text:
Density texture in Voxel to mesh?

Hi ,
I am working on a scientific illustration.
This is a porous structure of a membrane.
How can I create the bottom part of the block?
Can I convert the density voxel to mesh?

I've tried it this way:

Create bezier curves with bevel, convert to mesh, you have pipes.
Create a cube, Boolean it with the pipes.
Sculpt with Dyntopo to give it smoothness and bumps.
Decimate the mesh to reduce the amount of vertices. Give your object a Shading > Smooth.
Give it its surface bumps with a Noise Texture.


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Animating Animation node parameters...?
I am making an animation of atoms in random motion which decrease in speed along with the decreasing temperature.
I made the atoms using animation nodes. Instanced sphere and added vector wiggle to create random motion. Time info node added to animate the evolution which creates the random motion.
Now, I am animating the 'speed' from higher value to lower.
It moves at the speed of 5 first then I keyframed it from 5 to 1 where it acts abnormal and comes to the speed of 1 instead of smooth transition from 5 to 1. Please note that I added time info node to evolution

enter image description here

Don't keyframe Animation Nodes properties, instead, use an Animate Node:

I am a beginner in animation nodes. Then where should I connect this green falloff node ? From which frame to which frame the animation will happen ?

@RafeequeBinUsman Don't use the Wiggle Falloff node, just use the Vector Falloff as you were using. The animation will start from frame zero, to start it from another frame, you can use the Delay Time node.

source: Stack Exchange

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

sort: votes


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Hard to catch a vertex because of the gizmo
Edit: Ok so it has been fixed by RJG, thanks to him, I had the same shortcut for select vertices and select gizmo, which seems the case by default? and I had to came back to right click for selecting vertices, which is perfectly fine to me.

I meet this very bad problem with 2.8. when the gizmo is displayed.
In Object mode it causes less problems, but when I switch to Edit mode and try to select a vertex close or even not so close to the gizmo, as if it seems like it's the same shortcut, Blender thinks I want to select and move the gizmo instead of the vertex, as if the gizmo was on a layer over the mesh, and not the opposite, which messes up a lot the work with the mesh, it makes you often move inadvertently some vertices.
In 2.7 it didn't work that way, because it was not the same keying for selecting vertex and selecting gizmo.
This doesn't seem logic nor convenient at all to me, it's even very bad   :/  Am I missing something like an option to activate?
In advance thanks for your answers...

Same behavior in a more or less current master build. However I don't find this particularly problematic because you can either just switch to select box or zoom in which will shrink the gizmo relative to the object size and the vertex can be selected without problems.

switch to select box or zoom in are not really solutions, on the contrary I find it very annoying   :((

Don't really catch the point? Are you left click select or something?

yes left click, is it not left clik for both selecting vertices and gizmo in 2.8?

@lemon Isn't left click is the new default?.  Been giving it a go atm.. takes some getting used to,   Have the issue with the gizmos.

@batFINGER !! left click select?? have you all became misbelievers?? ; )

In the beginning... I couldn't believe it was right click select, took a lot of getting used to. Surely we must believe in and follow the path recommended by the creators?

@batFINGER, yes surely, but they cleverly kept RCS... you know what, after a blender session, I still don't understand that other tools (gimp, or other, but also visual studio, why not) does not gives so simple and direct abilities that Blender gives. Surely once kept, this is the more efficient (far away to other tools). I hope Blender's creator won't forget that. To sum up my mind: Blender RCS and others, should become a standard. Others are misleading (whatever their popularity is).

It is what it is.  I am about 2 weeks into checking out LCS. Why? The abomination that is auto save settings took out my old 2.80 settings.  Thought I'd muddle thru default for the ... pain lol.  On solving the issue for LCS's  Maybe a swipy swipy mouse gesture disable  the gizmo make it disappear/// fade and pass thru events for some time frame?.  Gizmo code looks like a dark art.

ok it seems like I'm not the only one who think it's a very bad configuration, I hope they will fix it  :/

I'm currently not at my computer, so I can't test it, but perhaps this is the solution: https://twitter.com/YegorSmirnov_/status/1159588211963961346?s=19

Ooh yes fantastic, if fixes the conflict with the gizmo, please give my question the answer   ;)   now the world can collapse

Credit for the following answer goes to Yegor Smirnov who tweeted about this.
The solution for this problem is to set the Activate Gizmo to Drag in Keymap > Preferences.
The tooltip explains what it does:

Drag allows click events to pass through to the tool, adding a small
  delay.

thank you been looking for this solution

@barkest You're welcome, but the credit goes to Yegor. I just stumbled upon his tweet by accident.

Thanks from me too.  While Left Click Select is default (immaterial of whether one likes it or hates it), certainly looks like making DRAG the default too, would remove a  conflicting default.  In quick tests haven't noticed any undesirable side-effects.

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


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Issue with certain mesh vertecies stretching away from bone physics chain
So i have these two loops that attach to the head of my low poly model

but i found out that when I rotated the head certain vertices on the head mesh would stretch away from the bones. I thought that I could just leave it be since it wasn't that noticeable but I later found out that moving the head around from the origin of the "rope" armature  causes the same issue to a more noticeable extent.

The vertices affected with the problem stretch in the direction of the head being transformed, they act as if they are where they would be if the transformation value was doubled. I'm guessing there's something wrong with the mesh itself at these affected vertices but I am unsure of any way to identify what is wrong with them specifically.
I followed this tutorial for hair physics https://www.youtube.com/watch?v=02YYfXC7H8U , it's a string of rigid bodies connected by empties.
modifier stack of head mesh:

Can you add an image of your modifier stack? do you have 2 armature modifiers?

Yes i do, one for the loops and one for the rest of the armature since i have 2 styles of "hair" on separate layers.
i'll add the image.

It looks like you are getting some of the deformation applied twice.
In this case it appears to be a mix between parenting and multiple armatures.
The first thing to do is to check the "Multi Modifier" checkbox on any armature modifiers after the first.
If this doesn't work, you need to use the vertex group field on the armature modifier to make sure each vertex is only influenced by a single armature modifier.

I did make sure that the vertices of the loop were removed from any vertex group except for loop physics bone groups (And also made sure these loop groups weren't influencing the head).
when i turn on "Multi modifier" on the second armature modifier all the vertices that weren't affected by the issue become affected and the ones that were affected are no longer affected. Strange.
I'll try using the vertex group field to define the loop vertices and see if that works.

Its been a while since I set something up like this. You may only need the mask on the second modifier.

Ok it worked!, though not at first. It did nothing at first but I tried the "Invert Vertex group influence" button next to the textbox and then it worked.
Surprised I couldn't find a similar problem anywhere else, thanks.


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How to create a prism with an equilateral triangle base
I’m trying to make a triangular prism in Blender.
My first idea was to select the top four vertices of a cube and merge them at the center, but this made a single point on the top instead of an edge. I have tried a few other methods but couldn’t get a perfectly even triangular prism. What would be the best way to do this?

Another ways is by adding a cube and then merging the top two edges with SX0 and then remove doubles (WR).

Or select 2 edges in opposite side (in Edge Select mode), then Alt M > Collapse. :)

The base of this prism would not be equilateral.

@Garry The OP's original question did not make that a requirement. If you want equilateral, you are best off extruding a 3 vert circle as mentioned below.

sin(radians(60)) or sqrt(3) / 2 for the z scale would make it equilateral.

If you are talking about a triangular prism, ShiftAto add a Cylinder object, then F6 to set the Vertices number to 3.

The shape I am trying to create I think is called a triangular prism this could be done by following your first method and extruding the face

@qwertie I see, I've updated my answer. If you don't need to have the top/bottom triangles being regular, then gandalf3's answer is nice, as well.

I use this method with Circles quite frequently (to get equilateral triangles, pentagons, etc), and sometimes on Cylinders, as you described in your answer. It is indeed the most efficient way.

F6 isn't working for me on my mac. What command does F6 equate to?

@spuder When you add a cylinder, you have an expansion panel appearing in the bottom left part of the screen (in Blender 3+). That's where you change the number of vertices. (You probably figured that out, I leave that for others to wonder, the F6 shortcut seems gone.)

Add Mesh > Cone
Set Vertices to 3
Set Radius 1 and Depth to 1

If you are trying to make an equilateral triangle prism you can first make an equilateral triangle from a square plane.
Here's one way to do it:

Add Mesh > Plane.
Subdivide plane twice so it's cut into 16 squares.
Select vertices and press F to make new edges (see picture).
Extrude the edges into prism and delete the remaining vertices.

But in this way, two edges have length sqrt(17) and one has sqrt(18). So it's not really equilateral.

yeap. And this can be clearly seen right in Blender thanks to the function "Show Overlays >> Face Angle" chekbox

@Yi Wang
by the way, how did you find out about sqrt(17) and sqrt(18) edges length in square?

Use blender internal addon, "Add Mesh: Extra Objects".
Add > Mesh > Math Function > triangle
play with the options.
Be happy!

Draw a square (plane) at (0,0,0). So the "top" two corners are (-1,1,0) and (1,1,0).
Let A = (-1,1,0) and B = (1,1,0)
Then draw two circles at A and B, scaled by 2 (use S, 2, Enter in object mode with these circles selected).
Merge the square and two circles with Ctrl+J.
Note the INTERSECTION point of your two circles, directly above the square. Call it C.
If we can connect ABC, we have a perfect equilateral triangle!! (this is step one of building the pyramid, which is just 4 copies of it rotated around).

To get a prism with perfectly equal sides, do the following:

Add a cube
select the two bottom left vertices
press space, type snap cursor to selected, hit enter
set your pivot point to 3D Cursor (option on the bottom two next to Edit mode)
Add the two top left vertices to the selection
Rotate by 30 degrees
Repeat with the right side (-30 degrees)
Remove doubles

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Dissecting equal sized parts of cylinder
I am trying to create a cylinder that is dissected into 10 equal sections (filled layers!) to be printed later on. Essentially like in the picture but without those gaps in between, so far I have not managed to dissect the cylinder appropriately, it doesn't split up and I don't know how to separate the cylinder into 10 even parts. That model in the picture is from someone I know as inspiration - I didn't manage to create that!
Can someone help me please, ideally with some screenshots?
Thank you

Isn't this basically the same as your previous question? https://blender.stackexchange.com/questions/267664/creating-a-cube-with-a-set-height-of-layers

you can use the Array modifier but you say "without those gaps in between", so what will there be between the slices? If you plan to print, there must be a link between each iteration.

