text:
Calculating Area of Object as Rendered from the Camera
I am trying to build a program to optimise the position of a camera such that the object in question fills the render. The bounding box is inadequate for renders from 45 degree angles, for instance.
I am attempting to achieve this by projecting the vertices to their 2D representation from the camera perspective and finding the convex hull. This I can compare to the area of the viewport.
However, the program outputs the same vertices regardless of my transformation matrix. I am new to Blender and therefore am a bit lost.
Can someone suggest what might be wrong here? I am using Blender 3.4.1.
import numpy as np
from scipy.spatial import ConvexHull

def CalcHullArea(obj, location, distance):

    scene = bpy.context.scene
    camera = scene.camera

    m_0 = np.asarray(camera.matrix_world.copy())

    camera.location = location(distance)

    camera.update_tag()

    bpy.context.view_layer.update()

    m_1 = np.asarray(camera.matrix_world.copy())

    ## Check m_0 and m_1 are different.
    assert (!np.allclose(m_0, m_1))

    # Get the world matrix of the object
    world_matrix = obj.matrix_world

    # Get the inverse of the camera matrix
    camera_matrix = camera.matrix_world.inverted()

    # Get the projection matrix of the camera
    projection_matrix = camera.calc_matrix_camera(
        bpy.context.evaluated_depsgraph_get(),
        x=scene.render.resolution_x,
        y=scene.render.resolution_y
    )

    # Combine the world space matrix, camera inverse matrix, and projection matrix
    combined_matrix = projection_matrix @ camera_matrix @ world_matrix

    # Project the vertices of the object to 2D screen space
    verts_2D = np.array([np.array((vert.co @ combined_matrix))[:2] for vert in obj.data.vertices])

    # Compute the convex hull of the 2D screen space vertices
    hull = ConvexHull(verts_2D)

    # Calculate the area of the convex hull
    area = hull.volume

    return area

# Example usage
obj = bpy.context.active_object
center = obj.location
location =  lambda d: (center[0], center[1], center[2]+d)

A_0 = CalcHullArea(obj, location, 0)
A_1 = CalcHullArea(obj, location, 100)

print(A_0, A_1)

related: https://blender.stackexchange.com/a/160388/19156

in complement, looking at the code here https://github.com/dfelinto/blender/blob/87a0770bb969ce37d9a41a04c1658ea09c63933a/release/scripts/modules/bpy_extras/object_utils.py#L213 you can optimize things a bit


text:
Camera Matrix Not Updating After Moving Camera
I am developing a short macro to find the optimal distance to place the camera from an object, so it is fully contained in the render.
One simple solution is to use the maximum side of the bounding box. However, this gives silly results in the case of highly asymmetrical boxes.
My solution is to use the convex hull of the 'shadow' of the points comprising the mesh and minimise the mean square difference between the area of the convex hull and the render window.
However, I notice that the camera matrix does not update after changing the camera position. This can be seen either by printing the camera matrix or printing th loss.
My version of Blender is 3.4.1.
Can someone please advise what I have done wrongly?
    import bpy
    import numpy as np
    from scipy.spatial import ConvexHull

    def CalcAreaLoss(obj, location, distance):

        scene = bpy.context.scene
        camera = scene.camera
        #Change camera position to z
        camera.location = location(distance)

        # Project the convex hull vertices to camera space
        cam_vertices = [_v.co @ camera.matrix_world.inverted() for _v in obj.data.vertices]

        # Find the convex hull of the bounding box vertices
        hull = ConvexHull(cam_vertices)

        # Find the area of the hull and the frame
        area_hull = hull.volume
        area_frame = scene.render.resolution_x*scene.render.resolution_y

        # Calculate square difference
        loss = (area_hull-area_frame)**2

    return loss

    # Example usage
    obj = bpy.context.active_object
    center = obj.location
    location =  lambda d: (center[0], center[1], center[2]+d)
    loss_0 = CalcAreaLoss(obj, location, 0)
    loss_1 = CalcAreaLoss(obj, location, 5)

    print(loss_0, loss_1)

import bpy

cam = bpy.context.scene.camera
print(cam.matrix_world)
cam.location.x += 1
bpy.context.view_layer.update()
print(cam.matrix_world)

Thank you so much for this solution. Have been looking for a solution to a related problem (finding pixel space bounding boxes after camera movements) and I have been debugging this for 12+ hours and nothing helped. You are nothing short of a hero!

source: Stack Exchange

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

sort: votes


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Rotate object having animations
is it possible on Blender to rotate an object with its animations ?
As a proof of concept, i bought an character with animations. Then i tried to rotate the whole object and the result was strange.
I assume that it's just a bug when modeling/skinning/rigging the character but not so sure. What may cause this bug ?

I doubt very much it is a bug.  How this thing looks before you ...ed it up, and the steps you took to rotate will cast some light.

I had a similar-looking problem once, when I tried to edit a model—I think the problem may have been shape keys, but I can't remember.

You could try parenting the character rig to something else, maybe an empty or a non-printing object, that is centered right at the base of the rig. Then rotate that parent object, and everything should be good.
Actually, rigs often have a base object included. Check to see if your character's rig already has a base or handle that everything else is parented to. Then instead or rotating the whole character, just rotate the base. You should get better result.

I accepted this answer but i would like to add some precisions. I put an empty object on the very center of my object and linked it to the camera. Then rotating the empty would also rotate my camera that was my needs to have different view of the object. Thanks

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


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How can I save and close and reopen a blend file with a script?
How can I save and close then reopen a blend file using a script, so that all data blocks are removed?

Just call save_as_mainfile() and open_mainfile() operators:
import bpy

bpy.ops.wm.save_as_mainfile(filepath=bpy.data.filepath)
bpy.ops.wm.open_mainfile(filepath=bpy.data.filepath)

Blender3.6.2: I get this error: Error: Cannot read file "/MyHome/BasePath/SomePath/MyFile.blend": Not a directory. And it ends up renaming SomePath to SomePath1 (the path where the file is), and it creates a small blend file at BasePath with the name "SomePath" (the blend file receives the name of the folder without the .blend extension, but that file has not the contents of the file I am trying to edit using the script, it has the default contents, the single cube, when we open blender without a file).

If the above happens, you need to place the file before the options like: blender MyFile.blend --background -P /MyHome/BasePath/AScript.py, now it worked.

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


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How do i delete the inner side of this shirt
How can i select only the inner side of the shirt and delete it so that i only have the outside faces of the shirt?

One way to do this is:

Limit selection to visible
Select all outside faces with C (do not select faces on the edge)
Change selection type from faces to vertices
Press ctrl-I to select the inverse (now you should have the inside selected)
Delete selected vertices

But what if i also want to delete the faces on the edge?

This will delete the faces on the edge

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


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How can i let collision objects stop from going through cloth
I am trying to put a rope around the cloth using keyframes but the cloth is not moving backwards. Instead, the rope is moving through the cloth. How can i make sure the cloth simulates tight to the back of the rope.

Honestly, I would make the rope a cloth as well, but very very stiff. Then pin it's inner vertices to the outer vertices of the t-shirt.

Increase the cloth collision quality and see if that works. Also, does that rope have collision enabled? Sometimes a simple mistake is a cause.

can you elaborate more on "put a rope around the cloth using keyframes" and how you set the collision with the cloth object? maybe upload the file on http://blend-exchange.giantcowfilms.com/ then edit the question and paste the provided link


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Blender Armature Weight Painting - Bone does not move how he should
I got a little problem. When i was trying to rig my character i weight painted with vertex groups. Now after i weight painted every single bone i got an issue on one hand. Its just one claw, all the others work as intended, but this one just doesn't move the way it should.

The claw just doesn't want to move properly. When rotating it deforms itself in a weird position. When rotating the other claws (which are the same (mirrored and weight painted)) they just move perfectly.
Does anyone know what i am doing wrong?

Make sure that any other bone weights are not assigned to this one. Check every bone and if they share some weights with the one you pictured- just delete these weights. Example here: https://blender.stackexchange.com/questions/76715/while-moving-arm-leg-mesh-messes-up

Thanks you so much. It worked. I checked every bone and one was applied wrong. Now it works perfectly fine! :)

I had the same problem working with v2.8, and I found that if you move your object out of its original hiearchy where it was "linked"/"parented" from the armature in the scene selection (in "View Layer" top left) into just the scene selection (in "View Layer" top left); then you have the option of reset to parent Ctrl + P  > Set parent to > Armature Deform > With empty groups.
This seemed to solve my problem. I believe what caused it was after I weight painted some vertex groups along with vertex selections assigned to vertex groups, I used Decimate Modifier to create less face/vertexes.
After that I realized my armature bones doesn't move the object anymore.

Select your mesh and go into edit mode. Select single vertices and check Vertex Weights right in the properties shelf (see screenshot below). This way you can check for each vertex if it is influenced by an unwanted bone.
Another frequent error while rigging is if your mesh is mirrored. For modelling this is great, but when animating it's better to apply the modifier first.

I already applied the mirror modifier before starting to texture and rig. And i dont have that "Vertex Weights" Panel. the only thing i got is "Vertex Groups". But i already found my mistake. Had to check every single bone again. After selecting everything right, it worked. Still thanks for answering and helping me out! You guys are awesome! :)


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Is there a way to copy/paste keyframes to a extrapolation cycle?
I want to make all the keyframes appear like this
instead of the blank cycle like this
Is there a way? I want this because sometimes I need to make change on the cycle and without keyframes, a single new keyframe will ruin the cycle. I really dont want to copy/paste all keyframes on the dopesheet because everything will be a mess and will take too much time!
thanks

Is your intention to make a modification that affects all the cycles, or only deviate for a single event with future cycles unchanged?

For example lets say I have an arm cycle animation. At some point I want to change a single rotation keyframe of that cycle, but let the cycle continue. If I had the keyframes there instead of a blank cycle, I could just select that particular key and change it without having to worry about the cycle being ruined.

A manual process would be to use the Graph Editor.

