text:
Why is blender crashing when trying to render?
I am trying to make a room in blender, I finished making the beds that I now want to render so I can see how it looks when its rendered fully...except I can't seem to render it, I just finish my scene, set the samples number and resolution, and press render, it loads I what it need for it to render, but when it arrives at the point where its "updating Meshes" blender crashes without even an error, I sure its not a RAM issue since it didn't fill up the RAM in task manager.
Here are my 2 laptops specs (I tried the second one to see if there was a RAM issue):
First one (my main one)

Windows 10 1803 32-bit
2gb RAM
Intel Core 2 Duo T5870 @2Ghz
Intel Mobile Chipset Express Series integrated graphics card

Second one

Windows 7 32-bit
Intel Core 2 Duo @2.4Ghz
3gb RAM
Nvidia card (forgot which one) (512 VRAM)

Im dealing with:

I have 4k textures, its a 1920*1080 image, tile size is 128*128, samples 200
P.S: I still use 2.76 since my computers can't support opengl 2.1
Here is the file if anyone wants to diagnose it: (removed it since problem is solved)

As I suppose you render on CPU on that configuration tile size should be smaller, like around 64. 4K textures can be one of the reasons for crash since they need quite big amount of RAM, try using at least 2K. RAM usage can be relatively small because Blender isn't fitting there anyway so it crashes before even starting moving data to memory (often it would bring you a message but might be not). If really rendering exactly that scene on that hardware split it into render layers

I'll try reducing the texture size and tile sizes and I'll give you feedback in 12 hours at least @MrZak

I tried reducing the texture size to 2k and tile size to 6464 AND reducing the resolution from 19201080 to 720*480 and it kept crashing, maybe there is something wrong with the scene that makes it crash?

Check this answer to do render from the command line: https://blender.stackexchange.com/a/50236/110146

I agree with what cegaton said.  I've got similar specs as you, and wasn't about to wait and hour & a half for it to render, so these were the settings I changed.
It rendered all 3 layers in about 20 mins, but they didn't merge into one final image, so you'd have to add some sort of compositing step in there somewhere, or just move the beds to the same render pass as the headboard.
I'm on 2.79b so your settings may vary.

guess that makes sense.  with everything else reduced it did OK, plus it's quicker 'cuz you can turn samples down some.

Your method worked! But the branch path tracing step was uneccesary and since I wanted to render it in 1080p 64*64 tile sizes is better

I'm replying to help others searching, as this question came up in my search for a similar problem.
I have a scene with fur, it's pretty detailed and heavy on the rendering. The scene would work fine on my desktop but blender would disappear (kill itself) somewhere during 'raytree... building' on the laptop. It wasn't completely filling the ram, there was still half a gig left when it would disappear.
Both systems have 16gb ram, desktop and laptop and I had disabled the windows swap/pagefile under virtual memory on the laptop at some point. Once I enabled it again and rebooted, everything works again now.
Just google 'disable pagefile' to find out where the dialog is hidden so you can make sure your pagefile is enabled. (or maybe search 'enable pagefile')
(My pagefile was disabled because somewhere I read if you have lots of ram you don't need to swap to disk and you save that much ram in disk space. For most programs it was true, but blender can easily consume the 16gb ram I have with a detailed scene. Hopefully it might save someone else who is searching around 30mins or more and some hair pulling.)

In case it helps anyone, I was also having problems with Blender crashing my whole computer for render for a very simple scene. For Blender 2.9, I went under Edit - Preferences - Settings and set the memory from 0, which means unlimited, to 3000 megabytes, which was reasonable for my old computer. After that it started rendering properly, without using up all my computer's RAM.

For me, (blender 2.82a) kept doing this after rendering a very simple scene, until I checked off "Save buffers" under "Performance > Final Render" settings.
Hope that helps someone

Could you please explain where the "Performance" menu is?

Performance is under "render properties". You'll see the "Final Render" checkboxes under that.

Just an FYI, I was having a really bad problem with crashing during render, in a not very complex scene.  Playing with different settings eventually led me to turn off auto detect on threads and set it below the max number of cores on my CPU.  Instantly solved that issue, and at least seat of the pants had 0 affect on render time.

Could you please explain which menu or option is used to turn off auto detect on threads?

To access this option go Render (in the right sidebar) > Performance > Threads > Threads Mode (although this didn't help with the issue for me)

I solved this by changing the output folder. I was printing to C:\tmp\foldername but the new folder I made inside of C:\tmp did not allow Blender the same permissions as C:\tmp which caused the crash.

I had a very simple scene that was crashing just due to extreme feathering (defocusing) with transparent film. I just avoided rendering that particular frame and all came out good.
Or you could turn off the Alpha channel and have a try.

This could be related to the Windows TDR feature.
There is a nice documentation/tutorial from the Substance Painter people.

The TDR is only relevant when using GPU rendering.


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How to bevel edges without distorting the mesh?

I want to bevel outer edges of that hole. But it results in distorted object.
I have tried improving topology but it does not work.
Here is blend file

Hello :). I can see multiple possible reasons from your images. Please upload your .blend here https://blend-exchange.giantcowfilms.com/ so I can take a look.

@JachymMichal Done! : )

Hello. It was caused by flipped normals. Select all vertices and go to Mesh->Normals->Recalculate Outside. Then it will work just fine. CGMatter ecplains more here https://youtu.be/Z--dnYonag0

source: Stack Exchange

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

sort: votes


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Smoothing/blending a joint between two meshes
I'm modeling a car, but I don't want to add any polygons. I don't need to (I'm trying to have a nicer mesh) so I've got two separate pieces here. Unfortunately this doesn't give me the curved effect, as in the picture below.
I was thinking to fix this in a normal map, but I'm sure I've seen tools for doing this specific thing, and I just can't recall how I saw it done (whether it was in a texture map or not).
I wasn't really big on the solutions, I did find for this here.

Here's a picture of the wireframe.

I could model this, I just don't want to do it that way, I'm sure there's an alternate way.

hello, you don't give enough details, how is your mesh in wireframe mode, what part are you trying to do and can't, etc?

