text:
How to find unneeded/useless vertices
In some of my Blender files there are unneeded / useless vertices.
The screenshot shows this:

The vertex is not needed. Is there a way to search the model to find such vertices?
Edit:
This section relates to the answer given below which is is a good solution.
I simulated a poor 3d model as show in the picture (The selected vertex is the culprit I am looking for)

Simply using Shift + G > Amount of connecting edges locates the poor vertex

The area around it is not selected, so it stands out. In this case I would manually delete the vertex and re-connect the vertices together in the surrounding area to fix this problematic area.

You can try to select all the vertices (or needed parts), then X and 'limited dissolve'. Have a look at the option of the operator (bottom left) after that.

OK, that looks like the option that I was looking for.

Enter edit mode select one such vertex like you did in your screenshot and press Shift + G > Select Similar > Amount of connecting Edges
Exercise some caution as this will automatically select all vertex that belong only to two edges as the selected one. Be sure to inspect all the selected vertex to make sure no desirable corner vertex are mistakenly selected.
Then you can safely use X > Dissolve Vertex to delete the non-destructively

This is a good solution.

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


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Strange color noise in diffuse direct at material edges
I am getting strange color noise in my diffuse direct passes. It shows up at the edges of the model, and at material boundaries on the model. It happens even with basic shaders (just diffuse mixed with gloss) but does not happen when diffuse and gloss are both gray, even with different values (or maybe it happens but just isn't visible.)

I have never encountered this issue before, so I am very perplexed.
Debugging so far:
Does not seem to have anything to do with lights or edge settings.
Happens with both normal and toon shaders.
Only appears in diffuse direct, not glossy direct (or just isn't visible.)
Is not visible in the combined pass, but makes problems when working with Diffuse Direct in the compositor.
My main guess is that it has something to do with a render setting in Cycles. Anyone else run into this?
Other render settings:

Happens regardless of resolution
Samples: 2,000
Clamp: Happens regardless of clamp value
Pattern: Happens with both Sobol and Multi-Jitter
Shadows, Reflective Caustics, and Refractive Caustics are all on
Filter Glossy: 1.0
Bounces: 5 max/3 min, Diffuse 4, Glossy 4, Transmission 12, Volume 0
Film: Exposure 1, Transparent, Blackman-Harris, Width 1.5
Post Processing: Compositing and Sequence on, Dither 0.00
Turning down the Width for Filter type under Film reduces but does not eliminate the problem.

Upload a blend file so that we can experiment on it.

@10Replies I can't upload the blend as it involves work for a client (also why picture here is so small.) I will try to replicate problem in a fresh file.

Can you provide more info like system specs and render settings (CPU, GPU, AMD, CUDA)? Also better screenshots of material/pass settings would help.

@DuarteFarrajotaRamos I am using a Titan GTX on Windows 7 and Intel Processor, but this shouldn't have anything to do with it because a) it doesn't happen in other projects and b) it only happens in certain circumstances here. I'm adding overall render settings to the original question.

Then you better narrow down those 'circumstances' or provide more details otherwise it's impossible to diagnose with this little info

Diffuse direct is not meant to be used by itself, it is always supposed to be multiplied by diffuse color before being used to affect other types of lighting. Does the issue persist if you multiply the pass by diffuse color?

@JtheNinja the problem does go away once I multiply by color. However, there are things I want to do in the shadows that this is interfering with. And regardless of what is intended for the passes, this is not normal behavior.

What exactly are you trying to do? By that I mean, please edit your question with an explanation of what you're attempting to do in the compositor, what result you're getting, and preferably a screenshot of your node setup.

@JtheNinja I am doing some RGB curves, texture mixing, and displace on only the shadows. None of this is particularly relevant to the question as the problem exists in the base pass, it is not be caused by my node setup.

See: https://developer.blender.org/T48147 The problem is most likely in your composite setup (such as an operation not being applied to diffuse color, or diffuse color being multiplied in at the wrong point). Without a node setup, we can't help you with where.

This behaviour is correct and necessary, since the color pass will get premultiplied later. See linked question for how to composite the color, direct and indirect http://blender.stackexchange.com/questions/64319/firefly-halo-on-glossy-pass/64322#64322

@Leander Thank you. Do you want to put this as an answer?

Glad it helped. The question should be marked as a duplicate. (No extra answer.)

source: Stack Exchange

authors: Никита Кудряшов

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

sort: votes


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Paint over Render in compositor
I am trying to figure out the proper workflow setup to manually paint onto a render within Blender.
I want to:

Render an Image
Run it through a compositor node setup
Be able to manually paint on it afterwards, but non-destructively.

For it to be non-destructive, I need some sort of new layer. I want to be able to paint on top to add more light/shadow, lineart, color correction, etc. My first thought was to make a blank image and alpha-over it over the whole render in the compositor, and then paint on that. However, I don't seem to be able to have it overlay the render visually while painting, so I can't tell what I'm doing (the image editor showing the render is in one window, and the paint mode with my new image is in another, but I need them superimposed.)
I could also make new images or masks and combine them with the render in the compositor, but then I end up limited by mix modes, and still have the problem of super imposing over the render. If I just wanted to darken areas, then I could make a new image and combine it with multiply in a mixRGB node. But if I want to also lighten some areas, change color in others, etc, then I end up needing tons of new images.
Is it possible to make a proper multi-layer painting setup in Blender similar to what you can do in Photoshop or Sai? (I could take it into Photoshop or something, but I want to see if I can keep it all within Blender.)

Possible? yes. Good idea? no.

You can take a look at Ndee's Bpainter addon, as it has the best photoshop-like abilities for painting in the 3d view. It is a paid addon, however, but I find it affordable and worthwhile. https://www.patreon.com/andreasesau/posts

It's hard to gauge how complex your task is but have you considered substituting (non-destructively) the materials/textures of the media you wish to paint over?  A previous question gives the details here - http://blender.stackexchange.com/questions/74987/how-to-animate-a-superhero-zap-into-his-super-suit-in-blender/75005#75005

You might also try my work with Patrick Depoix on EZDraw addon - I have been using it for my own work and it uses the blender render texture slots for layers. I have only made a few videos on the first version as Artist Paint Panel, but here is the current version https://www.youtube.com/watch?v=Pdr3fM4DAuc&t=190s

What I would try is: separate out your render passes and then recombine them in a way that you have the glossy passes isolated separately from everything else. Because when you paint you will paint the highlights last, on top. I don't think you'll need as many layers as you think, based on the workflows of digital painters I've seen on YouTube. As for doing this all in Blender, it might not be worth the hassle, since image editors like Ps, Krita, or even GIMP are probably better suited for this task. I admire your Blender-purist ambition though!

By creating a new image in the UV/Image editor and using a mixRGB node to mix it with the render layer you can get the same result as a photoshop layer. Each image created and mixed in using the compositor will correspond to one layer in PS. You will find each blend type of the mix node will correspond to a layer mode in PS. The alpha of the image or a separate image can be connected to the fac of the mix node for a layer mask. We can also create and animate a mask. While the render result or viewer node preview doesn't update as you paint, it does update after you complete each stroke.
So while we don't get the simplicity of the way layers are presented and edited in the same location, we can get the same end results, even with some extra flexibility in how they are combined by using blenders compositor node system. The other factor to differentiate PS and blender will be the amount of painting tools available.


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Rigorous procedure followed by shape keys to merge models
Good evening, I would like to know how the Blender shape keys realize the merging of two 3D models after the shrinkwrap modifier has been applied. What is the algorithm exploited? Does it use interpolation? Are there refernces?

Hello. What do you mean by "rigorous"? Shape key is linear interpolation... but what is the question: how to merge two meshes (from same object) as shape keys?

I don't understand how the vertices move from one position to the other, but maybe with your answer it is more clear. After I use the shrinkwrap modifier the mesh topology of the two models become the same. For this reason, by changing the "value" setting, thanks to linear interpolation, the vertices are displaced from the positions they have on the basis key to the one on the target key. Is it right?

So... you want to apply the modifier as shape key, that's it? Yes the vertices are linearly displaced from the basis to the shape key.

I can use the modifier ahah. My problem was to understand the theory behind it!!!

I've written that the shrinkwrap modifier does not change the topology of the "shrinked" model, but it just projects all the vertices on the target surface. In this situation I've not a 1-to-1 correspondance of the vertices. This is the reason why I don't understand the linear interpolation that Shape Keys realize

And I don't understand what you mean by shape keys here, except if you're talking about applying the modifier as shape keys. Shrinkwrap in itself is not a shape key. So your question is about how shrinkwrap works? Or?

I've used the shrinkwrap modifier, than I have applied it as shape key. Now , going in Object Data Properties, I' m modifyng the Shape Key Value obtaining the morphing from one model to the other. I hope that in this way it is more clear. I just want to understand what is the logic the software used to move the vertices.... I thought the topology was the same, but it is not like this

ok, this is clear now. Thanks. I confirm that changing the shape key value is simply linear, but per vertex/for each individual vertex (not for the whole mesh in itself). Maybe provide an example in your question if something is more specific

Let's take an example. A plane projected onto some steps using shrinkwrap modifier:

We apply as shape keys.
And now, here is how the plane moves for several values for the shape key:

As you can see, this is linear.
If a vertex goes from X when shape key is 0 to Y when 1, then its position is:
X + <shape key value> * (Y - X)

Note that we take here shrinkwrap example, but shape keys go the same whatever the way they are produced from.

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


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Custom search data to UILayout.prop_search
I need to create a searchable material dropdown that excludes grease pencil materials. However if I do it like this
row.prop_search(item, "material_selector", bpy.data, "materials")

then all the materials in scene get included in material dropdown.
How can I give custom search elements to prop_search method instead of generic bpy.data?