Remove the Cycles modifier
select all keyframes
copy the keyframes : Ctrl-C
navigate to the last keyframe : Shift-Ctrl-up then (plain) down
paste keyframes : Ctrl-V

Repeat those last two steps until you have filled the timeline.
It would be possible to clone the keyframes via python, but unless you need 20+ copies, the manual process should be adequate.  (let me know if the python is required)

This can be done with F-Curve cycles modifier. The F-Curve modifier panel is located in the Properties region in the Graph Editor.
To add a modifier, select the curve you want to add cycles to, select Modifiers tab in the properties region, click on Add Modifier and select Cycles.

Tried that but that doesnt add the keyframes like I wanted.


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Euler formula for geometric modeling faces, holes
I don't know if I'm in the right place to ask this question!
I have two 3D modeling and I want verify the Euler-Poincaré Formula on them that include face,holes, vertex, etc. Anyone knows about that?

It is not entirely clear what you are asking, but the Euler formula is
V - E + F = 2 (1-g), where g is the number of holes (the genus).
Perhaps you also have cavities? Then look at this San José State exposition.

That what I want! I want to use those Euler formulas for those 3D objects

@Ja_cpp if the answer helped you upvote it, and if it solved your problem please consider marking it as correct

@DuarteFarrajotaRamos I didn't upvote it. I already know those formulas but my question is how can I apply them


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Displacement Modifier Leaves 0 Height Around 2 Edges of Plane when Applied
Good evening,
I am working on creating terrain using planes, a greyscale Heightmap and the displace modifier.  Everything is working wonderfully with the exception on a "Lip" I guess it could be called, being left around the edges of each terrain I import.

The heightmap is set to clip, the terrain is non-square, so it is mapped to the UV.
These pieces are all cut from the one massive terrain that I am breaking into individual screens and I need these edges to match up for when I pull it all into Unity.
Thank you very much for any assistance with this.

I did not see any kind of extra pixels along the edges of the HM I am using.


text:
I have a problem with splitting an object
I'm doing an illusion kind of animation, where a rules is split in two and where the other part is closer to the camera than the other, but they should seem to be connected at first. The camera will slide showing that the two parts are actually not attached.

My problem is a line which is created by a shadow in the front part. It breaks the illusion of the parts and i don't know what creates this shadow as it cannot be erased with a light.

I made the 2 parts of the ruler by duplicating the object then created 2 cubes and used them as masks with boolean to create the 2 parts.
Any Ideas what creates the shadow and how to remove it?

It looks to me to be a problem with smooth shading as in https://blender.stackexchange.com/q/88654/29586.

It would be easier to diagnose if you could include the .blend file: https://blend-exchange.giantcowfilms.com/


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How would I import my model from blender to unity to look exactly alike?
How would I import my model from blender to unity to look exactly alike?
I've tried importing the model and setting the material naming to the models material. I then drag and drop the texture into the albedo for both materials.
As you can see by the pictures, the crystal isn't refracting light like it should and the empty face is showing through the transparency. The top image is from blender and the bottom is from unity.

What do you mean by "import my model from blender to unity" ? Are you exporting from Blender and importing in Unity or are you exporting from Unity and importing in Blender ? Either way materials are never transferred, see https://blender.stackexchange.com/questions/57531/fbx-export-why-there-are-no-materials-or-textures

Exporting from blender and into unity. How would I get a more accurate representation of what the unity rendering would look like in blender? Also, how do I recreate this refraction effect to work better with unity?

You can't, don't even waste your time. Completely different material system and rendering engines, so don't bother unless utterly necessary. Unwrap and texture your models properly in Blender, export then create your material inside Unity, see the provided link above.


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Modular clothing for RPG
What would be the best way to create multiple articles of clothing/armor to be compatible with multiple different character models of varying shape and size?
For example, if I have a character mesh and I extrude his stomach out a bit more and save that as a separate mesh then design an armor piece for the first mesh, would there be a way to have that armor piece recognize the changes between the two meshes and adjust accordingly?

"What would be the best way..." This would be an opinion based question, the rest seems both far too broad and not very blender related. Is this for some sort of game engine? What have you tried so far, could you show some screenshots

I haven't tried anything as I'm not sure how to go about this in an efficient manor. The best way would be subjective and hard to define but I'm mainly taking in factors like ease of use and scalability. The idea is that I'd have multiple player models and armors/accessories, all interchangeable with automatic shape fitting. Some may have larger arms, broader shoulder, bigger heads ect... I was thinking that I could define key points on the player models like the neck and head for example and calculate a delta transformation between models which is then applied to the armor/accessories.

I'm still relatively new to blender so I'm not sure how I'd go about doing this delta transformation idea. My general concept is to group all the vertices into manageable segments where I would apply articles of clothing (head, torso, legs). These vertices will be consistent throughout my character models since I'll pretty much copy them and move them around slightly. I would then store the tranformations to each vertice compared to the base, design the clothing around one character model, and apply said transformations to the clothing. Is there a way to do what I described?

Maybe look into shapekeys


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cube appears bright white when trying to do volumetrics
been trying to create some fog by using a volumetric cube, although keeps appearing as what is seen in the image below

You have emission on

As @AllenSimpson said, your emission is turned on, or rather too high. If you want it to be completely dark, set it to 0, but if you still want some glow, use some small value.


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Why do my lights appear like this (opaque) behind the glass shader?
I'm currently working on an animation where the camera starts filming infront of a fireplace and then slowly goes back and then flys through the window. There the problem appears. As soon as I render the scene from behind the glass my lights look like this. I assume this is some basic and easy to solve issue but I couldn't figure out what it is. Can anyone help me out?

Looking at this question, do you have Properties > Scene > Simplify unchecked?

Does this answer your question? How to illuminate the darkness inside glass objects in Cycles?


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Is there a way to speed up or slow down movie clips that are on a plane?
So in Blender it is quite easy to put movie clips on planes via the 'images on planes'-addon. But I couldn't find a way so change the playback speed of the individual planes. Is it even possible, or will I have to edit the videos themselves?

No, there is no way to control the playback speed of video used as texture.

As it happens someone has found a way - it's via keyframing the frame offset. https://www.youtube.com/watch?v=l84oLfb0HgU


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What is this orb attached to my object?
I have an orb that just appeared attached to my object in Object Mode. It disappears in Edit Mode. If you zoom in the orb stays the same size and you can see it is attached at a specific vertex. When I go to Edit Mode and delete the vertex the orb attaches to a nearby vertex when I go back into Object Mode. If I export to an stl it doesn't appear on the file. How do I get rid of it?

If you're talking about the big sphere it's probably a particle that you've created (if your object is very small it makes the default particle look big), go in the Properties panel > Particle, and delete ParticleSettings:

Perfect. Thank you!


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Grease pencil, selection problem
Newbie question. When i go to a layer in my animation  to draw -  two of them are selected  and I can only deselect by using 'none'  in object mode. Then I get no response to drawing/erasing  or selecting normally in those layers.  They are not locked  and are selected in layers.  I know I'm missing something simple and obvious and basic - but what is it?  Help greatly appreciated.

If I understand your question and your aim, the fastest way to deselect all strokes of a Layer is to lock it.
When a Layer is locked you will not be able to draw on it, nor edit its strokes.
You can also lock strokes by materials lock.
In object mode if you deselect one object you cannot edit it in any way.

Thank you, Josh  - now I think my problem relates to the tiny little dot which turns into a pencil icon.  Thanks for your help.


text:
2.8 Measuring tool on angles - no decimal on degrees
Tried different platforms and relases, and some YT videos says the same to me:
- In the version 2.7 the measure tool was hided like discouraged but on angles showed 2 decimals after the angle, so I measured with a certain precision (like 12.76°)
- In the version 2.82 the measure tool is presented in the main bar, but when I measure an angle the precision is something embarrassing, no decimal point after the entire part... (so the precedent angle will be 12° or 13°).
This change is a wanted behavior (and so... why?) or a bug?

Hi! Did you found a way to show decimals in degrees?

You can use MeasureIt addon which is available in Blender 2.8 itself


text:
Merging multiple Objects, removing excess inner geometry for 3d printing 2.82
I tried searching but could only find old non-2.8+ related info
I am trying to merge 30 disks to a supporting geometry, and the intersecting geometry will not let me 3d print properly.
Boolean search removed the carve solver in 2.8
I have tried doing individual Boolean merge but get glitches

Can anyone suggest a ways or add-ons to make this seamless for 3d printing? preferably without doing an operation 30+ times
Thank you in advanced. Cheers

Try to post a blend with this part, but there is not a straight one click operation, from what i noticed, but we can check glitches if they can be fixed in some easy way ...

so turns out theres an Add-on called 3D Print toolbox!

Lucky you if it solved your issue, this addon mostly inspects a mesh, so I don't think the Clean Up > Make Manifold will solve your issue. If so, can you please provide full answer so others can benefit from your search? Thank you


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Reset children in Collection Info node
The Collection Info node in geometry nodes has an Original/Relative transform space options. I understand that Relative sets the local transformations of each object such that its final position is the same as in the scene, whereas Original preserves the local transformations that the objects may have.
Independently from that, the Collection Info node has a "reset children" setting, which removes all local transformations. Why is it a separate setting, and not one of the transform space options?
In other words, what does changing Original to Relative do, when reset children is clicked?

The Original/Relative switch refers to the position of the Collection relative to your current position, and has no influence on the position of the individual elements if the Reset Children option is activated.
This has to do with the fact that with Rest Children the positions of the individual objects in the Collection always use the current position as a starting point.

I see, shouldn't it be a 3 way switch: Original/Relative/Reset in that case (as there are really 3, not 4 options)?


text:
How to capture curve radius in geometry nodes
I am trying to make a tree generator in geometry nodes. There is a bezier curve defining the root, and I would like to recursively define smaller stems extending from the root.
This is how the stem is defined:

I would like to pass the current radius from the root to use it as "starting width" on the stem so that the width of the stems extending from the top of the tree would be thinner. See how the "tree" looks like without it:

I tried connecting Radius node to the "starting width" directly, but then the radius is taken from the smaller stem geometry, and not the root geometry. I also tried capture/transfer attributes, but haven't managed to make them work. I managed to eye-ball the size and pass it through "scale", but I don't like this solution.