I told you about these new users. This is the reason why I need to remind them to vote for the answer....

@moonboots Here's a picture of the wireframe https://i.imgur.com/CsHuDWv.png I could model this I just don't want to do it that way, I'm sure there's an alternate way

I'm afraid you have no choice but to do it with one mesh

@moonboots I suppose I can always make this piece a plug in MeshMachine when it comes to 2.8 https://youtu.be/2DpjEHxjh2s?t=61 To be honest I hadn't considered the solution when I made this post D:

As it turns out I can make this piece into a 'plug' with MeshMachine and place it on my mesh with the additional smoothing in the corner modeled onto that plug.
Example https://youtu.be/2DpjEHxjh2s?t=61
Just waiting for the 2.8 version

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


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Fire that turns to smoke
I want to make a stream of fire where drips of it fall off, and then it turns into thick smoke.  How can I do that?
.

Step 1. Learn to make fire and smoke. Step 2. Make a particle system that will emit the dripping off bits.


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Weird thin lines after unwrap cube uv mapping
It shows a very thin lines at edges after I uv-mapped a cube into a 3x2 grid env-mapping as shown below:

By right it should not show the thin lines and the texture should go smoothly between faces. I also make sure there's no extra spaces between the uv vertices in uv mapping editor by setting the uv vertex into exact x and y position. Why does it still have the thin lines after all these?
Add-on:

I'm using Blender internal GLSL rendering.
After rendering in image, the lines still visible. The lines appear at all edges.
After I export fbx and use it in unity3D, it has the same issue as well.

Source file: skybox.blend

are the lines also visible in the final render? do you use blender internal or cycles render? Do the lines appear on all edges, or just the ones that lay on the border of the uv-sapce?  (please edit your question and add more information, this will make it more likely, that you get a fast and focused answer).

hi @yann, yup i updated my question. I'm using Blender internal GLSL rendering.
After rendering in image, the lines still visible. The lines appear at all edges.
After I export fbx and use it in Unity3D, it has the same issue as well.

that sounds strange. could you provide your .blend file and the skybox so we can have a look? Blends can be uploaded here: https://blend-exchange.giantcowfilms.com/

I uploaded to google drive and updated in my question. U could try download n see

You are running into Blender interpolating your texture a little, so that when it "smoothes" the pixels of the texture, it's grabbing the next texture over and averaging with the local color, creating an off color along your UV edges.
You can:

Turn off interpolation, but beware, this will make the texture a little more pixely.
Unpack your UV's a little and put an "average color" in the space in between so it interpolates better.  It looks like you baked this texture, you also might want to try just re-baking after doing this.

[Edit]
Downloading and messing with the file showed that interpolation was not the issue here (or at least turning it off doesn't help).  It seems that the UV's overlap so perfectly that the line is an artifact of that.  Fixing it is simple:

Go to the UV editor, press a until all UV's are selected.
Switch pivot type to "Individual Origins"
press s and scale all the uv's down a hair, doesn't take much

Should be fixed after that.

I turned off interpolation and it's still not working. Is the interpolation under Texture Tab -> Image Sampling?

Yeah, that's the one.  I downloaded your file and found another thing to try, editing answer.

Wow~ it works! Why does it happen that way? By right, uv shud be at the exact position to work, right?

I re-read your answer. I think I got the idea. Didn't know putting uv vertex in exact position causes overlap. Thanks for your help thumb up


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Eevee screen space refraction weird black shadow
I noticed there's a weird second shadow in a plane with screen space refraction in Eevee. How to remove that weird duplicated shadow?
Weird duplicate shadow in Eevee:

Correct result in Cycles:

In Blender:

Blender file here
Using Blender 2.83.4
Edited:
Although setting Refraction Depth to small value such as 0.1m works removing the unwanted "shadow", but it also removes the refraction effect. To get refraction effect, the value has to be more than 1m to see noticeable effect. Putting another object on top of the plane with refraction along 1m value, the "shadow" is back.

New edited Blender file here

You have set Refraction Depth to zero.
It is not clear to me if values below are correct, but you get rid of the "shadow" thing.

Glass Plate
Go to Properties Editor > Material > Settings > Refraction Depth and play with value.
In your case 0,1-0,4 m works. It seems to be distance from glass to Monkey.

Deep Water
It seems to be more complicated ... it depend if it should be glass plate or deep water. In second case probably make sense increase to 4 m, that is distance from surface to bottom.

In that case you have to also increase Thickness under SSR Render Properties.

My theory notes behind
The "weird shadow" (as you call it) is a part of bottom plane surface that is not visible from current point of view on background plane. You can see actually through the plane what is behind in that place.
You can actually confirm that by your self. Check where is the issue located on glass plane and switch to wire mode. Real monkey object is placed exactly on the same place on background plane from current point of view .
I guess by default this is some kind if refraction clipping to keep Eevee real-time.
Similar thing happens when you try set reflected floor with object howering above - in a floor is not reflected bottom part of mesh that is hidden from point of view. Like here – Screen Space Reflections in EEVEE
See also ...
Eevee Limitations
Manual - Refraction Depth

Did you mean u solved it using glass distortion? I'm also using Glass BSDF for the refraction floor. From the screenshot, it seems worse than my case. Could you explain further?

Sorry it wasn't clear. Edited

Cool it works! Managed to remove the weird "shadow" by setting the refraction depth to 0.1m. @vklidu Thanks for the detailed explanation!

i noticed setting Refraction Depth < 1m removed, but it does not have refraction effect anymore. By setting > 1m, and putting the object on top of the refraction plane, the "shadow" comes back. I updated my post to include the new Blender file and screenshot

0,1 works like thin glass plate. I don't think you can achieve something like that. See links at the end of my A. I will have to edit answer anyway ...


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How to merge/morph/transform an object into another object in Blender?
The letter "A" is walking from left to right and slowly evolves into the letter "B".
How is this done?

