If painting directly on the map, outside of the borders of your UV, fixes it, then it is a filtering/mipmapping issue that can be solved by increasing the bleed.

Don't worry about what your texture looks like out of the borders-- don't worry that it looks weird.  It's supposed to look like that.  That's not an odd image, an odd image is an image without any painted margins.

How much bleed should you use?  About half of the smallest distance between UV islands.  Ideally, your UV map is so well arranged that all verts of all islands are equally spaced and your entire image gets painted with bleed.

Increasing the bleed alone is not enough; it only paints bleed when you actually paint.  So in addition to increasing bleed, you need to actually paint over those edges again.  From the looks of your image, you painted, then increased bleed, then painted some more, but did not necessarily overpaint areas you already painted.  Which could easily explain your edges appearing only in some places....


Where are clouds, stucci, wood textures in cycles materials?

Cycles is a completely different rendering engine, with its own system, separate settings, materials and different workflow. Blender internal materials and textures are not available under Cycles and the opposite is also true.

Cycles has it's own musgrave texture accessible through the node editor Add Menu > Textures > Musgrave. It has it's own set of settings and can be tweaked as just like Blender Internal.
You can even use other textures com combine, mix or deform the current one.


Having difficulty with unwrapping a simple part of an object

UVs after choosing "Unwrap" from the "UV Mapping" might not be accurate most of the times so it would be better to choose "Smart UV Project" instead of "Unwrap".


See answers to question 3516

Dyntopo is increasing the density of the mesh for you as you sculpt and it is very demanding on performance at that resolution. To see this:

In Properties panel -> Object -> Display, enable Wire and Draw All
Edges.
Repeat your test of resolution 50 at constant detail on a default cube with dyntopo enabled

If you need to sculpt at this level of detail, you will have to upgrade some hardware.

Tablet vs. mouse is not relevant.


How to append and swap materials with the same name?

You should link materials and not append them in mutliple projects, by linking you have the benefit of only updating your master blend file or library and see the changes propagate in all blend files that use that material.

see also :
What is the differance between Linked and Appended data from external .blend files?


i cant edit collection, no object in collection

Did u directly open the blend file or append/import it? Can you share the blend file so that the problem can be understood properly?
Generally, a linked collection cant be opened to edit because the mesh isn't actually imported.


Judging from the rounded surfaces and the post-application deformations, I'd wager that you have an unapplied Subdivision Surface modifier. Once you've applied the boolean operation without applying the subsurf, the subsurf operation is now operating on the circular cutouts as well as the original mesh.

Consider not applying the boolean operation if possible. One of the biggest advantages of the boolean workflow is the procedural aspect of it. If not, backup the model and apply all other modifiers before applying the boolean.


How does Blender figure out the normal of a face?

Yes, the order in which we define the vertex indices of the Face directly influence the Face's normal.

See this thread on StackOverflow for some insight

Usually when constructing geometry you can keep track of the order and never encounter this problem, just be consistent. If you suddenly change the order in which you specify the vertices, you will get an inverted normal on that face (which is what happens to you). There's no way for Blender to know if that's intentional or not.

Sometimes it can be more convenient to let an algorithm recalculate normals at the end, as an extra processing step.

bmesh.ops

There's a bmesh.ops to recalculate normals .

bmesh.ops.recalc_face_normals(bm, faces=bm.faces)

See TextEditor > Templates > Python > Bmesh Simple for the template to get a bmesh representation from an object.

import bpy
import bmesh

verts = [(1.0, 1.0, -1.0),
         (1.0, -1.0, -1.0),
         (-1.0, -1.0, -1.0),
         (-1.0, 1.0, -1.0),
         (1.0, 1.0, 1.0),
         (1.0, -1.0, 1.0),
         (-1.0, -1.0, 1.0),
         (-1.0, 1.0, 1.0)]

faces = [(0, 1, 2, 3),
         (4, 5, 6, 7),         # (4, 7, 6, 5) --> (4, 5, 6, 7)
         (0, 4, 5, 1),
         (1, 5, 6, 2),
         (2, 6, 7, 3),
         (4, 0, 3, 7)]

mesh = bpy.data.meshes.new('CubeMesh')
scn = bpy.context.scene
mesh.from_pydata(verts, [], faces)
mesh.update()

bm = bmesh.new()
bm.from_mesh(mesh)
bmesh.ops.recalc_face_normals(bm, faces=bm.faces)
bm.to_mesh(mesh)
bm.free()

cube = bpy.data.objects.new('Cube', mesh)
scn.objects.link(cube)

You may want to work this into a function for clarity.

bpy.ops.mesh

You can use normals_make_consistent() if it's more convenient, there are however general reasons to avoid using bpy.ops within a scripting context. See the post on why to avoid bpy.ops

def make_object(name, verts, faces, normal_recalc=True):

    scn = bpy.context.scene

    mesh = bpy.data.meshes.new(name + "_Mesh")
    mesh.from_pydata(verts, [], faces)
    mesh.update()

    ob = bpy.data.objects.new(name, mesh)
    scn.objects.link(ob)
    if normal_recalc:
        scn.objects.active = ob
        bpy.ops.object.mode_set(mode = 'EDIT')
        bpy.ops.mesh.normals_make_consistent()
        bpy.ops.object.mode_set(mode = 'OBJECT')

    return ob

make_object('my_cube', verts, faces)
# make_object(name, verts, faces, normal_recalc=False)


Error in addon: "wm_operator_invoke: invalid operator call"

As pink vertex pointed out, the method needs to called execute.

What happens here?

An operator added to a panel shows as button, and if you click it, Blender will try to invoke it by default (which means it looks for an invoke() method in the operator).

Since your operator has no invoke(), it will try to execute it instead (thus try to call execute()). Your operator doesn't have it, and Blender gives up with the error mesasge:

  wm_operator_invoke: invalid operator call 'OBJECT_OT_my_operator'

So it means it couldn't find a method for the operator context (invoke for a button in a panel by default), nor an alternative (execute).

You can override the operator context in layouts if you need to. If your operator defines invoke() and execute() alongside, you might want a button in a panel that executes the operator, and not invoke it. Create a layout sub-element (column, row, ...) and set its operator_context attribute to the context you want to run it in (see API docs):

import bpy

class OBJECT_OT_my_operator(bpy.types.Operator):
    bl_idname = "object.my_operator"
    bl_label = "My Operator"

    def invoke(self, context, event):
        print("hello invoke")
        return {'FINISHED'}

    def execute(self, context):
        print("hello execute")
        return {'FINISHED'}

def draw(self, context):
    layout = self.layout
    layout.operator(OBJECT_OT_my_operator.bl_idname, text="Operator 1 - invoke (default)")

    col = layout.column()
    col.operator_context = 'EXEC_DEFAULT'
    col.operator(OBJECT_OT_my_operator.bl_idname, text="Operator 1 - execute")

def register():
    bpy.utils.register_class(OBJECT_OT_my_operator)
    bpy.types.RENDER_PT_render.append(draw)

def unregister():
    bpy.utils.unregister_class(OBJECT_OT_my_operator)
    bpy.types.RENDER_PT_render.remove(draw)

if __name__ == "__main__":
    register()


How would you approach a shader for a glittery eyeshadow

A good way to approach a glittery material that I've found works well is using voronoi cell noise as an input for a normal map:

By changing the strength of the normal map, you can change how non-flat the glitter effect is, and the size with the Voronoi scale.

If the object will be moving or animated, it would be recommended to plug a UV Map Node into the Voronoi Texture

Here's an example node setup with some basic blending via vertex color:

This method also works great for snow, car paint, and anything else that has a glitter to it!


"F" Button in Shape Key Editor Not Showing Up - Why Not?

The "F" button is to tell Blender to save a data block even if it has no user, so it appears only when... you have a data block!

In your picture, you have this situation for that eye:

the " + new " button means, there's no data block, and you can add one (an action in that case). Then, the "F" button will appear.

edit

I think that eye has something different than the other...

selecting that green NLA editor stripe, and using TAB it expands, and the " + add " becomes usable, but acts weirdly, at least...

I'm not an expert though, and can't understand how to fix it. But maybe you know what happened to that strip?


You could also use Knife Project.

Subdivide the face you want to be engraved (knife project needs some geometry)
Place the text above the face.
Select the text
Select the cube (must be the active object)
Change to Edit Mode
Click Knife Project
Extrude the selected faces (in or out)


How not to lose quality of image with brush

When creating your texture that you are going to paint to, increase this number. (smaller is lower resolution, larger will allow for more detail) It is a good idea to keep powers of 2, such as 1024, 2048, 4096, 8192 Etc.

In your case, when you already have an image made, you can adjust the size of your image in the tools panel of the UV/Image Editor


bpy: how do I list the "pivot center for rotation/scaling" items?

Window manager context operators

Just as there is a window manager operator to call a pie menu, there is also a cluster of bpy.ops.wm.context_blah(...) operators, including

bpy.ops.context_pie_enum(data_path="")

which  expands the enum property elements in a pie menu.  The data_path parameter is the path from context. In this example  context.space_data.pivot_point the RNA string path from context is "space_data.pivot_point"

Test script, needs the context of a VIEW3D space. For convenience I prepended a button to the VIEW3D header.

import bpy

def piebut(self, context):
    layout = self.layout
    op = layout.operator("wm.context_pie_enum")
    op.data_path = "space_data.pivot_point"

def register():
    bpy.types.VIEW3D_HT_header.prepend(piebut)

def unregister():
    bpy.types.VIEW3D_HT_header.remove(piebut)

if __name__ == "__main__":
    register()


In the transparent object's properties go down to the display tab. In there is a box called "Transparency" Ticking or unticking that may solve your problem.


How to turn off screencast mouse highlighter?

Hit the dismiss button, labelled "Capture",  to the right of the render engine select box.


How to Copy ( CTRL L ) Object Data to Many Objects while keeping all their Transforms ( Location Rotation & Scale )

If you want blue cubes to stay in their position after you link their mesh data to the gray cube, you need to reset their origin to their individual centers.

You can use that devil shortcut Ctrl+Alt+Shift+C for that.

I hope it is what you are going to achieve :)

Here is your .blend with this "fix" applied.