How do I capture the radius of the curve to be able to pass it as an input to another subgeometry?
I also have a problem with the smaller stems being generated from the same seed even though I pass a random value. How do I pass a different seed per instance?

The main problem with your setup is, that you try to change the object, that shall be instantiated. The Instance on Points node will normally generate multiple instances of exactly one identical object. You cannot change the object before instantiation. Instead, you may scale, rotate or translate the instances afterwards or you may realize the instances and modify the resulting geometry.
You have the option to provide a collection of elements, so that the Instance on Points node will choose one of these instances for every instantiation by choosing Pick Instance. But the principle is the same here: If you instantiate one element of this collection multiple times, every of these instances will be the instance of exactly the same object. And you may change it afterwards following the same rules as mentioned above.
Following you will find a solution to your questions. I won’t describe everything in detail, because many of the concepts, that I used, are explained in this video from Erindale. Instead, I will focus on your two questions.
This is the complete solution:

Here you find an overview, that I will explain below:

At (1) the lines for the trunks are generated. They are scaled randomly in length on instantiation. Next the instances are realized, so that they can be modified in (2). Every trunk gets modified individually. This gives me the opportunity to capture the radius, when setting it.
Creating the branches works correspondingly. In (3) the lines for the branches are created. Next the instances are realized and in (4) they are modified individually.
Coming back to your questions:

Capturing the radius is shown in my example. But this would not work, if you tried to apply it to the object, that should be instantiated. You have to use it on the realized instances.
You can only use different seeds after realizing the instances and not on the object, that should be instantiated, because it is only one object, that can only have one seed.

And here you can see the result:

wow, thanks for the detailed explanation!

I don't exactly know what you mean with your second question.
For one:
In your stem group after you set the curve radius, capture the radius attribute with a "Capture Attribute" node. Connect the captured radius attribute to the group output.

We need to instance a curve not a mesh, since we set curve profile later.

Then set the curve radius from the stems to the radius from the trunk.
With a "Endpoint selection" node we select the first 17 segments. Same number
as the "Quadratic Bezier"-Node resolution, otherwise you get strange results.

Final result.


text:
Changing frame extremely slow in Sequencer
i have a simple png sequence and an audio. 2000 frames 24fps. very simple setup. no other effects. it used to work fine but all of a sudden when i click into any frame in the sequencer it is extremely slow to respond. i have set cache to 8GB, i have 32GB memory. this is only 1 minute animation. do i need to click something to "load all frames" into memory so it instantly can change frame on demand because it is virtually impossible to do a frames scrub.

have you tried with another version of Blender? Also are you using proxy (which will lighten the calculation)?

yes i tried it on 2.93, 3.0, and 3.1 all take 3-4 seconds to click change frame. how do i use proxy? i read that it is deprecated?

well, it's weird if it used work fine, but actually PNGs are quite heavy and 2000 of them starts to add up, so dunno... Proxy is the way to go for a responsive VSE when editing, but they only work with videos, not image sequences. Personally I probably would render those sequences as lossless videos, have Blender proxy them at 25%, then edit that


text:
Why is video sequencer render different for 100% resolution and 80% or lower aspect ratio
I'm doing a video edit on several screen capture videos with 1920x1080 resolution so no problem with the video size since it is the same setting as in blender output. I do alot of zoom in/out and position transform animations in blender of the videos to give focus on certain parts of the video. In addition, i set the transform origin differently for each clip depending on how i will zoom it. For example, if i need to zoom the left part of the video, it makes sense to have this clip have an origin of (0.0,1.0) and if i have a clip that zooms focus into the center, it makes sense for me to let the clip have a transform origin of (0.5,0.5). I'm not sure though if that is good practice and if i should have the same origin for every clip in the video. I have a hunch that this might be causing this bug.
I noticed that when i render with resolution percentage 100%, it renders exactly like in the video sequencer preview like this:

but when i set the resolution lower like 80%, the output is shifted, in this case the rescaled video is shifted to the left and lower:
And also i've noticed that some frames in the video when rendered at 30%, don't display at all if not set to 100%.

Yeah, I'm not exactly sure what the problem is but I have had issues with messing with the origin of the clip and transforming it. I remember at the time I couldn't tell if the problem was a bug or something I did but I ended up just setting it to it's default and redoing the zoom keyframes. Maybe it is a bug. You could probably report it  as such.

I agree, this seems to be a bug. Consider reporting it here: https://developer.blender.org/


text:
Is it possible to animate a rigid object while it's running its physics course?
I was planning to create an animation of a rubiks cube, which will be a set of rigid cubes with core locking the parts together like a real rubiks cube, solving itself as it is resting on the floor, so whenever it flips one of the 3x3 planes it will jump around if the flipping pushes itself from the ground up. So you would have a rubiks cube that jumps around as it's flipping sides. Is that even possible?

Yes it is possible.  Do you want precise animation or less than precise animation?   You may consider an armature of 2 bones or so.  For less than precise animation rotation might suffice barely.

wow that sounds interesting, can you be so kind and show me a simple working example of a precise animation using bones? maybe a cube is enough resting on the floor and animate it to rotate on the X or Y whose force will push it upwards strong or weak depending how strong the rotational force animation applied? that'd be really helpful

Perhaps related to gear animation.

I may or may not have time for more.  Animation currently baking.  Is the rotation face of Rubiks Cube RK causing the whole cube to move or not?

yeah the rotation animation demonstrated on the right side of my image will cause the whole cube to move like in the real world. so if the animation is slow it will slowly tilt cube while if the rotation animation is quick it would cause it to slightly bounce up. so the tilt or intensity of the bounce would depend on the speed of rotation.

Armature Technique
The armature rotates the cube on either the left edge or right edge.

Armature of 2 Bones is present. Copy rotation constraint is present.  Single line driver is present.
Bone.002 is the parent . See image.  The other bone has the same modifier and the inverse of the driver condition.  This activates rotation in one bone or the other.

Above you see a two bone armatures replicated for illustrative purposes.  A box floor is present and a cube rotated which pierce thes  floor just as sources of rotation. Rotation about the Y global axis in negative - and positive +.  Rotation + and - shows edge switching.  In rest position the two bones are antiparallel and coincident. Both bones are equal in length to the width dimension of a cube.  Bone name Bone.002 is the object parent of the entire cube.  The somewhat coincident bones are similar to some foot rigs allowing toe heel hell switching. We assume one edge of the cube is always placed exactly on the floor plane.  Please excuse the view of edge occluded by armature structure.  Z axis adjustment can be added easily if bounce or jump is needed.  Tested for ∠a : -Π/2 < a <  Π/2.
Edits to follow

OP was asking about animating an object that is a rigid body in a physics simulation, in a way that the set animation interferes with the physics simulation.

@AlexandreMarcati yes. i think it is not possible.


text:
Why is the element type in the list data_from.scenes changing to another type?
I have the following script. What exactly is happening in the background, why does the element type in data_from.scenes[0] change from class 'str' to class 'bpy.types.Scene'. From this thread I quote:

It's just a special case of reusing a variable, which is a bad idea - mainly because it makes it hard to understand what a variable contains at any given point in the program flow. See e.g. Should I reuse variables?

import bpy

filepath = "/path/to/blend/file.blend"

with bpy.data.libraries.load(filepath) as (data_from, data_to):
    data_to.scenes = data_from.scenes
    print("T1:", type(data_from.scenes[0])) # prints class 'str'

print("T2:", type(data_from.scenes[0])) # prints class 'bpy.types.Scene'

The sudden change in data type confused me.

It doesn't really surprise me much, with makes it an inner scope than the global scope, and you're accessing data_from when this scope has been closed, which is not prevented by python, but can lead to funky behaviour, because you don't have a say in what happens when the with scope closes. Basically it's a wrapper like python decorators that executes some arbitrary code written elsewhere when its scope finishes.

@Gorgious hey that's actually a very good point, i didn't realize it indeed is out of scope and python didn't throw an error.

Exactly that happens: "The sudden change in data type"
Sybren explains it a bit in his "scripting for artists" series (asset linking around 8:40 https://studio.blender.org/training/scripting-for-artists/5eabe54d521eafd0953f6d45/).
Ok, not really explains, but Blender does this "magic" -> it exchanges the value from a string list to a collection. So Blender assigns just a new value to this variable. That's all.


text:
Mantaflow not working in 2.82 release
I have repeatedly tried setting up a simple flow and domain liquid simulation in 2.82. Following tutorials very closely. The strange thing is it works like 1 time in 6 build attempts.
But most times there are no particles after bake.
On the rare occasion that there was I saved the file, but when I opened it again it was not working.
Is anyone else having this trouble?
Thanks
Murph

Welcome Murph! I think that's worth to file a bug report over at https://developer.blender.org/


text:
CAD Sketch Add On
I am quite new to Blender and loving it.
I come from a background in Fusion 360 so I am very used to being able the make a sketch on any surface and extrude and cut into complex shapes.
Are there any Add Ons that add a similar function?
Thanks

https://blender.stackexchange.com/questions/7928/how-would-you-cut-a-shape-out-of-an-object-using-another-object https://blender.stackexchange.com/questions/50538/how-to-cut-an-object-along-a-curve/50560#50560


text:
How not to have a face left over when extruding a face inwards?
Here's a screenshot showcasing my problem:

I found some resources on this issue, but for some reason, it's not working for me. I'm using the Inset tool, and setting the depth to a negative number.
Do I need edge loops first for that to work? There's no way for blender to create vertices at the right spot automatically?

Please look at the 2nd answer.

this Push/Push Extrude operation will soon be implemented in Blender

I believe destructive extruding will come in 2.90 (it's an often requested feature), so perhaps August 2020?

Ok, great to hear it's coming to Blender!
@Leander cool, but it's only for 2.79, not 2.8, correct? Otherwise that'd be exactly what Im looking for indeed.

