules/bpy/ops.py:132

What is the meaning of this error?
What change does the read_factory_settings operator bring?
I use blender 2.92.0 on Debian 10.
A basic file mesh.ply:
ply
format ascii 1.0
element vertex 8
property float32 x
property float32 y
property float32 z
element face 6
property list uint8 int32 vertex_index
end_header
0 0 0
0 0 1
0 1 1
0 1 0
1 0 0
1 0 1
1 1 1
1 1 0
4 0 1 2 3
4 7 6 5 4
4 0 4 5 1
4 1 5 6 2
4 2 6 7 3
4 3 7 4 0

AIUI it throws out the current file, including state for the current script. Easiest fix is to pass --factory-startup on the command line instead.

Separate into two scripts..
As commented by @scurest the read factory settings operator, naffs the contest, in this case context.window becoming None and throwing the error as shown.
Would either make a read_factory.py script
import bpy
bpy.ops.wm.read_factory_settings(use_empty=True)

and with script as above (read factory settings commented out) (-P is equiv of --python)
blender -P read_factory.py -P load_ply.py

Opening a new file with just your imported ply mesh.  (Whereas starting with --factory-startup results in default startup objects and imported mesh)
For me the issue with doing this is my eyesight isn't what it used to be, and need everything a wee bit larger than default.
Another way would be to save an empty blank.blend  Could make your startup file blank.
blender -P load_ply.py blank.blend

downside being if accidentally saved rather than save as is no longer blank.
Similar option is making a blank application template
New default file template?
(Note can add to your user config folder, eg on linux  ~/.config/blender/2.90/scripts/startup/bl_app_templates_user/blank/)
blender --app-template blank -P load_ply.py

other options commonly seen is removing or unlinking all collections / objects from scene / blend,
How to completely remove all loaded data from Blender?


text:
How to shade in recesses in a glass shader with Eevee?
I am attempting to create a frosted glass shader similar to the art below. I would primarily like to do this in Eevee with the potential of seamlessly switching between Cycles and Eevee. I know that this affect would be possible with the pointiness input in Cycles but is there a better way to approach this?
While I would like the shader to have some transmission it is not a must have.

Tho this solutuion kinda looks good in eeve, the result is not the same in both render engines
Solution 1: (if background if a flat color)

Solution 2: (less shiny: dimmed with flat color bg; no super reflections with hdri)

**Solution 3: ** (super reflections are there but you can tweak their opacity with To Max value in newly added map range node at the bottom
you can also play around with other map range node values, it manipulates amount of super reflections

Solution 4: (balanced super reflections (for me it's the best)
here you can tweak same values of map range node, as well as bright/contrast, value in hue saturation value node, roughness and IOR in Refraction BSDF node

For different hdri, different solutions will work better, pls test.
In addition, here is the .blend file with all the materials:

Thanks a lot this works really well with a flat colour background but with an HDRI it is hyper reflective. I can adjust it somewhat by changing the Contrast value of the Bright Contrast Node but that limits the reflective areas.

i'll edit my answer

Thank you so much, this is perfect!


text:
Jaggy edges, dull output after rendering
I did a company logo design but after rendering,

the image was dull
the edges of the design was too jaggy and rough.
Light effect at the down right side of the image
Again I like the image to have metallic sides, while the surface area retain white color.
I like to send the .blend file so that experienced can help check the problems. I don't mind someone fixing and send back to me.

Thank you all.

Hello, Nwabuisi.. The difference is sometimes subtle, but we're not here to fix your file. We're here to answer questions for you, so you can fix problems for yourself :)  By all means share your .blend on https://blend-exchange.com/ , pasting the generated link into your post, then hopefully some of us will come up with suggestions for improvement to the problems you indicate. It's hard to help with this one without a share, because there are quite a few variables to take into account.

I really tried to upload a .blend file with the link, but it cant send. Please guide me

HI, there, maybe your file is too big for blend-exchange .. what size is it? Sometimes people come up  geometry that's way too dense .. If you;'re not sure, can you switch on a wire-frame view (Object > Viewport Display > [ check 'wire frame'].. and send a shot of that, so we can see?


text:
Why do objects in front and back view look reversed?
Whenever I model objects that has different look at front and back. Viewing it from front perspective or orthographic the model displays back of the object.

Welcome to Blender.SE, Could you share a picture of the problem?

Often see the terms forward and up for this in importers / exporters. Blender uses -Y forward Z up.  Add a default suzanne (zero loc rot unit scale) and the monkey will be facing in front view because the forward direction of the mesh is the negative local Y axis. (put in local axis mode to visualize)  Your character above is Y forward, that's why you see the back in front view and vice versa.