Use a pointer property with a poll.
To distinguish a regular material from one for a gp object there is the handy attribute Material.is_grease_pencil
Similarly to https://blender.stackexchange.com/a/159155/15543 and using a poll method https://blender.stackexchange.com/a/101303/15543
Will narrow down the selection based and offer the same choices as the regular material drop down.
import bpy
from bpy.props import PointerProperty

def poll_material(self, material):
    return not material.is_grease_pencil

class TEST_PT_layout_panel(bpy.types.Panel):
    bl_label = "Prop Panels"
    bl_category = "Test Panel"
    bl_space_type = 'PROPERTIES'
    bl_region_type = 'WINDOW'
    bl_context = "scene"

    def draw(self, context):
        scene = context.scene
        layout = self.layout

        col = layout.column()
        col.prop_search(scene, "prop", bpy.data, "materials")
        #or
        col.prop(scene, "prop")

def register():
    bpy.types.Scene.prop = PointerProperty(
        type=bpy.types.Material,
        poll=poll_material,
        )
    bpy.utils.register_class(TEST_PT_layout_panel)

def unregister():
    bpy.utils.unregister_class(TEST_PT_layout_panel)
    del bpy.types.Scene.prop

if __name__ == "__main__":
    register()

Kinda related:
How to populate UIList with all material slot in scene? 2.8

Never got notified about your comment here (coming from https://blender.stackexchange.com/a/203312/31447) after reading your answer. I feel honored, thanks! However, I guess I'm too grumpy for that and don't like the lazy peps just asking something... I honestly was in hope you would participate. Regarding python questions as well as flagging dupes the reality is that nothing really changed after the election -> your vote, duartes vote, my vote, which is a bit disappointing IMO. We will see, hopefully that will change. Cheers

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


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I would like to simulate spiky ocean waves from an old animated cartoon
Recently I watched a German movie called Käpt'n Blaubär: Der Film. I loved this movie as a child and when I re-watched it I was really impressed with the wave physics. They are unrealistic and over the top spiky but that's what I like about them. I have attached a YouTube link where the waves can be seen. My goal is to recreate them in Blender, and although I have some modeling experience, I have never worked with physics and liquids so I do not know how to approach this project. Is there any modifier I could use for this or maybe a displacement map? I would appreciate some help with this!
https://www.youtube.com/watch?v=_3yK-LWCCQY&feature=youtu.be

Would this be close enough?

How it looks when animated:

The Ocean Modifier creates a pretty realistic wavy sea, and the Simple Deform modifier enhances the vertical component.

Hi, sometimes even youtube links go down, would you care to elaborate on the answer? Answers that rely on links are generally discouraged, the link should be supportive of the content in the answer. Thanks :)

the link is merely showing the moving ocean effect (since I can't upload a video here), it's not the whole answer.
the actual answer is clear enough, I hope - two simple modifiers. But I guess I can improve that.

@CBarr only as an animated gif.

fixed it!
I didn't know GIFs could be used as images, cool.

@CBarr much better:) thanks for the edit


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Blender Eevee render is fine. Cycles messes up my mesh!

This is what its supposed to look like (Eevee)

Huge Lighting improvement. that's what I like. But now The floor has bloated up! (Cycles)
I Think the it might be the material screwing with things or maybe my UV placement.
i import my textures from CC0 using lily surface scraper.
its weird because the pillars are fine just the floor doesn't want to accept the texture
IDK
It Seems no one else is having this problem
Please help
I Will include the BLEND file!

This is pretty common. You need to lower the displacement node scale

@Gorgious How would I do that? Do you have an example?

https://www.youtube.com/watch?v=RRilLLyyn1Y&list=PLa1F2ddGya_-UvuAqHAksYnB0qL9yWDO6&index=16&ab_channel=Blender

As Gorgious said, take a look at the floor material, there's a Displacement node plugged into the Material Output, it creates these bumps, so either lower down its value or unplug it


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How can I move many vertices with few dots?
I was looking some blender guides on internet and I've found this
So I was wondering how can I do the same thing ? By that I mean manipulate this object that has so many vertices and faces with these few selected dots ?

Create those few vertices and use Mirror modifier and Subdivision Surface modifier. BTW search image by Google https://zestedesavoir.com/tutoriels/655/debutez-dans-la-3d-avec-blender/601_les-bases/2866_tp-modeliser-un-petit-personnage/

This is standard subdivision surface modeling. The very general idea is that you create a base mesh that is comprised of very simple geometry, and then add a subdivision surface modifier to increase the amount of detail or mesh density.
In your screenshot, the "few selected dots" is the low poly base mesh. The part that has "so many vertices and faces" is the output from adding the subdivision modifier.

To edit the mesh, you just manipulate the low polygon base mesh, and the high resolution version will conform to your edits.
Here is a fantastic tutorial that covers the basics of subdivision modeling:
https://www.youtube.com/watch?v=xmIIIcCUm8E

While Subdivision modelling is generally the recommended approach, if you already HAVE a complex, high resolution geometry here are two approaches you could take.
The longer method is to manually build a low poly mesh approximating the form of the high poly one using retopology or other ways to stick the low poly form onto the right places.
A quicker method that you should also be aware of to try is the Lattice object.  If you have a high poly mesh such as (for examples sake) a Suzanne, and create a Lattice object, you can parent the Suzanne to the Lattice (using the Lattice Deform parent type, which creates the modifier for you), and the lattice's vertices start affecting it as if it were a low polygon cage like a subdivision surface.  You can adjust the lattice's size, resolution before the parent operation to fit it to a mesh you already have.   Unfortunately the lattice cannot be reshaped to fit the mesh better, so it's a faster but less convenient method in many cases.  However, you can animate a model passing through a lattice deform which can be useful in specific cases.


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How to give each hair particle system in one object its own color
How to give each hair particle system its own color (ideally from a texture)?
Example: an object has two hair particle systems, one which is blue, second which is red. The mesh underneath is a third color or one of the previous two (but one can achieve that by assigning a material in edit mode to all the faces in the mesh).
Is there a way to assign a material to a particle system? Multiple hair particle systems all seem to only be using the very first material in an object.
Vertex groups can control so much, but not what color the hair particles have. There is a "textures" tab in particle settings, just below the vertex groups, but it doesn't seem to do anything color-related.

You need to create 3 Material Slots and 3 Materials for your emitter object (1). In  this example, Blue and Red aren't assigned to any face.
For each Particle System, under Render/Material (2), select the desired material in the list.


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Auto Weight Ignore tooth
I apply auto weight i think it look ok, but it not ok. My character tooth move without character.

do you mean the opposite? the teeth don't move? if so, you need to select the teeth in Edit mode and assign them to the good vertex group, the one with the name of the bone that is supposed to move them

I not sure what you mean select teeth. All character is one mesh.

go in Edit mode, put your mouse cursor over the teeth, press L to select, then in the Properties panel > Object Data > Vertex Groups, select the vertex group that they are supposed to be part of and press the Assign button


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sRGB footage in tracking clip panel looks washed out, unless the color space is non-color
If I import footage into the tracking clip panel from a default Blender project I have noticed that even though the color space is set to sRGB it looks very washed out unless I switch it over to non-color!

Video is never Non color. Hi-Def video is usually recorded in Rec709 color space, it uses the same primaries than sRGB, so the correct setting is sRGB, but might need a slight gamma correction.

it was generated in a professional or semiprofessional camera then it could be in other space, like Bt 2020 or a color space and log determined by the manufacturer (Arri, Red, Canon, Sony, Panasonic, blackmagic, etc). Images will only look correct when they are using the proper color transform that converts the data to the display color space. More information is needed to help you, as we can't guess what camera was used, only you know that. But Non-Color is not the correct setting.

@susu it was ripped from YouTube so I assume it's sRGB.

Also make sure that the color management is set to sRGB as well, and not to Filmic. read: https://blender.stackexchange.com/questions/176754/blender-image-output-is-greyish-and-not-white/176760#176760 https://blender.stackexchange.com/questions/175835/world-displays-as-grey-even-though-set-to-white/175844#175844


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Push vertices outside of other object/setting ceiling to location of vertices
I am looking for a way of creating a sort of Z ceiling for the position of my vertices, but cannot find anything by searching. I am most likely not knowledgeable enough to know what keywords to search for.
I have a plane with a wave modifier appended.
Above it I have another plane.
I want the waving plane's vertices to be capped/constrained by the above plane. So that if a waving vertex tries to go above the Z of the above plane, it will be capped and placed on the above plane's Z.

You want to use the shrinkwrap modifier and constrain it to a postiive/negative axis.

Can use a "schrinkwrap modifier".

Using the following settings:

Projection, on the plane surface, along Z axis, for the Suzanne parts that become negative relative to it.


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How do I get my GPU to start running in blender?
I have a graphics card and when I'm in blender, it does not show up as running. I switched the render to GPU, but it gets greyed out and still uses my CPU. Im wondering how to make it so the render uses my GPU instead of my CPU.

What kind of GPU do you have? Some are not compatible with GPU render.

Go to Edit>Preferences>System The at the top of the window you should see cycles render devices. Select CUDA and then check the devices you would like blender to use.


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Issues exporting animation to FBX in Blender 2.90
I am pretty new to blender and so I started off simple with this wolf animation. The problem occurs when I try to export to FBX. I have been searching the internet for a day or so now but no solutions have worked. My weights are all 1.0 for each bone and I have followed the export methods of countless forums.

My biggest clue for my problem is when I go into edit mode.

As you can see, my mesh (and also rig) is very tiny compared to the object mode. I am at a loss for how to fix this though. My limited experience with this and UE4 tell me it is some small setting I am glossing over. Any insights would be amazing, thanks!

Did you apply (ctrl A) the scale of both mesh and rig before exporting? BTW there's no need of having all weights at 1.0. Be aware that applying scale should be performed before animation: every previously made animation will break.

Hey @joshsanfelici, I did apply the scale to the mesh and rig before exporting. And weights were already at 1.0 but I read from a previous post that differing weights could produce something similar to what I am seeing.

I think it's a problem of scaling, because every bone that have only rotation informations do their job, while those having also loc infos appear to have a bigger influence than they should (you can try to scale on Y in graph editor every loc related keyframe). The animation seems to have been done before correctly applying scale. Try also to set the armature in rest pose, then apply the armature modifier of the wolf, then add a new armature modifier pointing at the rig (you will not loose the weights in this way).