I found this thread, maybe there is the updated addon. Didn't read it, downloaded a version, didn't work, did a quick fix for 2.82. You can download it here from my github if you can't wait till August =) Quick test seemed to look ok, message me if it messes up.


text:
How to get a body part to always stay attached to the center of another with an armature?
I have an issue when rigging a mech character (im a complete rigging novice):
I have these 2 metallic bars that are attaching the thigh with the joints of the lower leg. I have a bone for the thigh, 1 for the 2 metallic bars (maybe I could use 2?), and then 1 for the lower leg (Image 1).
You can see in Image 2 that when I move the leg forward, the mesh if moved with it, but the metallic bars are not lining up with the round joints anymore. That makes sense, but how to I fix that? What kind of constraints am I looking for so that these bars will always be pointing towards the center of these joints?
Image 1:

Image 2:

Thanks.


text:
Particle as Hair on oval Sphere act wired, goes crazy
I changed form on a Sphere, added hair and the hair acted crazy.
Tested when Sphere is round, everything works fine. But the moment I change shape from round to oval, hair explodes from the sphere.
What's wrong here?
Add particle like hair to sphere
2. Changed the length and set hard dynamics = true
Start animation and hair will go crazy.

You probably made the scale in object mode, press Ctrl + A  to apply the scale. Use edit mode to change the mesh properties

Thank's, Add all transforms worked.

@Frank If so, please consider to accept the answer. How this site works: https://blender.stackexchange.com/tour


text:
I want to have water flowing nicely out of the water tap
I am testing water flow out of a water tap.
But I only get water splashing out.
Any one knowing have to make/set the scene to have water running out nicely as it does from a real water tap?

can you show us your inflow settings please?

if you want to solve your special problem (which might be other reasons like water colliding with your rigid body object) ...please provide your blend file. You can do this here: https://blend-exchange.com/

just give your inflow some initial velocity like this:

so you get something like this:

Thank, I changed the inflow vetocity from 4 to 1, but no change.
I also tried to disable the water tap in order to avoid collide problems there. But no change. Still splashing out.
How do I upload my blend file? don't see any attachment button.

I found the problem, it was the velocity settings. It was way to much with -4 on Z.
Changed it to 0, now it is running nicely out as it should.
Thank a lot.
I will post a picture later of the result of my test.


text:
what do i do about this?

everything shows up in render mode but otherwise, this is all I see.

Looks like you set a Clipping Region by mistake. Hit Alt+B to cancel it.

that worked! thank you for the help


text:
Transparency/Opacity-What is the easiest way to make an object partially transparent without shaders?
What is the easiest way to make an object partially transparent without shaders? It looks like the Transparency checkbox from the Viewport Display area has been moved/removed in version 2.8.2a...
I've followed several tutorials, changing the alpha channel of the Material's Base Color in the Material Properties tab, Viewport Display, toggling between the Material and Object Color selector in the Viewport Shading window, etc. Enabling Alpha Blend or Alpha Clip, to no avail. I've tried both Eevee and Cycles.
Whatever I try, as I drag the alpha value, the object will instantly disappear completely at a certain point, like a clipping level has just been passed. I cannot get a partial transparency/opacity.
I am just trying this with basic Cube mesh objects, and just looking for the simplest method for creating partially transparent objects in the Viewport and when rendered.


text:
Smoke simulation "Bake" is missing (or moved?) from 2.8.0 to 2.8.2
I'm trying to do a Smoke simulation following the various tutorial videos I've found, and could do it in 2.8.0 (after figuring out I needed to delete a BSDF texture on the Smoke Domain), but since upgrading to 2.8.2, a lot of the settings have moved and/or changed names.
Most importantly, the "Bake" command is missing in 2.8.2 (or at least moved from where it was in the Physics:Cache menu in 2.8.0). I found a "Bake Animation" command in the Object:Animation menu, but this doesn't seem to do what I need. When I render, it is always the same frame (somewhere in the middle of the animation).
See attached images for menu differences.
Any help/suggestions would be greatly appreciated.

You need to change cache type for Modular or Final.
In case of:
Modular - Bake button appears in settings
Final - Bake button appears in Cache tab (still under Physics)
Modular:

Final:

It is now named 'All'.

It's now under Settings : Bake Data / Free Data.
Blender 2.82 use a brand new simulation engine (Mantaflow) for fluids and smoke, so any tutorial prior to this version is outdated.
For the given screenshot Cache > Type change to Final then the Bake option appears below.

Hi thibsert, Thanks for the reply. Sorry for the newbie question, but I can't find "Settings"... you don't mean "preferences" do you? (I didn't see anything there either). Should I be able to see it when in Layout mode?

Ahh- never mind- I found it. Thanks again.

In your second screenshot you've got "Noise", "Guides" etc. In that same panel, "Settings" should be the first one.

@Ari If you ask something on forum and found solution, you could write where you have found this...
Someone shared knowledge with you so it is not well maniered to write "I found it".


text:
I have an issue where the vertices on my project glitch and create spikes any time I move another vertice
I have an issue where certain vertices that are moved trigger another vertice to spike away from the object and move out of place. Once it has spiked, it mimics the moment of the vertice I original was trying to move.If I try to put back the spiked vertice, it moves another vertice. Sometimes selecting proportional editing puts the spiked vertice back in place, but it will move again on the next adjustment.

This can happen when you use Mirror Editing with non-uniform rotation.
Disable Mirror Editing (up in the toolbar) and make sure you have rotation applied before you use it.
Object > Apply > Rotation

Thank you very much! I will try that!


text:
Creating 'Independent' Child Bone
Suppose I am attempting to make a hinge joint for a box for an armature.
The hinge should only affect the movement of the flap, and move relative to the bone of the box.
Naively, I have set this up by creating two bones: one to control the global translation/rotation/scale of the combined object and a bone to control the local rotation of the flap.

However, perhaps expectedly, the box deforms with the movement of the hinge. This is not what I want.

I am sure the answer is trivial, but how do I 'divorce' the hinge bone from the control bone so that I can have both a moving flap I can control which moves relative to the box?

There's a complete tutorial from Derek Elliot on a folding box animation here which might be of use to you.

Thank you. While that is helpful, it does not explicitly resolve the example I am struggling with, which is analogous to the one I am actually trying to solve in the project.

@JackRolph: if you would have watched the tutorial John was recommending you should have noticed that he did parent to empty groups and assigned the faces manually to the vertex groups in contrary to your attempt by using "with automatic weights". For beginners i can only recommend following exactly what the tutor does, else you will fail. Because just a single difference can make the whole scenario fail - except you know exactly what you are doing and what's going on (i know this by my own "often failed"-experience

you have wrong weight paint on the box.
Maybe you know - the bones and the vertex groups get the same name by Blender if you are using "parent with automatic weights". If you check the weight painting of your bone.001 you will see, that the box is colored. That's the reason why bone.001 also moves the box.
So one way to repair that is ...

delete vertex group bone.001
select the face in edit mode

in object mode first select the box, then shift select the armature
go in pose mode, shift select bone.001

press ctrl-p -> choose bone

result:


text:
Importing my svg creates weird lines
When I import my svg file into blender some lines are gaps and some just aren't even there, is there a fix to this?

Hello and welcome. Can you share the SVG file?

An option might be to use Blender's own facility to trace a Grease-Pencil object, directly from your image (Right-Click menu, on a reference-image):

.. which can then be converted to a curve. My 2D curve, after conversion, kicked up a fuss about being filled, in its own 'Shape' panel. But a Geometry Nodes Fill Curve node did the trick.
Here, the curve, further subdivided and deformed, to test:


text:
PBR Texture Direction
I'm trying to create a very basic page texture (over the top example used here for visuals) and I'm a little more than stumped. I am using a simple procedural texture and do not want to make use of jpgs for this project.
First, let me just say that my modelling and mapping skills are 25+ years out-of-date and I'm somewhat new to blender ... I'm shooting in the dark with this problem.
The model is a basic open book which has some modifiers applied to provide the page thickness and curvature.
When I apply the basic PBR texture I can't figure out how to get the texture to follow the curvature of the geometry.

As shown above with the green arrows, I can't get the (red) direction to follow the geometry.
I'm including the blender file here if you're curious.
One bit of frustration is with the modifiers — if I disable/remove or touch a modifier then the texture magically follows the geometry and remains good until we close the file.  Then it reverts back to the directions shown in the image. Unfortunately when I render the book using a custom python script the direction reverts to what's seen in the image as well.
Any practical help would be greatly appreciated.

One approach to this would be to preserve the mesh coordinates before deformation, one way or another, and use those to guide the procedural texture.
The Generated texture-space will do this for you
Here, the pages are a subdivided cube, with the near-side sloped, deformed with a Curve modifier:

Above, the Generated space is hooked in. An alternative is also given, which would be to stash the pre-deformed coordinates on the mesh-vertices using Geometry Nodes, and to access those from the shader-tree.
The Multiply and Combine XYZ nodes are just to make fine-tuning of the Z of the texture easier, to get white on the top surface.

Apologies for the moiré pattern in the picture, should have made thick pages to illustrate.

Sorry, I got so lost in life I forgot to return and thank you for this answer.  It was very helpful to us.

@ubuntux  God forbid... Real Life! :D Thanks. No Problem.


text:
Isolate objects in only one viewport
I split the screen to Render viewport and Solid viewport. I want to isolate the object only in Solid viewport and want the Render viewport shows all objects. However, whenever I isolate in Solid viewport, the Render one also shows that object only. How can I only isolate in one viewport and not affect the other one?

Hello and welcome. Have you tried pressing numpad / forward slash?

You're not in isolated view, looks to me like you've hidden all objects except the one you're viewing. This will cause them to be hidden in all viewports. Use "local view" (/)
What are you pressing to "isolate in Solid viewport"?


text:
Can Geometry Node Point Instances be exported as animation in FBX?
Just wondering how to export Geometry node Point Instances that are animated.I have tried exporting as FBX and the instances don't show up.Can anybody please help me on this one?

Alembic works for that animation

Thank you I will try that!

It works Thank You, but do textures and materials need to be baked as they did not show up?