Front in Blender is considered to be Y axis, when the camera is facing towards positive Y you see the side of an object facing negative Y direction. This doesn't have to make any sense, it is not supposed to as there is no one logical reason to have it any one particular way.
You can use the shortcuts Numpad 1, Numpad 3 and Numpad 7 to quickly switch the viewport to front, side, or top views, you can also hold Ctrl to reverse the direction when using these hotkeys, Numpad 2,Numpad 4, Numpad 6 and Numpad 8 rotate the view, holding Ctrl with these 4 will pan it and Numpad 9 reverses to the other side.
You can also use the gizmo at the top right corner for this:

See the documentation for more info
That should really cover all your precise navigation needs whatever side you need to view.
And I just realized, you might be talking about inverted normals...
Would it hurt to post a picture to help me avoid wasting my time when trying to help?.. Anyway, if you are seeing something like this:

Go to edit mode(Tab), select all(a), open normals menu(Alt+n) and choose flip normals(f):


text:
Objects in front and back view look reversed?
Am reposting this because I wasn't clear in my previous post.
Check the image to understand my headache.

Please re-read https://blender.stackexchange.com/questions/164318/why-do-objects-in-front-and-back-view-look-reversed#comment277945_164318  You have aligned your car pointing Y forward.  Y is the green arrow of the axes. Blender uses -Y forward.  On your car the -Y axis is going from bonnet to boot, hence you see the boot (trunk, back of car) in front view.  Another way to look at this is make the side view right ortho instead of left ortho.

This is exactly the same as  Why do objects in front and back view look reversed?  Please don't ask the same question again if you don't understand the answer, (or comments)

Am sorry for reposting it. I think I now understand the reason. What I want to know is how to reverse it. Can Rotation on Z axis solve it.


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some of my hdri thumbnails won't load, why?

All hdri's are from hdri haven and all files work when loaded but some thumbnails don't show in the menu. Are they too big of a file or something?

Yep. They are too big for your computer to handle. Also, if you have too many hdri thumbnails, there is a possibility that your blender might crash, but it depends on you PC specifications and how much it can handle.

ah cool thanks, ill download a 1k version for those so i can see the the thumbnail. yeah found that out haha

In fact making the catalogue of maps is somehow better cause You could have all maps in SUPER-HIGH resolution and simply choose the right one for your scene from catalogue. The other reason for doing so is that Blender makes thumbnails everytime You open-up that folder (at least in my experience).


text:
Why might an animation curve *not* affect the pose?
I have a mesh with an attached animation, but some of the animation curves do not seem to be moving the bones. It's such a basic problem, I figure there must be some basic Blender feature or setting I'm not dealing with properly. Here's an example:

This frame is before this bone (NPC Neck5) starts moving, the Y Euler rotation is 0 as the graph shows. (The gizmo is in local orientation.) Now advance a few frames:

At this point the Y rotation is 30 degrees, and that's what the graph shows. But the bone hasn't rotated around the Y axis at all.
What should I be checking for to fix this?

Found it. The rotation mode of the bone has to match the rotation mode of the curve. Setting it to "Euler" made things start happening.


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Two armatures. Two animations. Combine into one armature with both animations intact?
Like the title says. I have two bones which each belong to different armatures. For exporting purposes, I need to have both bones in the same armature. However, when I join the armatures, one animation is lost. Pasting keyframes does not attribute to individual bones so that messes everything up. Help?
Thanks

As long as the following rules are met it should be as easy as Copy/Paste.
R1 - Both armatures to be merged are simple - no bone constraints or drivers
R2 - Do not merge armatures that have rotation and scale - clear those transformations to be safe.
R3 - The names of the bones in each armature should not be the same in order to avoid bone renaming during the joining operation. Use Batch Rename (Ctrl+F2) to add some uniqueness in the bone names - say starting with different letter in each armature will do.
Let's say you have armatures A and B and you merge B to A.
You will loose all animation data from the animated bones in B.
Pose mode:
In the merged armature select only the bones previously belonging to B and add keyframes to all of them on frame 1. Make sure to add as many channels as needed (say LocRotScale)
Then go to armature B, select all bones and select all keyframes in the Action Editor, then Copy (Ctrl+C).
Lastly, back in the merged armature, with still selected bones from B - Paste (Ctrl+V), again in Action Editor (while still on frame 1).
This should work on fairly complex armatures and I suggest to practice on simple armature merging first to get the hang of it.
The problem still remains for more complicated armatures that introduce Bone constraints and Drivers. And I think the best approach in this case is via Python scripting

Whoah I had to paste together a bunch of answers online but heres a start to doing just this:
create a new bone in the armature and use bone constraint to copy whatever attribute you need from the other armature bone. Then in pose mode, do pose -> animation -> bake action and THEN select
only selected
visual keying
clear constraints
overwrite current action - thats the one that missing from most answers online


text:
Can't bake two actions together
just like the title says. I've followed a tutorial exactly but still the product of baking the "action" and "rotator" action together is not the complete merging of both animations.
Could someone please take a look? Thanks
https://www.dropbox.com/s/oq6kckhbr6ln7lb/loading%20animation%20one.blend?dl=0

Checked the file but what exactly U want to achieve? Cause it looks like a merge to me...

if you bake both "action" and "rotator" into a new action and then delete action and rotator so that only the new action remains the animation is different, right?