Can Blender be used to simulate the transmission of sound waves
  through a medium (most likely air)?

No, blender is designed to create images and animations (including soft and rigid body physics) which may include sounds, having that said blender copes with light not with audio.

The only support for audio (besides playback) I'm aware is to bake the amplitude (volume) of a distinct frequency range to an f-curve.

These f-curves could be used to animate an object in an animation like the vibrations of strings, or to visualize sounds like a spectrum analyzer does (scaling boxes).

Tutorial here

IMHO The best would be to play around with these possibities and evaluate the options provided and in case blender is still a candidate (for your project) too ask a more specific question.


Proportional Edit Saves Time

The image above shows using a sphere as a starting point for mesh.

If its educational for you to draw vertices one by one then so be it.  No one can argue with that. Or can they?

The model does not appear to be an organic model or face model subject to high levels of inspection.   Also I am assuming a bowl shape with a drape is above.  Below a plane with moderate vertex density created in a few seconds with edit mode Subdivide.

If you choose to take a different approach I suggest you use

Proportional Editing.  That term can be searched here at BSE.

The image above shows edit mode proportional edit. The arrow shows the proportional edit button with tool tip.

There are many completed introductory videos on the famous video website that rhymes with noonoob. Video may serve you better. This writing is not a tutorial. You may also want to include shape keys. One could could also used a hemisphere as a starting mesh rather than a plane.  No artistry here. Just a technical suggestion.  Of course there are plenty of other ways to  achieve a similar mesh model.

Once you have practiced a few times with proportional edit you may recreate your model in 8 minutes or less.

Tutorial Link

https://www.youtube.com/watch?v=MrNVVHdKd3E

I suggest seeing many of these videos and especially one on Shrink Wrap or Cloth Simulation.


If your particle spheres are sinking through the floor to the center of the particle Sphere, it would indicate that you forgot to check the 'Size Deflect' check box in the Particle's Physics panel.

Also, you need to check the  'Activate Self Collision' check box in the Collision panel and adjust the friction and damping settings for the Molecular add-on to take the individual particle spheres into account when they collide against one another.

Here's a blend file in case you need it:


Ok, this is what you could try, I hope it fits with your workflow, or at least inspires you to find a better way:

put the body in rest pose
apply the vertebras modifier (array+curve)
separate vertebras mesh into separate vertebras objects
then, create a vertex groups (1 vertex each) on the body back skin, one for each vertebra, which will get "attached" to that vertex later.
then I would create a "child of" constraint for each vertebra, with the right vertex group as "target"

eg: if this is your rigged body (here posed)

select the "body" and create (eg) two vertex group, one "skin" vertex each:

and

then "attach" each vertebra (here is a sphere) to its vertex group using the "child of" constraint (after adding the constraint, you may need to reposition the "vertebra" where it should be, if it goes elsewhere):

then, when you pose the rig, the body follows the rig, and the vertebras follow the body, without deforming.

here is my example .blend:

Note: parenting is not the same, will not work well, use this kind of constraint.

edit

after understanding better the rig/model pose, I expand to add details of what I intended...

preface:

I reverted the rig to the "rest position"
you created an "array" of 14 vertebras but not using the array modifier, instead you parented one base vertebra to a curve and used the "frame duplication" feature of such setup, setting the "path animation" frames of the curve to 14.

since what I intended to do above needs 14 real vertebras, not duplicated ones, after setting the mesh "duplication" frames end also to 14 (it was 99, default probably), I used the "make duplicates real" comand, and removed the "base vertebra" parent to the curve.

and

obtaining 14 real vertebras, with no duplication

then I've hidden all vertebras but the first 2, to keep the example simple to visualize (the whole model is really complex)
after that, I went in edit mode of the body mesh, and created two separate vertex groups, 1 vertex each, each to be the "hook" for a single vertebra.

then, I added to each vertebra the constraint "child of", targeted to each vertex group, and placed them where they should be in rest pose

in solid mode

from the side

now, going back to posed mode, each vertebra sticks to and follows its vertex group, without deforming, but you may need to adjust something to make them move as you desire: the model spine moves quite a lot, and that move vertebreas also... maybe using vertex groups of more than 1 vertex blends the vertebra movement better ... I just tried to keep it simple.

here below you find the updated model with the 2 example vertebras seen in the screenshots above...


Inset the face you have with I, invert the selection (since the area which was inset will remain selected) with Ctrl+I and then extrude.

Note that depending on the case you might need to change topology in the end to convert Ngons to something more appropriate. Though if no subdividing with modifiers like Subsurf is used then it won't be that necessary.


You can access it manually via Edit > Menu Search...
You could add the Menu Search to quick favorites by right clicking on it and selecting Add to Quick Favorites. Quick favorites can be accessed by pressing Q
You can also redefine your keyboard shortcuts in Edit > Preferences > Keymap (search for Search Menu)


What is pin goal strength for Hair Dynamics?

The Blender Manual describes it as:

Spring stiffness of the vertex target position.

To my understanding, this is how much the hair wants to "spring" back into its initial/styled position. A lower value makes the hair looser and a higher value makes it stiffer.

This is something probably best understood by simply experimenting with the value and seeing how it affects the simulation (this description just comes from my own experience).


How to fix mirror modifier doing weird things?

Is very likely that you have the object rotated in one or more axis. You can do 2 things (as far as I know):

Apply the rotation (keeping the current visual orientation): press, while in object mode, Ctrl+A and then select rotation.

Set the rotation values to 0 (this will rotate the object to a different orientation): in the object properties menu, in the transform tab set all the rotation values to 0.


How to display vertex colors in Viewport Shading Mode

Well I have egg on my face. Very simple solution, after deviating away from tutorials and just playing around. Here is the solution. Thanks for the upvote and hopefully this helps someone else:


Why can't I use a loop-cut on this simple mesh?

You have 2 problems that make Blender unable to know how it could build the edge loop, as it needs quads to create edge loops automatically with ctrl R, and it can't deal with ambiguity:

A face inside your mesh that is not visible in Object mode. You need to select it and delete it with X > Faces
An edge loop coming from the bottom which makes a ngon at its end. You need to select it and delete it with X > Edge Loops

Now you can create a new edge loop.


How to draw a Panel only in the Shader editor node editor (object type based)?

Poll the ui_type
With the advent of more than one UI in a particular area type, when this is the case look at the Area.ui_type
Unaware of, but there may be a bl_context (or similar) class property to do this.  As with 99% of blender the UI code is there to peruse.
Look up the docs for options, put a print in draw method, or find quickly via blender's python console
>>> C.area.ui_type = 'XXXX'
Traceback (most recent call last):
  File "<blender_console>", line 1, in <module>
TypeError: bpy_struct: item.attr = val: enum "XXXX"
not found in (, 'VIEW_3D', 'VIEW', 'UV',
'CompositorNodeTree',
'TextureNodeTree',
'ShaderNodeTree', 'SEQUENCE_EDITOR', 'CLIP_EDITOR', 'DOPESHEET', 'TIMELINE', 'FCURVES', 'DRIVERS', 'NLA_EDITOR', 'TEXT_EDITOR', 'CONSOLE', 'INFO', 'OUTLINER', 'PROPERTIES', 'FILE_BROWSER', 'PREFERENCES')

Notice there are three obvious candidates for nodetrees.
Test script.  Polls if the context area  ui_type is 'ShaderNodeTree'
import bpy

class ADDON_PT_Panel(bpy.types.Panel):

    bl_label = "Test"
    bl_idname = "ADDON_PT_Panel"
    bl_space_type = 'NODE_EDITOR'
    bl_region_type = 'UI'
    bl_category = "Test"
    #bl_context = "scene"

    @classmethod
    def poll(self, context):
        return context.area.ui_type == "ShaderNodeTree"

    def draw(self,context):
        layout = self.layout
        #print(context.space_data.ui_type)
        layout.label(text="Hello World")

bpy.utils.register_class(ADDON_PT_Panel)


Viewport material shading looks like face orientation is wrong but the issue is something else

Edit: So my answer fixed the problem on my computer but not on yours apparently...
Show Backface seems to be the option you want to disable, it will affect the Material Preview in Cycles, it won't affect the Render, except in Eevee:


How do I align the viewport to a face normal?

In edit mode with a face selected press ShiftNumPad 7 That will align the view to the active face.
If you want to align the view to a different axis relative to the face, ShiftNumPad 1 and ShiftNumPad 3 can be used. Ctrl can be added to any of the key combinations to invert the view.
For example, CtrlShiftNumPad 7 will look at the "back" of a face.

For those of you without a numpad the same can be accessed through the menu.
From the 3D view header View > Align View > Align View to Active. Then pick the orientation you want (Top is used the most).

Do note that there can be faces that are not flat. In such cases the view will be aligned to the face, but any manipulation will warp the face.

This answer is valid for blender version 2.50 and up (including 2.8). For the 2.4 series the shortcut was ShiftV, but I doubt you wanted to know that.


Making sure that faces have the same dimensions

I went with @moonboots answer (all glory to him).

Delete the group of faces that A is composed of
Duplicate the group of faces that B is composed of
Snap that duplicate at A's position


What does "users" means in term of datablocks?

Blender organizes its data in datablocks. These are chunks of data (bits and bytes) that belong together, like all the settings of a material or the verts and faces of a mesh. When you give a mesh a material, this data isn't merged, but linked. You tell Blender: whenever you use mesh X, display it with material Y.

When a material is linked to something, it has a user. Another datablock that uses this material. When a material is used by a lot of objects or meshes, it has many users, displayed by the number to the right of it's name.

That way you can have a thousand objects all using the same mesh, which takes up less memory and enables you to edit one mesh and affect all linked objects simultaneously.

Fake users are a way to keep a material alive even if no object or mesh uses this material. If a datablock has no users, it will not be saved when you save the file in order to decrease file size. Think of it as some kind of garbage collection. However, the fake user takes care of this problem.

To illustrate that, I have resurrected Blender 2.28 because it has a view called OOPS schematic that shows the linking very well. Below, you have four objects all linking to one Suzanne mesh. I'm in the edit mode of the upper left Suzie and mess with her ears. Since all four objects use the same mesh, all objects are changed simultaneously.