It looks like he wants to slice the object instead of duplicating each piece. Even if it ends up with the same result

Array modifier copies the whole object, I just have a plane circle, without any filling.
If I can duplicate each piece that would be fine as well - I just need a DEFINED dimension that is repeating itself to create these layers.

I dont see why an array modifier wouldn't work then. You can set it to a constant offset and define that exact value on the XYZ coordinates.


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Export simple Key Frame Animation | Export an animation the way I see it in the viewport to fbx (and then to Unity)
I have an animation I did with key framing a "simple deform" and armature.
I dont want to neither apply the modifiers nor apply the scale because it totally breaks my animation.
I just want to use the animation how it is. Simple as that. I tried to bake it but it some how 'deletes' the animation.
To do anything in Blender is a pain in the B*** due to lack of any logic or intuition and bugs.
I hope someone could help me with this very basic and simple thing to do.
Best regards

I guess from what you wrote that you must apply the scale and then rig your model to the armature.

@Yvain thanks for answering. It has nothing to do with the scale. I did an empty project amd just keyframe the default cube with a deform modifier. There is no way to export it.

How are you animating the cube ? Via deform or armature ?
You can't use the deform in unity only the armature.

@Yvain Hey thanks for helping. I deform it with Simple Deform Modifier. I dont want to use it in Unity but export so to say the vertices how they are presented in Blender. So to say bake the animation, for every frame say: this vertice goes here, that one there and so on.
The Simple Deform does that already in Blender. If I cant export that it would be a big draw back (why having keyFraming at all if you cant use it outside of Blender?)

Why are you not deforming it with armatures ? effect will be the same for a bend if you rig it to say 3 bones and use IK solvers.
If you need to bake it then your refering to keyshapes, and if that is possible then after the bake don't forget to remove your modifier, maybe that is the fix.

@Yvain thanks for your involvement,but I havent found a fix. Armature is not near the effect I need (to simulate this I would need hundred of bones).
I will write my own Animator in Unity and Export an fbx for every frame of the animation and manually change the mesh.

Yes I just checked and it's not possible to apply deform modifier as shape key, it'll yield one that is empty. You must stick to the armature.


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Problem in blender's knife tool
I have a question. I used the blender's knife tool to join two vertex points that weren't connected, and after I did so and verified, I noticed that another line vertex had been formed in the model; I'm not sure why that happened (I checked, and the mirror wasn't on). How should I proceed?
like this image  , i  connected this two vertex points and i made a edge (which i select) and when i look around i see these edge (I drew a line around them)

I have no idea, depends on where that line vertex (whatever that is, is it an edge or a vertex?) appeared and how you did that. Most likely you can select it and press X > Dissolve Edges. But why did you use the Knife tool in the first place? Select the two vertices and press J.

You should add an image to take a look


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Why is Blender deforming my texture?
I clearly need someone's help on this problem ! I did a texture map on substance painter and got a pretty good result.

I pluged all the maps on a blender material and the texture is anormally displayed.

I figured out it's the base color map who does this but i doin't know how to fix this. I tried on Marmoset and everything was good.

So why Blending is deforming my texture map ?

i don't understand what problem you are describing. can you maybe encircle the areas you are referring to that are "abnormally displayed" ?

@HarryMcKenzie I edited with a new image to highlight the anormal spots !

is it possible to share the file? https://blend-exchange.com

This is possibly the result of triangulation, Blender triangulates the model in other way, which leads to this result. To deal this it, try following:

Select this face, then press Ctrl+T
Select edge, that's created by triangulate operation, then press E ⇾ Rotate Edge CW

It works ! Thank you so much !


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How to delete bezier points from curve splines with low-level code
I'm trying to edit curves via python, but deleting bezier points is causing me trouble. I'm able to do it using high-level operators (see sample code below), but I would prefer edit the data more directly, for speed and cleanliness.
#Define vars
one = bpy.data.objects['Curve']
point_to_remove = one.data.splines[0].bezier_points[0]

#Set 'one' to edit mode
bpy.context.scene.objects.active = one
bpy.ops.object.mode_set(mode = 'EDIT')

#Select point_to_remove and remove it
point_to_remove.select_control_point = True
bpy.ops.curve.dissolve_verts()

I've tried using .add() to create a dummy object with the desired set of bezier points and then setting one.data.splines[0].bezier_points = ..., but bezier_points is read-only.
I've tried python's del() and the blender API's `remove()', but they either aren't supported for bezier points or I'm using them wrong.
Any help would be much appreciated.
Edit: It seems this is a special case of deleting instances of the bpy_struct class, which I also don't know how to do.

Surely there's an easier way to do this.
Had a fiddle with this and came up with code below,  which I'm not sure wins on either count of speed nor cleanliness.  Adds a new spline with the same coordinates, and handles as bezier points of spline zero in original, with one point popped off.  Even with all that code didn't copy handle type for left and right.
import bpy

context = bpy.context
obj = context.object
curve = obj.data
s0 = curve.splines[0]
index = 0 # index of bez point to remove.
points = len(s0.bezier_points)
x = [0] * points * 3 # flat list of vectors
hr = x[:]
hl = x[:]
s0.bezier_points.foreach_get("co", x)
s0.bezier_points.foreach_get("handle_left", hl)
s0.bezier_points.foreach_get("handle_right", hr)
# pop off index 0
for i in range(3):
    j = 3 * index + i
    x.pop(j)
    hl.pop(j)
    hr.pop(j)

# one less for removed, one more less for splines new
points -= 2

# add a new spline
spline = curve.splines.new('BEZIER')

spline.bezier_points.add(points)
spline.bezier_points.foreach_set("co", x)
spline.bezier_points.foreach_set("handle_left", hl)
spline.bezier_points.foreach_set("handle_right", hr)

#remove spline 0
curve.splines.remove(s0)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Reversed UV image
I am trying to add a texture to a simple mesh with a front and back side. I have mapped several similar meshes without problems but this one is stumping me. For some reason the "back" texture is reversed and I cannot get it corrected.
I have tried reversing UV's, flipping normals, and UV unwrapping from both the front and back view (not sure if that does anything). I tried all combinations of the aforementioned, to no avail. Any clue as to what I'm missing here?

The render behaves the same as viewing the material in the viewport. I've uploaded the node screenshot.


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Reflections are displayed nicely in preview, but not in final render
I'm running into a strange situation in Blender, where reflections show up nicely in Preview, but not in the final render (using Cycles). What could be the cause of this?
Preview:

Render:

here are my settings for Cycles:

and my blue, glossy material:

Is there some settings I'm forgetting about?
Here's the file:

not sure why this is, under "light paths" try changing the drop down to "Full Global Illumination" and see if that fixes anything. If so, then you may not have had enough light bounces. If not try changes the clamp direct and indirect to higher numbers (around 15)

Check also if there's anywhere lamp available for preview render but not final one.

I tried your suggestions, but it didn't help. This is still a mystery to me... I added a .blend file, in case that would help solve this problem. Thanks a lot!

Oops, sorry about that (and thanks for letting me know)! in this particular case, we are only missing a colored texture (the blue shade), but (I hope) this doesn't change the reflection issue.

This is caused by the simplify option in the scene-tab (at the bottom  of my screenshot).
simply disable it and you're good to go. you can also set the "AO bounces render" to 0 if you want to use other options of the simplifier (simplify subdivisions etc.). This option limits all non-diffuse bounces (0 = no limit)


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Problems with Texturing in Blender Game Engine
Posting this question again and maybe I'll find any help this time. So, recently I was trying to port model from Mass Effect, this model is a helmet on the image below.
So, the problem is that I had to apply the texture on it using Blender Game Engine, not the cycles or Blender Render. And the outcome after UV mapping the helmet resulted in this:
Can someone please tell me what I had to do to get rid of it? I am just losing hope atm. It worked fine in the Cycles but not in the Blender Game engine.
Any pieces of advice would be helpful!

Is backface Culling on?

"Can someone please tell me what I had to do to get rid of it?" Get rid of what exactly? I'm not sure it is very clear what you are asking, could you please clarify?

How to make all faces flip to the right/consistent direction?

Judging by the images you posted, this is probably what's wrong with you scene.
Flipped normals

Steps to fix:-

1. Select your object and go to edit mode
2. Move over to the shadings and UV tab
3. Select everything in your mesh
4. Click on recalculate

5. Go to properties panel and find the shading section and turn off Backface culling

Explanation:-

What Backface culling does is cull or clip the back sides of the face, and the back side is determined by the normals. Your model, judging from the picture, has its normals flipped inside out, and you have backface culling on therefore it's culling all the backfaces. If recalculation does not work, then it means some of the faces are flipped unevenly, thus they need to be manually flipped by using the Flip Direction button in the same shading panel in the tools tab region.

Hey got something for you!
You need to reverse the normals of the model.
Select the mesh and go into Edit Mode.  Select all of the mesh vertices by clicking the A key, click Mesh > Normals > Flip Normals. Go back into Object Mode and then you're set!


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Cannot draw image using gpu module from modal operator
TLDR:
I can use the provided sample code to draw a texture using the GPU module, when I use exactly the code from the sample.
But, if I load the image when my modal operator is invoked, and then draw the image in the bpy.types.SpaceView3D.draw_handler that runs when the operator is running, then the image is all black.
Finally, if I also include the sample code, then the image is properly drawn from both the origin sample and in the modal operator draw function.