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Why my faces were created at an angle?
I created edge loop cut and extrude this 2 faces which Y constraint. But the side face is slanted a little but. WHy this could have occured?

Hello, it's hard to understand, slanted on what axis? Are you in othographic view? Maybe share your objects if it helps to understand: https://pasteall.org/blend/

Hi Moonboots. Thank you. I solved it. I scaled them on the axis to 0 and it become vertical edge :)

You simply made a mistake somewhere and moved something that you did not notice. That's it. There is no conspiracy or magic here. This happens all the time to pretty much everybody.

Ok. I will try recreating faces.

I scaled edge on the relevant axis to 0 and it become vertical.


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why there is no difference in render after denoise is on?
Why there is no difference even though denoise is on? Am I doing something wrong?
The only difference (very minor), I can see is on the reflection of glass at bottom. Also, I don't see it as a good quality render, any suggestion to improve are welcomed.
Render Settings are:
GPU ENabled
Tiles 256 x 256
Sampling: 250
Denoising: Open Image
The first image is with denoising on.

This image is with denoise off:

However, when I see viewport with denoising off, I see much noise!

In 2.9 versions denoising is enabled by default... I'd suggest share your settings and version of blender.

I am using 2.9 and I was able to check and uncheck denoising too. I shared most of the settings. Resolution was 960*1020

Let me give you a subtle hint of one possibility why this might happen:

What you may have noticed in the picture is that there are different sampling settings for the render and the viewport.

...but what could be the reason for having the same result with "denoising"on and off?

This might be when you take a clean image rendered with enough samples for it not to have much noise and try to denoise it. The difference is minimal in that case because the denoiser does not have much noise to remove. In your specific case the difference is there and I would not even call it that small. Let's actually look for the difference in the images you have provided for a minute:

but what could be the reason for having the same result with "denoising"on and off? Yes, for the viewport thing you are right. I tested :)

There is a difference. See the updated answer with a gif.


text:
How to create 'Jeep stick shift' shape?
I have been redirected to Stack Exchange from Stack Overflow to ask my question.
I am relatively new to blender and have been working on my first blender project for a while now. I have come across this shape and I am kind of baffled at how I would go about creating it.

I have no trouble creating the actual stick except for that weird shape below the stick that looks almost like a rounded pyramid.
Thank you for your time and any help would be appreciated!

https://blender.stackexchange.com/questions/118460/whats-the-fastest-least-destructive-and-most-scalable-way-to-create-a-step-py/118467#118467

Create a plane in edit mode.

Then, scale it along the y axis until it is slightly longer than it is wide. Exit edit mode with TAB and then press CTRL + 2 to add a subsurf modifier. Adjust length and width with the scale commands until it looks like the base of the "pyramid". Add edge loops by pressing CTRL + R and sliding to make the sides flatter. Scale the two end edges to make it rounder. See the first picture for the end result. Then, press I to inset faces into the shape. Use extrude (e) and scale (s) to build up the shape. Remember, you can use e+s to extrude the shape outwards. My example isn't awesome, but I also didn't pay a whole lot of attention to proportions. You could easily do better than me! :)


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GLTF to OBJ Textures/MTL not exporting correctly
I have several models in GLTF format and want to export them to OBJ, of course with textures / MTL file.
I import the GLTF files using "KSon's GLTF Importer" addon. In Blender, they get displayed correctly, with the textures. When I export them to OBJ, an MTL file gets written, but in the MTL file there are no paths to texture files, just some materials defined. "Write Materials" is checked in OBJ-export settings.
Any ideas? Any help ist appreciated.
Note: I am very new to Blender

Might be worth trying the official gltf importer in Blender 2.8.

Tried it, got the same result. Correctly displayed in Blender, exported to obj, mtl gets written but no textures in it.

https://blender.stackexchange.com/questions/57531/fbx-export-why-there-are-no-materials-or-textures

Just to avoid misundestanding the mtl itself doesn't contain any textures, it will just reference them. If you open the file in an editor you should see entries named map_Kd followed by the file name. In order to open/import the obj with textures in another software the .obj, .mtl and all texture need to be in the same directory.

yes, i know that. the mtl file looks like following:
`# Blender MTL File: 'untitled.blend'
Material Count: 2
newmtl 07___Default
Ns 323.999994
Ka 1.000000 1.000000 1.000000
Kd 1.000000 1.000000 1.000000
Ks 0.500000 0.500000 0.500000
Ke 0.0 0.0 0.0
Ni 1.000000
d 1.000000
illum 2
newmtl lambert2
Ns 323.999994
Ka 1.000000 1.000000 1.000000
Kd 0.800000 0.800000 0.800000
Ks 0.500000 0.500000 0.500000
Ke 0.0 0.0 0.0
Ni 1.000000
d 1.000000
illum 2)`

sorry, dont know how to properly format as "code".
There is no "map" paramter. The model contains at least one texture (jpg)

Is the texture packed into the gltf or is it an extra file? If it's the former you'll have to save the texture to disk first and assign that one in the material before exporting to obj.


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My painted texture has disappeared
I painted an object, but the texture suddenly disappeared. I didn't save the texture before but I didn't close blender either. please is there any way to have the texture back?

Please add some more info about your specific situation, based on what you've supplied so far it would be very difficult for us to narrow down what you're missing.

The texture file may not actually be gone. One way to check is in the Outliner, where at the very top left, you can select the "Blender File" display mode to see the entire contents of your project. Expand the "Images" category in the resulting list to see if your texture still exists in the project.

If you see it, then it probably just got unlinked from your object. In that case, you definitely don't want to close Blender, or the texture really will be lost. You would want to re-link it to your object in that case. You can do this by clicking the link button to the left of the current node name in either the UV Editor or the Texture tab of the Properties panel, under the Settings section.

Once re-linked, you still need to manually save the texture or else you'll still lose any progress made on it since it was first created.


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how do I render my animation and the rest of the scene seperately
I have a scene that scatters over a million grass plants on a landscape and also an animated river that runs through the landscape. As the river is the only thing hats animated is there any way I can render the landscape and grass once instead of over and over each frame along with the water?

You can render the first static frame, save it as image and then plug into Alpha Over node in compositing.

Disable animated river. Uncheck Disable in Renders icon in the Outliner tab:
Render only Statics and save on disk:
Enable the river in Render and disable all statics (same as 1)
Check Fill>Transparent (available for both Eevee and Cycles):
Set up compositing Alpha Over node:
Render the river. Compositing will be executed for each frame of the animation:

thanks but because the river water is inside the the river bed on the landscape the wtare seems to be floating and doesn't look right

You can split what's closer to camera than the river and what's further into two main objects, render them separately and use two Alpha Over nodes. Nodes: https://i.sstatic.net/UgOnZ.png Result: https://i.sstatic.net/8AAEq.gif If I misunderstood you could you please show an example of your floating river?

some part of the water should be hidden behind landscape, how to add image in comment?


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How can I use the "Fill" in texture paint on only a single face instead of the entire uv map?
Kinda like what I did with the red in the image, but more precise with the drawing. Also I'm pretty new to Blender so don't expect me to know everything yet

Might be easier to isolate the face in the 3D viewport in edit mode and paint directly there

If all your "painting" is per face you can use vertex paint mode and paint per face (instead of vertex). https://blender.stackexchange.com/q/80205/2214

select your object

choose texture paint from the menu

tab -> edit mode

choose "face select mode"

select the faces you want to paint on

tab -> texture paint mode

click this button: paint mask

paint what you want -> now you just paint on that faces you selected

you can select the faces in the texture paint view too...just tap on select and choose your favorite selection mode

you can check a tutorial video here:
https://youtu.be/TYq49SLlot8.  (just be a little bit patient, my internet is not fast)


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Auto Normals by default
Is it possible to turn on Auto Normals by default when creating new objects in Blender? Now you need to apply it manually for each new object in the scene when switching to Smooth Shading and it's not very convenient. Maybe there are some ways to do this by default?

Subscribe to msgbus

Very similarly to answer to Origins to the down of the object by default can check when a new object becomes active when it is the result of being freshly added by an add primitive operator.
Run this code, and any newly added primitive will have auto smooth on with 18 degrees.

as shown in origins to default, can change up all sorts of things.
import bpy
from math import radians

handle = object()

# make some default value
auto_smooth_default = (True, radians(18))

# Triggers when an object is made active
subscribe_to = bpy.types.LayerObjects, "active" #

def notify_test(context):
    if (context.object.type == 'MESH'
            and getattr(context.active_operator, "bl_idname", "").startswith("MESH_OT_primitive_")
            and context.mode == 'OBJECT'):
        print("Setting auto smooth")
        me = context.object.data
        me.use_auto_smooth, me.auto_smooth_angle = auto_smooth_default
        # set all faces smooth
        me.polygons.foreach_set(
                "use_smooth",
                [me.use_auto_smooth] * len(me.polygons),
                )
bpy.msgbus.subscribe_rna(
    key=subscribe_to,
    owner=handle,
    args=(bpy.context,),
    notify=notify_test,
)

bpy.msgbus.publish_rna(key=subscribe_to)

@JachymMichal It's a bit "hacky" and relies on operator having the idname prefix. Would take some effort to make sure any operator that adds a mesh is picked up.


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Weird drawing lines on donut (Vid 3, level 1 with Blender Guru)
I am trying to make the donut following the tutorial by Blender Guru.
Just wondering why there are some weird lines on my donut before even getting to making the dripping, have you experienced something like this before?
Grateful to have your insights!

Can you update your question with a picture so we can see? I did this tutorial two months ago

So you've duplicated the top half and solidified it to create the bump. Was it before or after this action. Or did these lines start showing after you started pulling the icing to create the dripping effect?

“Weird lines“ is not enough information!  Please add a picture to your question.


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Why is the image not transparent in when I import as a plane?
I'm very new to blender and I'm trying to make a simple character with a 2d face. I was following along with this tutorial (https://youtu.be/YGjwOEMgDGw?t=60) but I can't get my image to look transparent.

This is what it looks like in the blender image editor. The transparency shows up in that view.

The starting Shader setup is also different from the tutorial (I don't know enough to know what all this means)

But when I make it like the tutorial it looks like this, still not transparent (it also looks like in the image editor if I set the alpha to none).