One easily overlooked feature is copying lamps with altD. All the lamps then share the same data. This way you can change every lamp's brightness in one go. Think of a row of street lamps.


What do you do if you dont have a numpad

On a mac, you can use the Funtion key (fn) + U or I or O or j or k or L or M.. please check this image:


I didn't find the reason for the strange behaviour. There must be something wrong in the scene settings, maybe someone can investigate further.
But when I made a new scene, copied all objects from the old scene to the new one, everything rendered fine. Do not try to copy the old scene by using Full Copy, in this case the new scene won't render either.
This is just a workaround to help you rendering the animation. Hopefully someone finds a better answer.


Have an empty follow the curve.

For the boids set your empty as goal.


assuming you have the video all cut together in the video sequence editor pannel, open a properties panel and go the the render section (first button with a picture of a camera) there will be all your render setting whch you may personalize. For rendering 3D you would want to first export as PNG files and then post render bring the PNG sequence into the Video sequence editor render it into a final video file, but it sounds like you are trying to do a final video render in which case you go to the output section and choose FFMPEG video, Then under encoding > container you generally want to go with either Quicktime (.mov) or mpeg-4 (.mp4) and for the codec use H.264


How do I properly use an alpha texture to create variable transparency areas on a surface?

I have a solution of sorts. Here is my final node array:

That's just Texture mode (to illustrate how the alpha is figured out).
For a quick and dirty solution, this is just fine. I even went ahead and omitted the alpha map and just drove that value via the diffuse map.
If someone has a superior node-array in mind, I'm sure happy to listen though.
Here's a final render:


Character disappearing, normals are good

Some points to check:

When you do not see the object at all, the normals are normally not the problem. Unless all faces are facing away from the camera you should see at least something. On a closed mesh it is not possible that all faces are facing away from camera when the camera is outside of the mesh.
And there we are: ensure your object is within the camera's frustum (the view of the camera). The object should not be behind the camera, or above or somewhere else.
Ensure all parents of the object are supported by the BGE. E.g. parenting your mesh to a curve. The curve is not supported and therefore not loaded. The mesh as child will not be loaded too.
Check if the mesh and the parent are at a place you expect them to be. Start from top view. Use wireframe mode too se through the faces. Add a cube and parent the character to it. Un-parent the skin mesh to see it is rendered at all. Switch the armature to rest pose etc. These are little steps to see if it changes something.

Remarks: You should only enable backface culling when simulating very thin objects where you might be able to see both sides at the same time (like paper sheets, leaves or curtains). It doubles the workload of the renderer.


Rotate an object but do not rotate its alpha image texture mask

Change texture coordinate to "Object". Then Change Extension from "repeat" to "clip". And adjust location and scale like in the image below. Now Z rotation works like you need.


Why are some of these vertices being ignored by edge loop selection?

Your topology has corners, which break the edge loop.

You can solve it by a small Inset, to keep your edge loop connected.

If you want to continue selection through corners, just click again :).


What are the faces with dotted patterns on them that seemingly cannot be subdivided

The dots mean the face is Active. See Why does one of the faces show dotted in editmode?

The reason why it apparently can't be subdivided is not due to it's selection state, but rather because it is an n-gon. An n-gon is a faces made up of more than four edges.

Subdividing an n-gon won't create edges running through it, but will still add vertices to it's existing edges:

While in Face Select mode these verts won't be visible. To see them, switch to Vertex Select mode
(⎈ Ctrl↹ Tab).

Depending on what you are doing, n-gons should generally be avoided. See When should N-Gons be used, and when shouldn't they? for some more info.


Menu list keeps on growing every time I debug my Operator script

You can test whether menu_func is already part of _draw_funcs list and if so, do not prepend:
def register():
    bpy.utils.register_class(CUSTOM_OT_operator)

    if hasattr(bpy.types.VIEW3D_MT_uv_map.draw, '_draw_funcs'):
        if menu_func.__name__ not in (f.__name__ for f in bpy.types.VIEW3D_MT_uv_map.draw._draw_funcs):
            bpy.types.VIEW3D_MT_uv_map.prepend(menu_func)
    else:
        bpy.types.VIEW3D_MT_uv_map.prepend(menu_func)

def unregister():
    bpy.utils.unregister_class(CUSTOM_OT_operator)
    bpy.types.VIEW3D_MT_uv_map.remove(menu_func)

if __name__ == "__main__":
    register()


How and where can I post a video for review of Blender users, that shows my students work?

Unfortunately, this site is not a forum for posting or sharing work. I'd recommend posting it on BlenderArtists.org.


tldr: The default anti-aliasing setting samples significantly outside one pixel which reduces the effective resolution. For a maximum effective resolution use the "box" setting which acts as an incredibly high multisampling anti-aliasing filter.

From my own experiments and the information provided in the discussion from the patch https://developer.blender.org/D1453, the sampling with the Blackman-Harris-Filter happens in a circular pattern around the center of the pixel, with the density following the Blackman-Harris-Distribution.

In the default case, with a "filter width" of 1.5 pixels, this means that up to 5 pixels in a horizontal line contribute to the central (third) pixel. Not only the nearest neighbor but also the next nearest neighbor pixels. This leads to a significant "blurring" of the image. Only "filter width" values below ~.65 pixels guarantee sampling stays within the original pixel. This however leaves out the corners of the pixel.

Chosing an "optimal" default and distribution is not possible as per wikipedia:

  The goal of an anti-aliasing filter is to greatly reduce frequencies above a certain limit, known as the Nyquist frequency, so that the signal will be accurately represented by its samples, or nearly so, in accordance with the sampling theorem; there are many different choices of detailed algorithm, with different filter transfer functions. Current knowledge of human visual perception is not sufficient, in general, to say what approach will look best.

However what originally motivated me to post this question, was the blurring when working with pixel accurate sprites. With the default anti-aliasing setting it felt like detail got lost in the renders. However turning off or reducing the width of the filter too far killed the anti aliasing even inside the pixels.

When using the "box" anti-aliasing filter and adding a Gaussian blur in the compositor, I can no longer distinguish the results from the Blackman-Harris filter, but I have the freedom to adapt the sharpness in after the render.


Saving image in uv editor with seams showing

You can't. You have to export it separately:

The UV layout isn't supposed to be contained in a texture usually. It's supposed to be a tool to help you to create the texture, not something displayed as the object's texture itself. Unless you're really going for something special.


Is there a way to assign a material to a vertex group without the vertex group being editable mesh data?

In this case, the modifier provides a Material Index Offset setting for generated geometry.. (just above the Vertex Group assignments)  so you don't need any get-arounds..

(This circle is solidified downwards, from red to blue)
In general, until a node is provided, this method by @Nathan can get vertex-groups / weights into shader trees.


Install external package in Blender (python websockets)

You need to have the modules youre planning to use, on the python path where blender looks for the modules. blender comes with its own python installed. browse the blender directory youll find it. This is probably the cacuse.
just copy your python/lib/sitepackages folder on it and I think youll have it done...


I rigged a human model with Inversed Kinematics but it is not working. How can I debug this?

Just unparent the IK control in Edit mode. Now it will work.

Change the LowerLeg pole angle to 0. Your pole is inversed like a chicken leg.

In Edit Mode select the foot and uncheck Inherit Rotation. This will make the foot return to the right position.

Just in case an animated gif:


Fluid, object, childof constraint animation - won't work

This is a limitation of how blender works, constraints are the last step to placing an object, which means the fluid sim will never see the inflow object in the constrained location.

The way to get this working is to bake the animation into keyframes for the inflow object then remove the constraint. Object->Animation->Bake Action... will do this for you.

You want to turn on visual keying so that you get the location after the constraint is applied.


I want to curve an object like a roller coaster using a path

Important

Make sure your track model's origin is moved to align exactly on the edge of the model. The modifier will depend on the origin's Position to make duplicate and alignment.

Use the Array modifier to create copies of the track model.
Create a bezier curve representing the curve and length of track.
Add a Curve Deform Modifier and target the bezier path curve object.

The blend file ...

Extra Note
Instead of "Fixed Count" use "Fit Curve" on the array modifier Fit type drop down menu to improve control to the duplication of the mesh according to the length of the curve.


Why does camera this tracking fail completely even when the solution value is very low?

For this kind of shot, where the camera hardly moves I don't think you're going to get good results using motion tracking.

There is so little parallax information for the reconstruction.

For a detailed post on motion tracking read:

How can I get better results when doing camera motion tracking?

I'd suggest you stabilize the footage as if it was a fixed shot and then do the reconstruction using BLAM ( https://github.com/stuffmatic/blam ).

  NOTE: Blam is no longer mantained and has been replaced by Fspy: https://fspy.io/, but there is no importer for blender 2.79 or previous versions.

For a detailed post on how to use blam and Fspy read: How can I recreate geometry using a photograph?


How can I set the image to use the UV Map using the python api

Every UV face needs to be set to the image datablock:

image = bpy.data.images.new(name="test", width=512, height=512)

for uv_face in cube.data.uv_textures.active.data:
    uv_face.image = image

bpy.ops.object.bake_image()

Note that a uv_texture can't be accessed in edit-mode.

In addition to the UV face assignment, every mesh face should get a material with an image texture assigned (same image as for UV faces) and the texture coordinates be set to UV. Otherwise the texture may not show correct in viewport, although it might be baked correctly (better test!).

Have a look at the Material Utils addons, it let's you transfer UV face image assignments to material texture assignments and vice versa.


You could try setting the curve shape to 2D in Curve > Shape until you want to adjust it in Z axis:

Note that you will still be able to rotate the curve in Object Mode, so you can use this to lock the curve in any direction.

Another option is to fix the curve afterwards:

Select all the control points (A):

Scale to 0 on the axis you want to lock. E.g. SZ0
This will scale everything to be on a plane with the Pivot point, so you can easily control this by using the 3D cursor:


smoke to use gradient from red to violet through rainbow

Here's a variant of the 'Quick Smoke' material (as created by selecting the default cube, pressing Space and typing 'Quick Smoke' Enter).

The differences are the addition of the Emission shader to make the smoke glow (this would normally be the 'flames') and the additional of a Color Ramp set to vary based on the Generated 'Z' coordinate (adjust the color ramp colors to get the desired 'rainbow').