So, here is the sample from the Blender documentation, slightly modified to import the icon I want:
from gpu_extras.batch import batch_for_shader
icon_path = Path(os.path.realpath(__file__)).parent / "icons" / ""
icon_name = "MYICON.png"

bpy.data.images.load(f"{icon_path}/{icon_name}", check_existing=True)
image = bpy.data.images[icon_name]
texture = gpu.texture.from_image(image)

def draw():
    bgl.glEnable(bgl.GL_BLEND)
    shader = gpu.shader.from_builtin('2D_IMAGE')
    batch = batch_for_shader(
        shader, 'TRI_FAN',
        {
            "pos": ((100, 100), (200, 100), (200, 200), (100, 200)),
            "texCoord": ((0, 0), (1, 0), (1, 1), (0, 1)),
        },
    )
    shader.bind()
    shader.uniform_sampler("image", texture)
    batch.draw(shader)
    bgl.glDisable(bgl.GL_BLEND)

bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_PIXEL')

This sample works...
But I have to split the code a bit, I want to draw the image only when my modal operator is running.
So, this function is ran when the operator is invoked and load the images:
def load_icons():
    global icons
    icon_path = Path(os.path.realpath(__file__)).parent / "icons" / ""
    icon_name = "MYICON.png"
    icons[icon_name] = gpu.texture.from_image(bpy.data.images.load(f"{icon_path}/{icon_name}", check_existing=True))

And I put this in the draw function added to the bpy.types.SpaceView3D.draw_handler_add that runs from the moment the operator is invoked.
global icons
shader_2d_image = gpu.shader.from_builtin('2D_IMAGE')
batch = batch_for_shader(
    shader_2d_image, 'TRI_FAN',
    {
        "pos": ((200, 200), (300, 200), (300, 300), (200, 300)),
        "texCoord": ((0, 0), (1, 0), (1, 1), (0, 1)),
    },
)
shader_2d_image.bind()
shader_2d_image.uniform_sampler("image",icons["MYICON.png"])
batch.draw(shader_2d_image)

When I do that, only a black square is displayed. But, if I print the content of icons["MYICON.png"].read() in the draw function, it does show the right rgba values. So the GPU texture has the correct data.
And, if I include the sample mentionned above, then the image is properly rendered twice, once for the sample, and once for the draw function just above.
It looks like it fails to draw the icons if it is not loaded and rendered from the moment the module is loaded... I am a bit lost to be honest.

I got the answer to my problem by iceythe on Blender Artist.
My problem actually came from part of the code that I did not even mention, stupidly thinking that simplifying the problem would be better.
My code was using bgl.glEnable(bgl.GL_BLEND) to use alphatest on the picture, I thought this would not impact the rest of the situation but I was wrong.

Blender had a major rewrite to the opengl backend which meant that
state changing api calls (like glEnable/glDisable) effectively caused
Blender to no longer being able to do its own state bookkeeping and
the opengl context would be invalidated.
The gpu.state.blend_set function is a drop-in replacement for
bgl.glEnable(bgl.GL_BLEND), with some added functionality like
specifying premultiplied alpha and common blend operations like
invert, multiply, subtract and additive.

Here a similar code to the original one above, that works as expected:
icons = {}
shader_2d_image = gpu.shader.from_builtin('2D_IMAGE')
def draw_image(image):
    gpu.state.blend_set("ALPHA")
    if image not in icons :
        texture_path = Path(os.path.dirname(__file__)) / "icons" / f'{image}.tif'
        img = bpy.data.images.load(str(texture_path), check_existing=True)
    icons[image] = gpu.texture.from_image(img)
    batch = batch_for_shader(
        shader_2d_image, 'TRI_FAN',
        {
            "pos": ((100, 100), (200, 100), (200, 200), (100, 200)),
            "texCoord": ((0, 0), (1, 0), (1, 1), (0, 1)),
        },
    )
    shader_2d_image.bind()
    shader_2d_image.uniform_sampler("image", icons[image])
    batch.draw(shader_2d_image)

    gpu.state.blend_set("NONE")

import bpy
import gpu
from gpu_extras.batch import batch_for_shader

def draw_image(image='MYICON'):
    ''' Draw an image.

    image (str, optional) - Image to draw.
    '''
    img = bpy.data.images.load(icons_dir() + image + '.png', check_existing=True)
    texture = gpu.texture.from_image(img)

    shader = gpu.shader.from_builtin('2D_IMAGE')
    batch = batch_for_shader(
        shader, 'TRI_FAN',
        {
            "pos": ((100, 100), (200, 100), (200, 200), (100, 200)),
            "texCoord": ((0, 0), (1, 0), (1, 1), (0, 1)),
        },
    )
    shader.bind()
    shader.uniform_sampler("image", texture)
    batch.draw(shader)

    if image and img.gl_load():
        raise Exception()

    bpy.data.images.remove(img)

Thank you for this solution. It does work, but the first part of the code (Load icons from icons directory) is actually useless, the rest of the code works without it, and is simply not using the preview icons.
It is also loading the images at every draw() call, which is really not optimal.
There must be a way to cache the images and draw them later on.

After looking into it, the key here that make your code works and not mine is that you remove the image from bpy.data.images. If this line is removed, the code renders a black picture.
I also tried replacing  bpy.data.images.remove(img) by img.reload() and it works too, but I would really like to avoid reloading the picture every frame.


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weird artifacts when doing Boolean operation

As shown at picture above I have some problems when doing Boolean operation. The cube bound box is where the operation is happening but somehow Boolean is affecting totally different parts of mesh and breaking them. For example here there are some shading errors but it acts very randomly, sometimes flipping some normals here and there.
I recalculated normals for all objects including cutter and I think I checked all the meshes looking for some holes or something. My question is what should I do or where to look to try to fix that problem? Could be because of bevels, some settings or for example order in the modifier stack?
Here is additional picture of my modifier stack:

Please share your blend file (How to add a blend file).  It will beeasier to figure out issues if we can experiment with it.

@MartyFouts Sorry, that for sure might help you guys  in finding my problem, i think it should available now :)

it's not the boolean operation but your bevel. Just hide it and the problems are "gone"

@Chris Thanks! but shouldn't i have an option to add bevel? i mean it shouldn't behave this way right? It's not a big deal but i would like to have that bevel on the model.

You could try a remesh modifier and then bevel - but i didn’t try that.

It behaves that way because the Boolean modifier „destroys“ the clean topology

Thanks a lot @Chris! I will make an update when i will find other ways to fix that but for now i will stick to your advice.

Your main problem is that you are working all out of order.
The typical workflow is,

Blockout/Low-Poly: This is where you use random primitives, and boolean to your hearts content just get an idea of how everything will fit together, keep everything loose and easy to adjust, don't worry about quad-topology too much. Try to separate things into logical components (e.g. don't make it to where the trigger is fused topologically to the handle, make it a separate object like it would be in real life, etc.)

Medium Poly/ Cleanup: start applying modifiers/booleans, to get real geo to work with, start cleaning things up and getting things at least vaguely uniform. Quads are a little bit more important to keep in mind but not absolutely necessary.

Bevel/Subdiv/High Poly: Add in control loops, bevel modifiers and/or subdiv mod to get the shading as clean as possible and the curves super sleek and realistic.

Right now you have your Subdiv modifier set as the first modifier in the stack. This is giving the boolean modifiers way to much geo to try to work around, and then the bevel is trying to cleanly split those edges. There's hardly any room to work.

What you should be doing is something like:
Low Poly: Separate objects, just getting the idea of how things will fit together. No details.

Mid Poly: Add some preliminary geo before Boolean to make it easier after we apply it.

Add/Apply the boolean, and then finalize the Geometry.

You mainly just want to make sure there aren't any massive random n-gons or tiny slivers of triangles. Just get things looking neat and even

Then, if you've done your job well enough, you might be able to just add a Bevel mod with the profile set to one (to give yourself automatic control loops) and a subdivisions surface on top of it. If that doesn't work you can just use normal control loops. You might need to tweak things a bit with the topology and fiddle here and there, but it should be nearly done at this point.

Final Result:

Thank you for your detailed instructions! i may not need it right now but it will be really helpful in the future!


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Object Randomly Going Transparent When Rendered
I have an animation that I did with a tree falling over. It's going to be put over some footage I have so I'm just rendering the object and the animation itself. I added transparency to the background and am rendering it out with a shadow catcher and transparent background fine.
The problem I have is that every 10 frames or so the top part of the tree, the part that's being animated, just randomly goes transparent for no reason.
There are no keyframes at those frames to turn off the layer or anything like that. It just for seemingly no reason disappears and then reappears a frame or 2 later.
Edit (More info and download link added):
Here is a link to the blend file
https://we.tl/t-bnLkoReFz9
For example here is the tree at frame 6 in the animation:

And here is the tree at frame 7 in the animation:

When you watch the video as a whole it just looks like it's stuttering between visible and invisible. https://www.youtube.com/watch?v=kjYkSg0Ze8E

Hello and welcome. While files, images, and external videos or links may be helpful additions they should not be the only way to obtain information about your issue. Don't make understanding your question rely on downloading a file, watching a video or visiting an external site. Use the builtin tools to upload images or gifs, along with thoroughly explaining the problem in written form so it can be indexed and searched for thus helping future visitors with similar issues.

Any chance you are using a Cell Fracture add-on to make this?

Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.

without having seen any of your settings how should we know!? can be tons of reasons...so pls provide blend file so we can check it out

I added the blend file and some screenshots of the render to show as an example

I'm not sure what is happening here, but when Noise texture node is plugged to Roughness, Blender crashes in Material Viewport View (=Eevee) mode. So try to exclude this node from node-tree (or mute) and try render in Cycles to see if make it difference. ... also your Mix-ing Texture Coordinates is not clear to me so it can be an issue for Curve object (Tree trunk).


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Rotation of an object around its local axis
I've been trying for a while now to rotate a rig around its local axis.
Given 3 angles I would like to rotate the bone around its axis.
I saw that in the UI method that is used bpy.ops.transform.rotate method, however this method has an argument called orientation matrix which I'm not sure how to calculate.
Does anyone know how I am supposed to calculate this arg?

Are you trying to rotate an object or a bone in pose mode?