Here's my search process:

"Blender merge one rig into another"
returned articles on how to combine various armatures.
"Morph blender character in timeline" returned a beautiful answer merging one object smoothly into another while animating but I need one object to 'disappear' completely into the other object over time.
"How to transform a moving object into another form in blender" returns searches about copying and duplicating objects.
"How to merge  two moving objects in blender" returns articles on combining objects into a single object, like building a Transformer.

Most reference shape keys and target morphs, but will these work with complex objects? Or simple objects only?
e.g. Could a white rabbit run across a field and change into a blue duck?
I am new to Blender, so if I'm not asking the right question or using the right terms or if there's a better way to ask this question, I'd be happy to be pointed in the right direction.

Took a while, but found the answer watching an Olav3D Tutorial on Transformation Animations:

Basic Steps:

Add two objects (Object A [Default Cube] and Object B [Suzanne])
Add shrinkwrap modifier to Suzanne, select target--> Default Cube
Apply shrinkwrap modifier as shape key
In Object Data Properties Panel, edit shrinkwrap shape key: Increase shrinkwrap value to 1.0 (this shrinks it down to default cube size)
Click "i" to insert keyframe
Go to frame 100
Decrease shrinkwrap to zero
Click "i" to insert another keyframe
Set up camera and add materials, background, and lighting to taste
Edit render output settings (resolution quality, render samples, etc) to taste
If adding a material to Suzanne, add it to the default cube as well
Change render end frame to 130
Change file format output from PNG to AVI JPEG
Set render output quality to 100%
Render animation and voila! We're done, we successfully transformed(merged/morphed) Object-A into Object-B along the timeline.

Final Result (Better late than never!)


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How to unwrap uv's on multiple objects at the same scale?
when i do use blender for complex architectural scenes, there are some times that i don't have time to unwrap uv's of each object carefully , and i do want to uv my objects asap , smart uv project and cube projections are doing absolutely great , but the problem is when i select multiple objects and go into editmode then apply these operations, blender just resizes the uv's and it turns out ugly , only if there was a plugin or setting out there that im mising which do me the favor and unwrap my multiple objects with true size not exaggerated at once it would be amazing .

What version of Blender are you using? It would be easier for someone to help you if you could add some images to your question that show what you mean by "blender just resizes the uv's and it turns out ugly".

Try "Average Island scale" on the UV editor menu.
In my example two cubes with different sizes (scale applied), after using this operator.

god youre a genius , it's been years im looking for this thanks man .


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iteratively key shape keys only on active object
I need to keyframe shape keys and have a script that's nicely working -
import bpy

frames = bpy.context.scene.frame_end + 1

for frame in range(frames):
    for shapekey in bpy.data.shape_keys:
        for i, keyblock in enumerate(shapekey.key_blocks):
            if keyblock.name != 'Basis':
               curr = i - 1
               if curr != frame:
                   keyblock.value = 0
                   keyblock.keyframe_insert("value", frame=frame)
               else:
                   keyblock.value = 1
                   keyblock.keyframe_insert("value", frame=frame)

The issue is, I need it to work only on the active object, not every object in the scene.
Anyone any pointers?

Will this do?
import bpy

frames = bpy.context.scene.frame_end + 1

# For the active object...
ob = bpy.context.active_object
me = ob.data

# Remove ['Basis'] from a shallow copy of *ob's* shape-keys list.
kblocks = dict(me.shape_keys.key_blocks)
del kblocks['Basis']

# Keyframe shapekeys' values to 1 for the frame corresponding
# to their position in remaining list, 0 for other frames
for f in range(frames):
    for i, kb in enumerate(kblocks):
        kblocks[kb].value = (f == i)
        kblocks[kb].keyframe_insert("value", frame=f)

This may get burned down by a proper Pythonista.. :)

Perfect! :) Thank you for helping out!  Still getting used to Blender API as well as python.

This is probably the other way around.
import bpy

End_Frame = bpy.context.scene.frame_end
ob = bpy.context.active_object
me = ob.data

kblocks = me.shape_keys.key_blocks
l = len(kblocks)

for a in range(1,l):  # This can point your specific shapkey
    kblocks[a].value = 0
    kblocks[a].keyframe_insert("value", frame=End_Frame - 3)
    kblocks[a].value = 1
    kblocks[a].keyframe_insert("value", frame=End_Frame)

Please don't add "thank you" as an answer. Once you have sufficient reputation, you will be able to vote up questions and answers that you found helpful. - From Review


text:
Problem with retargeting BVH bones
I am trying to retarget bones (armature) from BVH file to my armature of the low poly model and I have a small problem. After retargeting my bones twist in the wrong direction. How to fix this? I created second bone skeleton (armature) and I retargeted bones from BVH file and for this new skeleton (blender default), everything works fine.
I think in my skeleton for low poly character rotation transforms are wrong, but I might be wrong. The animations seem to be ok but the bones placement and rotation aren't syncing.
Is there any option or method to fix this?
Thank you for help in advance :)
Problem with my armature.

Good version with defult blender armature.

First try Makewalk from Makehuman Blender Tools. It works beautifully.
If you didn't skin the rig yet, you can adjust Roll of bones, that tend to rotate wrong. In my case also helped using DAZ friendly BVH instead of Max or Motion Builder friendly ones. If you have problem only with end bones, which are not parents for any other bone effected by the animation, you can also adjust the rotation in Graph Editor by moving all frames of the channel with wrong rotation up or down.
Hope it helps, cause fighting with bvh's can be really annoying.