I have no idea what settings I might have wrong or what I'm doing wrong. I've been stuck for about 2 hours on this so any help would be appreciated. I used photoshop to make the image (just incase there is some setting I need to set there), and also here are the import settings for the image.

Again any help is appreciated. Thanks :)

Ok I found my own answer here. I wasn't asking the right question or at least wasn't asking it well. I was using Eevee instead of cycles. didn't even know those things were important.

If you imported your image by first creating an image plane (Add > Image > Background), then you will want to click on the resulting plane object in Object Mode, and then look in the Object Data tab of the Properties Panel to find its Opacity slider.

If you created it as a Background Image, you will want to select your camera instead (this is easiest to do in the Outliner window), and then look in the same Object Data tab from the Properties Panel, which will now show the object data for the camera. This will expose you to a different opacity slider.

Hope this helps.

I'm trying to use the image plane, but the object data for that doesn't have the picture icon. it instead has a triangle with squares are each corner and no group of settings that look similar to the first picture. I also tried the background image and that one was transparent, but it still had a white outline. I want to use a image plane object and not a background image. is there something else I have to do?


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Normal map is cut off - what is this problem called and how do i fix it? (uv map? face orientation?)
my normal map is is weirdly cut off, I'd like it to continue just to the very left an right of the sausage, it is a combination of multiple objects that I'be merged with CTRL + J.
I didn't work with blender for a while but i remember there was an easy option to fix this. everything I found on the net isnt working though. can anybody explain whats wrong and how to fix it?
the geametry is uniform so id shouldnt be  a mesh problem.
thanks in advance!

Can you provide a screenshot of your normal map?

And a screenshot of your UV map and the mesh maybe?

If you merged two objects, and this kind of thing happens, there’s a good chance the UV Maps for the two had different names, and so were not merged. Thus, your texture is only using one of them, and the mesh part that had the other one is effectively not unwrapped. You may want to undo the object merge, change the names of the UV maps to be the same in the Mesh data properties tab of the Properties editor, and then merge the objects. Another less maintenance-friendly solution is to set up two different materials for the two different parts, and configure them to use different UV maps, otherwise being identical (I mention this mostly to help explain, not as an actual suggestion: It would work but you shouldn’t use it).

what if i cannot undo the merge?

You could use geometry nodes to transfer data from one uv map to another...

can you point me to a good guide for that please?

I had a backup where they objects arent merged yet but the uv maps name is the same for all objects so what can i do now to prevent the map getting messed up?

You mention Face Orientation in the title of your question. Have you checked that after the objects were merged? - Viewport Overlays > Face Orientation. If one part is red and one blue, go into Edit mode, select All and hit Shift-N.

You can Select Linked limited by UV, and then split by selected.


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Ocean looks real close, but plasticy and undetailed when far. Can't find setting for this
I re-asked this question and added all necessary files and images, so its more clear what my problem is: now u can download the textures and blend file and render and see what i'm talking about :)
I followed this tutorial here: Youtube Tutorial
When zoomed closer to the ocean, it looks great but as soon as i zoom out wide, (what i want to do for a clip i need for my bachelors exam, it looks plasticy suddenly, it loses detail and looks horibly undetailed. like an 90's cgi scene.
I want the sun reflections on the ocean but it looks way off when zoomed out.
Download Blend file: Ocean blend file
Download Ocean displacement textures: Ocean texture files
All ocean displacement renders,for the entire animation duration are uploaded at wetransfe.
Can someone please help me and explain why this happens?
Closeup

Wide

maybe add some noise in the material etc?

The thing is, i want to use real life numbers, so my camera is like 2km above the ocean surface, i have this sun - world hdri -  from the tutorial and i want to move a plane through the shot, so in reality, u would see detailed waves and shimmer from the suns reflection, but it just looks flat, how big and where would i have to add the noise then?

I have never been in this situation but I wouldn't be suprised if a calm ocean looked like this from 2km in the sky with the sun this close to the horizon.


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Activating Audio for background image (Movie Clip) possible?
I can't believe I couldn't find any thread anywhere about this but here's my problem.
I want to use a video with sound as background and animate a model according to the acoustic Cues given in the video (for timing). But for the life of me I can't find any way to hear the sound track of the video when playing back the timeline. what am i missing? Please don't tell me that this isn't possible that would be just ridiculous...
Regards. Oz

I found a way, go to the sequencer, add the same video in there as well. Now you have audio while playing back. Remove the video track in the sequencer, keep the audio track, that way you can render your animation while working and see it, otherwise it will be overlayed by the video track.
Hope it helps anybody else.


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Displacement settings in Materials turn material black
I've been trying to fix this forever and I dunno what to do anymore,
I have a plane (over 100k subdivisions)
I set cycles render to experimental (every tut tells me to do so)
now I read that in order for displacement to work you have to change the displacement type in materials settings from bump to displacement and bump (thanks for the default settings which disable functionality?!). I saw that in Blender guru's tutorial.
But when I do that, the Material turns black, I can only use bump only in material settings.
BLENDER FILE: Blend file - displacement bug
All i basically want to do is to displace my ground material i downloaded from quixel megascans.
Every image I see of the quixel megascans looks photoreal, but when i export via bridge they never displace and are flat. So i always have to find a way to displace them, when i do with the displacement modifier it only displaces one the texture i load in, i want to use a bigger plane and use the texture multiple times (using blender gurus poliigon addon).
Does anybody know a good tutorial for ground material + displacement ? I am 100% sure there's gona be a silly problem anyways, so far there wasn't even one tutorial where i could just follow along without any functionality, interface, location, glitch or bug issue.. This is by far the most tiring software i learned (and still learning) hands down. But I won't give up! Sorry just had to let some steam out...
Appreciate your help!

the default settings are geared towards the average user, and one of the considerations when using microdisplacement is that there is considerable calculation every time you do anything in rendered view - you can change anything you like and save a new startup file

although perhaps that particular option is a per-material setting, so maybe I'm talking out of me arse :D

its quite disturbing that such settings, which u can access are avaliable (at least one would think because u can use the nodes and all) but there is one thing somewhere in some window which actually disables it. I mean how on earth am i supposed to know that "yes we put this thing in there, and u can use the nodes and set it up, but its disabled somewhere", really weird design decision. I could still live with that if the entire GUI and functionality wouldn't change so drastically all the time so even if i look up solutions, those aren't up to date neither.. its like a witch hunt sometimes :D

Just a few notes to Horyzon's in depth explanation ...

for this kind of displacement (on pixel level) you don't need necessarily to subdivide your mesh destructively. You can use simple Plane with four vertices and Subdivision modifier > Adaptive Subdivision feature that does the same job.

care about object Scale to be 1 otherwise Displacement node > Scale value has to be Multiplied or Divided when Object Space is set in this node.

and as already pointed by Horyzon values are off ... since in your comment you provided another blend file with different setup fail, here is a node setup

BTW I don't see your displacement texture dark (or black) I see it more bright (it could be even darker), anyway it works as it is. You can play with darkening or brightening with this kind of texture, but be careful when you are working with terrain (like satelite) data, even they looks dark they precisely specify under and above sea level.

Thank you kind Sir !!

Luckily this is a easy one, the only problem was your Displacement node having the wrong values. I downloaded your file and saw that you set the scale on your displacement to something around 47 which is really big, this value controls the overall scale the displacement has meaning a higher value makes the displacement stand out or drop down more.
The middle value called "Midlevel" was set to 5 in your file, but it should be around 0.5 in most cases as it marks the height of the overall displacement (the Midlevel specifically controls what height the colour on your height map right in the middle between black and white would be at, in short its the height of the entire displacement.) Due to it being at 5 in your example, the whole texture got sent up into the air so you couldnt see it anymore, therefore making the object appear invisible because you could only see the orange outline which doesnt go up with the rest of the texture.
Lastly, the displacement texture you're using is almost completely black meaning the texture gets sent down anyways as black indicates a drop in the displacement and white tells it to go up.
I would reccomend you to play around with the displacement node in a test file and learn how the different values work so you can set them up correctly in the future, as well as making your texture artificially brighter so it ideally spans the whole range between black and white, either in a image editing program like Photoshop or using nodes in Blender.
I hope this helps, if it doesn't make sure to comment here again so I can help you further :)

Hey, Thanks for the help! So I changed every setting but i didn't expect any changes since you said that the displacement is black, so i opened it up in photoshop and the file has a red tint, but an intense red tint, I would love to show you but It's not allow to answer as a post so i can't attach any pictures in a comment. I took out the saturation and saved again, replaced the displacement map, still flat and it still turns black if i change to displace and bump in material settings. https://we.tl/t-xKHfVndhEo What am I doing wrong?

@Ozzy Why did you connect displacement texture into Normal socket of Displacement node in this case and not to Height as in your Q? Since Horyzon is right I added a few additional notes that was too much for just a comment.


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How to blur a single object, Layers dont exist anymore? (2.92)(Permanent interface changes confuse every new user)
I've tried to find a solution for 2.92. As the title suggests I am not able to do this simple thing.
I want to blur a single object, not motion blur with he camera I mean simply blur an object.
I have looked around forever and as usual every video is either too old or the blender version has changed and the buttons are somewhere else, or the way layers work has changed or something else... It is REALLY hard for newcomers to learn properly since it gets so frustrating after searching for up to date tutorials.
So all i could find out (thanks to Stackexchange) is that the render layers don't exist anymore and that i have to work with collections now, i created a collection, put my object in there but all tutorials only talk about render layer nodes in the compositor, but that doesn't let me pick the collection, I also changed the pass ID to greater than 0 and if i pick the pass node i cant connect it to my collection since its so confusing to find out what combo works atm..
Can someone please explain to me where i can find actual up to date infos about blender or a place in general where changes are shown or explained, I wouldn't have any problem with old tutorials if there would be a clear way of checking how to replicate the steps in the newer version.
This is really sucking out the fun of learning.
All help is appreciated.