Note that setting the smoke domain objects to be 'Smoke Adaptive Domain' the smoke rainbow will dynamically span the height of the extent of the smoke.


Eevee how to render without black boxes in textures?

Alpha Channel in Eevee?

This has already been answered here. You have to switch your Material Settings Blend mode to Alpha.

Edit : This goes hand to hand with this kind of node setup of course :


Why does editing a material on one object change lots of other object's materials as well?

The comments give the right answer (sorry to "steal" it, but otherwise they won't be marked as an answer). If you want an object to be the only user of a material you've given to multiple objects, click on the number next to the name. By default, the material called "Material" in your example will then be duplicated and renamed to "Material.001" and the active object will be the only user. Of course you can now assign this material to other objects as well if you want them to have the same material.
The advantage of having the same material on multiple objects is of course to be able to change materials, textures etc. on many different objects without having to merge them into a single object.
The advantage of duplicating a material by clicking on the number is, especially if you have a very complex node setup, that you can easily assign a material on one object that is similar to a different object and only make slight changes.


Rotate object's mesh so it matches another object's rotation

If your objects are in Euler rotation mode, then the quaternion wont be set. For any mode using

ob.matrix_world.to_euler()
ob.matrix_world.to_quaternion()

will give the global euler and quaternion rotation respectively.

import bpy
import mathutils
from mathutils import  Quaternion, Vector, Matrix
import bmesh
import math
from math import radians

context = bpy.context
data = bpy.data

obj1 = data.objects['Cube']
obj2 = data.objects['Cube.001']

from_quat_rot = obj1.matrix_world.to_quaternion()
to_quat_rot = obj2.matrix_world.to_quaternion()
from_euler_rot = obj1.rotation_euler
to_euler_rot = obj2.rotation_euler

difference_quat = from_quat_rot.rotation_difference(to_quat_rot)
difference_angle = difference_quat.angle

print(f"difference angle: {difference_angle}")

vector_zero = Vector((0, 0, 0))
bm = bmesh.new()
bm.from_mesh(obj1.data)
bmesh.ops.rotate(bm,
        cent=vector_zero,
        verts=bm.verts,
        matrix=Matrix.Rotation(difference_angle, 4, difference_quat.axis))
bm.to_mesh(obj1.data)
bm.free()

This rotates the mesh as expected.  Running again will have an accumulative effect.

could also

M = difference_quat.to_matrix()
obj1.data.transform(M)
obj1.data.update()


How to make a "rope" like object with even width throughout the whole object? (image inside)

Probably the most common solution to this problem is to create a Bezier curve and use another Bezier curve (often a circle) as the Bevel Object (in the Bezier > Geometry properties).

https://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro/Bevelling_a_Curve has detailed documentation.

Your question is almost a duplicate of Make a 3D tube with a Bézier curve? .


How to create a workable leaf spring in Blender?

This is the closest simulation I could think of (also made video version available):

Create a Cube Shift+amc and scale down it sz.1Returnsx.5Return.
Create and instance with Alt+dy2Return. Repeat several times with Shift+r, making sure to end with an uneven amount.
Select all newly created cubes and and make active rigid bodies Control+r.
In the the Tool Shelf under Rigid Body Tools, click Calculate Mass and select Steel.
One by one go along selecting each of the neighbouring cubes and click the Connect button (also in the Rigid Body Tools).
Finally select the centre cube and set it to passive Control+Shift+r.


First of all put the armature modifier before the subsurf and check the two buttons of armature modifier so it acts in edit mode also.

As you can read in the N properties panel, the not moving vertices heve been weighted to the wrong bones (shoulder and upper arm), instead of "spine.006".

Then go to the vertex groups tab, select all wrong moving vertices, remove them from the wrong vertex groups, and assign them to the "spine.006" one.

In general, when an object has to move exactly with one bone, without any deformation, you should avoid automatic weighting, and parent the object directly to the bone (bone option, choose the bone in pose mode), or choose "with empty group" option and manually assign all vertices to the corresponding vertex group.


How to correct non-connected edges/faces?

This was caused by the Edge Split modifier, which, as its name infers, split your mesh at the edges. To fix it, select all the vertices and click the "Remove Doubles" button in the Tool Shelf.


By default, blender is set up with turntable navigation style, which means the Z is held vertical through your orbit manipulation. There is another style of navigation which used to be common in 3D, called trackball. This lets you orbit without the restriction of Z-up, but it also makes it easy to lose your sense of space in the scene. You can change this setting in the user preferences, under the input section. The left column contains those settings.

In 2.8+ "trackball" option is now in the "navigation" tab of the preferences:


For game assets is it ok to intentionally stretch UVs, or does this interfere with pixels per units?

I don't think there's anything wrong with stretching UV's from a technical perspective, it might even be desirable.

The main thing is that from an aesthetic standpoint it looks good. I would say that as long as it looks good, and is not giving you a blurred or pixellated effect (unless that's what you want), then you should be fine.


I have figured it out, the particles don't show in simple render, unless they're activated in scene before. If they are, the render show them statically at their place. If I want them to move in render, I need to use animated render (ctrl+F12).

Thank you all for your attention!


Question about unjoined/unconnected mesh/object

I think there are two questions here:

Should the parts of my model be manifold?
Is it OK for my model to comprise several parts, manifold or not?

For all the reasons given in it, the first question has a nice answer here

As for the second, IMO,  wherever possible, model parts which are separate parts in the real world as separate parts in the model. Reasons not to do that include:

3D printing as one piece.
Needing a surface to behave well under (possibly unrealistic) deformation when animated
Economy. Simply reducing complexity and poly-count, modeling time.

But you often see people struggling to achieve good topology across regions of a model which could be separate surfaces with no harm done at all.


Blender model keeps squishing my vertices

It looks like there are some places where the distortion is focused.  There's someplace where Blender just can't give us a flat map, and it's distributing the distortion across the map a bit to make it so that no one place is awful.  If we enable sync-- those doubled diagonal arrows in the upper left corner on my UV editor below-- then select the distortion plus a bit more, and hide everything else, we can get a closer look at the problem area:

So when we look more closely, we can see that there are some places where we have what amounts to an unseamed box, at this particular doorway.  Let's seam appropriate edges so that we can unwrap this without distortion:

The selected areas are places that need seams.  One way to think about seams is where we'd need cuts if we were going to wrap this object up for Christmas. For things that are roughly box-shaped, sometimes I think about making fold-up dice as a craft project as a child.
Now that we've created a few more seams, we can unwrap and see how we did.  Don't forget to unhide everything if you don't want to create more islands than you need.

Much better!  There are still a few issues which you didn't ask about (those lines stretching across the UV map).  You should take a look at those as well, using UV sync to find them and then hiding stuff so you can see what's happening.  (Hint: they're due to non-manifold geometry.  You can find non-manifold geometry by using the "select non manifold" operation and learning what its options do.)


How Can I Select A Single Edge Among Linked Duplicates?

Actually I don't really know that in linked selection method is it even possible or not!
But I can tell you another way to achieve what you want.
You can use (shift+d) method to duplicate.
Then select all the duplicates and join them as a single object with (ctrl+ J). You can also move them individually in edit mode. But you can't move them separately in object mode,  they are all now one single object. Hope that helps.


How to generate spherical gradient volume

Volumetric Emmision

add Emmision shader plugged into volume socket of material Output
add Transparent
add Mix shader - with Emmision up
add Gradient texture > Spherical as factor

Volumetric Absorption

Instead of Emmision use Volume Absorption node.

3D Illusion

In some cases it's quite efficient to fake it by simple circle object with Spherical Gradient texture assigned to alpha. Circle orientation Tracked to Camera, so moving object is always facing to camera that make in illusion of 3d object.

(In case you don't care about shadows.)


You must have an object selected for the modifiers panel to be visible.

Once you have an object selected (yellow outline), it will be in Properties > Modifiers. Then click on Add modifier and select Decimate:


How to add and play video in the 3d viewport?

Internal

Add the object.
Add a material.
Set the material to shadeless
Go to the texture tab and add a texture.
Load the movie as your texture.
Upon loading it enable Auto Refresh and press Match Movie Length once. The length should be updated.
In the 3D viewport, switch to textured or material shading mode.
In the shading options (Properties Panel N), select GLSL.

In the file you linked, the movie is playing, but you have set mapping to UV without specifying a UV Map (the object is not unwrapped). This part doesn't have anything to do with playing a movie, but with UV mapping.
Set the mapping to another type or create a UV map.


Use the Separate function.

Enter Edit Mode (Tab)

Highlight (select) the object you are breaking apart, press space, type "separate" (or use the keyboard shortcut P) then pick "Loose Parts" from the list of options.

To help you select the parts, you can select one vertex of or the specific item you want to separtate and press CtrlL to select all of the connected vertices. Then separate using P

A different way to select different parts is using Box select (CtrlB


Is it possible to add a Child Of modifier without changing position of the child?

Yes, in the constraint, click on the Set Inverse button. By default, the child will stick to its parent, but if you click Set Inverse it will keep its original position (like a Parent > Keep Offset).


Create Plane.
Create icosphere.
Select Plane, go to properties tab, particles:

Create a new particle system.
Go to render tab on particles properties and select object. Use the
picker and select the icosphere.
You will see particles being emitted downwards.
Go to world tab, scroll down to gravity tab. Mark it off.
Play animation. Bubbles start coming up. Great!
Go to the property tab-particles and choose emit number: use 25.
Next change life: set life 6 frames.
Next change emission from faces. Choose Random.
Now play with life parameters RANDOM to give particles a random
timing of death between 0 and 6 frames.
After you set that, you can add a turbulence force field. leave as
 default. Watch them bubbles.

Now: Any changes you do to the icosphere will reflect on the bubbles.

Create a sphere move it to intersect half of your icosphere. Select icosphere and use a boolean modifier. Select the sphere as boolean operation set to SUBSTRACT.

Play particle sim, you'll see your bubbles have a hole.

Now, animate the boolean sphere up and down quick enough in the timeline (you can press play and move it with G) and some will come complete and othera with just half bubble.

If you animate this consistently you'll get desired BASE effect.