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Setting the correct Python data_path for vertex motion?
I am currently using Blender 2.80, and am attempting to follow along with the tutorial at this link on animating mesh objects (https://medium.com/@behreajj/creative-coding-in-blender-a-primer-53e79ff71e)
Specifically, I am referring to the section where the author morphs the shape of Suzanne.
I am attempting to do the same for the grid object, and while the graph editor clearly shows the vertices are moving to where I want, the animation shows that the mesh does not change whatsoever.
I am puzzled as to how the tutorial works for Suzanne, but this does not. I see that there is an alternate method using shape keys, but the code below should still work right?
import bpy
import numpy as np

pi = np.pi

#Clear out the objects on the screen
scene = bpy.context.scene
for obj in bpy.data.objects:
    bpy.data.objects.remove(obj, do_unlink=True)

#Make a grid object to animate
bpy.ops.mesh.primitive_grid_add(x_subdivisions=20, y_subdivisions=20,size=10)
obj = bpy.context.active_object
mesh = obj.data

frames = np.arange(0,250,20)
T =15*6
for fram_num in frames:
    scene.frame_set(fram_num)
    t = fram_num * 2*pi/T
    #Move all vertices and add keyframes to each one
    for i,v in enumerate(mesh.vertices):
        x,y,_ = v.co
        z = np.sin(x+y-t)
        v.co = (x,y,z)
        v.keyframe_insert(data_path="co", index=-1)

Edit: Curiously this code works in Blender 2.79, but not in 2.80! Is this a bug, or intended?

Handler workaround.
Personally would  lean towards using shape-keys for this.
Not sure why the animated mesh doesn't update, hopefully someone will answer with a required setting, or it is an oversight in deps graph and may change up in future.
As a work-around, calling mesh.update() on a frame change via a handler gives the desired result
import bpy

def animate_meshes(scene):
    meshes = set(o.data for o in scene.objects if o.type == 'MESH')
    for m in meshes:
        m.update()

bpy.app.handlers.frame_change_post.append(animate_meshes)

clear all frame_change post handlers with
bpy.app.handlers.frame_change_post.clear()


text:
Creating a generic IK/FK snap script
I've tried deconstructing the Rigify addon to isolate the script part that handles IK/FK snapping, but so far I've had no luck. Rigify is a very nice tool, but I'd like to get the snap functionality into a simpler script that could be applied to any type of IK/FK bone setup. It's worth noting (though it may be obvious :P ) that I'm relatively new to Python in Blender.

I usually have 3 separate bone chains in my IK/FK setups:

"Main" chain with two "copy rotation" constraints on each bone alternating between IK/FK-chains

FK control chain with 3 bones: FK_a, FK_b and FK_c

IK control chain with 3 bones and swivel control: IK_a, IK_b, IK_c and an IK_swivel

Then I have drivers that handle the switching of the constraint weights.

I have a relatively good grasp on making UI items, so I'm thinking the simplest approach to snapping would be to have Python commands that gets and sets rotation and location, something like:
FK to IK UI button:

FK_a.rotation = IK_a.rotation

FK_b.rotation = IK_b.rotation

FK_c.rotation = IK_c.rotation

IK to FK UI button:

IK_Swivel.location = FK_b.location

IK_c.location = FK_c.location

IK_c.rotation = FK.c.rotation
I remember doing this successfully with Max-script (in 3Ds Max) a while ago, but I haven't been able to find the equivalent solution in Blender yet.
I'm currently putting time into learning Python, so hopefully I'll find a decent solution myself at some point, but I thought I'd put the question out there in case I'm not alone :)

Does anyone have suggestions for how to achieve this? Or maybe knows of another (answered) question on this site, or a good tutorial on the subject? Any help is appreciated, thanks in advance!
Edit:
After a couple tries with the pose_bone.matrix commands I think I am getting close to a simple version of what I was seeking. It is not yet "clean code", but it basically works the way I intended it to:
import bpy

def FK_to_IK():
    armature = bpy.context.scene.objects['IKFK']
    FK_a = armature.pose.bones['FK_a']
    FK_b = armature.pose.bones['FK_b']
    FK_c = armature.pose.bones['FK_c']

    IK_a = armature.pose.bones['IK_a']
    IK_b = armature.pose.bones['IK_b']
    IK_c = armature.pose.bones['IK_c']

    FK_a.matrix = IK_a.matrix
    FK_b.matrix = IK_b.matrix
    FK_c.matrix = IK_c.matrix

def IK_to_FK():
    armature = bpy.context.scene.objects['IKFK']
    FK_b = armature.pose.bones['FK_b']
    FK_c = armature.pose.bones['FK_c']
    IK_c = armature.pose.bones['IK_c']
    IK_pole = armature.pose.bones['IK_pole']

    IK_pole.matrix = FK_b.matrix
    IK_c.matrix = FK_c.matrix

FK_to_IK() # to be added to FKIK snap button

IK_to_FK() # to be added to IKFK snap button

However, I am having a problem with the FKtoIK function; I have to run the script three times, where each run updates one bone in the chain. The IKtoFK function runs smoothly in one go. Any ideas as to why this happens?

You should try to do it yourself and when you encounter problem(s) that you were unable to find answers for ask it here. You transform the bones by doing matrix operations or setting those matrices on bones. There are couple questions on this topic on this site, you may find them interesting, like this one

Thanks a lot for steering me in the right direction, I am certainly getting closer to achieving the desired effect

Have you tried forcing a scene update (to recalculate the positions) bpy.context.scene.update()?


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Custom splash screen in 2.68a?
I was wondering if it's possible to change the splash screen of the newest Blender version (2.68a). You could change the splash in previous versions via splash.png but I can't find it in 2.68a?

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


text:
Modify object's geometry after animation has been applied
I have just made some animation on object (applied some Rot, Scale, Transform keys on different frames so object is performing motion) and suddenly it is understood that object must have some other proportions (a little bit more). The question is: how to change geometry of such an object without affecting (remove, change or other actions) all animation keys?

This depends on how you animated the object. If it's just simple transformations, you should be able to edit  it and have it behave fine, if it has any deformation, it might be a bit tricky or next to impossible. If you could share the blend file, we might be better able to assist you.

One trick you can use is to parent it to an Empty object. Any transformation to an object will affect any other object parented to it, compounding their own transformation without needing to change any single keyframe. And an Empty is the simplest to setup as the parent, for such purpose.