Hey there, may I suggest to look under View Layer Properties and there if using Cycles you will find your layers/passes (from 2.83 the UI got cleaned up a bit but not removed). Regarding only wanting one object I believe you should consider the Passes->Data->Object Index or Passes->Cryptomatte->Object. For that to work, you need to give the object in question a pass index under Object Properties->Relations->Pass Index.

Hey, thanks for the answer, appreciate it!
I did that. (gave the object another pass) and set the object index, but I don't know how to do the rest, i mean everything i can find online is about using the render layer node in the compositor but i can't select my pass there, and theres i so layer interface where i could follow all the tutorials. I am talking about this window (ignore marks): https://blenderartists.org/uploads/default/original/4X/b/c/e/bce427c4cda474500b042ac65791094595fdbee9.jpeg
How do i access a render pass in the compositor and only affect the object with hat pass?

Not much of a compositor user (still learning myself), I posted my answer to the degree of my best knowledge in hope that it helps you.

I am by no means used to work much with the compositor, that said, I hope what I am going to show here is not too far from what others would do.
Object Index method:

Activate the Object Index in the View Layer Properties:

Make sure the object in question has its own Object Properties -> Relations->Pass Index:

Render the image with F12 if only that one object needs special treatment, otherwise give each object that needs it its own Pass Index like in step 2.
Go in the Compositor and activate Use Nodes:

simple example of a cube and sphere, whereas the sphere has pass index 1 and cube has pass index 2

Using the ID Mask node you can get the mask for the specific object or objects(same pass index objects are in the same mask)
Multiplying the rendered image with the mask we obtain the separate object and adding a Blur node we can then blur the specific object:

This would be blurring a specific object

Cryptomatte method:

Activate View Layer Properties->Passes->Cryptomatte->Object:

With the object already having its own pass, you can then render and get new output sockets on the Render Layers node in the compositor.
Connecting those to a Cryptomatte node and later the Blur node you get this:

The Cryptomatte node needs to be set up first
With the Pick output used, you can easy use the eyedropper Add to select the wanted object and switching to the Matte output this will show the mask created.
Switching now to the Image output you get only the selected object from the entire render.
Routing this image through the Blur node will then result in the same as above Object Index method.

UPDATE (Compositing the blurred object back into the image)
While not 100% sure, I believe this should be the result asked for:

All the difference is an Alpha Over node

Thank you so much, i am slowly starting to understand how this works! So I was able to recreate this! What if i have my scene and just want to keep everything the way it is and blur just one object while keeping the rest of the scene the way it is. Would that be possible? or would I have to render each object separately and then composite in lets say After Effects? You have to understand, I am coming from Macromedia Flash originally, then Photoshop, then After effects & premiere, The concept of just clicking an object and blurring it seems to simple to me, yet it is so complicated in Blender.

I'm no expert with the compositor, so I hope this is what you asked for.

Alright, thanks a lot!


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Python script: Problem in copy object location
i am trying to copy z location of my object and storing it in a list for a range of keyframes but the location is not updating
c = 1
s =list()
while c < 251:
 bpy.data.scenes["Scene"].frame_current=c
 bpy.data.objects['Empty'].select_set(True)
 loc=bpy.data.objects["Empty"].location[2]
 s.insert(c-1,loc)
 bpy.data.objects['Empty'].select_set(False)
 c=c+1

i wrote list s in a file and saw that the loc does not update in the loop. Need help.

Try using scene.frame_set(c)  Also please use 4 character indent. 1 is frankly ridiculous.  If the empty is being moved by constraint or parenting etc try using empty.matrix_world.translation

Although it is not part of your question ... a suggestion regarding Python is here.  You may want to use ... for x in range(250) ... if possible. For the Python displayed, it may be a little simpler.

An extra thing, why are you using the insert method? Why not just use append() ?


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Geometry Nodes - Color Value as Float
First, I'd like to provide some context.  I have a low resolution 3d map.  I made this map by subdividing a hexagon and applying a Displace modifier to it.  A little color-ramp magic in the shader, and I have something that's conceivably usable for my purposes:

However, switching between the displacement texture and the rendering shader is inconvenient for painting changes onto the model.  Before, it was the only way to do things, but now, I thought I'd try to use the Geometry Nodes system to displace my vertices with Vertex Paint as the input instead of a texture.
The problem is, the Displace node uses the texture's HSV value at each vertex directly, which is different from the color values visible in the spreadsheet editor.  For instance, while a color with an HSV value of 0.0 has an internal value of 0.0, and a color with an HSV value of 1.0 has an internal value of 1.0, a color with an HSV value of 0.5 is stored with a value of 0.216 per the spreadsheet editor.
How do I convert the stored value into something approximating the HSV value?

Does this answer your question? How are color images used as input values in nodes?

@Gorgious No, that question is 100% unrelated.  Firstly, I'm not using images here.  Second, the problem is that the value I'm expecting - the color luminance - is not the value reflected in the spreadsheet view.  This difference is reflected in the vertex color itself, not post-conversion, so the conversion described in the linked question cannot be the problem.  Furthermore, a lot of the nodes for working with colors simply don't exist in Geometry Nodes view, so I couldn't solve my problem the same way I might if I were working with Shader nodes.

Could you maybe add a little more information then ? Post a screenshot of you spreadsheet editor and the expected behaviour, etc.

I'm voting to leave this question open since OP can't use the linked answer.

Also might be helpful: What happens when a vector is fed into a value slot of the add node?

In Blender 3.3+ you can solve this as follows:

In this version the node Separate Color offers you the possibility to choose between RGB, HSV or HSL.
The value for the vertex color is stored in the attribute Col, which you can query with the node Named Attribute.


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Change all references to an image texture
I have several different shaders in my .blend file that point to the same image.  Problem is, that image is in the wrong place, so it's showing up magenta on the model.  Is there a way (perhaps using the outliner) to re-point all references of one image to another image?

Hi :). You're actually asking two things at once. To repair broken links use this answer. To remap all references to a different image use this answer

you can use this python script:
import bpy

for ob in bpy.context.scene.objects:

    if ob.empty_display_type == "IMAGE":
        if ob.data.filepath == "/old_path/old_file_name.png":
            ob.data.filepath = "/new_path/new_file_name.png"


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Even with all bone transformations cleared, as soon as my rig is in pose mode, it distorts my model
I've tried a lot of different fixes for this, but it has happened to me many times. Everything looks fine in rest mode, but as soon as I switch to pose, it distorts the positions of certain parts of the mesh, such as the eye. Clearing all transformations doesn't do anything, and I've checked multiple times that all the bones are visible. For some reason, applying the pose to rest tends to fix this issue, but it comes back on occasion.
Additionally, at some point, without changing anything, the rig started controlling the wrong parts of the mesh--with the eyebrow denting the middle of the head, for example, while many still work fine. I've tried all different ways of fixing this but been unable to succeed. I feel like it might be connected to the way the skin mesh is attached to the eyebrows (again, something that is unclear, since I cleared parenting and made sure there weren't any deform modifiers).
On said topic-- the eyebrows are created using a mesh deform cage on some lines, which then has a surface deform o some planes. It has repeatedly told me "target has edges with more than two polygons" and I've tried all the cleanup tools, even remeshes in voxels and blocks, just to experiment, but nothing has fixed it, so I'm not sure how to find those edges.
I am new to blender, learning off of youtube videos and etcetera, but this seems like a bit of a trainwreck.

A possible solution to a similar issue I had was that I had left over vertex groups from parented to the metarig and it deformed the character after I parented it to the created rig. I had to delete all the non DEF vertex groups (associated with the bones, not other vertex groups that I created).


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Rotating repeated Image Texture/ Tile a Texture in 90° increments
I am trying to figure out how to randomly rotate an image texture that I apply to a simple plane.
So basically, I have an image of tiles and I would like to have "the duplicates" to rotate randomly by scaling the UV Map.

After some days of researching I found some Videos and Blogs regarding this matter. Unfortunately neither of the proposed solutions were applicable to my problem. Most often, the solution was in regards in how to randomize an image texture over a large plane by rotating it in a random degrees (to tile a texture without repetition > BlenderGurus Video for example). In my case I just want to have the texture rotating in 90° increments. I'm relatively new to Blender and still learning how to use Nodes, so I would appreciate if somebody could help  me out or push me into the right direction, maybe even give me an alternative way of to this.
Thank You in advance

A possible node settings:

Use a "vector rotate" node with UV as input and a random rotation around z.
The random rotation is given by picking one random value per tile:

Take the floor part of the UV (so one value per tile)
Use a white noise to get a random value between 0 and 1
Multiply by 4 as we want 4 cases: 0, 90, 180, 270°
Take the floor of that to be aligned to the integer values
Multiply by pi/2 to obtain the rotation in radians


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Blender skull joining problem
I am new to blender. I tried to build a skull based on blender cloud character tutorial and in one step it asked to add boolean modifier. So I did. And the this appeared: the skull, mask and optimised display disabled. And when I want to add dyntopo it says vertex data detected. And when I want to smooth the skull it only allows me to do it on quoad and not on cylinder. How I should fix that?

The warning "Sculpt: Hide, Mask and optimized display disabled." appears when you have active modifiers on your object (the Boolean Modifier). Then in Sculpt Mode a few things like the Mask and Facesets, etc. don't work.

If you activate Dyntopo it warns you because simple objects like the Cube, Cylinder, etc come with UV maps for texture painting. You find the UV map in the Object Properties Data (the green vert triangle icon on the right side of the screen). You can inspect the map in the UV Editing tab (right next to the main menu). Sculpting destroys the UV map. You can ignore this because you don't want to texture high-poly sculptings anyway. It will make your Blender freeze and crash. If you want to color it use Vertex Painting or retologize it.

You can't sculpt on the cylinder because the Boolean Modifier doesn't work in Sculpt mode and there is no mesh geometry to sculpt on. If you activate dyntopo you will get warning "Not supported in dyntopo" in the modifier tab and the cylinder will vanish if you hide the cylinder in the outline. There are the original cylinder and one temporarily created by the Boolean modifier.