Thank you for your consideration to vote this as answer by ticking the check mark at the left side.

BFCT_Schiller


Complex SVG file fails to import correctly into Blender

The importer for SVG is quite basic (I feel like I keep writing this over and over)
Whatever you can do to simplify the file, will help you when import it to blender.
Effects on SVGs, and nested objects in groups (or in groups within a group within a group) don't translate well.

Un-group all of the objects in the SGV file and import.
A crucial difference between 3d graphics and 2D illustration is that in 3D you can't have surfaces occupying the same plane.
On 2D Illustration object's layers just occlude each other, but when imported to to 3D software, they will be created on top of each other causing Z-fighting(when two or more surfaces occupy the same space and the render engine cannot differentiate them). In 2D graphics you can get away with overlapping planes in layers, in 3D you can't. Coplanar faces cannot be on to of each other: no two faces can occupy the same plane.

How to fix this? You would need to edit the paths on the original file, and make sure that no paths are overlapping or intersecting. You will need boolean operations like path union, difference, intersect, exclusion, etc. to clean up.
Or you might choose to separate some of the elements on different files, and import them individually to blender, and edit them there, by joining different curves into the same object.
Since you are dealing with a single basic shape, and multiples copies of it, so you can get rid of most of the file to make your life easier, once you have the basic shapes you can make instances in blender.

Here's a picture of the file after cleaning up in inkscape, mostly using boolean exclusion and difference.

Ideally you should be dealing with only four curves that contain all of the elements with no overlaps:


How to convert mesh back to text object?

It cannot be done.  I mean, as m.ardito states, you can undo, or duplicate the text and keep a copy for backup, but converting to mesh is a one way, destructive action.


It appears, that you want to apply your new pose to the model as well as the armature.

To do that, make sure you are in the desired new rest pose. Then apply the armature modifier on the object first. The object will now be unlinked from the armature, but it will be in the target pose.

Now, you can apply the Pose as Rest Pose to the armature. Following this, both (armature and mesh) have the desired pose as the default pose.

To clean up, re-add an armature modifier to the mesh and select the armature as the target object of the modifier.


How to get procedural shader to deform with bone deformation?

If you UV-unwrap your model and use the UV coordinates as "Vector" input for your procedurals, you should be fine independent of deformation.
You will probably need to readjust the scale of some of the procedural textures after using a different set of input coordinates, though.


bpy ray_cast doesn't find intersection from camera position to object position

Transforming the world coordinates to local coordinates fixed it.


Object not appearing in Render View or final render

Go to Layers and see what is wrong. Generaly this is the problem. Maybe your object is no more on the render layer


Blender does have this industry standard keymap (and has had it for years).
In blender 2.8 and up head to the user preferences, Edit > User Preferences.
Then in the Keymap tab change the key configuration to "Industry Compatible".

In older versions of blender open up the User Preferences, File > User Preferences. Go to the Input tab and change the key configuration to "Maya".

That is it. Now the viewport navigation, and many other shortcuts will act like other industry standard programs (maya).


I'm trying to set up a workflow to build PS1 low-poly 2D/3D environments and I have a few questions

Blurry Reference Image
Your reference image is blurry because it's only 32 x 32 pixels small and Blender needs to scale it up to the actual size on the screen. The default algorithm to scale an image is Linear which interpolates the pixels. It's a setting of the Image Texture node. Switch the Texture Interpolation setting from Linear to Closest and the image will keep the pixelated appearance.
Units and Sizes
Blender's default Unit System is Metric. It can be changed in the Scene properties but there are only 2 other options: None and Imperial (inches). No pixels. So it's up to you to create a mapping. For example, you can say that 1 pixel of the reference image is 10 cm in Blender. That way your image would be 32 x 32 cm.
Of course, when you export the 3D object it will be 32 cm tall. This might be too big or too small in the game engine. It's probably best to import a sample asset into Blender and check the size. Then you will have the correct mapping between pixel and meter.
You can check the Dimensions in the "N-panel", the viewport's side panel. Press N to open it. There you also can lock the scale values so that you cannot accidentally change the image's size.
Helper Add-On
Blender comes with an add-on called "Import-Export: Import Images As Planes". You can activate it in the preferences. It might be handy if you need to work with a lot of reference images.


With your camera selected open the properties panel (N) and take a look at the top part, the Transform section.

Here you can see, and change, the exact location and rotation of your camera. (Or any active object, not just the camera.)

You can get to the same information my going to the Object tab of the properties window, I just prefer to stay in the 3D view.

So for your two scenes, you can simply pick a location and orientation that you like, then copy the transformational values to your other camera.


First he added a circle consisting of eight vertices that was rotated by 22.5° on z-axis in object mode. The quarter circle was made by inserting a vertex on each side to align with the axis and then deleting the rest. You can use CTRL+R then point and click at the space between the circle vertices with your mouse to create one vertex in the middle.


You can get something similar this way:

Create your object, keyframe it at frame 0 and frame 30, parent it to an empty (1), parent this empty to a second empty (2):

Create a first keyframe for empty 2, keyframe it at frame 0, move to frame 30, rotate it 90° on the X axis, keyframe again:

Put your cursor at the center (ShiftC), choose Transform Orientation > 3D Cursor, select your object and empty 1, link-duplicate with AltD, rotate 45° on the Z axis:

Repeat the operation until you have your 8 objects:

At frame 30 select one of your object, move it, rotate it the way you want, and keyframe. As they are all linked, they will all inherit the same action, it can give something like that (of course it's not exactly your animation, make something more sophisticated with both empty 2 and object animations). Invert the keyframes in order to have your animation go the other way (select keyframes and S-1):

As all your objects are different, in the Properties panel > Object Data, replace each object by its correct mesh:


Why does "sin(frame)" where frame is "1" set a shape key to 0.841 and not 0.017?

The sin function expects angles in radians, rather than in degrees,
which is why the correct driver expression will be:

sin(radians(frame))

Here's an example of this expression driving the Z value of a cube (you can see that it does indeed get negative values as well, and oscillates between -1 to 1):

Though as you pointed out, shapekeys have a min value of 0 and a max value of 1.


Blender fails to import XYZ scanned model

Import is correct: change origin and shading mode

Once you correctly export the file to OBJ format, there should be no issue related to the source.

Blender is correctly importing the geometry in the scene while keeping the object's original coordinates (Meshlab doesn't). You con manually reposition your object or run the "Set Origin" operator (choose Origin to Geometry option) and then the "Clear Location" operator to move the object to the center of the scene.

Blender is also loading the texture, but they are not shown in Solid mode. You'll have to switch to Texture mode, or Render, or even Material mode (after simplifying the nodetree in this case). You can find a detailed explanation of the Shading mode for the 3D viewport in the Manual's page

.


Texture unwrap does not appear as expected

To show the texture in 3D View in Cycles, Texture Node should be created in the material and viewport switched to Textured Viewport Shading


Creating a model for Garrys mod. How can I copy/paste my model in the edit mode to create a phys model?

one way is (the tutorial one):

select the object (be sure you are in "object mode" and not in "edit mode")
control c to copy
control v to paste
g (move), x (move only on X axis - so you can position better your object), move the mouse, left click when you want to drop the copied object

the other is:

select the object you need to copy (be sure you are in "object mode" and not in "edit mode")
shift d (duplicate)
x (move only on X axis - so you can position better your object)
left click to position the object

otherwise you can do your copy stuff directly inside "scene collection"
right click, copy, bla bla - see gif -->


Fire simulation does not show when I re-open the file

I have successfully fixed it
There was problem with cache
Freeing data and re-baking helped


How do i know if rendering my animation is finished,

There are three things you can look for.

Most of the information that will be useful to you is in the Render Result view of the Image Editor window. The Render Result usually comes up automatically when you start rendering. You can also bring it up by pressing F11.

This is by far the best place to get information about a render process.

At the top of this window is a row of text that has information about the render. As a frame is rendering, it will show the number of the last tile that finished, or the number of samples done/remaining. It will also show information "between" frames about loading images, synchronizing geometry, calculating BVH caches, and stuff like that. That should give you some indication of whether the render is busy with something or not.

In the image below, you can see the bar I'm talking about says:

  "Mem: 17.09M Peak:17.09M | Time: xxxxxx | Done | path Tracing Sample 10/10"

That text will be a little different depending on a number of factors (like image vs. animation), but that's what you're looking for.

Another thing you can look at is the render progress bar. It will show the progress for each frame (not the whole animation), but if the progress bar isn't being displayed at all, then Blender isn't rendering.

Blender provides pretty good feedback while rendering, so the previous two solutions should be plenty. If, however, you want to look at something else, the last thing you can check is the output file. You should be rendering the frames as individual images (for a host of reasons). You should be able to look at the creation time of each image and determine how long to wait for the next one. If the next one takes too long, you can use that to determine if it's still rendering.

If you're rendering to a video file, you can still look at the size of that file, and it should be increasing regularly as each frame is finished.


how do you change the keyboard shortcuts in blender 2.8?

Changing the search hotkey is available, like all of the shortcuts, in the "keymap" section of the user preferences. You  can change any shortcut there.


How to make a particle simulation like this?

I suggest you to try in 2D with a plane and a noise texture. You could add keyframes to change the texture over time and make it move like in your example. Then multiply it to another noise texture (with a MixRGB node) to create this noisy particle effect. Otherwise if you want to go with particles : create the scope with a simple shape and collision property, remove gravity from particles, and add a turbulence force in the scene. Then rotate both emitter and turbulence.