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


text:
bpy data out of sync with the actual scene
My python command line shows names for objects that are not on the scene anymore when I try to autocomplete on
bpy.data.meshes

like
bpy.data.meshes['Cube']

is a valid reference even though there is no object named Cube on the scene anymore and no error or warning is issued, my script just goes on and does nothing .
I'm supposed to keep the Python API in sync with the scene manually - and in this case, how ? - or I'm missing something ?

bpy.data.meshes is all of the meshes in the all of the scenes. Meshes are different from objects, a mesh would be like the vertex positions while an object is made of a mesh, and contains the modifiers, materials, etc.
If you have an object selected you can see the name of the mesh by going to: Properties Panel > Data here you will see the name of the object's mesh, you can also get a list of all the meshes in the scene.
I am guessing that you have a cube, or an object that at one point was a cube and that is why the mesh name is Cube.
If you want to get rid of meshes that aren't currently being used then you can do something like this
import bpy
for mesh in bpy.data.meshes:
    if mesh.users == 0:
        bpy.data.meshes.remove(mesh)

yes, but why they don't go away when the associated object is not there anymore ?

@user2485710 if the mesh isn't being used by any objects, then it will be deleted on the next opening of Blender or by Ctrl + Shift + O, and reloading your current file. Just make sure to save first. If that doesn't get rid of it then it is still in use. A way to check if it is not in use is go to Properties Panel > Data and find the name of the mesh in the dropdown and see if there is a 0 beside it

and what's the equivalent via Python ? How to force this update via script

@user2485710 check my original post, I updated it


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What is wrong with this OSL shader?
I don't understand what is wrong with this shader
shader simple_material(
    color Diffuse_Color = color(0.6, 0.8, 0.6),
    float Noise_Factor = 0.1,
    normal Normal = N,
    output closure color BSDF = diffuse_toon(normalize(Normal),1.1,0.0)
    )
{
   color material_color = Diffuse_Color * mix(1.0, noise(P * 10.0), Noise_Factor);
   BSDF = material_color * diffuse_toon(normalize(Normal),1.1,0.0);
}

What I'm doing wrong and why the output is black ?
I checked and re-checked everything but still I don't think there is something obviously wrong with this .

It seems that you missed one of the following settings:

Diffuse color of you OSL input node
Tick Open Shading Language in the render settings
Set Render device to CPU (GPU can't handle script nodes)


text:
How to unfold mesh with a principled BSDF material onto a flat object in 2.8?
I'm trying to unwrap an image that I've applied to a mesh with a Principled BSDF shader. Here is the material node graph:

Is there a way to include the material I've applied to my icosphere in the UV unwrap?
Here is the UV map I want to unwrap to:

Add an image texture node
Click on new on it and create a picture file, this node must be active (select it)
Switch to Cycles render
Decrease the render sampling to 1
Select diffuse in the Bake tab and select only Color for the influence
Click on Bake then save the baked picture


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How do I find appropriate UV coordinates at seams in geometry nodes
In the example image embedded below, the positions are offset inward if their uv coordinate (y) equals 0.5. You can see that the seam has a uv coordinate of 0.5 for some reason. I believe that it is because it is average 0 and 1 (where it would be on either side of the UV island). For my project to work, I would be happy with it using either 0 or 1. Any ideas on achieving that?

I have tried splitting the geometry at the seams, but that messes up the normals.

It's quite confusing, because, as you deduced, there's a  hidden implicit interpolation of attribute values from Face-Corner to Point, when you plug the maths straight into Set Position.
In order to sidestep that, you can explicitly execute the comparison in the Face Corner domain:

Which makes this difference:


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Cleaning up topology and hiding lines when shader auto smooth
I've created a plane model and I'm happy with the wings and engine topology the body of the plane has horrible topology. I used a Boolean modifier for the windows(I'm sure there are better ways but I'm not advanced enough to know them) there is also some ugly lines that go across the body when shaded smooth. Would anybody have any tips to fix these?

(Using Blender 3.6.8)
The fuselage is indeed "interesting". There are many issues to solve before trying to improve the shading.
In Edit Mode, the menu entry Select > Select All by Trait > Non Manifold could help to visualize where to improve the mesh (for example by merging vertices) as illustrated in the following figure:

Here are two examples of interior/duplicated edges or faces that should be merged:

In Edit Mode also, the menu entry Select > Select Sharp Edges could help to visualize where unexpected sharp edges are detected setting a very close to 90° Sharpness value as illustrated in the following figure:

As a conclusion, it might worth it to start from a "clean" thickness for the fuselage skin before cutting the windows, as most of issues are a consequence of extra faces inside this skin.

I'm not sure I understand do you suggest that I should solidify the model and then cut out the windows or are you suggesting that I clean up the mesh manually? I really appreciate the help, thank you!

Because you have issues at each window, I would recommand to solidify the fuselage, to make it a manifold. Then to cut out the windows. Otherwise, you will spend a lot of time, not being sure that every window is the same.


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Texture is "inverted" when object has a face in front of another face
It's kind of hard to explain what's going on. I sketched a flower in Photoshop, saved it as an image, and imported it as a plane. From some directions, its transparent depth is inverted.
I knifed a couple extra points on it so I could "cup" it like an actual flower.
When you view it where you can see all the faces, it looks just like I wanted:

The problem is when you view the flower at an angle where a face overlaps another face between the camera, the rear face shows in front:

The blue petal should be fully in front of the red petal, but when you look from a lower angle, the red petal seems to show in front of the blue one? I didn't do anything fancy - just Image as Plane > Knife some points > move them around.

If EEVEE.. (maybe tag your question)... could be similar to this problem. Does switching to Alpha Hashed make a difference?

Sorry, I wasn't sure, it was just in Viewport Shading: Rendered (whatever the default is). That was the issue though! Alpha Hashed fixed the issue - thanks for pointing me in that direction!

Cool. EEVEE is used as the full renderer by default on startup, (and always for Material Preview mode).. switched in the 'Render' tab of the Properties region. I won't turn the comment into an answer.. someone out there might be able to explain why this happens.


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How do I fill in a 3d mesh?
I want to 3d print a model I made using mineways. The print fails because the model is hollow though and I need to fill it. There is a post asking for something similar to what I am asking but I want to keep the color of my statue too. I wanted to voxel remesh my object but when I do it comes out solid green.