Yes, you have to either bake before and use the textures or make your material nodes after that

Hey Emir, thanks again, I am new to Blender after 12 years Maya!


text:
How stack cubes together to form a multiresolution 3D grid without z-ordering issues?
I am using scientific quantum chemistry software where we represent electronic orbitals in an adaptive grid based on multiresolution analysis and multiwavelets. I would like to generate a rendered image of such a multiresolution grid. I have successfully loaded in all the individual cubes that build up grid, but I am running into the issue with weird shading effects due to the faces of adjacent cubes occupying the same space.
The 260 cubes are defined by their origins and their sizes (length of their sides):
origins:
-32.0 -32.0 -32.0
-32.0 -16.0 -32.0
-32.0 -16.0 -16.0
-32.0 -32.0 -16.0
-16.0 -32.0 -16.0
-8.0 -16.0 -8.0
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-16.0 -8.0 -8.0
-8.0 -4.0 -4.0
-4.0 -2.0 -2.0
-4.0 -2.0 -4.0
-2.0 -2.0 -4.0
-2.0 -2.0 -2.0
-2.0 -4.0 -2.0
-2.0 -4.0 -4.0
-4.0 -4.0 -4.0
-4.0 -4.0 -2.0
-4.0 -8.0 -4.0
-8.0 -8.0 -4.0
-8.0 -8.0 -8.0
-4.0 -8.0 -8.0
-4.0 -4.0 -8.0
-8.0 -4.0 -8.0
-8.0 -8.0 -16.0
-16.0 -8.0 -16.0
-16.0 -16.0 -16.0
-8.0 -16.0 -16.0
-16.0 -16.0 -32.0
-16.0 -32.0 -32.0
0.0 -32.0 -32.0
0.0 -16.0 -32.0
0.0 -16.0 -16.0
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8.0 -8.0 -16.0
0.0 -8.0 -16.0
4.0 -4.0 -8.0
4.0 -8.0 -8.0
0.0 -8.0 -8.0
0.0 -4.0 -8.0
0.0 -4.0 -4.0
2.0 -4.0 -4.0
2.0 -2.0 -4.0
0.0 -2.0 -4.0
0.0 -2.0 -2.0
2.0 -2.0 -2.0
2.0 -4.0 -2.0
0.0 -4.0 -2.0
0.0 -8.0 -4.0
4.0 -8.0 -4.0
4.0 -4.0 -4.0
8.0 -8.0 -8.0
8.0 -16.0 -8.0
0.0 -16.0 -8.0
0.0 -32.0 -16.0
16.0 -32.0 -16.0
16.0 -16.0 -16.0
16.0 -16.0 -32.0
16.0 -32.0 -32.0
-32.0 0.0 -32.0
-32.0 16.0 -32.0
-32.0 16.0 -16.0
-32.0 0.0 -16.0
-16.0 8.0 -8.0
-16.0 0.0 -8.0
-16.0 0.0 -16.0
-16.0 8.0 -16.0
-8.0 8.0 -16.0
-8.0 0.0 -16.0
-4.0 4.0 -8.0
-4.0 0.0 -8.0
-8.0 0.0 -8.0
-8.0 4.0 -8.0
-8.0 4.0 -4.0
-8.0 0.0 -4.0
-2.0 0.0 -2.0
-2.0 0.0 -4.0
-4.0 0.0 -4.0
-4.0 0.0 -2.0
-4.0 2.0 -2.0
-4.0 2.0 -4.0
-2.0 2.0 -4.0
-2.0 2.0 -2.0
-4.0 4.0 -4.0
-8.0 8.0 -8.0
-16.0 16.0 -16.0
-16.0 16.0 -32.0
-16.0 0.0 -32.0
0.0 0.0 -32.0
0.0 16.0 -32.0
0.0 16.0 -16.0
0.0 8.0 -8.0
0.0 4.0 -4.0
4.0 4.0 -4.0
4.0 0.0 -4.0
2.0 0.0 -2.0
0.0 0.0 -2.0
0.0 2.0 -2.0
2.0 2.0 -2.0
2.0 2.0 -4.0
0.0 2.0 -4.0
0.0 0.0 -4.0
2.0 0.0 -4.0
0.0 0.0 -8.0
4.0 0.0 -8.0
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0.0 4.0 -8.0
0.0 0.0 -16.0
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8.0 0.0 -16.0
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16.0 16.0 -32.0
16.0 0.0 -32.0
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-8.0 -8.0 4.0
-8.0 -8.0 0.0
-4.0 -8.0 0.0
-4.0 -4.0 0.0
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-2.0 -4.0 2.0
-2.0 -4.0 0.0
-1.0 -2.0 1.0
-1.0 -2.0 0.0
-2.0 -2.0 0.0
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-2.0 -1.0 1.0
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-1.0 -1.0 0.0
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-2.0 -2.0 2.0
-4.0 -2.0 2.0
-4.0 -2.0 0.0
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-16.0 -16.0 0.0
-8.0 -16.0 0.0
-16.0 -32.0 0.0
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2.0 -4.0 0.0
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1.0 -1.0 0.0
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1.0 -2.0 1.0
1.0 -1.0 1.0
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0.0 -16.0 8.0
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0.0 4.0 0.0
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0.0 16.0 0.0
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0.0 0.0 16.0
16.0 0.0 16.0
16.0 16.0 16.0
16.0 16.0 0.0
16.0 0.0 0.0

Lengths:
16.0
16.0
16.0
16.0
16.0
8.0
8.0
8.0
4.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
4.0
4.0
4.0
4.0
4.0
4.0
8.0
8.0
8.0
8.0
16.0
16.0
16.0
16.0
8.0
8.0
8.0
8.0
4.0
4.0
4.0
4.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
4.0
4.0
4.0
8.0
8.0
8.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
8.0
8.0
8.0
8.0
8.0
8.0
4.0
4.0
4.0
4.0
4.0
4.0
2.0
2.0
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I am adding the cubes to Blender via the following code:
import bpy
import bmesh
import numpy as np

f_origins = 'origins.txt'
f_lengths = 'lengths.txt'

origins = np.loadtxt(f_origins)
lengths = np.loadtxt(f_lengths)

def clear():
    objects = bpy.data.objects
    for ob in objects:
        bpy.data.objects.remove(ob, do_unlink=True)

    collections = bpy.data.collections
    for c in collections:
        bpy.data.collections.remove(c, do_unlink=True)

    materials = bpy.data.materials
    for mat in materials:
        bpy.data.materials.remove(mat, do_unlink=True)

def setup():
    # Add collections to hold objects
    scene = bpy.data.scenes['Scene']
    coll_cubes = bpy.data.collections.new('Cubes')
    scene.collection.children.link(coll_cubes)

def addCube(origin=(0, 0, 0), length=1, id='Cube', explode_factor=0):
    mesh = bpy.data.meshes.new(id)
    obj = bpy.data.objects.new(id, mesh)

    bm = bmesh.new()
    cube = bmesh.ops.create_cube(bm, size=length)

    obj.location.x = origin[0] - origin[0] / 2 + origin[0] * explode_factor
    obj.location.y = origin[1] - origin[1] / 2 + origin[1] * explode_factor
    obj.location.z = origin[2] - origin[2] / 2 + origin[2] * explode_factor

    bm.to_mesh(mesh)
    bm.free()

    bpy.data.collections["Cubes"].objects.link(bpy.data.objects[id])

if __name__ == "__main__":
    clear()
    setup()
    for i, (o, l) in enumerate(zip(origins, lengths)):
        addCube(origin=o, length=l, id=f'GridCube_{i}')

Is there a clever way to get a clean representation of my custom cube grid?
The image below is a matplotlib generated figure, kind of similar to what I want to achieve.

For a graphic result of this kind, to avoid fuss eliminating coincident faces, you might consider shading, not the object, but instead the World, as seen through it. In Cycles, set with a high 'Max Bounces' for transparency..

Shade the object 100% transparent.
Select 'World' at the left of the Shader Node Editor's header:

Shade the World (using a Light Path node,) a colour dependent on the number of transparent surfaces the ray has passed on the way to the camera:

BTW, I could get Freestyle to stroke this correctly only by:

Marking all edges Freestyle
Setting up 2 identical Line Sets, one for Visible and one for Invisible lines. Unchecking the 'Visible' check-box didn't work.
Switching off 'Chaining'.

Cool, thanks! Could you share the blend file? I am a bit of a noob, so having the file would help a lot :) I am using Version 2.93.4

@Yoda Here you go..  https://pasteall.org/blend/1cd3a6f6eb6e42209ba503d022480e30


text:
Possible to import and apply multiple animations for one pre-rigged model?
I’m working with imported pre-rigged models and pre-made animation files from a couple video games. Since the models are already rigged and the animations are already made, is it possible to import and combine multiple animations/actions for one model to make a longer sequence instead of having them all be separate blender files and separate animations? Thanks!

There is the Pose Library that seems to hold entire sequences. It may do what you want. Exploring that is on my to-do list...

The short answer is yes. But what are you going to do with them? Are you trying so combine them into long storytelling animation, or you want to edit them and add more?

This is what NLA editor is there for.


text:
Time Speed Control for Scene Animation
Need to slow down the video when a glass piece seen on camera. But i cant do it with rigid body speed cause of baking for solution for the parts animation. How can i animate the speed of everything that animated on their normal speed. I cant do it on video sequencer or after effects etc... video needs to be 60fps and its not good for time stretch.

From what information we have, it sounds like there can be no soup, but it’s vague. Can you more clearly describe what is happening in the scene?

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.

ive a scene with rigid body simulation. i just animate this scene with rigid body world speed but now i need to animate global time speed. Baked all simulation to animate pieces. if i edit the render in video sequence editor fps really down so its ruining the video how can i slow down all the world time with animation? like time remapping but need to animate it


text:
Procedural texture shows up in eevee/viewport shading but not cycles
I've made a procedural texture, and I want to bake it, but the texture doesn't show up in cycles. Here it is in cycles:

And here it is in viewport shading/eevee:

And here is my nodes:

I'd appreciate any help!

this sould normally work, id say. can you share a simplified file. For example a cube with the procedural material?