Script to select all vertices in an object and assign new vertex group

The code below is loops trough every selected object:

delete all vertex groups
create a new vertex group named as the object itself
then assigns every vertices in the object to the group

So all you need to do is, select your objects then Run Script.

import bpy
import sys
import logging
# config for logging
logging.basicConfig(level=logging.DEBUG)

def createVertexGroupForObject(aObject):
    # set to object mide : "VertexGroup.add(): cannot be called while object is in edit mode"
    bpy.ops.object.mode_set(mode='OBJECT')

    # remove all vertex groups
    for vertexGroup in aObject.vertex_groups:
        aObject.vertex_groups.remove(vertexGroup)

    # add new vertex group with the name of object
    newGroup = aObject.vertex_groups.new(aObject.name)

    # assign objects vertices to vertex group
    verticesToAdd = []
    for vertex in aObject.data.vertices:
        verticesToAdd.append(vertex.index)

    try:
        newGroup.add(verticesToAdd, 1.0, "ADD")
        logging.debug("\t\tvertex group added")
    except:
        logging.error(sys.exc_info())

# get selected objects
selected = bpy.context.selected_objects

for obj in selected:
    logging.debug("\tselected: " + obj.name)

    createVertexGroupForObject(obj)


Aligning bone's roll accurately to rotated objects

Riggers usually set the bone roll to have the main movements on the X axis (like in your example, possibly having the main rotation with positive values of X). But if you simply parent the external bones to the central, all 3 bones will rotate on the central bone X axis, which is not what you want. One good approach could be setting two drivers, so that every rotation of the central bone will be reflected by the external bones (on their own axis).


Is there a way to get a unique value per dupli group instance?

Using Particles as host for DupliGroup

Thus we can use cool feature of mesh-emitter called From Dupli. This means duplis will inherit location of corresponding space on UV map.

Create emitter mesh and unwrap all faces of emitter as separate islands (avoid overlapping in order to have unique values)
Add PS system, so amount of particles is equal to face count (disable
emit random, even distribution and set particle/face ratio to 1)
Choose Whole group as source for duplicating


You should be able to proxy, but you haven't given quite enough information to make offering a viable answer entirely clear.

Let's assume that the TGAs are of very large dimension, say 4k. A 50% proxy would only put the resolution at 2k, which is still likely too taxing for your system if I had to wager.

Best advice is to start at the lowest possible proxy resolution and build up. If proxies are failing you, then generate your own proxies using a lightweight format such as a JPG, and keep the dimensions small.

Also bear in mind that the VSE isn't much of a compositor, and as such, you can seriously tax your realtime playback by stacking several semi-transparent strips. Even if proxied, the layers will all be composed on your CPU and will likely drag your system's performance well down. The tip that gandalf3 linked to is also relevant and worth respecting.


The operator bpy.ops.mesh.primitive_cube_add() returns the status of the execution and not a reference to the created object. It does set the newly created object as active though, which means it can be accessed by using bpy.context.active_object.

Since you already know that you want the location on the x-axis to be zero, you can set this right when the object is created instead of changing it later.

In your current code the objects are not linked to the newly created collection. You can add an object to a collection by using collection.objects.link() where collection is an object of type bpy.types.Collection. You can unlink the cubes from the currently active collection where it was originally added to, if you don't want them to appear in both collections.

import bpy
from random import randint

num_cubes = 3
master_collection = bpy.context.scene.collection
collection = bpy.data.collections.new("Cubes")
master_collection.children.link(collection)

for i in range(num_cubes):
    y = randint(-10, 10)
    z = randint(-10, 10)
    bpy.ops.mesh.primitive_cube_add(location=(0, y, z))
    active_object = bpy.context.active_object

    # Link to the newly created "Cube" collection
    collection.objects.link(active_object)

    # Unlink from the active collection in the view layer
    # (otherwise it will appear in both collections)
    bpy.context.view_layer.active_layer_collection.collection.objects.unlink(active_object)

If the changing of the location was just meant as an example and you do need the objects in a list, you can store them at each iteration through the loop:

import bpy
from random import randint

num_cubes = 3
master_collection = bpy.context.scene.collection
collection = bpy.data.collections.new("Cubes")
master_collection.children.link(collection)

cube_list = []

for i in range(num_cubes):
    y = randint(-10, 10)
    z = randint(-10, 10)
    bpy.ops.mesh.primitive_cube_add(location=(0, y, z))
    active_object = bpy.context.active_object

    # Link to the newly created "Cube" collection
    collection.objects.link(active_object)

    # Unlink from the active collection in the view layer
    # (otherwise it will appear in both collections)
    bpy.context.view_layer.active_layer_collection.collection.objects.unlink(active_object)

    cube_list.append(active_object)

Alternatively you can retrieve them from the Cubes collection by using:

collection.all_objects()

This assumes that you still have the collection variable in scope with the reference to the collection. Otherwise you will have to access it through:

bpy.context.scene.collection.children["Cube"].all_objects

The latter two examples don't give you a list, but also an object which is iterable of type bpy.types.bpy_prop_collection. Therefore it can still be used in a loop similar to how you would iterate through a list.

import bpy

objs = bpy.context.scene.collection.children["Cube"].all_objects

for obj in objs:
    print(obj.name)

Be aware though that when creating multiple collections with the same name, Blender will automatically append a number to avoid duplicate names. Which means if you're executing the script multiple times, you will have collections called "Cubes", "Cubes.001", "Cubes.002", "Cubes.003" etc. If you want to avoid this and only have one "Cubes" collection, you will have to check if it exists before creating a new collection:

import bpy

name = "Cubes"
master_collection = bpy.context.scene.collection
collection = bpy.data.collections.get(name)

if collection is None:
    collection = bpy.data.collections.new(name)

if master_collection.children.get(name) is None:
    master_collection.children.link(collection)


As you have noticed the FPS can only be set to integer values. To get a fractional frame rate you need to also set the framerate base which you can find right under the FPS.

The easy way to get the right base value is to enter a calculation which is the set fps divided by the target rate. eg 30 / 29.75, when you then press enter it will show the value of 1.008 and the frame rate will show as Custom (29.75 fps)


There is likely nothing wrong with your setup.
The issue is with the render viewport not being able to display emissive and transparent pixels.
To check this try either

Disabling Film>Transparent

or compositing your image over some color (or black) background,

or simply looking at the RGB image with no alpha on the viewer.
Related: Transparent Image different in viewport than render  - and How do I get the Glare node to output transparent instead of Black background


Wrong normals & overlapping volumes

Your geometry is not 100% with the same characteristics: the carving object has some elements with inverted normals right where the problem occours:

And some elements that are everlapping each other (next to the inverted normals element):

Al boolean modifier works best with enclosed volumes, you should avoid both situation. You can for example recalculate normals and gap the overlapping elements till there is a gap between them.

Result:

Side notes: apart the cases when you would like to create a particular effect, the edge split modifier is used once at the very end. You have three. those are splitting the faces, and this may reduce the success of boolean operations. Also the displacement is being applied on a big poorly subdivided N-Gon: you should provide proper resolution&topology for a good displacement effect.


My mouth deform connected to my mouth bone collapses when i move my head bone?

Your head mesh is parented to the head bone. The mouth vertices are parented to the mouth bone, which is parented to the head bone. So, when you rotate the head bone, those vertices get a double rotation in space: one relative to the object position, and one relative to the vertices position.

Instead, the correct way is:

In object mode, select the head
Unparent the head from the head bone (Alt P, clear parents)
Shift select the armature, and parent the head to the armature (Ctrl P, with empty groups)
go to edit mode, select all vertices and remove all weights from all vertex groups.
Assign a weight of 1.0 to all vertices of the head, except thoose of the mouth, in the "head" vertex group
Assign a weight of 1.0 to all vertices of the mouth in the "mouth" vertex group
Assign a weight of 0.5 to all vertices that are between the head and the mouth in both "Head" and "mouth" vertex groups

I noticed also that you should recalculate normals of the head vertices, and resolve some topology issues, but that is another topic.


If you want 0 gravity movement for your character, The first step seems rather obvious: turn off the gravity in your scene. To do this, open the world settings, and set the gravity to 0.

Great! now the scene has no gravity.

But we have a problem - the objects stop moving completely. that should not happen if we are simulating space. This is done by blender as an optimization. Essentially, when blender sees that an object is going slow enough, it just halts it's position (stopping the calculations for that object, freeing up processing power.) Once another object applies a force to the "sleeping" object, the physics calculations will resume for that object. We don't want that, so check "no sleeping" on all objects you want to continue moving indefinitely. This is perfectly fine to do on a few simple objects, but Beware - doing this on a lot of objects or a few more complex shapes could potentially eat up a lot of processing power.

These results are much closer to what we want - but we still have have a problem. The objects are slowly decelerating. Why? This is because of the dampening on each object's rotation and location, set by default. This dampening is normally to simulate air resistance, which adds to the realism on most games. We don't want that resistance here, so we can also set the dampening to 0 on the character. (Here I'm setting the dampening to 0 on both example objects, do this for all the objects you don't want to slowly lose velocity.) Changing or eliminating the angular or linear dampening should not significantly effect performance.

Now we have (for this question's sake) realistic 0 gravity movement. Now to add thrust. This is actually simpler than it might sound.

All you need is a logic setup like this.

(The X axis is forward on this example object, which is actually bad practice - it should be the Y axis. adjust your logic setup depending on which direction is forward on your character.

This setup ignores the rotation of our example cube, it only controls linear velocity. To make it work with rotation, simply use a similar setup, but influencing torque instead.


After updating to 2.81, my previous works (done in 2.80) doesn't show colors

You're now in Solid view where colors don't appear.
Switch to Material preview or Rendered preview, and your colors will all be there :)

Good luck with your donut :).


I have a problem in my split-screen game

Try using a background scene for the skydome instead of a parent.


Why do I get different results for my H.264 encoded .mov videos depending on the file format + encoding settings i choose?

You appear to be confusing encoding systems with containers. AVI, MOV, etc. are containers. H.264, MPEG and many, many others are compression systems.

Blender's manual has some great reference info here: https://www.blender.org/manual/data_system/files/media/video_formats.html

VBR is better for most work since it allows the compresssor to alter the data rate (and therefore file size) according to the amount of detail. Rapidly changing shots require huge amounts of data whereas slowly changing ones require very little.

H.264 and MPEG-4 are very well supported and deliver excellent bang for your buck. (H.265 is better but requires serious processing power to encode.)

Another solution might be to render your video out in a low loss or (ideally) lossless format and then downconvert it in a dedicated system such as Handbrake (Www.handbrake.fr) which will give you presets or let you tinker with all manner of settings until you find something that fits your needs.


Blender's progress reports are flooding the terminal, how to disable?

To quiet the output you can override progress_report's print function, after this is done, any use of the progress module won't print to the terminal.