All polygonal models are surface-only .. can you say what you mean by 'hollow', if not that? Maybe even share your file on https://blend-exchange.com/

Here is my blender [file] (https://blend-exchange.com/b/Xyma8DDx). When I say the model is hollow I mean it is empty, I'm new to blender so maybe there is something I'm not getting here. When I tried to print the model, it failed because it was hollow and the roof caved in. Or at least that's what my librarian told me ( I use a library's 3d printer ).

I have answered my own question. What I did to fill and add support to my model was to import the model in cura. Then I set the infill to 20% and turned on support on trees mode. It's printing now and doesn't seem like it's going to fail.

You cannot 3D print non-manifold geometry. Go into Edit Mode and then menu Select > Select All by Trait > Non Manifold. It will select all non-manifold edges which you have to fix. There are around 100 edges in your model that are non-manifold.

An object being hollow is not the issue. For as long as your mesh is airtight, it will get printed as a pure solid (wasting a lot of material) like the Default Cube on the left unless you have explicitly modeled it to have hollowness like in the below example on the right where you can see it in x-ray mode having thickness inside. Just make sure the Face Normals are facing in the correction direction as seen in the cross-sectional view. So your first option would be to create an interior so it has some thickness which can also save you alot of material when printing.

The other option is to separate the 2 cubes by giving them their own separate edge which isn't shared. What you can do is select the shared vertex and go into menu Mesh > Split > Faces & Edges by Vertices. This will create 6 vertices overlapping each other. To visualize how that looks like I have explicitly moved them apart. You need to join the encircled vertices back together. Just be careful that you don't accidentally merge the 2 resulting merged vertices back together when you do a AM > Merge By Distance operation.

Unfortunately, it looks like you also have internal faces which is also non-manifold. Read more about non-manifold geometry here.


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Shape Keys are inactive in Edit Mode
How do I activate shape keys?
In edit mode, ( Properties Window --> Data )
The + and  - buttons in the Shape Keys tab are gray and inactive.
Any pointers?

Shape keys work by storing two states for your mesh and allowing you to blend between the two. First off though I would caution just adding shape keys with no armature. They can have uses without armatures, but they are most commonly used to either correct bad/weird deformation or to add additional details to the deformation that are hard to make with an armature.
Here's a quick rundown of how shape keys work. This isn't extensive by any means, but should get you up and running with shape keys.
First step is to start in object mode, then add a shape key with the little '+' icon. This will create a shape key called Basis. This is the first state that blender stores, and as the name suggests, it is the default, original shape of your mesh, as if it had no shape keys.
Next, add another shape key. You can name this one whatever you want by clicking on the name. This will be the second state that is saved for your model. By default, the slider will be set to 0, which is fine.
Now, with the second key selected, go into edit mode. You can edit different keys by selecting whichever key you want to edit. Note that you do have to be in object mode to select a different key, which is why they are greyed out in your case. Now you can edit your mesh to be whatever state you want to blend between. You could, for example, close an eye, or create some wrinkles that would appear when the mouth of your model would open, or whatever you like. Once you are happy with your model, go back to object mode. You will notice that it will go back to your original model.
The slider under your shape key will now do something, and if you adjust to anything other than 0, you will see your model blend between the two states. You can continue to edit and add as many shape keys as you like as many times as you like.
One thing to note, in addition to what I cautioned at the start, is how shape keys deform your mesh. Unlike an armature, which connects the vertices to a bone and makes them follow the bone, shape key deformation is linear. Basically what that means is each vertex will go in a straight line between its position in the Basis key and the additional key. To give an example, if you made a shape key to bend a characters elbow, and you went into edit mode and rotated the mesh about the elbow, so that in edit mode the motion is proper, the shape key would not pay any attention to how you moved the vertices, just the start and end positions.
Here is a link to the Blender Manual page for shape keys (link) which you can go through to find out more about each setting and the workflows behind it, but I would suggest trying things by yourself a bit first to see what you can figure out.


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Is there an addon for making the timeline BPM-based?
I've found one called Rhythm 1.0 but it seems it no longer exists. Anybody know of something similar?
Thanks!

Timeline markers.
Have a vague recollection of Rhythm. To display on timeline Could use timeline markers.

Test script. 180 bpm at 24 fps comes out as 8 frames per beat (fpb). A timeline marker is added at every fpb frames starting from 1. The "|" name can be set to nothing "", or whatever.
import bpy
scene = bpy.context.scene

bpm = 180
fps = scene.render.fps
fpb = 60 * fps / bpm
print("frames per beat", fpb)
frame = scene.frame_start
while frame < scene.frame_end:
    scene.timeline_markers.new("|", frame)
    frame += fpb

Thank you, yes, this worked alright!  This literally made me say: "okay, screw it, I have to learn python now" So if I ever make an addon of this sorts I'll be sure to quote you on this. Thank you.


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TexDraw doesn't actually draw anything onto the model
I'm quite a noob with blender so it probably has something to do with something I haven't ticked, so I'll give as much information as possible.

So I've built a very basic building to later export it into a game, I have made the UV and Unwrapped it, but when I'm trying to draw a texture into it by using Tex Draw, the texture doesn't actually get applied:

I don't know if it has something to do with the shading or what to be honest, here comes my shading settings too:

Here are the settings for the brush too

If there's anything I am missing please do let me know and I'll answer as soon as possible, I just really want to start with the texturing as I've been working hard (as hard as you can when you are a beginner really) in this model, thanks :D
Here's the .blend file:

Hello, maybe pack your images and share your file: https://blend-exchange.giantcowfilms.com/

@moonboots Done!

You have created a Texture Mask, and as it is completely black you can't paint anything, you need to remove it:

Also maybe lower the stencil Opacity:

And make sure the normals are correctly flipped (ShiftN):


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Cut is not as expected
So, I'm making a building and I'd like to make a molding around it on the top, so I press Ctrl-R to slice it and this is what appears. `

But instead what I want the slice to look like is like this (the slice is in purple):

CTRL + R is a Loop Cut. It's not literally a "cut" but a seam (of sorts). You may need the Knife Tool but i am not well versed with it. Im sure someone will help you.