Sure! in a bit. I gave myself an injury I need to take care of

Hi :). Any chance of a duplicate mesh covering the result?

not really, there are no duplicate meshes. also it changes when I change the nodes. There are also some weird effects that might be insightful. When I separate the XYZ of the tangent and only use two of the three coordinates, it shows up. But not with all 3. Also I get the same effect using the tangent instead of the cross product.


text:
Change Color According to a Location
So I basically ask for points of this cube to color according to their distance for the origin. So if the color ramp is black to the white furthest point should be black and the closest one must be white. Is there a way for me to colorize the object this way? I also want to change its location so it needs to be updating its data live. Thanks

Yes it is possible but I am not entirely sure what exactly are you looking for... you can use a spherical gradient like this and this could be your starting base... use some plane as a reference object while using it on the more complex objects like this cube:

Hi :). Just to add, you can control the gradient spread and position using the Math > Multiply Add node https://imgur.com/a/U5vPjxg (click image to play the gif)

Check out the Grading Texture in the shader editor with set to spherical.
For an indipendant center set the Texture Coordinate to Object and use another object as reference.


text:
Are there any individual settings that should be checked after shrinking the model with the S key?
After scaling the models down to a tenth of the size I was working before, the animation preview would not play. (I down the size by S key.)
When I tried to play it back, it would freeze at frame 1, and then the Blender window turns milky white and automatically close. Other than playing the animation, I still can operate other edit.
The project contains a simple cube, a UV sphere with hair particle, several plane model (Principled BSDF), wind, turbulence, some lights, and two cameras.
When I play animation, I show only the bare minimum of objects. They are the plane objects, wind and turbulence.
For now, the only thing I changed after scaled down all models at once, was to reduce the Radius of Hair Children of my fluffy UV sphere.
The view mode during animation playback is "not" camera view.
When playing the animation, I ran it in solid mode or wire edges.
The wind have added Noise Modifier.
I've tried to change Shader of plane objects from Principled BSDF to Velvet, but that doesn't help.
I've tried updating the driver, but that doesn't help.
What else should I check?
Any suggestions or advice would be appreciated.

Did you scale in object mode? This can result in something called non-uniform scale, which can affect any number of things (depending on the object being scaled and its relations). Generally, the convention after scaling in object mode is to select the object and press Ctrl+A (apply) and select "Scale". You will likely need to re-bake any simulations and/or animations after doing this.

@Christopher Bennett As a blender newbie, I always fall into a new hole every time I take a step forward, but I appreciate the knowledge and advice you provide.
When I press Ctrl+A (apply) on an object that I have shrunk, the Hair Particle becomes long again. Should I just bake it again without fixing this long Hair Particle?

Not necessarily. I don't know what steps you took to get where you are, so I don't want to advise you (possibly badly). If you want, you can upload your .blend file (or a minimal example of it) here - https://blend-exchange.com/ - and users here can take a look and see what's going on.

@Christophe Bennett Yes, you are right, each case will have a different solution. I understand. Your advice has given me one more knowledge what I should pay attention to when I re-size the objects. Thank you very much.


text:
How to name the node groups?
I have a number of materials: M1, M2, M3, and vertex groups V1, V2, V3 on a mesh and would like to apply the materials proportionally to their corresponding vertex groups. In a previous question I got an answer how to map the vertex group into an attribute that the shader editor can take.
Now, I would like to mix different materials. What I have been doing so far:

for each material, create a node group which takes the texture mapping and exposes the BSDF output
create a meta-material, where I would input the node groups and mix them with the mix shader.

Problem:
The node groups created have names like NodeGroup.001 which makes it hard to distinguish different materials from each other. In the meta-material shader, it's possible to rename the group node, but it doesn't change the name of the underlying node group, so if I were to use it elsewhere, I still need to remember what NodeGroup.042 corresponds to:

Note that even though NodeGroup node was renamed to rock, it still appears as NodeGroup in the Add > Group option.
Questions:

is there a way to rename the underlying node group, as opposed to its corresponding node in the meta-material?
isn't there a better workflow for what I'm doing? Ideally I would not have to create node groups at all, I'd rather have a version of Mix Shader that takes the whole materials (which can be easily named) instead.

I saw this question, which only answers the question of naming the node group in the outer group.

Nodes have a name (unique - you shouldn't need to worry about that if you don't plan on using the python scripting API) and a label which can be shared among many different nodes. Node groups are "instanced" via node group nodes, which have a Node Group data block as a mandatory parameter. Here you re-labeled the node, not the underlying node group. Click in the field inside the node group to rename the underlying node group.

Alternatively open the right hand side panel with N or clicking on the arrow in the top right of the node editor, expand the Properties subpanel and change the name there.

No, it is not possible to access external material outputs inside other materials.

to clarify for posterity: by "click in the field inside the node group" you mean to change the  text that's "My Node Group" on the screenshot. I assumed that by changing that I would be changing which node group I'm using, but it's working as you suggested, only changing the name of the underlying node group. Thanks!

Ups right yeah I meant clicking on the white label on black background, not the material icon with the dropdown arrow. Cheers


text:
Affect only locations in geometry nodes
I'm trying to do an assembly animation where there I start with elements of a collection scattered and they progressively join the final object.
To start, I would like to change the locations of my objects as if I was scaling them away from their common center, but without affecting the scales of the objects; only locations: in the regular layout tab this could be done with Options > Affect only > locations.
Is it possible to do something like this in geometry nodes?

To solve this I put the pieces into a collection in their final location. Then Created this node tree

EDIT: You can replace the position node with a noise node connected to vector math node subtracting 0.5 to have them scatter randomly.
If you want your pieces to not move towards the grid origin you can add any arbitrary location to the position. Here I've created an empty that lets me change where the center is.

how does it work? shouldn't "position" correspond to an origin of the (invisible) "Cube" object (so scaling it would scale differently when placed in different places in the world, and the number of vertices in there won't match "geometry")? Why do you need to "separate children"? How could I spread them in the XY-axis more than in then in Z-axis?

When you feed in a collection it treats the collection as the instance. So instead of a point or edge or face its the entire collection. We use separate children so that it treats each member of the collection as an instance.
The caveat is that each members location needs to be unique. Otherwise this method won't work.

When we use the 'Position' node it will scale from the origin. or (0,0,0). If you want them to move away from a a different place. Add an empty and then add it's position to the node tree. I'll update my answer to reflect that.


text:
Converting "child of" animation to regular location one
I have an animation involving two nodes: there is a character, who takes an object to his hand. Both character and the object have an armature, and there is a "child of" modifier between the bones. I animate the influence parameter of the parameter putting a keyframe of 0 when the hand is far from the object and 1 when it gets close to it. The animation works fine in Blender.
Now, I would like to export the animation to a game engine (Godot). The game engine doesn't understand the child of modifier between the bones, so by default only the character's hand, but not the object, gets animated after importing to the game engine.
Is there a way to transform the animation in Blender to replace the "child of" relationship of the object with a sequence of keyframes copied from the character's bone, such that I can export the animations to the game engine as two independent ones?
I know I can make the animations separately from the start, but it's more tedious than using the child of modifier.

What about Pose > Animation > Bake Action, then in the pop-up panel enable Visual Keying?

Perfect, thank you! Feel free to promote to an answer

Select your bone and in Pose mode go into the header menu > Pose > Animation > Bake Action, then in the pop-up panel enable Visual Keying, it will give you a series of keyframes.


text:
Joining an array before using a displacement displacement map
Stupid question, but here goes.  I am modelling a greyhound track.  I have used an array along a curve to create the track and am looking to use a displacement mask to create tracks in the procedural sand. I am now trying to get my head around how I can actually do this. I have applied the array and thought that the easiest solution would be to make the segments (of the quarter of the track that will be visible in the shot) into one piece, subdivide this with loop cuts and then use displacement. If that is the best way forward I am afraid I am failing at the first hurdle as I can't seem to join the segments.
Undoubtedly I am being dense but any advice would be welcomed.
Thanks
Adrian

Can you be more precise? What exactly is going on when you try to join the segments? Screenshots?

Thanks for getting back to me. I am having problems posting a screenshot but in terms of details.  The track was made by modelling and texturing a section then using an array along a curve.  I have separated a segment out but when I Ctrl R I am only able to add loop cuts to one small segment. When I try any of the merge functions all of the segments disappear.

The fact though that Iam failing to add a screen shot may suggest that the answer is easier than it is in my head.  I could just be being an idiot.

@Adrian - You can add a screen shot by clicking the "edit" button under your original question and then clicking the add photo button [img]https://i.imgur.com/jdFtGMN.png[/img]

I'm not sure what your situation is without a .blend file, or at least some screenshots. The best advice I can think of is: Apply the array modifier before doing anything else. If your going to use a displacement map after, then I guess you'll need to UV unwrap again.
Hope this helps


text:
Animatable Hair?
So this is my first time posting on here, I have some experience with Blender, im pretty good with sculpting and 3D-Modeling but have to get some more knowledge on texturing as well as animating.
However, as a project in school I`m trying to produce an animated short of a few minutes at max. Now i have the model for my main character, did the retopoplogy and so on but i dont know how to create hair with realistic physics for my character that will do its job in animation.
I can only seem to find tutorials on how to do hair that doesnt move, so how do I apply physics to the hair?
If you don`t know but know a good tutorial about this subject a link to that will be enough to help me out big time.
Thanks in advance


text:
Why is it making the same material for two different objects?
When I was working on something, I wanted one of the objects to be solid and the other to be material. But when I finished making the first thing solid when I tried making the other thing material but it turned the first thing into material too. I searched up and tried some answers, but it didn't work, please help me.

You just have the same material on both objects.  Simply create another material and assign it to only one of the objects.  All mesh objects with faces have a material, even if it's just the default Diffuse.  It's what defines how the light paths should be handled.

can you show the picture of the steps, sorry i'm a beginner to blender..

Do both objects share the same mesh?

i'm not sure, i probably do.

If you duplicated these objects after assigning a material to them then they still share the same one, see https://blender.stackexchange.com/questions/23386/how-to-put-a-unique-material-on-duplicated-objects-separately. Your question can have different solutions depending on your exact case, [edit] it and provide more information with screenshots.