This argument is optional ; but if you really want to deal with linear transformation matrices, you have to understand how it works.
You could use matrices in order to compute translation, scale and rotation.
Here, the matrix is a rotational matrix, which expect some value according to the axis you choose given an angle t (aka theta) :

for the x axis, the matrix will be
(( 1, 0, 0), (0, cos(t), sin(t), (0, -sin(t), cos(t))

for the y axis, the matrix will be
(( cos(t), 0, -sin(t) ), (0, 1, 0), (sin(t), 0, cos(t))

and for the z axis, you will have ((cos(t), sin(t), 0), (-sin(t), cos(t), 0 ), (0, 0, 1))

If you select the default cube, you can see its transformation matrix:
>>> obj = bpy.context.active_object
>>> obj.matrix_world
Matrix(((1.0, 0.0, 0.0, 0.0),
        (0.0, 1.0, 0.0, 0.0),
        (0.0, 0.0, 1.0, 0.0),
        (0.0, 0.0, 0.0, 1.0)))

Now, you can use a mathutils.Matrix in order to rotate the object to 20° on the X axis:
>>> rotation_mat = mathutils.Matrix.Rotation(math.radians(20), 4, 'X')
>>> obj.matrix_world @= rotation_mat

I use the @= python operator that provide a matrix multiplication

Does anyone know how I am supposed to calculate this arg ?
Now you know how to calculate this arg ; but not how to use it !
The way bpy.ops.transform.rotate use the orient_matrix argument is not clear ; it seems to have no effect here, because you have to provide the mandatory 1st argument which set the angle value and do the same thing. With the Blender Python API, Some parameters are historical, some others for future use, and some others are not implemented at all but still documented. You could ask the team because I tried many way to use it without any effect.
Last but not least, playing with Maths is really easy if you read the right book: 3D Math Primer for Game Dev - Fletcher Dunn - 2cd Ed.- 2011 is definitively the best book for anybody having to play with math without any skills. You will find 3 chapters on Matrices, very well explained.


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Change default rotation and orientation of imported model?
If you import this OBJ model this Luigi model in Blender, the model opens face down.
How can you use Blender to change the default orientation and rotation so the model is standing vertically (90 degrees) upon opening the file?
The goal is to export a new OBJ file that lets the Luigi model open in a vertical standing (90 degree) posture.
These questions are similar, but the solutions did not work:
1) Could not apply rotation to entire model (Applying rotation after manually rotating the axes with two-finger panning does nothing. Blender says, "Objects have no data to transform."): Imported object shows aligned to the wrong axis
2) Did not work: Imported object shows aligned to the wrong axis
3) Could not apply rotation to entire model (Applying rotation after manually rotating the axes with two-finger panning does nothing. Blender says, "Objects have no data to transform."): Rotate Default Model Orientation

Not sure if this will work but it’s worth a shoot. Manual rotate/move the object to how u want it and the press control + a and apply rotation and location

Tried that, but it doesn't seem to work? How do you rotate the entire model at once? For instance, if you use the trackpad with two fingers while in Object Mode you can move the whole model at once, but applying rotation does nothing. It says, "Objects have no data to transform."

Dam not sure, when I get home in and hour I’ll see if I can find a solution if u still need help by then

Select all the parts of the object then press r to rotate you can also press x/z/y to control which way it rotates

The model consists of multiple objects. So it's not possible to save the rotation/view after using panning with two fingers while in Object Mode?

Not sure what u were doing wrong but i got it to work with want i was saying. I fixed it for u https://www.dropbox.com/s/in5dhsbznpy31p6/BudgetLuige1.obj?dl=0

I am very interested and have just send u a email

Nothing seems to have come through

Just came though


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OBJ files: How to subdivide materials for model?
The model in this OBJ file (https://poly.google.com/view/534TY_Ie4jz) contains one material.
Is it possible to import the file in Blender, then "cut up" or divide the material into different sections?
Specifically:
1) If we want to make the stick red but the top of the popsicle green, there's no way to do this because it's all one material.
Changing the material color changes the color for the entire popsicle. Is it possible to change red to green?
2) If we want to subdivide the red area into an arbitrary number of subareas, is this possible? For instance, could we turn the red area into 5 subareas of different colors?

You can assign materials to specific vertices, probs what you want

@VRM Thanks so much! What if we want to divide the popsicle into an arbitrary number of materials? For instance, if we want to divide the red area into 5 subareas, is this possible? Or are we constrained by the mesh?


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Export textures + Nodes into one image?
I am using blender for an online game (Roblox) and they only allow you to use one image for textures.
I made a rock mesh, with a pretty good texture and some nodes that make it look great, but without the nodes and texture it looks horrid.
Mesh + Textures + Nodes in Blender

I looked up how to export textures but nothing seems to work.
I tried UV Unwrapping but (im a noob) and keep getting stuck on this...
(This is in UV/Image Editor)

I tried most of the answers on this site, but then this happened in the game...

UV Unwrap

Wrap up;
How do I export Nodes, and Textures into one image

Possible duplicate of How do I bake a texture using Cycles bake

Note that exporting diffuse colors and bumps on surface into one image isn't possible, there will be 2 images required for that

my answer explains why you are not getting the export you want.

Edited the question,

With that kind of UV map it's not surprising. It also isn't matching with image shown there (I suppose bake) so likely bake was done using another UV map. Note also to use as much texture space (that square where everything in UV editor happens) as possible


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Alignment of Segmented Teeth along curve and Animation
I am working on a small project that involves drawing a curve over a set of misaligned teeth then transforming/ aligning them accurately along a curve that is drawn over the teeth as a guide to their optimal final position. So far I have only managed to segment the teeth but having a challenge tracing the curve over the teeth from a reference image then moving the teeth to their final position. After the above task I would like to animate the object showing the movement.
This is a screen shot of the intended setup:

Below is a video of the intended result:
https://youtu.be/XPgm0JDAGQc

Have I addressed your question?

Basically, I import an stl file of crooked teeth, segment each individual tooth, then align each tooth along an ideal curve using a reference image that I can import into blender. After all the changes, I would like to create an animation of the teeth showing how they looked before being aligned then how they look after the alignment.

Is the issue with getting the curve to render, or are you having issues getting the teeth to move? You would probably need to make an armature/rig to move the teeth. You want to create a nurbs curve and adjust the bevel depth to have the curve so you can render it.

Why don't you want to use shapekeys like your reference video?=

https://wetransfer.com/downloads/12144ebb17030f82e562d93c9375679120190521171639/c55ccfb744135dae58866bacfa76743c20190521171639/1a49c0?utm_campaign=WT_email_tracking&utm_content=general&utm_medium=download_button&utm_source=notify_recipient_email

I have attached the exact blend file of the crooked teeth that I am working on. I have already segmented the individual teeth, so kindly download it and let me know the steps to follow to achieve a similar final result. Thanks for the responses.


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Why my active rigid body objects not collide with passive rigid body objects
Why my active rigid body objects not collide with passive rigid body objects?
I used rigid body for the hair and I want it to collide with the body,so I make some collider.I set the collider as passive and the hair as active,but they do noy collide.

Not sure your hair will be inlcuded in the rigid body simulation stack even if you apply a rigid body to the empties. Might want to look into the molecular addon as it calculates collisions for particles, etc


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Version 2.8/May 23 - Assemble multiple textures and export them in one single texture?
What I currently have =

Blender 2.80 Beta Windows 64 Bit (May 23, 01:37:23, a1ad71304c2d) (portable version) (downloaded at https://builder.blender.org/download/) - What I see when I open it
file.obj (one model and multiple positioned jpeg textures inside the obj) + his file.mtl - What I see when I import my obj

What I want =

Please, I would like to assemble all the jpeg textures and export them in one single texture. Another way to say it "Join image textures into a single one upon export". Visual way to understand my question

Please, consider (to not waste your time and mine) =

The Blender version I am using.
That I don't want 2/3 or more solutions to do it. I want 1 effective solution only.
That I don't want tips to do it slower/faster.
That I don't want to have a nicer Blender interface/menus/icons.
That I don't want to edit my model.
That I don't want to edit my textures.
That I don't want to add more models or textures.
That I don't want to make animation.
That I don't want to add a lamp or a camera.
That you don't need to share me videos or screenshot if your words are clear.
That you don't need to share me tutorials/wiki pages if it doesn't answer my question.

Why I ask my question =

I am looking for a simple answer to my question above because there is 3 millions of different tutorials with different Blender versions, for different solutions ("Bake" "Wrap" etc), situations and needs. A "visual way" to understand my question https://i.sstatic.net/d0qbL.jpg .

Thank you for your time and answers. I will give more information if you need.
B
NB : I already have searched online since 2 days. I do not come here because I didn't make some effort. I am frustrated at not being able to use such great software as Blender. I will record the steps/make a tutorial and post it to my Youtube channel.

What I see when I import my obj = https://i.imgur.com/ZIlCf95.jpg .

HI. Please upload images directly using the built-in uploader. See: https://meta.stackexchange.com/questions/75491/how-to-upload-an-image-to-a-post

You very clearly stated what you don't want but I'm not sure I got exactly what your do want. You are trying to join image textures into a single one upon export, right? Could you clarify that it in your question body?

Hello. Sorry if I wasn't clear. Here is a picture of my need. I have edited my thread => https://i.imgur.com/NONinM7.jpg (sorry Ray Mairlot I don't see any option to add my picture on stackexchange in comments fields).

I have found the stackexchange image button. Sorry. I have edited the thread.

I think you are saying that you have many material slots assigned to your model, each with different textures associated with them. The different faces of your model are then using those different images to show, for example, an eye on some faces but a fingernail on some others. You are after one big image so that you can just map different faces to different parts of one image, rather than having lots of different images. Is that right?

Yes @edna it is exactly what I am looking for. Sorry to not be able to explain it clearly in my thread. Have you an idea to do that ? (Please if you advice me a tips, write also the Blender version you are using for)

It's a bit of a cheat, but I think this gives you the answer you need. Maybe there is a function that does this better, but at least it works ...
Once you have applied your textures, make them Emission shaders so that they will render as shadeless. Then bake the output using Cycles to create a single image map that contains them all combined into a single image.

Ok. Thank you a lot for all your answers! I'm gonna test that. Also I've seen the plugin CAT to make such need.


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How to Convert Curves to Grease Pencil in Blender 3?
Using the Import-Export SVG addon, I imported an SVG as curves so I can make a 2D animation with it. Only problem is, curve layers don't evaluate in 2D-style top-down layer stack, so all the layers show through each other. I need a way to convert them to grease pencils so the layers stay behind or in front of each other depending on index position. This looked promising, but the solution is a script which no longer functions in Blender 3.
Note: Import > SVG as Grease Pencil only seems to work for really simple SVG files.