To solve this you need to apply the Boolean modifier. Click the drop-down arrow right next to the blue monitor and camera icons of the modifier. Select 'apply'. It will permanently union (copy) the mesh data. It will not modify the cylinder object. Hide the cylinder object to get rid of the overlapping objects. Last but not least, activate dynoto, choose Draw brush, set strength to a very low value and click on the new cylinder part of the sculpt object. This will add more vertices to the new low poly part so you can use the other brushes without problems.


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Can I create an isosceles triangle 2d curve that I can move points and sweep it on an arc?
I need an isosceles triangle 2d curve that I can move points and sweep it on an arc.
Can a 2d curve be made in this shape?

That’s way too little detail, but yes, of course it can be that shape. What do you mean by “move points and sweep an arc,” though? Curve points are not expected to be animated, and if it’s just a triangle why not use a mesh instead?

Maybe draw an image and post it showing what you mean by " isosceles triangle 2d curve that I can move points and sweep it on an arc"  showing directional arrows of it sweeping in the direction you mean.

I love this social media colon restoration after peristalsis. The right to comment without knowing the product fully. There is enough detail for anyone who has seen this problem using a curve to mesh sweep node. So I get a downgrade. The answer that I found is one must create meshes first then position them into a boolean node by transform.

Do you want to create the triangle "inside" the GN modifier attached to the curve (the arc ?), or do you have the triangle created in Edit Mode and it is an input to the GN modifier ? In the first case, how are you "moving" the vertices of the triangle ?

Blender does not do parametrics, as in create two geonode 2d shapes then boolean them then sweep them on a path. Instead Blender builds the 3d shapes then you can boolean resulting in a huge amount of vectors getting deleted after getting created. So booleaning a 3d model is very cpu/gpu consumptive in animations for each rendered frame. If I am spouting ignorance please correct me. I have done many tests on this and fallen prey to being told I am doing it wrong.

Blender is not wrong and parametrics has a place for better performance.

Here's a couple of nodes to get you started.  I'm not that mathematically inclined so I didn't understand the arc portion of your question.

The arc portion is the curve input on the curve to mesh.

(Using Blender 4.2.3)

This GeometryNodes modifier is attached to the curve along which "an isosceles triangle 2d curve" is swept. Dark pink nodes are modifying the vertices of a Curve Circle to make it isosceles, based on its Height and Half-base provided as user-defined inputs.
(Blender 4.2.3+)

This adds to Rick T's answer, which I upvoted.
The triangle would be swept with an arc, as below, but you also need the shade auto smooth modifier.
Handily, it is also a node group.


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Reducing internal faces generated by extensive curve extrusion?
Excuse my title gore.
I've been modeling Gothic architecture:

(reference)
Here's the blend file I've been practicing with.
So I'm extruding along curves a lot. The complication is the fact that just one curve with a highly detailed bevel object won't work. You'll often need part of your beveling to split off into additional tracery, or to omit it in certain places. So you'll need a bunch of similar curves with different bevel objects.
I end up with a bunch of meshes running perfectly parallel to each other, which prevents the use of the Boolean modifier, the obvious answer to this question, even after dealing with n-gons. I also have lots of hidden faces from tucking curves inside each other to hide my end points. Cleanup and decimation are often necessary to prevent Blender from hanging when you tab into edit mode, actually.
What I'm asking is how I can reduce/eliminate internal geometry, ways to reduce my face count (especially parallel faces), or any other advice you  might have relevant to the end of modeling Gothic architecture. I'm probably doing something wrong or inefficiently.

While I'm here, when I extrude along a sharp angle, there'll be some "pinching". Is there any way to address this other than manually mending the mesh after the fact? Here's an example of what I'm talking about: http://imgur.com/0MD0czo

It's probably better to create a new question if you want a full answer. There's not much you can do about it it's a known limitation of the curve system in Blender. Try adding an edgesplit modifier see if it improves. Otherwise you can probably clean it up in the end manually by converting to mesh.

There are a few things you can do:
1 Reduce curve resolution - Both in your curves and in your section defining objects

2 Eliminate unnecessary vertex - In straight line segments you don't need all that useless points adding additional geometry

3 Turn Handles to Vector - In straight segments change your handles type to Vector, so no additional subdivisions are created without need.

4 Clean up your sections Eliminate segments for parts that are never seen or end up inside the geometry

5 Use Bezier handles in curved parts wherever possible You can then take advantage of dynamically and easily adjustable resolution using the Resolution setting as shown in the first step, for sections curves too.

6 Use a mirror modifier Use a mirror modifier whenever possible. This will not necessarily reduce polygon count, but it will save you time, guarantee symmetry and save cleanup work (you only need to do half)

As for the self intersecting parts, it's probably more trouble than its worth. You may try using Booleans to intersect them, but you will have to destructively convert to mesh, and the resulting intersections (if they can even be made easily) will likely create more geometry and complexity then they solve.

Most excellent. Though regarding the mirror modifier specifically, it seems to chew up my geometry near the divide more often than not.

You can adjust that by controlling the "Merge Limit" setting in the mirror modifier, or if it doesn't suit you, you can disable it all together by unchecking the "Merge" and "Clipping" checkbox

You can "lower" the problem by reducing this value :

But this is not a perfect solution, because it will decrease the resolution everywhere. So eventually, you will need to compensate that by adding vertices to your curve.
Edit : you should try a subsurf modifier in complement

using wireframe view or activating wire in object properties panel will help you finding the best resolution and reduce the "pinching". This will reduce your face count, but making some low poly bevel object will reduce it too (every edge will produce a face, less edges=less faces)


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Blender 2.8 One God Ray Effect
I am setting up lighting for a scene and I want one light to have a god ray effect, however, when I use the volume scatter on the scene it works for ALL lights. How do I isolate a spot light source for this effect or if there is any other way please let me know. Thanks.

Instead of a volume scatter for the scene you can use an object with a volume scatter material around your light.

@AllenSimpson I agree with you.

@AllenSimpson Could you explain more? I have the same question and I want god rays for the window only. I'm using eevee. Should I assing volume scatter to the material of the window? What could be the node setup?

@user2824371 I have an example in a scene at home, I can share later.  This was the last thing I typed before I passed out in bed x)

For this answer my scene is just 3 Spot Lights pointing down at a plane with a Strength of 200w.

If you're not using world lighting, this could be as simple as a primitive cube bounding box around the light in question with a Principled Volume node.

You might already see the problem in this image, but introducing any world lighting makes it much more apparent.

Which is that any lighting will be reflected towards the camera at a certain rate by the volume.
The core idea is sound for Cycles, since we can just use a different shape for a volume object.  Unfortunately, in Eevee every volume is rendered as a cube bounding box around the object.  I think it would be applicable in Eevee, but it may take some additional work.  I'm not that familiar with it to be honest, so someone else may have a better answer.
I will continue for the sake of a complete Cycles solution.  If we replace the cube with a cylinder we can move and scale the top and bottom faces such that they envelop the effective area of the light.

You'll have to do a little adjustment to the bounding box and see how it looks.  Generally the lower your density is the harder it will be to detect any cutoffs, but that depends on what you need.
To make this animation-friendly you can make the light the parent of the volume object, and any transformations you make to the light will carry over to the child.

So hopefully that gets you started. :)

In the View Layer Properties just enable in the Light Settings In
EEVEE: Light > Volume > check Light.
Cycles: Light > Volume > check Indirect.
Now when you click Render you will have a combined Pass and a Light Pass/Indirect Light Pass. It looks black and white because the volumetric light is isolated.
That Means you now have to disable all lights except the light used for the godray effect.
Then you can use the rendered Light Pass (with the isolated Direct Light from the godray) to mix it in the Compositor with the rendered scene (without any Volumetrics and all lights enabled excepts for the Godray Light).


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Light Source to Affect One Single Object in a Scene
I have an object in a scene that uses multiple light sources, however, I only need the lights to hit the object and nothing else in the scene. Is there any way to fix this problem in Blender currently? Eevee is being used to render.

it seems there isn't yet a native solution: https://developer.blender.org/T68915

Yeap ... Compositing


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Can't control knee in blender 2.92
I'm new to blender. I want to make some animation using rig. When moving foot_ik.L, the knee has strange behavior. I Have searched and viewed some Youtube videos then I noticed I am doing something wrong. I found this link as most relevant video to my issue.
I tried to remove red-marked bones(first image) in order to add pole bone but can't select them(can't select red-marked, but can select green marked bones).
Note: Edit > Lock Object Modes is deactivated
Please guide me for this approach or offer better solution.

When you're use Rigify for a human character there is no need to add or remove bones to have the knees working. How have you laid out the bones of the meta rig?

I just used scale and move to match metarig to mesh. Those two bones are generated automatically and is child of rig. So how to correct the knee position in second image?

Share your file. http://blend-exchange.com/

After hours of searching google and youtube found the solution finally. For those who may face this issue:
1- Select metarig
2- go to edit mode
3- rotate thigh.L and thigh.R (90 degree in my case)
4- go back to pose mode
5- under Object Data Properties > Rigify Buttons activate Advanced Options then Overwrite then click on Generate Rig
If any bone has problem for generating rig:
1- copy the bone name
2- remove it
3- create exact same bone(start and end points are important)
4- set parent
5- set children
6- set the name again
7- rigify again
Don't forget to apply transforms before any generations specially for rigify!


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How to select individual parts of alembic (abc) file in Blender
Question:
How can we select individual parts "mesh" or parts thereof in an alembic file in Blender?
We've tried the "edit mode" ->P and then selecting by loose parts..  No luck.. nada.
Background:
we're busy working on some pretty complex geometry. For this, we imported an animation from C4D via alembic into Blender. So far so good, the animation works, but, now we would like to selected individual objects "within" the alembic file, in order to isolate parts and later use Geometry Nodes for some additional effects using only specific areas of geometry.
We had no problem trying opening an obj file, that was easy and we could see all the individual parts, but not in alembic..
Thanks a ton. Best regards

Alembic should work as a regular mesh, but probably the transition from c4D to Blender does not have some functions, have you tried with FBX? you could also make a simple animation in C4D and export as Alembic to Blender and see if that works if so, then is probably the scene file

Hi, yes, we made an animation in C4D and exported that to Blender via Alembic.. that's the issue, that we aren't able to "break down" the geometry afterwards in Blender. With FBX no problem breaking down the individual parts of this tree, but no animation..