The following examples show how you can disable printing on startup using the command line argument --python-expr, the same code can be run from your own scripts too.

2.7x stable:

blender --python-expr "import progress_report; setattr(progress_report, 'print', lambda *_, **__: None)"

Master and 2.8x

blender --python-expr "from bpy_extras.wm_utils import progress_report; setattr(progress_report, 'print', lambda *_, **__: None)"

Note, this is known as a monkey-patch and is generally considered bad practice in Python, longer term we should probably have a way to manage progress output for import/export scripts.


2.8 Bone editing and pose problems, cant select single bones

I'm facing a similar problem. I just went into Animation mode and deleted my mesh to grab a bone in pose mode. That's not a full solution, but at least it gives some control to explore the problem further.


Viewport render image > How to render custom background color?

It should work just fine.
This is the way I do it:

Viewport shading overlay > Background > Viewport (adjust to your needs)
View > Viewport Render Image
Done


Selecting 1 side of an edge loop in a mesh

As long as you don't have any other vertices hidden you can hide (H) the edge loop to have to separate parts of the object in edit mode.

Then you can select one of the separate parts by using select linked (L).

After that you can reveal (⎇ AltH) the hidden vertices which are then selected automatically.

Now you have everything to the right or left from the edge loop selected!

In this example the right side of the edge loop plus the edge loop itself are selected.

Note that if the part left and right of the edge loop are connected somewhere else this method won't work unless you hide the other connection as well (e.g. a torus).


Blender background image stretch fit crop missing?

According to the Blender manual, the stretch/fit/crop apply to the camera view only. They do not apply to the Top, Left, Right, or Bottom views in the 3D view-port.

I don't have Blender in-front of me to be able to check, however, I suspect those options will only appear when your image is set to display in the camera view (on your screenshot, your image is set to display in the Top view). They might only appear when you are looking through the camera (Numpad 0).

I will verify next time I have access to Blender.


is it possible to make a reflection sit at infinity, like a reflex sight or a HUD?

As the wiki page said, you need your lens to refract parallel light.

Key Points

the lens need to be perfect refraction lens or it will cause distortion
the iron sight laser thing need to on the exatly same position of the lens focus point
the reflective plane should be 45 degree above the lens

Workflow

You can create a nearly perfect refraction lens by intersect two ball.

After the lens is setup, you need to know its focus length. It can be done several ways. I use a sun light with orthogonal view to tune the point on a plane:

You need to change parameter in render panel, for those thing will clamp indirect light, turn it off to get accurate result.

And last thing, your 45 degree reflective glass need to be fully transparent without distortion, recommend to use transparent shader + Glossy shader, and place above the lens correctly:

Then the result can be stable in sight with slightly distortion:

The full scene is extremely complicated in rendering, consider something else.

And for the file I test for it in Blender 2.80:


Can I define variables to be used in number buttons across the interface?

This is what drivers are for. You can use them to take some mathematical expression (or a bit of Python code) to determine the value of settings.

For more information on this topic, see the Drivers section of the Blender manual.


Boolean non working, shows red box in the modifier panel

If the name of a modifier is higlighted in red, it means that the Modifier is currently not having any effect because its parameters don't produce any effect (for instance, if you add a Subdivision Surface with level "0").

In your case, your Boolean modifier hasn't got an effect because you haven't selected an Object in the "Object:" dropdown menu of the modifier.

Indeed, the boolean modifier doesn't work by selecting two object and adding a modifier, but selecting ONE object, adding the modifier, and telling the modifier what other object to use for the operation

Example usage of Boolean: cutting part of the green cube using the white cube

Note that only the green cube is selected. The white cube is just chosen for the operation. As soon as the choice is done, the red highlight under "Boolean" is gone.


Cannot unsubscribe function from bpy.msgbus

Owner can be any python object.+

Using example here https://developer.blender.org/P563 can use the simple python object class to instance a handle.

handle = object()

Can also use

handle = 4
handle = set()

Simple example throws callback when context object name is changed.  Running in  text editor (main thread) the handle is lost. A quick workaround is to  save it to the driver namespace.

import bpy

handle = object()

# all branches below work
if 1:
    # To get some properties we need to prevent them being coerced into native Py types.
    subscribe_to = bpy.context.object.path_resolve("name", False)
elif 0:
    subscribe_to = bpy.context.object.location
else:
    # all object locations
    subscribe_to = bpy.types.Object, "location"

def notify_test(*args):
    print("Notify changed!", args)

bpy.msgbus.subscribe_rna(
    key=subscribe_to,
    owner=handle,
    args=(1, 2, 3),
    notify=notify_test,
)

# In general we won't need to explicitly publish, nevertheless - support it.
bpy.msgbus.publish_rna(key=subscribe_to)
bpy.app.driver_namespace["handle"] = handle
# ... to clear
# bpy.msgbus.clear_by_owner(handle)

To clear the callback via python console

>>> bpy.msgbus.clear_by_owner(
clear_by_owner(owner)
.. function:: clear_by_owner(owner)
Clear all subscribers using this owner.
>>> bpy.msgbus.clear_by_owner(bpy.app.driver_namespace['handle'])

If an immutable type like int is used (eg handle = 4 can clear from console with

bpy.msgbus.clear_by_owner(4)

but not for a dict handle = {}, possible the hassle in question code when setting the scene ID property.

In an addon can define the handle globally and remove in the unregister method, as it has the addon's module scope.

handle = object()

def register():
    # set up a callback with owner = handle

def unregister():
    bpy.msgbus.clear_by_owner(handle)


To answer the question, you will have to add the line:

sys.path.append(__path__)

before importing anything. This will add the current folder into the path Python looks in for imports. Then you can import files  with:

import foo

instead of:

from bar import foo

.


How would i create a realistic coat material for a horse model of mine?

I have a similar problem; I need to render a horse in Blender Render for work, and the best thing I've found so far is to add noise to your texture, and then use the noise layer as a bump map. With horses, I've found, having good definition of the muscles on the body really helps a lot.  Alas that's something I'm still working on.


Are you currently looking through your camera? If so, by selecting everything in the scene you also select the camera. By then using GKey to move, you're moving all your parts and the camera as well, so it'll appear that only the scene grid is moving.

Try locking the camera in place (the X, Y, and Z locations on the N Panel) and see if that helps.


Where is the implementation of the Cycles image-nodes sampling?

What you are looking for is in

\scripts\addons\cycles\shader\

You want to look into:

node_texture_coordinate.oso
node_image_texture.oso

You will find there links to appropriate .osl or .h files.

In those you will find the code and implementation.


Determining if Cycles light rays provide direct illumination or self-shadow

As mentioned in a comment, it would be incorrect to model this situation with an emissive material, as no light is being emitted. Fortunately, there is a shader in Cycles that supports your use case.
The Translucent shader emulates light passing through a thin sheet of material, and being diffused on the other side. This is frequently used for materials such as paper or grass - very thin layers that let the light pass through.
You can also use it for the ring material. However, you need to mix it with your current material, as only a fraction of the light is let through - part of it is still diffused. Example setup:

Results
From the top:

From the bottom:

Ring shadows:

forgive the lazy texturing
Note that we have not used any shadow "hacks" or emissive materials - hence the rendered result is reasonably physically accurate. In particular note that:

No fake light is being created
Rings diffuse light as expected
Rings catch shadows (on both sides) from other objects
Rings cast shadows on the planet

Possible improvements
To further improve the material, you could:

Tweak the mix value so that the material is just as translucent as it should be
Adjust the opacity of the material depending on the view angle (perpendicular angles should be more transparent, but slanted angles should be more opaque, because light has to travel further through the asteroid cloud, so it would have a greater chance of being diffused. If you wanted even more physically accurate results, you could give the rings a small amount of thickness and render their volume)
Adjust textures, colors, etc

Why this is better than hacking with shadow colors
This sort of setup will simulate light bounces more physically accurately. In particular, it will ensure that no light is being "created" from nothing - the amount of light redirected from a material will be no more than the light that has shined on it.
This would be difficult to achieve manually. As you already realized, dealing with shadows yourself would be tricky, even if you had access to shadow data. In addition, you would have to ensure that  the material doesn't emit too much light - for example, if the light source is at an angle, there should be less light than if it was perpendicular to the surface.


Here is a solution for this kind of object. After step 3 I've assigned a Mirror modifier to the object so that you only need to work on 1/4 of the object. Remember that the center of the mirror is at the origin of the object, and activate the Clipping option. You can keep the Mirror as long as necessary, you can even apply, work on your object, then feel the need to bring back a new Mirror. After the extrusion on the Z axis, make sure you've not created some inner face, otherwise it will mess up the mesh. Give your object a Subdivision Surface modifier, add some edge loops to sharp the edges.


the same thing happened to me, what worked for me was to first voxel remesh it at something like .0001 then all of the normals were fixed and I clicked quad and everything worked fine.


Convert flat roundish meshes to angular meshes

this is one possible way to make roundish curves  into angular meshes:

this is a curve object (closed):

in edit mode you can select all nodes and convert them as vector

which will "straighten" curves changing nodes handles

which will become

if you can get those shapes as svg, you could try steps above...

edit:

note, you can get perfectly square shapes if source svg curves have suitable control points, like in this example below:


How to make all quads or ngons on your mesh planar (2d)?

First thing first: How to check for non planar faces and amount of their distortion:

Second thing: How to make them planar?

There is no way to make them all planar without changing overall shape of the mesh a lot or the topology. Here is why:

To make faces planar, we need to move the vertices. So for each vertex we will see all the faces around it, get their normals, from each of these normals construct a plane and where those planes intersect store a new vertex. From all these new vertices then make a new mesh with the same topology and switch it for the old one. Very simple, but it has one catch: when a vertex has more than 3 surrounding faces, their planar intersection does not necessarily exist - it would be actually very rate if it did:

To meet them at single point, some plane translation is inevitable and depending on the angles this translation can be huge and ruin the shape of object.

So to create mesh from these intersecting planes (made from normals of faces) one would have to create a different mesh with a totally new topology, different vertex count (depending on the mesh shape) by basically chiseling a solid with these planes (would you accept this solution?).