Turns out you can convert multiple objects by selecting all of them with  Ctrl+LMB and then clicking any object with RMB > Convert To > Grease Pencil.


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Merging Meshes Ctrl+J but everything looks off (normals, uv?)

https://i.sstatic.net/nnhql.jpg
tried renaming/flipping UV, recalculating normals, didnt seem to do much, any idea why?

have you tried reunwrapping the objects?

Select the metallic object, rename its UV Map (in my example UV_B_Set_0).
Join with Ctrl J.
In the metallic material add a new Input > UV Map node, select the renamed UV Map and connect it on every vector input of every texture.

amazing, thanks alot! I guess i missed out some steps when using the uv map node


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Triangulate multiple faces with only two triangles
I need to fill in all the empty squares in the top image, then I need to triangulate them as shown in (B). However, if I use the "triangulate faces" tool, I get (A).
(For your information, I used the knife tool to get (B) but I can't do that for all the squares...)
Thanks.

a new problem has arisen. If I use the technique proposed by FFeller (use Knife for a structure and multiply with Array), I get the following mesh when exported in stl...

Why don't you create the base geometry first, than use the Array modifier for a repeating pattern?

That's a good idea indeed. Thanks

Maybe applying the array before exporting would help?

Stl contains only triangles. The large "triangles" on the mesh not really triangles because they have 9 edges and 9 verts. Those have 6 180° angles but they still 9gons. What you can do is select the 9gon and press Y, this will separate it from the mesh, then select the 180° verts then press X>>Dissolve verts.

It worked perfectly! Thank you so much FFeller !


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Why does the object move when scaling on the Y axis?
I try to resize the object on the Y axis, but the object moves from where it is. There is no such problem with the X and Z axes.
What is the reason for this strange behavior?
X-Axis (S X):

Z-Axis (S Z):

Y-Axis (S Y):

It looks as if you may have the Transform pivot point set to 3D Cursor (middle of the top toolbar), but since all your images were taken while you were scaling, the toolbar isn't visible. Try setting it to Median Point and try again.

The object's origin is at the world's center.
Go to menu Object > Set origin > Origin to Geometry


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Is there a way to highlight only the red faces which has the normals faced the wrong way and then flip them? Without manually pressing every face
I have a lot of faces, around 500k. Some of the normals is flipped the wrong way, is there a way to highlight only the red faces which is faced the wrong way and then flip them? I have tried to highlight everything and choose recalculate inside/outside but my mesh doesn't seem to grasp it. See picture below.

If this is a completely connected mesh, then recalculate inside or outside should set them all facing the same direction. So I guess there are other issues with your mesh as well. Some double vertices? Or unconnected geometry? Have you tried selecting all, then hit M > Merge by Distance? Or is it supposed to be unconnected? Then what about hovering your mouse over a blue part, hit L so every connected face gets selected. If all blue parts are selected, hit H to hide them. If now only red faces are left, hit A to select all, then Alt+N > Flip.

I appreciate your help but unfortunately it did not work :/ this is a pointcloud which was given to me so it is really messy, a lot of holes and vertices everywhere. I think the problem is that it's one mesh, one unity, but the normals is flipped/reversed, I will share another picture for you to see. So the bottom part is red when the top part is blue and contrariwise. So recalculate doesn't work here. Do you have any tips to fix this? (I will add the picture in the original post). *The blue area on the floor is where I have repaired holes.


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Circular Lighting Artifacts
How to avoid the circular patterns on a plain diffuse surface while projecting light?

I am trying to project a few patterns on objects in Cycles render. When I project a plain white light on a diffuse surface (a plane), I could see concentric rings on close observation. Could someone help on how to avoid it? Thanks in advance.

that is kinda normal is most lighting shading though...

Try to render in 16-bit image, 8-bit is quite less for image to store data. It might still stay in strip afterward in a 8-bit monitor setup. But it help you to save more color information in your file.


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How do I Extrude Faces Along Normals, and also shrink in two other directions?

I am extruding plane surfaces along surface normals by selecting the plane, then hitting Option-E (Alt-E), then selecting Extrude Faces Along Normals.
That is all fine, but I also want to shrink the object along the two local axes that are perpendicular to the Normal. So, as the plane gets thicker in one direction, it gets smaller in the other two directions.
I would be grateful for any pointers.

Akin to inset then translate inset face along normal?

Truth be told, I do not know. If we call the Normal, the local Z, then I want to shrink in X and Y. The angles should remain right angles.
This works with Scale, I can edit in X,Y, and Z. But the Z does not exist until I have extruded the plane along its normal. As I do that, I want to also scale the two dimensions of the plane.

is this what you wanna do? https://youtu.be/UViI4VKy-Ww

@Chris Not quite. I want the sides to go in without the angles changing. So not a cuboid becoming a truncated pyramid, but a plane extruding into a cuboid and then scaling down in the two directions that are perpendicular to the normals.

can you show with two pictures what you want?

last try from me: do you want to change it like this after extrude: https://youtu.be/WEpuyZ1I2Ck

Yes, sure. I have added images to the question. 1. Plane. 2. Extruded. 3. Scaled.

Uniform scale around individual origins then extrude along normals.

Imagine the simple case: six square faces arranged as if they were the
six faces of a cube. I would want to scale the 'top' surface in X and
Y and not Z. I would want to scale the 'front' surface in X and Z but
not Y. I would want to scale the sides in Y and Z and not X. And so
on.

Here is the default cube, rotated arbitrarily in edit mode, and after applying edge split modifier to make each face a plane as described.

Uniform scale each by half S 0.5
Extrude along normal by 1 AltE 1
Notice the zero dimension along normal of each plane remains unaffected by scaling.

-To sum up for those who want to do this:
-Starting from the planes. Select all in Object Mode.
-Go to Edit Mode.
-Choose Face Selection method, Select All.
-Transform Pivot Point, Individual Origins.
-Then Scale (S) and after, Extrude Faces along Normals (Option-E).
-Thanks batFINGER and @Robin Betts Please edit my summary if needs be. Now to do it in Python!

If you think about this one the other way round..

The I Inset operator has a 'Depth' setting, which you can adjust in its F9 panel.
If you need further adjustments, perpendicular to normals, for unconnected faces, you could set Pivot to 'Individual Origins', Transform Orientation to 'Normal', and scale in the per-face XY... SShiftZ.

Oops, just read the commentary, but the second half might still apply.

Lol, thought exactly the same thing. Was also thinking  solidify modifier thickness driving scale.

in edit mode:

extrude with E and move the mouse up (so you got 4 vertices) - you know this

Tap A to select all vertices

Tap S to scale

Tap Shift Z to scale only on x and y axis - > move your move to your desired scale

An  issue will be in scaling step if the face normal is not axis aligned.., which kinda warrants going in other order, uniform scale then extrude.

@batFINGER You correctly anticipate what I am trying to avoid, but I have problems with the uniform scale. I have a large number of these planes, all at different orientations. I can select them all and extrude along their normals. Easy.

If I try to do uniform scale on all the planes, I have a problem even if I pivot around individual origins. Imagine the simple case: six square faces arranged as if they were the six faces of a cube. I would want to scale the 'top' surface in X and Y and not Z. I would want to scale the 'front' surface in X and Z but not Y. I would want to scale the sides in Y and Z and not X. And so on.

If it helps, I will be doing this in Python so perhaps I can scale only along axes that are not zero?

@Chris Thanks! That is working nicely for one object. I need to spend some time to see if I can do this on many objects at the same time.


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Can't see object through a certain camera
I can see my object fine in rendered mode.
I can even see my object fine with a particular camera in rendered mode.
However, when I switch to a particular camera, I can no longer see the object in rendered mode.  I have tried hiding/unhiding, clipping distances in camera settings and on viewport tab, the output looks good in the node editor, and I have gone through all of the solutions I could find on here.  Here is the camera that I can't see the object with:

Here is the camera that I can see the object with:

I am not too familiar with depth of field settings yet so it might have to do with that. I thought if I adjusted the aperture settings it would account for that. Here are the settings I thought you would need to see:

What're your thoughts and thanks!
Tyler

@cetaton I edited the question so it would be more relevant and just about to read that link you sent me.  I'll keep you updated

The link you referred me to was the answer.  Sorry I wasn't able to find that earlier.  Thanks so much for the help man!@cegaton


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Tesselation vs. Displacement Mapping
Just had a quick question, is there a difference between tesselation and displacement mapping?  On another forum I read this:
"Tessellation in itself only smooths out things by subdividing the polygons.
Displacement Mapping tessellates and deforms a surface based on a height map."
I also found this on wiki when looking up tesselation:
"Tessellation can also be used for implementing subdivision surfaces, level of detail scaling and fine displacement mapping.[4] OpenGL 4.0 uses a similar pipeline, where tessellation into triangles is controlled by the Tessellation Control Shader and a set of four tessellation parameters"
This would suggest that tesselation is a process that can use fine displacement mapping.  I am just seeing this come up in other 3D programs and want to keep all of the terminology straight in my head.
Thanks guys!