Not sure how it's working right now, last time i used C4D (R20) FBX had the option to export animation, if you are making the animation with mograph, you need to bake the animation before. Make a basic animation and export usign alembic as a test, if that does not work, share that basic animation and probably someone have the answer


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Why rendering black areas in cycles?
Thanks for reading this.
When rendering I get black areas using Cycles. It happens with path tracing and also branch tracing. I tried to deactivate all different light sources but problem still persists. I have checked the geometry and that seems OK too.
Blender version 2.92
I have included the blend file in the following link.
https://drive.google.com/file/d/10B9H-IZI_4YW23S_orMQxuBohhXw6plb/view?usp=sharing
Thank you very much for helping out.
Best regards.

Your Normal and displacements are connected in the wrong way, you need a Normal map node and a displacement Node, also your normal image needs to have a Non color on the color space.

Thank you so much for getting back so quickly. Really appreciated! Regards!

@Emir I'm at the phone right now so I can't download the file to check materials and textures... but is it intentional that you've plugged the Alpha output of the texture into the Color input of the Normal Map node?

You are right, wrong right side screenshot, sorry I was testing the texture and did not notice the screen, I will edit that later

Additionally to Emir's answer, some more findings:
You have created the bunkers with the Boolean Modifier. To get a smooth result you should enable Auto Smooth and Shade Smooth (right-click the object in Object Mode)
No auto smooth
Auto smooth enabled
For the material you need to add the Normal Conversation group before the Normal Map node that you had forgotten to add. This will remove the black area as seen on Emir's screenshot at the inner of the concrete bunker.

You have also node groups named "NodeGroup", "NodeGroup.001", "NodeGroup.002" which all do the same as the "Normal Conversation" node does. They just use an Invert node instead of a Math Subtract node You might have accidentally duplicated the groups.

Why do you need the normal conversion node?

@AlexandreMarcati It's because the used image is in DirectX normal format but Blender uses OpenGL normal format. Have a look here: https://blender.stackexchange.com/questions/100017/directx-vs-opengl-normal-maps


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How come files become so incredibly large in Blender
We are putting together a pretty large scene, approx 1km x 1km.
On it we are placing piping and other industrial equipment.
The question is how come a simple steel pipe of approx 1m diameter and 12 meters long with some textures comes in at over 150MB? There must be something we are doing wrong. I write this, because the elements we have built and want to populate our large scene with come in at over a 1GB to start with, which is crazy and we obviously must be doing something terribly wrong.
What do we need to do to drastically improve file size and optimize objects with textures?
I'll add the link of the file, so maybe somebody could have a quick look and tell us how to improve this. In our example, we need to make 100s and 100s of these pipes linked together...
Here's the link to our sample pipe with textures:
https://drive.google.com/file/d/1uRKtmXMbQK7SgIb_dAkG8FQ4CeqDuXa1/view?usp=sharing
Thank you very much.

You pipe is unnecessarily subdivided and has a needlessly dense mesh

Hello. Not sure why your question was closed "off-topic". The pipe has 1.1 million faces. Do you need so many faces for a simple pipe? If I decimate the faces to 8000 the file size shrinks to 1.6 MB.

It looks like that the UV map alone takes about 50 MB of the file size. My PC can't handle this and just freezes. When I delete the UV map the file size is reduced to 96 MB.

Thank you very much for your terrific help!


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How to optimize super large objects for large scene rendering
we are trying to render a large solar farm.
For this we used procedural textures, pipes with textures you name it.
Each solar panel strip is about 100m / 100 yards long.
Our goal is to have a complete "farm" of these panels.
By the time we try and put them all together in the final scene it's just too big with gigas and gigas
of file size, something in the order of about 6GB for simple simple rows of solar panels with piping. Crazy!
It seems that somehow blender multiplies everything in order to achieve these in my opinion crazy files sizes, instead of somehow linking the procedural textures and not increasing the file size.
In the included link, I have uploaded photos of what is we are trying to do and
a blender file (2.92) with the object we have created from which we multiply into these large 100m strips.
I've attached a photo of what it is we would like to render (in the final this will be multiplied by a multiple of 20 or 30).
I've also attached a link with the objects in it, maybe somebody would be so kind to take a look and see how and where we could optimize this.
https://drive.google.com/drive/folders/1TB8ifa89ATvDatlNoAeRez-BMDKZ5bms?usp=sharing
Are there any tools that could optimize such a process? Any baking tools that could help slim down these objects automatically?
Much appreciate your help!
Thanks a million :-)
Kind regards!

You've got about 50k faces on a single nut and bolt my guy!

Wow! Thanks. We'll look into that one right away.


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How come my radius is way small?

I cant seem to get the gap closed with the current radius span.
What can be done to get this with a usable range.
If I set to 0 the radially dispersement goes down to one unit.

Hello and welcome. Please don't crop out essential information from your screenshots, this hides away any details that could possibly hint at what your issue is. As it stands a partial screenshot of the subject without context or further information makes it impossible to diagnose the issue. Please edit your post and replace your images with full uncropped screenshots showing the user interface, properties, full node tree, and any relevant parameters that might help us solve the issue.

You've hit a floating point precision limitation. Typically in softwares such as blender you can really work in dimensions varying by a degree of up to 6-7 magnitudes. Here you have 7 significant digits so in a perfect world there is no gap but the renderer can't be precise enough to both render meters and render nanometers at the same time. Try changing the project units in the settings

Thank you for the answers. I made adjustments in previous nodes and the final object came out perfect.


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Why are the radially objects not directly from center using?

When I increase the radius the object translate away but from the center at an offset.

The origin of the instances must be aligned to what you expect to be the axis. Either you got misplaced origins or the translation in X only is affecting this. If the origin is aligned, the translation in X and Y should use cos(60º) and sin(60º) respectively. (ALternatively, you rotate the original geometry 30º so X crosses exactly in the middle of the arc)

Thanks. And yes that was the issue. I rotated the previous node on X -60 and viola. the alignment was great.


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How can I use geometry nodes to extrude a tube from two concentric circles that are not connected in any means yet?
I used 2 curve circle nodes to create the concentric rings.
My basic need is to create a tube that I can alter the radius and wall thickness.
I have used curve to mesh nodes before with curve circle and it creates export geometry problems that show up in Unity and Tinkercad.
So this attempt is proving daunting to me.My thinking is to create the 2 concentric circles and join them in a mesh where the circles become inner and outer walls then extrude the filled ring to a required height.
Thank you. Any help would be appreciated.

It seems like you might be making things more complicated than they need to be. If you could give more info on the problems you were having for previously just using Curve to Mesh, then we might be able to find a better solution. I am guessing that it is probably a problem with the normals of the generated object.
The below node tree generates a tube of given length and radius just like you are after, but the normals aren't properly all facing out. In the viewport we can turn on Face Orientation to visualise the direction of the normals. The red shows we are looking at the back of a face.

We can use the same node tree setup, but add the Flip Faces to flip the direction of the normals on the original extruded mesh, before joining and merging my distance. Now we have a watertight tube with the correct normals. Is this what you were after?

Thank you.  I was testing the Blender creations to find the best structure creation for importing to Tinkercad. What I found is that Tinkercad import ruins geometry. This proved to be a failure. Unity importing does not. Unity has no problems at all with Blender obj exports to import. My answers were hard won and now I can continue.


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Why Extrude Among Normals don't give me same Depth
I try Blender 2.83 and 2.90 and I have the same results.
When I extrude face among normals, the 2 faces seems to go on a different depth causing some not even shapes.

I try to check Offset Even and it doesn't solve the issue.
Would be great to have some help on that one ;)

you probably need to apply the scale in Object mode (ctrl A)

That's it ! Thanks mate ! help a lot !


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how to make a filled arch in blender
I have a super problem, I'm a beginner in blender, about 2 weeks, and I wanted to make an arch, but only it should be filled and with rounded edges, I was able to make the arch itself, but there were problems with the rounding. I just created an arch point by point, filled it inside and did an extrusion, everything would be fine, but now I need to somehow round off the edges and here everything is not going according to plan, I don't know if there is any normal way to do this, then what I ended up with when using the surface subdivision modifier - it's just awful, it's impossible to do uv, please help me, I searched the entire Internet and did not find anything.
I also tried to use bevel along the edges, but nothing worked, since there is no geometry in the filled place.

why did you apply a Subdivision Surface modifier? did you have a reason?

I'm assuming you want to smooth out the mesh. To do that you can do shade smooth, which can be accessed by selecting the mesh and 2 finger clicking, which will give you a menu that has shade smooth as an option. You can also search "shade smooth" in the search menu (relatively new as well so not sure what it's called).

Yes, I did smooth shading, but it does not smooth out much, I would like to round the edges, but without the geometry inside, nothing happens, it starts to break

What are you referring to, when you say "without the geometry inside"? Shade smooth essentially tries to "average out" the mesh using the vertices you have, so if you want the edges to be rounder, you can probably remove some of the vertices .

I mean one big polygon, in the middle, I built an arch point by point and then filled it

You can delete the faces you don't want, and then select the edges of the new face that you want. Then you can press F to fill the edges to create a plane.


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How to attach an object to a cloth simulation
I created a rope and added a cloth simulation to it, it works as it should.
But now I need this rope to attach with another object. Let's say I have a ring and I inserted this rope into the hole of the ring. When starting the animation, the rope goes through the ring.
Questions:

How do I tie a rope to this ring? I used a hook and it didn't work.

How to make the ring move on the rope when cloth simulation, that is, so that the rope affects this ring and it moves together in the rope

Related: https://blender.stackexchange.com/questions/192863/best-way-to-attach-objects-armor-to-cloth/192923#192923

Help me, I tied a piece of rope to a null object, with normal movement everything works, but when I run the cloth simulation, then my rope does not hold on to the null object and dangles by itself

So, I sort of succeeded, I added a bone, tied it to a zero object, and tied the zero object to a piece of the rope, and when I move the bones, the rope moves, but when I start the cloth simulation, the rope dangles in place and the bones don't follow her


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How to make a rigid body go up?
I have 2 cubes, I want them to collide with one “falling” upward and the other downward, i tried to make the mass -1 but it set it to 0.001kg and not -1. How can I make it “fall” upwards

@Edgel3D that would work if i didnt need them to not fall back down when they collide

Maybe you could simply animate it by keyframing the location?