The other solution is not exact and is an iterative approach to a solution. This solution Blender offers under Mesh > Cleanup > Make Planar Faces. We call these iterative methods to a solution Numerical methods. Each numeric method (which is an algorithm) has it's stability. Making faces planar is in general a very unstable algorithm. You may find your mesh oscillating between different shapes never closing on a solution or vertices getting very far from their original location sliding away to infinity - also never closing on a solution. What will happen depends on the mesh shape and you may actually find meshes that this approach solves and converges to a single solution.

But usually it's best to apply this operator not on the entire mesh, but only to selected parts that you know will solve. That's also why the operator has limited iterations to 200 - if it does not converge in that many steps it's very unlikely it will converge in more.

So to make a mesh from planar faces one must start from the beginning:

Use the Bisect tool to make planar cuts.
Use the F2 Addon to make planar faces:

Rotate faces around edges to keep them planar: What's the easiest way to rotate around an edge that is not parallel to a primary axis?
Slide vertices on edges Shift V to maintain planar face (C to extend outside face)


Where are the Shape Key Editor / Fake User Setting?

I found the shape key editor and as @FFeller pointed out the F was replaced by a shield icon.
For some reason the shape key editor doesn't show up in the Layout workspace but when I changed to Animation it was there.


Problem painting multiple textures on same object

It appears to be a bug in 2.72 versions. I created a simple scene of a cube with a bump and a color texture in 2.72b and then downloaded copies of 2.69, 2.70a, 2.71, 2.72, 2.72a, and a standalone zip of 2.72b. Everything works as it should up to 2.71. The problem showed up in 2.72 so I didn't even bother with the a and b versions. I've put in a ticket on the bug tracker at https://developer.blender.org/T42769 so if anyone is having the same issue they can track the issue there.


You can find this in the Python tooltip:

In this example I would change bpy.data.cache_files['3DSMAX_character_armature.abc'].filepath to point to the new Alembic file location.

Iterating over all Alembic caches can be done with for cfile in bpy.data.cache_files.values(): …


Game Asset Workflow and Software Pipeline

There are many ways. Sometimes, I use this way:

model low poly first
UVunwrap it
texturing
In properties panel, go to "data" tab and then "UVmaps", add a second UV map
by clicking on the plus button, highlight it by clicking on it, unwrap the
low poly model for a second time for a good unwrapping because of the
texturing
create a new texture and bake "textures" and normal maps
Remove all materials and the second UV map
duplicate the low poly
add more details to the second low poly models
bake normal map of the the high poly mesh on the low poly one


How to make female's stocking as tight fit

The way to get the one mesh to snap to the other is to use Blenders snapping tools. The controls for this are located at the bottom of the 3D view on the right side of the row of icons just before the OpenGL render buttons.

There is a magnet icon, a small menu with a few options, and then numerous other options based on your menu choice. You will want to set the menu to face instead of increment. All of the other settings should be fine.

Now, when you select a section of your mesh and move it, if you hold Ctrl while you move it it will snap to whatever face from another object is under your mouse. The little magnet icon can be clicked to automatically snap without holding Ctrl if that is easier for you. Snapping also works when you move something on a single axis only or two axes. I your case you may want to try pressing Shift+Z while moving the vertices so that you don't mess up the vertical placement while snapping.


What is the physical foundation of Force Fields?

The "practical" definition of these parameters is here:

  Force Fields in the manual

I don't think there is much documentation about their workings under the hood.

Anyway, each Force type implements one particular type of force in Newton physics.

Forces, the $\mathbf{F}$ in the second law of motion $\mathbf{F}=m\cdot\mathbf{a}$, are the entities that cause an acceleration $\mathbf{a}$ on a object of mass $m$. Different kind of forces can be described as a function that depends on several features of the object being acted on, or of the space in which the force acts:

$$\mathbf{F} = \mathbf{F}(\mathbf{r}, \mathbf{u}, m, q; \mathbf{r_0}, \eta, \ldots)$$

($\mathbf{r}, \mathbf{u}$ = position and velocity vectors of the test object, $m, q$ = mass and charge of the test object, $\mathbf{r_0}$ = position of the effector object, $\eta$ = viscosity of the medium, ...).

Each force can or cannot depend on each of these variables, and it may depend on them in different ways.

Wind is an acceleration field with a total translational symmetry, if the falloff is 0 and there is no min/max distance, or a 2D translational symmetry otherwise. It doesn't depend on anything except its own force parameters and, if falloff is enabled, on $\mathbf{r_0}$
Force and Charge are (typically spherically symmetric) central force fields (they are aligned along the $\mathbf{r}-\mathbf{r_0}$ direction), the latter depending on $q$
Harmonic is a Hookean field. Same variables as Force, but a different equation.
Drag is a force depending on the object's velocity $\mathbf{u}$ according to Stoke's or Rayleigh's law

and so on.

Within each type of force, there are options that control the overall strength (Force Strength, a parameter that basically appears the $\mathbf{F}$ functions above as a multiplying factor); allow to tweak the dependence of the strength on the distance from the emitter (Falloff, ...); convert part of the dependence on $\mathbf{r}$ to dependence on $\mathbf{u}$ (Flow); ...


There are several ways to do this, this is one:

The horizontal bones deform the two platforms, the two vertical bones translate the connecting vertical bars. For the vertical bones, I unchecked inherit rotation in the bone tab.
The bottom green bone copies rotations of the top right bone. This is the control bone for the whole setup, you could hide all other bones.

Take a look at the blend:


How do I keep two softbodies in the same position?

Two options:

Assign all verts in BigCube to a vertex group.  Give SmallCube a copy location constraint, targeting BigCube and referencing this vertex group.  Give SmallCube a healthy Goal value (or group).

Join BigCube and SmallCube into a single object.  Create edges (only) between BigCube and SmallCube to create forces between the two.  These will act as any other soft body edges, seeking to maintain their length (and possibly, with positive soft body bending values, lengths to neighbor verts), causing SmallCube to prefer to float inside of BigCube rather than fall completely to the ground.


The problem is the last argument of setSource, which isn´t documented. Looking at the blender source code this argument is named "apply" and expects a boolean.

So:

shader.setSource(vs, fs, True)

should fix the problem. Note, that you should also switch to textured view mode.


Videos not uploading into video editor properly

Okay, after working on this all night, I found the solution. It was rather simple too.

While working on my original project, I had created proxies for all my videos, however, I wasn't aware that by creating those proxies I had inadvertently created an additional folder where those proxy videos were stored. Somehow the proxies that I created corrupted any similar video files so they wouldn't drop correctly in blender video editor. I've deleted that proxy folder, and now the videos are loading correctly into blender.

Thanks, Jan Kanderabek and 3pointedit for your feedback.


Missing objects when opening old file in blender 2.8

If it's been hidden in the viewport in 2.79 you can make it visible in 2.8 by going to the Outliner.

Click on the filter icon and under Restriction toggles select Disable in Viewport (screen icon).

You can now set the collection back to being visible by clicking on the screen icon behind the collection.


Why does my render result look different than the rendered preview in the 3D view

You seem to have an active compositing step. To disable all compositing, uncheck the Compositing checkbox under Post Processing in the Properties Area.

Compositing alters the image after it is rendered, it is set up in node editor. You could also delete all compositing nodes, alternatively to turning compositing off.


how to reset dynamic/physic simulation at frame other than 0?

Look for the settings for the simulation's cache.

There you can set the start and end frames for the simulation. The default values are 1 to 250, but you can change them to fit your needs.

in 2.79:

in 2.8:


What you are looking for seems to be a render pass for depth. I have found that the z render pass does not really work so try the mist pass.


Saved 2.77 blender file opens up different

That is the UV/ image editor, change it back to the 3d view in the header below on the far left.


Control how much influenced by its vertices a mesh will be (how much tight / loose will be)

If you change to edge mode and select the edges nearby
and press shift + E and the edges will become purple and will tighten
you can also just press N and select the edges and change the mean crease


Is freestyle Render in Viewport in v2.8x bugged?

There are 4 ways of creating object outlines in Blender:

Fresnel effect using a shader
Procedural geometric outline
Grease pencil
Freestyle

Currently I don't think it's possible to generate freestyle lines in viewport. The other 3 methods however, can generate outlines in viewport.
Fresnel
Fresnel is a shader effect and is very fast to compute once the shader is compiled. It produces good enough results on curved surfaces, but flat or near-flat surfaces produce horrible results. In addition, it's difficult to customize it beyond it's color.

Solidify modifier
Procedural geometric outline is a fancy name for solidify method. Add a solidify modifier to the object and invert it's normals. Change the material index to black emission. You can then play with the shape of the outline with a displacement modifier and change the vertex weight if you are experiencing any graphical glitches. Clipping however is still quite common and it effectively doubles your poly-count.

Grease pencil
If you are making an outline for a static object, you can try the method used by Janina Gerards. The method involves duplicating the object, deleting it's faces and possibly vertices and converting the remaining edges to grease pencil. You can find it here:
https://www.artstation.com/artwork/8lQdnQ
Alternatively, in Blender 2.93 there is a new modifier called Line Art that automatically generates grease pencil strokes in your scene. This Line art modifier feels like a solid replacement for Freestyle, because grease pencil can be customized in a similar fashion to Freestyle linesets (color, thickness, noise, type of edge, selected objects). It also supports face clipping another face, unlike freestyle.

I did not stress test the line art yet, just played with it for a while, so I don't know how it behaves with high polycounts (something that freestyle struggles with). I just know that the strokes are generated only from camera view, so the result will look horrible if you just move in the viewport. The strokes will look fine only if you are looking through the scene camera.
Comparison
Scene setup: 3 monkeys and each has 1 cube in it's head. All monkeys have a basic toon shader. First image is a final render, second image is viewport snap.
From left to right: Fresnel, Line art modifier, Solidify modifier


How to get a plane to emit an object in a fluid simulation?

you might want to use a particle simulation or something like that, because fluid simulations look good as mesh but as particles that have objects they usually don't look very good.
in order to get the collisions to work you might want to get the molecular script addon and learn how to use it.
https://www.youtube.com/watch?v=iLDCr9734r8
this is a video that explains how to make a bunch of balls but if in the particle settings you set gravity to negative and the corridor to a collider you can get it to look like balloons