Got it edited.  Sorry about that @cegaton

I think the most accurate thing would be to say:
Tessellation is the process of procedurally generating additional faces.  Such as subdivision, Catmull-Clark or simple.  There are other algorithms as well.  Procedurally as opposed to manually, although of course procedural tools are useful for the artist doing manual work.
Displacement mapping is technically the process of mapping vertices to arrays to specify displacements that a mesh should undergo.  Those "arrays" are just images (there's no difference, it's just in how you interpret the data.)  And the mapping, of course, is via UV coordinates.  But that's kind of pedantic and technical, and what we really mean is the process of displacing vertices-- of moving them a certain distance prior to rasterization or raytracing, as specified by our image/array, in a vector generally specified by the vertex's normal.
First, is there any reason to perform runtime displacement without tessellation?  Hell no!  You'd bake it into the model.  Why tell your video card to do math when you could precompute that math?  You'd just be wasting GPU cycles.
Is there any reason to do tessellation without displacement?  Well, yeah.  It'll improve the silhouette.  But once you do tessellation, you might as well start doing displacement too, it's not much more expensive, a texture lookup per vert is nothing these days.
So-- no, displacement mapping does not include tessellation, not necessarily.  (Try a displacement modifier in Blender without doing a subidivide first: possible, not recommended.)  Can tessellation be used for implementing displacement mapping?  Well, yeah, it's an important part of most displacement strategies, but it's not the same thing, any more than planting food is the same thing as eating it.
Does tessellation use displacement mapping?  No.  Not in the slightest.  (Try subdividing without a displacement map-- oh wait, there's not even a slot for a displacement map on the subdiv modifier....) It enables fine displacement.
Finally: I know you want to get organized, but words are just words, and what's important are the concepts, the meaning.  You'd think 3D programmers would have their terminology straight, but very often they don't, and the reality is that when you don't understand exactly how someone is using a word, it's always worth clarifying.  Yes, even if you're talking to John Carmack.  Good books will define their terms, and you should read those definitions, and the instant you pick up a different book, you should read its definitions and forget the old definitions (for the duration of reading that book.)  Even when speaking with a single person, we can use a single word in multiple ways.  Try to figure out what people mean by "specular map" someday, that's always a fun one.

Interesting read.  That clarified a lot of things.  Thanks! @Nathan


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Getting Error: The Encoder Timebase is not set when trying to render finished Video sequence
I cannot find any other posts to do with this and I don't to completely mess up my Blender while messing with settings I do not understand. I finished putting a video together in VSE and tried to render it and I got this error: The encoder timebase is not set .
How do I fix this? Also I am happy with a workaround such as copying my VSE strips to a second Blender window but I don't know how (Yet again) :) . Thanks
Edit: It seems to be something to do with FFmpeg because when I switch to an image format it renders fine. I will try removing the audio codec (mp3).

Hmm, thats weird. What are your output settings for ffmpeg? Did you try another Codec? I know that Blender's .mkv files seem broken

@3pointedit can you write a bug report about this, including how to reproduce this brokenness of .mkv? https://developer.blender.org/

@experimental-rocket can you install ffmpeg and paste the output of ffprobe file-that-causes-issues?

@dr.Sybren I have checked a recent build of 2.79 on the 7th July and can no longer find an issue with .mkv files. Sorry for noise

It was the frame rate i used screen capture for the video file uploaded to Blender and got the message
 "the encoder timebase is not set" Error, when I checked the frame rate it was Custom 30.06 FPS I changed it to 30 FPS and everything worked perfectly.

Try transcoding the source media first, it could be that Blender's ffmpeg just doesn't like the codec settings. Use an external transcoder to fix it, like mpegstreamclip or even VLC (its a bit flakey though). This can happen with variable frame rate recordings, like you get with some screen capture software.
I suggest moving the original media out of its folder then put the new copies in their place, as long as the names match then Blender should be able relink to these clips.


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Stopping fluid inflow problem
I'm new to Blender, here is my problem:
I've created 2 downward facing faucet inflows (Inflow Velocity X=0 Y=0 Z=-8) into a Tank that is half the height of the Domain.
I want the Inflow to stop as the water level reaches the top of the tank, leaving a few seconds for water to stop sloshing around.
I've tried it a few ways:

Animating the Inflow object out of the Domain,
Animating the Fluid's Enabled Property and
Animating the Inflow Velocity.

The problem is, once I insert a Keyframe on any inflow object, the flow of water out of that Inflow Object is reduced to a trickle.
Since there are 2 Inflow objects, I've tried keyframes on one, the other and both: inserting any keyframes on any of the Inflow Objects severely reduces its flow of water. (Baked at 65 and 200)
Please help in any way
Thanks

I played with the file for several days and posted 2 of them up to explain the situation. Both files are the same with the exception of one having keyframes to stop waterflow when the level reaches the top of the "Tank" (hidden in the view). I worked on objects and settings to stop the water flow when level reaches the top of the hidden Tank. If you open both files and bake them, you can see the difference between the flow of liquid when keyframes were added. Hope you can help.

maybe some good reference image from your setup would help people understand better....

Thanks m.ardito for responding. I played with the file for several days and posted 2 of them up to explain the situation. Both files are the same with the exception of one having keyframes to stop waterflow when the level reaches the top of the "Tank" (hidden in the view). I worked on objects and settings to stop the water flow when level reaches the top of the hidden Tank. If you open both files and bake them, you can see the difference between the flow of liquid when keyframes were added.  Hope you can help. Thanks Sam

I have it working, I started over and it works fine now.


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Liquid Grouping Around Rigid Body Flow Effector
I have a simple fluid simulation set up with rigid bodies that collide with each other before the water flows. The rigid bodies also have a flow effector so that they will affect the water. It seems to work in the first hundredish frames but then the particles suddenly start bunching around the rigid bodies. Why does this happen and how can I fix it? I do have a wind force field that affects the water, but I don't see why this would cause it to bunch up around the rigid bodies.
Thanks
.blend file & animation
picture:

I had an effector that was causing it. It was pointed so that it would push the particles away from the cubes, but it is probably some weird quirk with blender (maybe the effect somehow "bouncing off" the liquid domain.


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Matcap materials with alpha support
I'm trying to make stylized simple materials, using just matcaps and ambient occlusion (without light). I want to use semi transparent matcap textures but in my current setup they are not rendering with alpha. Any tips? :) I've attached my node setup.


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texture painting now showing up (and bugs explanation?)
i'm a complete beginner in blender. i've made a face using automirror but then texture paint were behaving weirdly. i disabled it and then used the mirror modifier on the mesh, but then the texture paint were working only on a half of the mesh (on solid view only the right side were painted, while on other modes it was the left side).
i then realized i didn't enable clipping while using the modifier, so i erased half of the mesh and made all again.. and then the painting got much weirder. when i painted on the backside the pattern apeared on the front side and vice versa.
i don't know what i did after that (maybe it worked when i tried flipping the normals) but now i tried again and it's finally painting coreclty, but the painting isn't showing on rendering and material preview modes (i linked the material to the uv image but nothing)
any clues of what happened so i don't commit the same mistake again (cause i really don't know what i did)? and why isn't showing up on other modes?

blender file:

Please upload your Blend file (with materials packed (via File > External Data > Pack Resources)  so that we can see what's going on. Follow the instructions here.

@JohnEason just uploaded!

I'm afraid I'm not going to be able to look at your file closely tonight as it's approaching 1am here. However, it looks as if the head has somehow been rotated 180 degrees. If you press 1 on the numpad it should show the front of the head, but it's actually showing the back! For some reason the UV unwrap of the face is offset too although the object itself seems to be symetrical.

@JohnEason wow, i really don't know what i've done, i got really confused, so thank you very much!

You've assigned the second material to your head, but you need to assign the first one. Select the face, switch to Edit mode, select all and click Assign:

Note that in the Material panel, under Viewport Display, you've chosen a pink color, so the head will appear pink and not grey when you'll be in Solid mode. Now you'll be able to see the texture and to paint on it when you'll switch to Texture Paint mode.
As for why, in Solid mode, you see the texture while it is not even assigned to the object, it's a bit confusing but it has to do with the image that is selected in the N panel > Tool > Texture Slot. If you stay in Single Image mode you'll see the selected image texture, if you switch to Material instead of Single Image you'll see the assigned material:

thank you very much! it worked!


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Particle hair Glitch when rendering
Is there a way to render this without the hair glitch?

Render settings:

File link: https://drive.google.com/file/d/1NNG_T-4PLe6EkcgeJOH88O0jk3T_NT8K/view?usp=sharing

can u share the blend file https://blend-exchange.com

I added the file

the textures are missing but to me it looks okay when I render it (frame 180)

Maybe because my computer is not strong enough to render that fast?


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Different objects, same material, animating alpha independently
In eevee, I would like a number of text labels to fade in and out of the scene at different times during the animation.
I know that after setting the material's blend mode to "Alpha Blend", I can keyframe the alpha level in the "principled" BSDF shader, but unless I am missing something, each object would need its own material for this solution to work.
Is there a clever way to have all objects share the same material while still being able to fade them in and out at arbitrary, independent time points?

Related https://blender.stackexchange.com/questions/185290/same-material-with-different-key-frames

Also see https://blender.stackexchange.com/a/163699/86891 (shameless plug)

@Gorgious.. it worked :)

You can animate the object color (from its properties panel).
I've pluged it in the color in the example below, but of course, you can use it for alpha too.

That provides three channels (RGB) useable in the shader node tree that can be keyframed in RGB color mode (as indicated by @Gorgious).

You can keyframe each channel independently but only when you set the color wheel to RGB. Also you can't access the alpha channel in the shader editor with this method but you can use one of the other channels into a separate RGB and use that as the alpha channel. Note that in the 2.92 version the alpha channel is available in the attribute node see https://developer.blender.org/rB6fdcca8de6 and https://developer.blender.org/rB9bc177d8de

@Gorgious, thanks. I'll update that.

Just tested it in 2.92 Alpha, this will be the way to access the object color alpha in newer versions : https://i.sstatic.net/yVjM1.png Although custom properties will be accessed directly by the attribute node (Yay !) https://i.sstatic.net/pTeSA.png

@Gorgious 2.92 will be a big one : )

@lemon, thank you, clever indeed. Looking forward to being able to access custom properties from the node!

One driver will be linked to the material for all objects and the propery used by the driver will be linked to one object, I think.

But as Gorgious said, 2.92 version will allow to access properties (around next february if I remember well).


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Morphing a mesh between more than two shapes
I want to morph a cube into a sphere, and the sphere into a cone, all in one animation.
Unless I am missing something, shape keys allow objects to go from A to B and back to A, or A to C and back to A, etc.
What is the most natural and efficient way to go from A to B to C?

Depends on the shape keys activation order. Can start with B set to 1, then B set to zero (so have A) and finally C set to 1.

You can set Shapekey B to depend on shapekey A, and shapekey C to depend on shapekey B.

It works, but: it seems to me that in order to obtain shapes B, C, D, etc, you always start from the original object. Is it possible to model each shape starting from the aspect that the previous shape has when its value is 1?