@StraightUp636 while that would work, it would be a lot of effort for it to look good.

Mass is different than weight. Having a negative mass would cause all sorts of physics problems.
There's no easy way to flip the gravity for one object without flipping it for all. However, what you can do is create a wind forcefield pushing one of your cubes up. I'm no expert so there could be a better way that I'm not aware of.

well that sucks that theres no other way

A couple of ideas:
Keyframe the cube moving upwards and keyframe the rigid body physics to on at the point of or shortly before the collision. Just make sure to set the motion keyframes to linear, or the motion will slow down considerably because it will try to ease the speed to stationary at the end.
Alternatively, bake the upward moving cube with negative gravity by itself first, but bake it to keyframes so that the animation is preserved and won't be reset with a new bake. Simply get rid of the keyframe a frame or two just before and beyond the point of collision. Again, keyframe the rigid body physics to on at the correct point. Also note that gravity is limited to a floor of -0.5, so the motion will be much slower for the rising cube, and you will probably need to remove every other keyframe and collapse the remaining keyframes down to be sequential animation frames.
The second option will create a more realistic simulation but will take a lot more work, especially if it is a lot of frames, while the first would be much easier to implement, but not as realistic motion on upward motion. You have to get a little creative to make two opposing physics models apply to the same space, but a lot, if not most, of 3D modeling and animation is just creative problem solving.


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How can I select random verts, not faces
I want to select random verts for something in blender, but every time I try to do random selection, it gives me random face selection. I don't want to select faces, just random verts.

Probably your setting is in 'face selection' mode, as if in 'vertex selection' mode:


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How can I uniformly apply an image as a texture to an object?
I'm trying to make an icosphere with a hexagonal pattern applied to it, but the image I'm using ends up getting completely warped and ripped along the faces. I don't know how to fix this, so please help.

I'm not attempting to answer your question: I just wanted to make you aware about some issues with balls and hexagons

There are two ways to approach this problem.
1) UV Unwrapping
There is a major problem with texturing a 3D sphere.
It is mathematically impossible to map a 2D texture onto a 3D sphere without distortion.
Here is a great Stack Exchange thread where such situation and possible solutions are discussed in detail.

2) Procedural textures
If your texture is simple, you might want to use procedural texturing, instead of an image.
This way you can get a seamless pattern without any distortion.
Here is an official Blender video about procedural textures.
Good luck.
If you'll need any clarification, let me know.

You might want to try the node setup shown below. Change the parameters in the mapping node to move the image around. This might not work, as it is possible that the problem is in the UV projection, but I've already solved problems like this using this node setup.
I hope this helps.

can you [edit] to explain why this might not work?


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How do I make a plane with two sides
I'm trying to make a plane that has two sides, or a plane that doesn't have a negative side. I don't exactly know how to explain it, but I want to have a plane where both sides are facing outwards. The normals should be pointing outwards on both sides of the plane. Thank you!

https://blender.stackexchange.com/questions/10711/double-sided-faces
Hope this helps you!

And seems like this option was in 2.79 but disappeared from 2.8+ and enabled by default.

How do I mark a solution? @AkaiShuichi answered my question sufficiently.

you can't mark for a comment, you can just mark if it was "Answered"

How?? I don't see a way to do it anywhere? There's no check mark?

I replied you in the form of "comment", unless I replied you in the form of "Answer" you can't Mark it, If I'm not wrong. Check this out https://blender.stackexchange.com/help/someone-answers


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How to get 2 different colored particle systems for the same mesh?
I want to make hexagonal Boron Nitride using Blender 2.83, which looks like the attached image.

So, I have used a "plane" mesh and turned into this structure of hexagons, which looks as below:

Now I have to add a particle system to emulate the atoms. Now the desired image has blue spheres and white spheres together. And I cannot achieve that.
I can only have the same particle system on all the vertices. If I try to select the alternate points which should be of one color in edit mode, and set up a particle system for that using a UV sphere, then all the wrong vertices end up getting that color; it doesn't go as per the pattern.
Please suggest how to deal with this problem.


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Check if a draw function exists in a Menu before registering
How can I check if a draw function exists in a Menu before registering? When I write prototypes in the Text Editor, I get multiple draw functions added in Blender's UI.
def menu_func(self, context):
    layout = self.layout
    # draw code here

def register():
    bpy.types.VIEW3D_MT_object.append(menu_func)

Though it has an append method, bpy.types.VIEW3D_MT_object is of type  bpy_types.RNAMeta and is not iterable.

Inspired by this post, I am iterating through bpy.types.VIEW3D_MT_object._dyn_ui_initialize() and comparing it to my draw function's name. If it doesn't exist, I'm appending it to the Menu:
def object_menu(self, context):
    self.layout.label(text="Test")

def register():
    omenu = next(iter([f for f in bpy.types.VIEW3D_MT_object._dyn_ui_initialize() if f.__name__ == object_menu.__name__]),None)
    if not omenu:
        bpy.types.VIEW3D_MT_object.append(object_menu)

Interesting. Although I would be wary of using it in production code, the underscore clearly indicates you shouldn't use that function outside of the class itself :) But it does solve the problem of stacking UI elements in prototypes.

To remove appended functions from menus (when addon gets deactivated) and to avoid double entries I prefer to check class.draw.
If any function was appended to a class there´s the new attribute _draw_funcs in class.draw that we can use to check all appended functions
bl_info = {
    "name": "check appended",
    "blender": (2, 83, 1),
}

import bpy

def menu_func(self, context):
    self.layout.label(text="lorem ipsum...")
    # draw code here

def register():
    cls = bpy.types.VIEW3D_MT_object
    search = "menu_func"

    # check if '_draw_funcs' in cls
    if hasattr(cls.draw, "_draw_funcs"):

        # check if function name in '_draw_funcs'
        if [f for f in cls.draw._draw_funcs if f.__name__ == search]:
            print("function '%s' is already appended to %s" % (search, cls))
        else:
            bpy.types.VIEW3D_MT_object.append(menu_func)  # append
            print("function '%s' was appended to %s" % (search, cls))

    else:  # no '_draw_funcs' in cls
        bpy.types.VIEW3D_MT_object.append(menu_func)   # append
        print("function '%s' was appended to %s" % (search, cls))

def unregister():
    cls = bpy.types.VIEW3D_MT_object
    search = "menu_func"
    if hasattr(cls.draw, "_draw_funcs") and [f for f in cls.draw._draw_funcs if f.__name__ == search]: # oneliner
        cls.remove(menu_func)
        print("function '%s' was removed from %s" % (search, cls))

if __name__ == "__main__":
    register()

to examine:
print(dir(bpy.types.VIEW3D_MT_object.draw))

if hasattr(bpy.types.VIEW3D_MT_object.draw, "_draw_funcs"): # last item

    # functions
    print(bpy.types.VIEW3D_MT_object.draw._draw_funcs)

    # functions by name
    for idx, func in enumerate(bpy.types.VIEW3D_MT_object.draw._draw_funcs):
        print("function[%s]" % idx, func.__name__)

I'll add a non-scripting solution, especially if this is just for debugging (which I run into):
There is a button in 4.x and higher called "Reload Scripts". This is mainly used to reload changed modules from add-ons. But this also has the side effect of unregistering everything so it can be a clean slate. So it will clear the menus of all added draw functions before re-registering them.
So I'll click "Reload Scripts" before re-running my scripts. Or in script, use bpy.ops.script.reload().


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Drag Events of a Panel UI Slider
Is there a way for me to listen for when the user has started, is dragging, and has stopped dragging a slider in a Panel in Python?
Thank you!

I'll show you one solution but I hope there is an easier way. Related Q&A
We're going to use a modal operator that runs when you click on the property field and loops until you release the mouse button.
import bpy

class DRAGGABLEPROP_OT_subscribe(bpy.types.Operator):
    bl_idname  = "draggableprop.subscribe"
    bl_label   = ""
    stop: bpy.props.BoolProperty()  # This is used so we don't end up in an infinite loop because we blocked the release event

    def modal(self, context, event):
        if self.stop:
            context.scene.my_prop.is_dragging = False
            print("End Dragging !")
            return {'FINISHED'}
        if event.value == 'RELEASE':  # Stop the modal on next frame. Don't block the event since we want to exit the field dragging
            self.stop = True

        return {'PASS_THROUGH'}

    def invoke(self, context, event):
        self.stop = False
        context.window_manager.modal_handler_add(self)
        return {'RUNNING_MODAL'}

class TEST_PT_draggable_prop(bpy.types.Panel):
    bl_label = "Test my draggable prop"
    bl_space_type = 'PROPERTIES'
    bl_region_type = 'WINDOW'
    bl_context = "scene"

    def draw(self, context):
        layout = self.layout
        layout.prop(context.scene.my_prop, "value")
        layout.prop(context.scene.my_prop, "is_dragging")

def update_prop(self, value):
    if self.is_dragging:
        print("Dragging the slider !")
    else:
        print("Beginning dragging the slider !")
        self.is_dragging = True
        bpy.ops.draggableprop.subscribe('INVOKE_DEFAULT')

class DraggableProp(bpy.types.PropertyGroup):
    value: bpy.props.IntProperty(update=update_prop, min=0, max=100)
    is_dragging: bpy.props.BoolProperty()

if __name__ == "__main__":
    bpy.utils.register_class(DRAGGABLEPROP_OT_subscribe)  # Register modal operator
    bpy.utils.register_class(TEST_PT_draggable_prop)  # Register Panel to see what's going on
    bpy.utils.register_class(DraggableProp)  # Register our custom prop
    bpy.types.Scene.my_prop = bpy.props.PointerProperty(type=DraggableProp)  # Setup our custom prop

Further reading

You are very helpful. Unless someone has a better way, this appears to work well to me!