Please uncheck Only Selected option to solve all objects in the scene and select Object and Pose too for storing all the scene data. Tested and works for me buddy (as You could see I already removed those Action strips),

Thank you so much! Probably nothing to be helped but I run into these snags alot and solutions like this don't seem so obvious to me. Did you just play around with it or was there reasoning behind this? Maybe it would help me in the future. Thanks again!

Just tried when saw those options in Bake and find a solution. Please check my answer as correct if so using the checkmark next to it Willem - thank You.


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Single Raspberry Pi to aid my PC in rendering - Practical?
With all the talk about cheaper render farms with RPi custers and the surprising amount of RAM in the Pi 4 (up to 4 GB), would it be practical to get a single one to 'help' my pc in rendering cycles? or are they really only helpful in clusters?
Also, how would that compare to simply getting a better graphics card as opposed to my integrated one?
My specs: Windows 10 Pro 64 bit, Intel Core i5-2400 @3.1GHz, 8GB RAM

See https://blender.stackexchange.com/questions/143670/feasibility-of-raspberry-pi-4-render-farm and https://blender.stackexchange.com/questions/77574/blender-build-for-raspberry-pi3. In addition, I think that the overhead of scene transfer etc vs the speed of the Pi is unlikely to make this worth while.


text:
Why does fluid stick to the outflow object?
Just setting up a basic fluid simulation with an inflow object and domain. The problem is that the fluid seems to stick to the inflow object, and when drops fall, they hit the bottom of the domain and almost immediately disappear. This is my goal: https://www.youtube.com/watch?v=VB5J4u0yMtQ
My setup and result: https://www.youtube.com/watch?v=fkbOo8CDIfc&feature=youtu.be

In the example you showed, the velocity was probably set to something like 2.0 along the Z on the Inflow Sphere which means the water hits the top of the domain and runs down the sides.

Also with your Domain object, I would try experimenting with some settings.
These are the settings I set to create this scene effect. I don't know if this was more what you were looking for with yours.

I baked this with very low resolution. I'm sure with higher resolution, it would look much better but hopefully you can see the effect.


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How do I use a cached/baked smoke simulation with command line rendering?
Under cache in the physics tab on the smoke domain, I have Use Library Path and External checked and a Path set in the path box. It says 26 frames found and works fine from rendering with the GUI.
When rendering from the command line, the smoke is not there. The command is:
./blender -b ../../Blender_Projects/Test33.blend -f 26 -o ../../Blender_Projects/Test_Renders/TestRender33.png

It seems that the command line isn't finding the cached/baked files. Do I need to pass the bake path as an argument? (Even though it's in the file already)?

This worked for cloud rendering via command line, as for a local computer or render-farm, I don't know.
Change the cache baking location with the file path " // ". It should auto-name it if it doesn't accept a custom name.
Save the .blend file, bake the simulation and it will appear where you saved the .blend. Therefore blender will "look" in the same folder, a dedicated location.
How do I re-Load Fluid Sim Cache?


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Can you create a new window from a non-main window?
If I have a window that is opened via Window -> New Window and I want to copy that window layout to a new 3rd window, is there any way to do that? There is no window menu on the window I want to copy because it is not a main window.
Can I convert a non-main Window to a main window (add the menu)? Or can I spawn a new main (or non-main) window based on an already opened and configured non-main window?
The goal is to create a new window with only one view like I already have in my second window, without the chore of cloning the main window and doing the "join area" Tetris puzzle.
This is a recent 2.8 Beta.

If I choose "window -> new main window" it creates a new window that is a copy of the main window. I want to create a 3rd window that is a copy of the 2nd window, but the 2nd window has no menu to choose "new window" from.

Change the editor type of your second window to "Info" instead of 3D View or whatever you currently have open. That will bring back the window drop down. Alternatively your could just shift click and drag the top right corner of the second window.

I use Window > Duplicate Window function and it allows me to create several copies of the main window. I can edit layout in the second and it will be copied to third, all windows will remain "linked" though, so e.g. rendering process will be synced etc. but as the window is fully copied menu with Window > Duplicate Window remains accessible. Did you mean something else?