I don't know of a easy way to do it, maybe someone else knows ?


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Splitting a mesh at the end of a shape key-based animation
I am using a series of absolute shape keys to progressively deform a mesh as shown below. Eventually, I want the soap bubble-like spheroid to detach from the originating plane and move away.
My naive approach was to create a further shape key, cut through the mesh at the last point of contact between the bubble and the original surface, and seal each of them separately.
But of course that does not work, as the split is really applied to the underlying mesh, not just to the specific shape key, so it is visible at each step, not just at the end.
How do I proceed from here?

How exacting do you want to be? Is this shape ... ever the central focus with extreme closeup ? Never the central focus? When does the bubble become transparent?

Suggestion. Please show an example of the most exacting close up of the joint between bubble and flat surface.

Consider switching from 1 mesh to 2 meshes if convenient.  Render or Not Render is animatable with keyframes.  Combined Mesh is replaced with Floor Mesh and Floating Bubble Mesh.  Advantage Seams are avoided. Disadvantage Shape Continuity efforts will be needed.
Consider your mesh as always 2 separate submeshes if the Viewer cannot see seam vertices which are joined for part of the animation.  Shrinkwrap Modifier and Warp Modifier.
Consider Metaballs with reservations.  Explained Below.
Consider fluid simulations.  Larger Compute Time Demands.

Two Separate Meshes
Preliminary Results.
Warp Modifiers. Shrink Wrap Modifier.  No Shape Keys Yet.

Metaballs
Lower Portion Connected in image below.

Lower Portion Disconnected in image below.

I wrote with reservations because I have seen metaballs stop working at the most inconvenient times and simple conditions.    Then they work under other conditions such as particles.

I accepted @atomicbezierslinger's answer, but thought to post the steps I followed (the two-mesh solution) in hope it may help novices like me.

I have an object with 6 shape keys, already arranged along a timeline (see screenshots above)
Select the mesh in object mode
Shift-D and Enter to duplicate in-place
Shift-H to hide everything except the newly created object
Set the Shape Keys' Evaluation Time to 60 (i.e. the end point of the shaping course)
Remove all shape keys
Switch to edit mode and split the mesh so that the bubble and the plane are now separate geometries
Switch back to object mode and create new shape keys to animate the bubble floating away while gaining a roughly spherical shape, and the plane returning flat
Alt-H to unhide everything
Animate visibility/rendering for the two objects such that the original one-piece mesh disappears at the same time the split mesh appears

authors: علی کاشانی مقدم


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Animating the development of an organic structure
I would like to create an animation of how a gland grows during embryonic development. Imagine tweening between these 4 steps:

As you can see, it's not just getting bigger, it becomes more complex, it changes shape, parts are added and sometimes parts are removed.
The techniques that I have discovered so far appear to require that the mesh stays the same throughout, which seems clunky to me. I do wonder if I have been missing a big-picture approach to this type of problem.

How about a liquid simulation with an obstacle shaped like the final structure? You could then bake the animation and turn sideways or whatever rotation needed.

Ciao Giuseppe, questo l'hai visto? --> https://www.youtube.com/watch?v=jPvLQH17Y2Q
did you check this tutorial? --> https://www.youtube.com/watch?v=jPvLQH17Y2Q

@Sanbaldo it seems this will not be available until future versions, maybe 2.9

@Luciano, I see, but I wanted to understand if the requested feature was the one of the video

@Luciano, if I understand correctly, your suggestion would happen to work for this specific shape, but my question is more general. The first 6 seconds of the video suggested by Sanbaldo are an excellent example of what I would like to accomplish (but see my next comment)

@Sanbaldo, looks promising, but I am not sure I truly understand the concept. Will the program interpolate between versions of the object, or is it going to be exactly like clay animation, where I need to sculpt every single step and if I change my mind I have to modify all versions?

Q: How to morph mesh shapes with different amount of vertices?
A: There is not an efficient way in Blender to animate mesh with varying topology (from what I know).
Blender is able to generate this kind of data as export of fluid sim or metaballs into Alembic (.abc) format. This format can be also imported back into Blender. A bit of setup can be found under Modifier tab - Mesh Sequence Cache (see Manual). But in general - you can transform only on object level (Loc/Rot/Scale or use modifiers on top of this format).
Like a hack of your proposal I tried to animate sculpted object with shapekey. When topology become to its limit I duplicate the object and continue to sculpting with dyntopo on specific part. It worked in kind of, but its was so painfull with pour result.

Q: How to animate growing an organic structure
A: You can try - Particles with Metaballs growing by gradient texture.
In this sample I used just a tree structure (addon Sapling), but you can model gland by your self (or some cool script probably exists for this kind of structure).

add MetaBall object (for later use)
create some gland structure (edges only)
subdivide edges evenly into dense vertex mesh

Particle System

add Particle System to this object with option Render as Object
as object select MetaBall
set a number of particles the same as amount of gland vertices
(it can be found in edit mode in bottom row)
you would have to set particles Velocity to zero and disable Gravity under Scene properties to stop particles to move

Animation

animation is done by illusion - particles scaled in time
particle scale is controlled by Particles > Texture
add new Texture and go to Texture properties
set Blend > Spherical, Influence > Size > enable, Mapping > Object
(You can animate size directly in this panel, but its more flexible use another object. I added Empty into scene.)
additionaly you can enable Colors > Color Ramp to adjust appearence of size in time, so it will looks like growing thickness

It has its limits to animate by texture, but you can probably get some more variations by adding another Particle Texture to "break" spherical growing shape (I didnt try that).

Looks promising. Would you go as far as stating in your answer that Blender currently does NOT directly support tweening between shapes of different geometry? While the example you provide is clearly not a general solution, it DOES address the specific question that prompted my post. Would you be willing to share the blend file and possibly some details? Thanks,

@Giuseppe What do you mean "Would you go as far as stating in your answer..."? With second Q - no problem, will post it later.

It looks very useful, in general.. a bit more detail would be great.

about blendshapes, remeshing, shape keys and non-tendrily stuff,
I'm not completely sure if it's exactly what you would want, but my first instinct was also to use "tweening between the shape of two objects" as you had mentioned in a comment on vklidu's post. However, blender does have a limitation in this respect. They're called shape keys, and allow you to blend between two shapes supposing both shapes have the same vertex numbers and ordering.. blendshapes are the same, but referance existing shapes, also with the same number and order of vertices. Otherwise, blender couldn't possibly know what vertex is supposed to grow in which direction. While it definitely is possible, it would require you to either plan out where you needed the resolution to sculpt the various arms out beforehand, or to model it, then somehow collapse the arms in later, till you get a flat or smooth object and a shape key for each layer of "branching" you do. This is definitely possible through proportional editing and sculpting if you don't use dyntopo. I would say for something as simple as a fetus to a small human, it's possible, you just have to be real careful how you sculpt- Maybe do it in steps. I know you can sculpt millions of polys, but you definitely get diminishing returns when making tendrils with them.
If you're just looking for a basic shape, with no need for anything beyond a very basic material (with not texture nodes) you could try the new remesh features to merge objects and "store" them in one another until they can get out, or using metaballs with multiple objects in much the same way. That'll end up looking a bit like https://www.youtube.com/watch?v=e087KzDOeyk, which can give a very micro-organic feel with some translucent materials. remesh is a bit like metaballs, but with fewer limitations and I assume more intense computing.
as well, using blendshapes or vertex groups with the skin modifier could also get you close to what you wanted... though I'm not sure exactly what that may be.

the best that I could manage without replicating another answer because I didn't see that little block at the top till I was done and did a branched growth thing all the same
I was able to get an effect like what you had mentioned, using drivers, curves, and the bevel options in the curve settings. I made a tree object out of curves (there's an addon for that- add tree). it's not elegant or totally procedural, but there's some good growth control there.
after that, I added a bezier circle, and set the tree to use it as both a taper object and bevel object, which essentially allowed me to grow a cone along the shape of every curve that made up the tree(there are a lot), and have those cones' base size be controlled by the circle.
The driver I added was a "sum values" driver, that used the distance between the origins of the circle and tree. This is where it gets wacky. I then installed an addon that allowed me to separate multiple curves at once ( https://github.com/agapas/separate-curves ). because they came from the same object, they all inherited the same driver and origin, which means they all grew at once, suddenly spawning a mess of cones, as their drivers still referenced the same original object, and were in the same spot anyway.
I needed them to start growing cones as the circle moved up, not all at once, so I selected them all, and set origin to geometry to move the origins to their appropriate places. Because the driver's values were only 0-1, I had to start editing the origins further to put them all in a .5 unit cube. Now all the origins were far enough away from each other to show a different distance to the circle.
I then... set to work. I only did the first few, but after all that, you still need to go into every object's driver, and have it reference itself as the last part in the sum, not the origin of the first branch. for 269 curves, it would be quite a pain, but it's probably scriptable. After that, I found the cones were spawning too early and growing too quickly (the origins with their drivers were seeing the circle too quickly) so I squeezed the origins on x and y, and reapplied transforms to the tree, to make sure they saw the circle in order from bottom to top and that distance from center would not overly influence growth.

it... works okay maybe? I think Vklidy's is definitely more elegant, though I can't say I know which of these methods you might like to explore more. Neither can be textured easily, and both have fairly large drawbacks. This is why people want everything nodes, so we can do this weird stuff using actually supported methods. I know Houdini does have an edge on blender in this kinda stuff. maybe look at that?
also here's the file. moving the circle up and down is how you control it. right click on the purple box in the curve>geometry>bevel settings to take a look at the driver, though it's nothing special.

Hey, I do appreciate all the effort you put into your answer, thanks a bunch. I upvoted it, but since it was not so substantially different from vklidu's, the bounty goes to his/her answer because it came first. Cheers--


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rigid body simulation - unwated spaces between objects
I've been trying to play with a rigid body simulations.
I prepared a project of a building made of domino tails. I've placed all objects very tight, but as soon as I start animation it looks like there was some tiny gap between objects, so they all fall down a little bit. For a high building it leads to a construction disaster as the whole building colapses.
Here is an example: https://www.youtube.com/watch?v=4seYWa1g53s (I'd suggest to use 0.25x speed).
How can I fix it?