It depends on the render engine, what Blender version, and whether or not you're in Object Mode or Edit Mode.  Can you add some more details?

Select the first object, and in the material panel, click on the + button (surrounded by a pink frame in the picture) to create a first material (named Material.001) and change its diffuse color.

Select the second object, and in the material panel, press again the + button to create a second material (named Material.002) and change its diffuse color.
Each object should have a different color.


text:
How do you make this theme?

Hi!
I found this image in one of the topics (Keep sharp edges when using subdivision surface)
I was wondering how can I make this theme!
Thanks!

The theme settings are in the user preferences area. File>User Pref, Themes tab

You can make a theme from the Themes tab of the User Preferences (from the File menu).
From the "Presets" drop-down, pick a base theme, and then just start tweaking! You can see the results immediately, and when you're done, you can hit the plus button next to the Presets box to save your theme.
On Mac, you can find your saved themes in ~/Library/Application Support/Blender/<version>/scripts/presets/interface_theme (hit Shift+Ctrl+G, paste it in, and put in the correct version).
(On Linux, it's probably somewhere in ~/.config, and I've got no clue where it is on Windows. If someone does know, please edit my answer!)
The theme in your picture actually looks like the Graph theme, which should be installed by default. You should be able to just select it. (But be sure to hit Save User Settings at the bottom! Otherwise you'll lose your changes when you quit.)
Edit: Fonts are not part of the theme at all. You can change your font in the System tab, by entering a path to a font file in the Interface Font box in the bottom right (of course you can just use the open panel button).

Oh, that's a separate setting, not part of the theme at all. It's over in the System tab—you put the path to a font file in the Interface Font box in the bottom right. I'll edit the question to include this.


text:
Glass object on video
i'm new on Blender 3D and i want to realized something.
I have a video during 250 frames, i just want to add a text object using Glass BSDF Surface material it is possible ?
Thanks for answer.

You can animate visibility of the object.  See: https://blender.stackexchange.com/a/88980/38953

I don't want to delete my object or want the object to disappear, i want it to be glass bsdf during the video

Maybe the language is not coming through well enough.  Please explain more clearly.  You want the text to have a Glass shader and that's it?  Or you want to animate (change) the shader from one to another?

I have a video during 250 frames, so something move. I want to put a text in front of the video and do glass on it. Like this i want to see the video behind the text while being able to read it. Sorry if i'm not well with my english ^^

Or maybe can i put my video on the text too ? maybe that should be an other solution...


text:
Packing Linked Blend Files with textures?
I'm struggling to get a file packed so that I can set up a render farm at my work, the problem I'm having is that the textures are not packing from the Linked files, everything else is working fine from Particle Systems to Actions to rigs everything except the textures.
I found this video by AgenZasBrothers youtube channel
https://www.youtube.com/watch?v=8I81FohzSjo&t=366s
It outlines the process from ensuring you pack the individual library blends first, so I've done that and those files are indeed packed, the file size increases and if I go to unpack them there are files to unpack.  I then go into the main file and hit space bar select 'Pack Blender Libraries' I then pack the main file again and save as a new file but it still has no textures.
I got nothing, please help.
Tom


text:
Problem with double display of meshes and objects in edit mode
When I switch to edit mode, as you can see in the picture, the mesh and the object are doubly visible.

The object is displayed with a little movement represented by bones, so I cannot access the hidden mesh beneath it.
Is there a display switch somewhere?
I may have accidentally changed the display settings without my noticing, as it did not display this way when I edited it before.
If anyone knows how to make the display setting mesh only, please advice.

are you sure that you don't have 2 objects? maybe share your mesh?

Yes, there is only one object. But this object is a "join" of two previously separate objects. Could that possibly be the cause of the problem?

I don't know, could you please share your file? https://blend-exchange.com/

Disable armature modifier in edit mode:

Or enable On cage:

Or use Rest position to disable bone movement temporarily:

Thank you very much! The problem is solved.


text:
Boid physics/ Particles/ The problem of lots of fish swimming backwards
I'm using particle Boid physics to move a lot of fish-shaped objects, but all the fish are going backwards. How can I make them swim in the direction of their heads? Any advice would be greatly appreciated.

Pls provide blend file

Perhaps you've modeled the fish in the wrong direction. Switch into Edit Mode, select all with A, then rotate the mesh on the Z axis by 180° with pressing R > Z > 180 > Return.

@GordonBrinkmann I fixed the settings as you told me. The fishes are moving forward and I am happy. Thank you very much for the clear instructions on how to do this!

@gecko You're welcome. Whenever you are using particles or hair for example to distribute trees or anything and they are pointing in the wrong direction, most likely the mesh is rotated incorrect relative to the object's local axis. Or different from what the particle system "wants", that's why in many tutorials on distributing plants or other objects people often have to rotate their meshes in Edit Mode (or in Object Mode with applying the rotation afterwards).

@GordonBrinkmann Thank you again. One more thing I want to ask about that, is it possible to know if my object is facing the wrong way before I see the results of the movement in the particle system? I feel like I could work a little more efficiently if I knew the steps to take to make an object in the right orientation and the state of Gizmo, instead of just making it randomly when I create it.

@gecko Well, that's quite easy: now that you got yours working you can just take a look at it ;) No, seriously: when your object's rotation is reset so that it's 0° on all axis, then (let's assume it's a fish) the head has to point in the positive Y direction, it's tail fin to negative Y. His dorsal fin should be pointing up in positive Z. So it's forward +Y, backward -Y, upward +Z, downward -Z, right +X and left -X. Just like the world coordinates are aligned.

@gecko But beware: this is for Boids, like fishes. If you use a flat plane, its normal pointing upwards to world's +Z and instead would set the Physics to Newtonian without any randomization on rotation etc., the fishes would spawn facing their heads in +X direction, dorsal fin upwards to +Z. And if you don't use Particles but Hair without randomization, the fish heads would point upwards +Z and the dorsal fins would point in +X direction.

I'm going to summarize what we talked about in the comments to make it an answer: to solve your problem, the fishes are going backwards because they are modeled in the wrong direction. To make them swim forwards, simply switch to Edit Mode, select the complete mesh by pressing A, then rotate it 180° on the Z axis by pressing R, then Z, type 180 and press Enter and tab back into Object Mode.
Now here's an overview about how the orientation on different particle systems work. As a premise, the plane carrying the Emitter has a reset rotation (all axes 0°) and the face normal is pointing upwards in +Z direction. The fish object also has a rotation of 0° on all axes.
To get the fish swimming in the right direction, it should be modeled aligned to the positive directions of the world's coordinate system like this:

If you now create a Particle System > Emitter on a plane with Physics Type set to Boids, the fish will start to swim forward:

But note that the emitted objects are aligned differently "forward" when you use other physics settings. For example, if you use the default Physics Type > Newtonian instead of Boids and make no changes to randomize the rotation etc. of the spawned particles, the fish will be spawned facing forward into the +X direction, with their dorsal fins still pointing upwards.

If you switch the Particle System to Hair, the direction is even more different. Hair is growing in the face normal's direction, which means the fish are facing now forward into the +Z direction, with their dorsal fins pointing in the +X direction:

I think I literally started using Blender "left and right". Your wonderful and clear explanations are very informative. And thanks for sharing the comparison to hair particles! Understanding these small things is important.

@gecko Usually when someone uses hair to distribute trees, flowers etc. a uniform rotation is unwanted and so they randomize them, also if you use Newtonian particles to create something like rain, snow or falling leaves the default rotation of the objects won't matter. It's mostly boids where you realize the birds or fish etc. are moving wrongly aligned, but since the alignment is not the same for different emitter settings I thought I'll give an overview. By the way, it can be that the Newtonian are initially not oriented like shown in the picture, but this changes after baking at latest.


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How to deform the width of an object's opening without losing as much of its shape as possible?
I want to reduce the width of the object's opening just as the green line on the screenshot image below (in this case the animal's eyelids).
However, because the mesh is already complex, it is difficult for me to reduce it smoothly without destroying the shape. Please let me know if there is a way to do this.

Please note the topology in  @Chromarict 's answer, too. If you're animating, and want an easier life later, I would recommend something like that.

@RobinBetts Wow - I've never paid attention to topology before. Thank you so much for letting me know :)

You could try Proportional Editing by pressing O or clicking the second icon from the right on the header near the top middle of the main viewport:

When this is enabled, it makes vertices in an area of influence around your selection somewhat affected by moving and scaling applied to your selection based on their distance from the center of your selection.
For example, if you select one of the corners of your eyelid, you can smoothly adjust the surrounding vertices without moving them all manually. Using a human model I have, I started by selecting a vertex in the corner of the eye and entering grab mode with G. Then I enabled proportional editing with O and adjusted the radius with the mouse wheel.

I then pressed X to only move along the X axis, and moved the vertices over. You could skip locking it to a specific axis if it works better with your eye being angled differently than mine.

As you can see, the vertices nearest to my selection moved the furthest, while ones near the outside of the circle barely moved. This also works for scaling and rotating, so you could try selecting an edge loop around your entire eyelid by alt+clicking an edge and then scaling it with S to see if that works better than moving the corners separately.
Although this method isn't perfect in dense areas, it's definitely a step up from moving every vertex individually. Also if you're having trouble getting things to keep their general shape, try selecting more than one vertex or playing with the radius of influence.

Your advice was very helpful. I appreciate it!


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The problem of cloth objects penetrating each other
I've been having this problem for a while. I've asked about the same problem here before, and I've taken your advice into account, but it hasn't solved the problem. I have tried to adjust the model to make it simpler. Can anyone tell me why? I am a beginner and would be  grateful if you could give me any help to understand how this problem occurs.
What's there:
Here we have two cloth objects (Object 1) that soar by  wind force field.
They both have the same Collision setting and Cloth physics setting.
On the other hand, there's a flat object (Object 2). Which is added only collision setting.
Problem:
When the simulation is played, two "Object 1" soars and approaches "Object 2."  Two "Object 1" avoid "Object 2" when they fly, but two "Object 1" penetrate each other when they come into contact.
I've already tried (but the problem was not solved):

Added Solidify setting to "Object 1."
Enabled self collision setting.
Raised Quality steps of the cloth to a maximum of 80.
Raised Quality steps of collision to 20.