Thanks! Yeah, the knife tool worked perfectly! I just got into an isometric view in one side, turned on the cut through with Z anc used C to fix to an angle, it cut like a charm :D

One of you please make an answer. It seems that you have found a solution for something others might also appreciate. And it would get this out of the list of unanswered questions. @Dontwalk

[Answer added for completeness.]
⎈ CtrlR initiates a loop cut and a new edge loop intersecting the chosen edge.
To cut through a number of edges, which are not connected by edge loops, use the Knife Tool.

Go to an orthographic view (front view).
Press K to enter the knife tool, press Z (to enter cut through mode) and C (to constrain the angle). Then draw a poly line with two  LMB clicks. Press ⏎ Enter to confirm.

The options you activate while the tool is selected.

Cut through Z
Allow the Cut tool to cut through to obscured faces, instead of only the visible ones.
Angle constrain C
Constrains the cut to 45 degree increments.

It's impossible because the loop cut tool is based on your topology, it basically creates one or more loops inside a loop.
However, what you can do is to use the Knife tool with K, if you watch the 3D viewport's header you will see the Knife tool's options. including the "cut through" Z which, once enabled via its shortkey Z, will allow you to cut a straight line through the mesh. Just set a side/front view and that will do the job.


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Merging two edges that are identical

Yes, I know, OCD is pretty bad :P
And while you're at it, if you want as a bonus :p

There appear to be random faces inside the 3d object itself, or that's what I think by seeing those little dots inside the column, and not in the center of any face.
how do you get rid of those?

I think Mesh>Vertices>remove doubles would work

Remove doubles?

In Edit Mode using "Vertex Select, Select the top left Vertex then while holding SHFT select the bottom left vertex press ALT+M > At Last.

Then do the same for the remaining two vertices. But as you can see from the drop down menu you can choose your own order to merge them.

As mentioned in comments, multiple vertices that are in the same place can be removed by selecting them, and then pressing W while your cursor is over the 3d view area, and selecting 'Remove Doubles' from the pop-up menu. It is good practice to remove any doubled vertices that sometimes appear due to minor mistakes now and then, by selecting all vertices and doing the same thing.
The last part of your question is a separate matter (and thus preferably would be a separate question for better clarity, but no worries). From what you say, it sounds like this is one object, a column, with everything joined together. If so, you can select everything connected to it by selecting any part of it and then pressing Ctrl + L. Then, select the reverse of that by pressing Ctrl + I. That will leave selected everything that isn't part of the column. You can take a closer look at what it is by pressing . on the Numpad, which zooms to what's selected.


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What tool to use for vertex intersection of three lines? Stuck on this
I hope this puzzle here finds you well. I hear tell this question has been asked and answered. If you are aware of that, please point me to a link that demonstrates as such. I can't find anything close. So here goes again:
I have three lines that need to intersect into a single vertex, but each line has a position on a circle that must also move without distorting the shape of the circumference. The picture shows a planar shape. There is no volume. I intend to extrude that later on.
Going backwards with boolean operations has proven unreliable because later artifacts interfere with the next steps in the design. There has to be a tool method or math function that will let me do this. I have tried loop cuts, knife tool, etc and then reduced down to planar space, but I still get a slight goof in the circle or straightness of the lines no matter how I approach this.
Has anyone encountered this kind of sub-d surface modification before? In AutoCad there is a trim utility where you can select a line segment as a knife edge (so to speak) and then the target segment gets split where they cross...
But I can't figure this one out and I bet it is something simple.

Could you just subdivide line C, B, A and then Alt + M to merge the 3 vertices?

Unfortunately that doesn't take into account the offset of the vertexes on the top and bottom of the circle. But thanks for trying. I know of course I have to introduce a vertex along each line at some point anyway. Subdivision may be the first step that you have hit on, but what to do next has me stumped still.

Marking the question I have posted as duplicate without referring the original question accomplishes nothing. Duarte - I would love to see the answer and not just a duplication indicator. So for the sake of explaining how it is different I will tell you this - it is different in every single last way since I see nothing resembling it anywhere else in the database. Care to share something a little more meaningful?

Ryan - they mutually average the sum of their distances and distort the original shapes involved. But thanks for the reply. Duarte marked my question as duplicate without referring the answer. Which makes zero sense. I have looked for the duplicate question and answer to no avail. I am still stuck on this.

Well - I take that back. A link has appeared at the top of the question I hadn't previously noticed before. So thanks for whoever placed it there.


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Shifting face vertex order
I need to shift the order of referenced vertices in a face. I've been trying to do it in python after being unable to find a "normal" way of doing it, but I've hit a bit of a dead end and I hope someone can help me.
To be more concise: Let's say, for example, a triangle face uses the vertices [1, 2, 3]. What I need is to shift those indices to [2, 3, 1]. Obviously it's the same triangle, but I need those indices to be in a certain order.
The furthest I can get is the following python script that shows the vertex indices of the selected triangle. I'd love to rearrange the "verts" member, but it's read-only.
import bpy
import bmesh

me = bpy.context.object.data
bm = bmesh.new()
bm.from_mesh(me)

for face in bm.faces:
    if (face.select):
        print("face index %u" % face.index)

        v0 = face.verts[0]
        v1 = face.verts[1]
        v2 = face.verts[2]

        print("vertex 1: %u" % v0.index)
        print("vertex 2: %u" % v1.index)
        print("vertex 3: %u" % v2.index)

I understand that bmesh is some kind of "working copy" of a mesh which then needs to be saved back. Do I need to make a new bmesh and then copy the old one while applying my changes somehow?
EDIT: Since I can't write comments myself, I'll address thibsert's comment here: As far as I can tell that just rearranges the "global" list of vertices of the mest, which I need to be untouched. It's the face's own list of corner vertices that I need to shift. I know this is a very fringe use case :)

The "normal" way of doing it is : Mesh menu / Sort Elements / Reverse. Edit: not 100% sure this is correct, I'll leave it here just in case that might help you.