@LukasValine: This is the answer: "your could just shift click and drag the top right corner of the second window".


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Merging objects while preserving the look of being several pieces?
I'm working on modeling realistic furniture. A real drawer is not one piece, but six; a bottom, side, side, back, and front.
Like this:

Having six separate objects is difficult to work with. But when you join them with Ctrl+J, you get this:

Which looks like an injection molded piece of plastic, instead of six individual pieces of wood nailed/glued together.
Joining them auto merges vertices. Now, it's said that it is not good practice to have vertices right on top of each other.
So the question is, how do you get an object that looks like it's made of multiple parts, but is inside of a single object for manageability, without violating best practices (like forcing vertices to occupy the same coordinates)?

One of the reasons doubled vertices aren't recommended is because seams and bleed-thru at the intersection tends to show up as white lines.  However in your case if it works for you, why not keep the components separate and hold them together as a 'virtual'single object by using a common parent, such as an Empty?  See here -
https://blender.stackexchange.com/questions/166114/partial-rotation/166148#166148

Unfortunately, there doesn't seem to be a way to use modifiers with this method...

Yes there is. Just parent an empty to the separate objects. That's it. Each object is still separate, they just move in tandem with the empty.

You could just turn off auto-merge vertices on join. When you use a tool in the lower left of the VP there is a little drop down to adjust the parameters. Click that right after hitting CRTL J. Also duplicat vertices are necessary for sharp edges, not using doubles is "good practice" but it's no mantra.

In the real world you would see a small gap between the different boards of the drawer.  Add a small bevel to each of the walls, so that they are not perfectly flush and square.


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How do you use a multiple leaf texture file on a sapling curve tree?
Textures.com offers leaf textures in a multiple-leaf-per file format. There are also six files for all the maps.
Is the expectation that I open these in gimp and make them into separate images (somehow keeping the edits identical across all six images/maps), or is there a way to use a file like this directly in Blender where you draw bounds around the individual leaves and it assigns one of the groups randomly to each leaf instance? This is for a sapling generated tree in 2.81a.

You can select or deselect random faces in the Select Menu. Then you can edit them in the UV Editor at the same time. (You can select each overlapping verts with the border[Button B] or the brush[Button C] selection tool).

Multiple objects can use different parts of the same material using UV mapping. In this example, The original UVs of the image plane are cut automatically when using the Knife tool. Split the edges and separate the loose parts to create multiple objects. Note the single material used.
That same material can also use the same UVs for applying alpha, normals etc...
Note: the "Import Image as Plane" is an Addon.


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How do you edit exr files in GIMP without loosing light values?
This is the world environment texture in the Gooseberry benchmark:

If I open the exr in Gimp 2.10, and save it under a new name, then switch to that new file in blender, this is the result:

No modifications were done, other than opening the file in GIMP and saving it again. Somehow, it gets much darker.
How can I open/edit/save exrs files for environment textures in GIMP, without making unintentional changes to the light values?

can you attach the exr file for me to try or link to it?

Hello :). This answer could help https://blender.stackexchange.com/a/102972/. If you wanna get technical, then this answer

Also this answer: https://blender.stackexchange.com/a/137373/78972

I don't know how to add an attachment... But the original exr is 60MB, and what GIMP saves is 20MB So it's probably too big to upload.

Looking at those other questions/ansers, I'm still not sure how to do this. It sounds like the issues is that Blender uses a linear profile that other programs don't (y default). Is GIMP not capable of doing it? Or is there an option to import as linear or export the color management data from Blender? What Linux program is best for working with HDRIs then?


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Create an edge between a "real" and an array modifier vertex?
I want to hit "F" and add an edge between the last vertex of the real object, and the first vertex of it's array-modifier-duplicated clone.
The problem is, selecting the first vertex of the clone actually selects the first vertex of the original instead, so the edge goes in the wrong place.

This is wrong: the new edge should connect the gear teeth together, not close off the tooth.

There doesn't seem to be a way to set the cursor to the cloned vertex either.
What's the fastest way to add an edge (and required vertex) as if the cloned vertex were actually there?

Scenario 1
Make one copy of Array real to be able snap extruded vertex and add Array modifier again. Like:

Duplicate Array modifier (and disable one of them)
Set Count 2 and Apply
Enable Snap > Vertex type
Create connection by Extruding E Vertex
Delete unwanted parts (second teeth)
Enable Array modifier back

Scenario 2
Do it out of edit mode by another object and than join them. Like ...

in Edit mode Shift+D first vertex
Separate > Selected P
in Object mode select separeted vertex, go to edit mode
enable Snap tool and to Vertex
select vertex, Extrude E, Snap to first Array copy
go to Object mode and Join these two Objects Ctrl+J

BTW Do you know there is a addon GearGenMaster?