Please see the screenshot images below for a detailed description of each object and what it looks like in a collision.
("Object 2" is currently based on the leather preset in order to reproduce paper).

I was able to solve this problem about an hour after I posted my question!!! :)
The answer to this past question helped me a lot. So thanks you.
All I had to do was select all the "Object 2" objects that existed as separate objects, merge them with "Ctrl+J", add Collision and Cloth again, and enable Self Collision in the Cloth settings. It was a very simple solution and I am very happy with the result.

You don't need Self Collision when the plane doesn't touch itself. Just uncheck Single Sided in the Collision settings so the collision detection works on both sides. Then you don't need the Solidify modifier for the collision detection but just for thickness.
Use default settings for the cloth physics.
Example
Here the topmost plane has a Subdivision Surface modifier to make it less stiff and more cloth-like and a Solidify modifier just to give it some thickness. Self Collision is enabled because it folds when it falls down. It also uses the Leather preset, so it has more mass => less air friction => falls faster.
The other two planes are duplicates but have only a Cloth and a Collision modifier and no Self Collision.
Good settings
Here are the settings, wireframe & face orientation overlay enabled:

As you can see the plane 2 is upside down (red face orientation). This happens when you have [X] Single Sided active in the Collision settings:
Bad settings

Thanks to your more detailed explanation of how it works, I now understand the intent of the advices that I have received from others in the past. The reference animations are also excellent and helped me a lot. Thanks again!


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How to convert a complex curve with depth into a clean mesh without overlapping faces?
I modeled a hexagonal grid mesh of interconnected vertices and edges which I converted into a curve via RMB > Convert To > Curve and gave it a Geometry Bevel depth of 0.25m and resolution of 1 which resulted in this nice thick hexagonal grid shape.

But when I convert it into a mesh with RMB > Convert To > Mesh, it gives me an unclean mesh with overlapping faces as shown in the left image which would give me problems when adding modifiers such as subdivision or bevel. How do I get a clean mesh such as the one on the right or any other clean mesh with connected faces? I got this mesh through manual/tedious editing. Is that even possible or should I avoid this "mesh to curve" and then "curve to mesh" process?

I would only model the inner part of one hex grid element as shown on the right in the 2nd screenshot. And then, create the grid from this part only. Except you want to have it fully procedural and customizable for some reason, of course.

@Blunder hey thank you for your response. Yeah in this scenario that would actually work perfectly, thank you! But I had more complex shapes like this shape in this thread where I had to use the "mesh to curve" then *curve to mesh" process and which yielded into the same overlapping faces problem at adjoining curve vertices.


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Why does the Default Cube's Mesh have a Reversed Vertex Index Position?
The new cubes that are added to the scene via (Add -> Cube) have a reversed index position. I would have to apply  a negative one (-1) scale to all the new cubes so they are consistent with the default cube's vertex position index sequence. Why is that?

i think you have to ask the developers for the reason... ;)

In case you want or don't know, you can enable the Indices overlay option by activating Developer Extras in the interface preferences. The Indices option will be below the Mesh Edit Mode in Viewport Overlays.

@Chris yes i should! Hulifier hey thanks for the info!


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Why does doing a "connect vertex pair" [ J ] of shared vertices of 2 intersecting planes only cut 1 plane?
While I was working on this answer How can I smoothly connect 2 faces with a curve?. I noticed something weird when two (2) faces are intersecting each other and sharing exactly the same vertices. You would have to tap J twice even though on the second tap, there is already an edge connecting them.
Here's my setup: Make sure you're in Edit Mode and tick the Auto Merge checkbox and the Split Edges & Faces checkbox under Active Tool and Workspace Settings. Then have two (2) planes intersect each other which will automatically create two (2) additional shared vertices.

Notice that on the first J only 1 face gets cut. I would expect both faces to be cut or else we wouldn't know which face to give priority while cutting. And even though there is already an edge between the vertex pair, tap J again anyway, which will then cut the second face. I'm not sure if this is intended behavior and what the reasons behind this are or should I report it as a bug?

Interesting.. (the 'Split Edges & Faces' tip in the previous answer is great) . You don't need the re-selection for it to work; a quick 'JJ' does the job... Personally, I'm OK with a single key-press representing a single operation, and thinking of 2 cuts as 2 operations.. but not knowing which is which is maybe a bit dicky,,

yeah exactly i can just do the double j tap, anyway there would never be a scenario wer i needed just one j tap


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How do you sculpt a texture into a 3D Model (i.e. stencil overlay)
How do you sculpt a texture into a 3D Model? Such as using a stencil in 3dCoat as shown below

Probably this could help you https://www.youtube.com/watch?v=YNxmh5UVi08

No, I tried to make this clear. I am not looking to texture a 3d model. I am looking to take a texture and literally sculpt out cracks etc into the geometry using the texture as a stencil

Set the texture mapping to Stencil in the brush settings

answer: https://imgur.com/6OM7STb

Load your texture in Properties panel > Texture.

Switch your 3D view to Sculpt mode.
On the left (tools panel), choose the Draw brush.
Open the N panel on the right of your 3D view and click on the Tool tab. Open your texture so that the brush will use it, choose Mapping > Stencil.

The texture should be displayed on the bottom left corner of your 3D view, it might be very transparent for the moment. In the same panel as before, under Display, increase the Texture Alpha if necessary. Enable Dyntopo if your object is not high poly enough and choose the adequate Detail Size, or give your object a Multiresolution modifier.

Move your texture in the 3D view: RMB to move, Shift RMB to scale, Ctrl RMB to rotate. Paint on your object.


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2 Colors on 1 object
After some tutorials this is my first own object in blender -a race track for unity. The main object should be white, but the road itself should be red, without creating 2 objects.
So I marked all the road-faces and assigned them to a new Material. But somehow the white color shines through depending on the camera angle.. even if I remove the white material, the grey default color also shines through. If I separate the road to an own object, it works fine -but I don't think that this should be the solution :/

(Object Mode)

(Edit Mode)

(Face Orientation)

(Unity)

I know this page already & actual I did the same thing mentioned there. I successfully applied already 2 different materials to the object. But like you see.. it seems to be buggy because the color underneath shines somehow through. Even the default grey color shines through..

from the screenshots it looks like duplicated faces / vertices overlapping

You need to slightly offset the road along the Z axis. This is what is called "Z-fighting" where the renderer does not know which material to render because the faces are overlapping, so they are randomly rendered on top of another.

But for this I have to split the road from the rest, right? So I have in the end 2 objects.  I mean, right now the object is hollow, so on the top there are "just" the road faces. Underneath there is no other face.

Well, I don't really understand how your model works. From what you are saying you might have double vertices. Select all your vertices in edit mode and choose right click > Merge > By distance. If that doesn't solve it would you mind sharing your blend file ? https://blend-exchange.giantcowfilms.com/

awesome thanks!!! The merging of vertices helped! So it seems, I had multiple faces overlapping each other... Also I checked, my starting part of the track had already doubled vertices.. I can't explain exactly how this happened, but nonetheless thanks a lot, problem is solved :)


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Blender moves and reizes my objects
Blender resizes and moves my objects when I close the file, and I open it again.
Also when I try it to render it, it gives a different picture than in the object mode.
Why and how could I solve this problem?
For example
In Object mode:

Rendering:

It is doing it all the time.

You have accidentally set keyframes to the location, rotation and scale of the objects. They can be easily deleted by switching to the Animation workspace, then in the Dopesheet right-click to open the context menu and select Delete Keyframes.


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Why is my camera irregular and how do I fix it

I need it to match the grid's width for a shot.
I don't see anything wrong with the render:

Not sure what you mean by "irregular"...? If you want no perspective, set the camera type to ortho.

In the Object Properties, under Transform, make sure Location X is set to 0.


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Why does it render smooth?
I know I did by mistake a key combination in sculpt mode but i dont know how to reset this. I just want a low poly image of this tiles:  but in sculpt mode and the rendert image (not render mode!) are smooth like u see in the picture

I know I did by mistake a key combination in sculpt mode....

From looking at your image, and from your description, it sounds like you most likely pressed Ctrl+2 or otherwise activated the Multi-resolution Modifier while sculpting.
This modifier has separate preview/ sculpt and render settings much like the Subdivision Surface Modifier as seen in the left column of the modifier settings.

From the manual:

Levels
The left column of settings control the general quality generated by
  the modifier in various contexts.
Preview
Set the level of subdivisions to show in Object Mode. Sculpt
Set the level of subdivisions to use in Sculpt Mode. Render
Set the level of subdivisions to show when rendering. Quality
How precisely the vertices are positioned (relatively to their theoretical position), can be lowered to get a better performance when
  working on heavy meshes.

If the render and preview amounts do not match, you will see a different result when rendering, although performance may be improved with lower sculpt/ preview amounts in some cases.
In your specific situation however, needing a low-poly object you can simply remove the modifier. (click the x icon)

It was the Multi-resolution modifier, thanks!

Consider to accept the answer, if it did solve your issue @cabriocat How this site works: https://blender.stackexchange.com/tour


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Can somebody explain me why I see this black thing everytime I try to viewport shading?
I have been having this problem for few days and I can't fix it, can somebody explain me or at least fix this?

You have Image Texture nodes, but in those no texture selected. Thus resulting in the shaded view showing a black object.
Solution:

Either disconnect the "Image Texture" node and set a color, or
Click on the little icon left to the "New" button on the "Image Texture" node and select a texture already loaded in Blender, or if there is none yet,
Click on the "Open" button and navigate to the texture you want to use to then load it. Dragging a picture(texture) from the system explorer into the node area will also generate a "Image Texture" node.
Last but not least, if you want to paint a texture yourself, you can click on "New" and create a new texture with some parameters to be created and selected in the node. This means though, that you will most likely need to paint or work on that texture otherwise before you have some results.

That said, i believe the most likely case is that you may want to use a texture and just did not yet load it, so in that case you may want to go with option 3.