Firstly, check your scale. A stack of 5m tall blocks of wood will behave vastly different to a stack of 5cm tall blocks of wood - with forces that are orders of magnitude more powerful, causing more ‘bounce’ and inaccuracies in the simulation.
Secondly, expect some gaps and a certain amount of ‘settling’ at the start of the animation. It is very difficult to avoid all gaps without causing overlapping surfaces which can generate huge repulsive forces at the start of your animation. I suspect the scale of your model is simply resulting in the forces being so large as to cause collapse.
Thirdly, tune the Rigid Body properties. The defaults (60 steps per second with 10 iterations) provide for a very crude simulation. Increase your steps and iterations (eg, steps 600 and iterations 300 - or even higher if required) until you get a stable simulation without causing too much CPU overhead (more steps and iterations require more computation time).


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Extruding, other side does not have face

As you see in the picture, after extruding the bottom face, it seems to simply move up. There really is no bottom face now. Sorry if it's hard to understand. I need it to have two faces instead of one. One on the very bottom, and one where it's extruded. I know you can extrude the bottom edges and then merge them, but is there any easier way? I don't want the bottom face when I extrude it to be one-sided. I think Maya actually creates a new face.
Thanks!

Could you add the steps? I can't reproduce the result everything works as expected.

Make a cube 2. Edge loop in half and take out a side. 3. Select bottom face and extrude upwards. I want a bottom face after extruding covering the very bottom.

May I ask, what is it that you are making? I can't understand your workflow clearly.

If you extrude a face connected to other faces, the extrusion will leave a hole.

But if you extrude a disconnected face, you will have a solid shape. If you press Y to disconnect the shape before extruding it, you will make it solid and have that bottom face.
EDIT:
But, beware, if you do this, you will get weird geometry. Things might not be connected the way you want. I feel a little dirty, doing it. :)

Could you clarify "I feel a little dirty, doing it."? It is because such practice is commonly shunned in the 3D community?

It's not so much that the practice is shunned, as much as it is usually the wrong way to solve the problem, or it's accidental. Basically "if you press y...you will make it solid" is not exactly the way to make this shape solid, which is why it feels wrong.
It also feels wrong because there are now 3 faces connected to the same edge (which is almost always a bad idea) and there is a section of geometry that's totally enclosed, therefore invisible, but still has to be rendered.

@Gunslinger would you like some soap?

If I understand what you are asking, the quickest way to do this is to select the face you want to extrude and duplicate it with ShiftD, next, don't deselect or select anything else but rather press E to extrude that face and adjust accordingly, finally, select the entire mesh with A run a W > Remove Doubles operation.

Remove doubles is no longer supported after blender 2.8. Now you have to  select entire mesh with  "A" and then Go to "Mesh" -> "Clean up" -> "Merge by distance"

This is how extrude tool works.
From the wiki:

One tool of paramount importance for working with meshes is the
Extrude tool. It allows you to create parallelepipeds from rectangles
and cylinders from circles, as well as easily create such things as
tree limbs. Extrude is one of the most frequently used modeling tools
in Blender. It’s simple, straightforward, and easy to use, yet very
powerful.
The selection is extruded along the common normal of selected faces.
In every other case the extrusion can be limited to a single axis by
specifying an axis (e.g. X to limit to the X axis or ⇧ ShiftX to the
YZ plane. When extruding along the face normal, limiting movement to
the global Z axis requires pressing Z twice, once to disable the face
normal Z axis limit, and once to enable the global Z axis limit.
Although the process is quite intuitive, the principles behind Extrude
are fairly elaborate as discussed below:

First, the algorithm determines the outside edge-loop of the extrude; that is, which among the selected edges will be changed into
faces. By default (see below), the algorithm considers edges belonging
to two or more selected faces as internal, and hence not part of the
loop.
The edges in the edge-loop are then changed into faces.
If the edges in the edge-loop belong to only one face in the complete mesh, then all of the selected faces are duplicated and
linked to the newly created faces. For example, rectangles will result
in parallelepipeds during this stage.
In other cases, the selected faces are linked to the newly created faces but not duplicated. This prevents undesired faces from being
retained “inside” the resulting mesh. This distinction is extremely
important since it ensures the construction of consistently coherent,
closed volumes at all times when using Extrude.
When extruding completely closed volumes (like e.g. a cube with all its six faces), extrusion results merely in a duplication, as the
volume is duplicated, without any link to the original one.
Edges not belonging to selected faces, which form an “open” edge-loop, are duplicated and a new face is created between the new
edge and the original one.
Single selected vertices which do not belong to selected edges are duplicated and a new edge is created between the two.

For a mesh to be able to exist in the real world, everything must have thickness. Generally speaking, it is a good idea to make your meshes work this way.
For example (using a cube), if you extrude the bottom face downwards, you can see it only creates four new faces around the edges:

The reason it does not create a new face for the bottom and leave the original bottom face is because you would then have a non-manifold mesh (not normally what you want):

To test a mesh you could use CtrlAltShiftM to select non-manifold geometry.
To get the shape I think you want you could inset (I) the one of the middle faces and then extrude it back. This will result in a manifold mesh:

Nice read but I don't really see how this answers the question.

@iKlsR Better now?

@iKlsR I believe it answers the question as for why it leaves hole underneath. Besides, gandalf3 mentioned about having thickness, which is crucial in extrusion without hole.

There must be some subtle detail within the steps you described in your comment, lead to:
Add a cube, loop cut (horizontally) and a take a face out leads to:

Extruding the bottom face selected constrained to z-axis

Looks as expected:

If you have moved the bottom face upwards (z-axis) the overlapping face would have been painted a bit brighter, but only as long you don't continue editing.

...then move that face up on the z-axis.

@Matt then you would stil have the white border and a visual feedback (brighter faces) that something is wrong.

Quite right. Your next-to-last image is almost right. Your answer began by trying to recreate the OP's original shape, which you have now done. The OP apparently wants faces both where you placed that last one, and covering the bottom as well.

@Matt Hmm, maybe,  never needed it this way then you answer would match. However he should provide more details.

Apologize if I didn't add more details. Gunslingers answer was perfect. Well, actually all of your answers were awesome! Thanks!

Probably the best way to make the shape you're going for is to:

make a cube
loop cut the middle (like you are already doing)
loop cut again, but below the first cut
delete one side face
select the four interior vertices and make them a face (using f)

I don't think OP is asking how to make a shape but rather how to have a persistent face after extruding.

That's possible, but I was keying off this: "I need it to have two faces instead of one. One on the very bottom, and one where it's extruded. I know you can extrude the bottom edges and then merge them, but is there any easier way?"


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How to export objects (.obj) and textures (.mtl) correctly?
Two questions :

How I can write my images textures at the same time as .obj and .mtl? The linked files are missing.
How I can write the files paths correctly.

I tested the file / external data but there isn't any changing.
Thank you for your replies
I try to make option copy, but it does not work, I do not understand.

https://blender.stackexchange.com/questions/57531/fbx-export-why-there-are-no-materials-or-textures/57541 https://blender.stackexchange.com/questions/5110/how-to-import-a-mtl-file https://blender.stackexchange.com/questions/24020/importing-obj-with-mtl-and-image-not-working-properly/24024#24024 https://blender.stackexchange.com/questions/408/how-can-i-use-my-blender-models-in-webgl/411#411 https://blender.stackexchange.com/questions/7920/blender-isnt-importing-mtl-correctly-with-obj

https://blender.stackexchange.com/search?tab=votes&q=obj%20textures


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Settings windows too small in 3.6.5 after running project that was saved in 4.X
4.0.1 was crashing constantly when animating so I wanted to go back to 3.6 but now the settings window that shows up when using any sort of functionality, like "triangulate faces" for example, is too small:

what it should look like:

I am in fact able to replicate this when running any other project in 3.6.4 that was saved in 4.X.
Is there any way to resolve this?
Ty.

edit: (I updated to 3.6.5 but the issue persists.)

Missing or problematic UI items aren't unusual when opening a file in an older major version than it was saved in. In the lower right corner there should be a warning message "File saved by newer Blender (4.0), expect loss of data." What happens if you hover your mouse over whatever that Triangulate Faces dropdown is called and then press F9? Even if that works for you as it did for me, there could be messed up UI in other workspaces. I have successfully copied and pasted objects from a new to an older version without problems. Continued...

... I found this with an Internet search, it is talking about a different method and older versions of Blender, but maybe it will help: https://blender.stackexchange.com/questions/195628/can-you-easily-export-a-blend-to-a-previous-version-of-blender

F9 works but who knows what other UI issues I may encounter if that's the case with running a newer file on an older version.
The warning message only shows for projects that were created in 4.X
link/append (from the method in https://blender.stackexchange.com/questions/195628/can-you-easily-export-a-blend-to-a-previous-version-of-blender) only seems to let me add individual objects from the newer blend file one at a time, but not the whole scene, is there a way to do that?

I wish blender gave me a warning that I can't go back if saving an 3.6 project in 4.0.1.
I was running blender off steam so I wasn't aware of the update before it was too late.

Have you tried selecting all the objects in your scene and copy and pasting them into 3.6? Here is an ~6 minute YouTube tutorial that might help if you go the Append way: https://www.youtube.com/watch?v=soWVMlBe_ww I just noticed when looking at the comments under that video that he has pinned one where the person uses copy/ paste. Here is something from the Blender Manual about compatibility that won't help with your problem, but might be of some interest: https://docs.blender.org/manual/en/latest/files/blend/compatibility.html

The issue you are seeing has been asked about here at least 5 times recently for instance here, so far without resolution. It appears to be a bug which should be reported via Help > Report a Bug in Blender. It doesn't necessarily seem to be due to changing Blender versions.

A solution I found is to use the latest release of Blender 3.6.6 which fixes the issue.
And you need to save the project in question in 4.X again before saving it in 3.6.6 so that the new versioning code runs.
this could be suboptimal because using the latest release is likely unstable.
I wonder if I can then reinstall 3.6.5 to see if the project is now compatible after being saved in 3.6.6. I'll need to test that.
Edit: it does work so I'll mark this as the accepted answer unless there is another issue.