Re last edit. (Try commenting if replying to a comment on own question)  The face verts are in a winding order. If two faces share an edge and you change order of one face's verts it may affect connected faces vert order.  Can make a mesh using Mesh.from_pydata(verts, [], faces) where verts is coordinates and faces is tuples of vert indices. Consider testing to see if what you are attempting to do is possible.  Also can you clarify, is the change in order always cycle one right?

I don't know how to do it with a bmesh, but it's easy with a regular mesh since mesh.loops[i].vertex_index is writable.
import bpy

ob = bpy.context.object
assert ob.type == 'MESH'

# If in edit mode, switch to object mode and switch back at the end
was_in_edit_mode = False
if ob.mode == 'EDIT':
    bpy.ops.object.mode_set(mode='OBJECT')
    was_in_edit_mode = True

me = ob.data

for poly in me.polygons:
    if not poly.select:
        continue

    # Get loops for this poly
    # Loop = corner of a poly
    loop_start = poly.loop_start
    loop_end = loop_start + poly.loop_total
    loops = [me.loops[loopi] for loopi in range(loop_start, loop_end)]

    # Get vertex indices for each loop
    vidxs = [loop.vertex_index for loop in loops]

    # Shift
    vidxs = vidxs[1:] + vidxs[0:1]

    # Write back
    for i, loop in enumerate(loops):
        loop.vertex_index = vidxs[i]

# Not sure if you need this
me.update()

if was_in_edit_mode:
    bpy.ops.object.mode_set(mode='EDIT')

With one loop.
Was seeking clarification on this, if the idea is to rotate the vertices of the face loop. Similar to @scurest can use the foreach_get and foreach_set methods to provide quick access to values without looping in python.  This will have a significantly increased performance for a high poly count.
The loop start is taken directly from the data. The loop end by accumulating the number of verts in each face.
Have used a deque to rotate the face vert list. A positive value for rotate rotates the list to n the right, negative to the left. eg to make the ith element first Deque.rotate(-i) For example could find which is face vert is closest to the origin and rotate each accordingly
import bpy
from collections import deque
from itertools import accumulate

rotate = 1 # rotate 1 to right

context = bpy.context

ob = context.object
me = ob.data
n = len(me.polygons)

loop_starts = [0] * n
me.polygons.foreach_get("loop_start", loop_starts)
loop_ends = [0] * n
me.polygons.foreach_get("loop_total", loop_ends)
loop_ends = accumulate(loop_ends)
face_select = [False] * n
me.polygons.foreach_get("select", face_select)
vert_indices = [0] * len(me.loops)
me.loops.foreach_get("vertex_index", vert_indices)
'''
# Note same as
me.polygons.foreach_get("vertices", vert_indices)
'''

for select, start, end in zip(
        face_select,
        loop_starts,
        loop_ends
        ):
    if select:
        face_verts = deque(vert_indices[start : end])
        face_verts.rotate(rotate)
        vert_indices[start : end] = face_verts

me.loops.foreach_set("vertex_index", vert_indices)
#print(me.validate()) # while testing just in case.

Test on default cube.
Before
>>> me = C.object.data
>>> for f in me.polygons:
...     f.vertices[:]
...
(0, 1, 3, 2)
(2, 3, 7, 6)
(6, 7, 5, 4)
(4, 5, 1, 0)
(2, 6, 4, 0)
(7, 3, 1, 5)

After
(2, 0, 1, 3)
(6, 2, 3, 7)
(4, 6, 7, 5)
(0, 4, 5, 1)
(0, 2, 6, 4)
(5, 7, 3, 1)

similarly with bmesh
>>> bm = bmesh.new()
>>> bm.from_mesh(me)
>>> for f in bm.faces:
...     [v.index for v in f.verts]
...
[2, 0, 1, 3]
[6, 2, 3, 7]
[4, 6, 7, 5]
[0, 4, 5, 1]
[0, 2, 6, 4]
[5, 7, 3, 1]

Note.
Still need to make sure of the winding order, if for example sake were to simply randomly shuffle (random.shuffle) the face loop verts
        face_verts = vert_indices[start : end]
        shuffle(face_verts)
        vert_indices[start : end] = face_verts

will end up with incorrect winding, and a mess

loop_ends isn't necessarily accumulate(loop_totals).

Can you provide an example  where it isn't?

If the loop_starts aren't in ascending order, it won't be true. You can make an example by picking any two quads and swapping their loop_start. I think it is true for anything that came from a bmesh, but it's just as easy to use start + total instead of end.

validate() returns False if it was already valid, and it doesn't change the loop_starts for me. Going through a bmesh (toggling edit mode) does reorder back to ascending order.

Yep know how validate works, even though totally naffed up the comment & .. forgot to edit.  Simply toggling edit mode returns to ascending order eg range(0, 4), range(4, 8) etc for default cube. Very f-n unlikely that the user has made it such that the order isn't ascending.  Happy to stick with accumulate.


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Create Surface from Selection
I have imported a .stl model into Blender with the goal of isolating and shading various parts of the model (painting it). I'm stuck with this format as a starting point.
In the Modeling pane I've selected the first part of the model that I want to isolate and I believe I want to create a Surface so that it can then be shaded.
Assuming that creating a Surface is correct, I can't figure out how to.  Right-clicking the selected vertices brings up the Vertex Context menu but I see nothing about Surfaces.
Is there a step I'm missing or a menu?
Here are some images to demonstrate what I'm seeing.
This is what it looks like when I select using the circle and box tools.

After some playing I realized I didn't have everything and after selecting 'more', I get this

Now it looks like I have the whole blade selected (although I'm really not sure).
So time to make some faces, and when I hit F, this is what happens.

I would expect to see something new in my Scene Collection, nope. When I pop over to the Shading pane, nothing new to see, in fact, the disappearance of the geometry is the only indication that something (who knows what) happened.

Blender calls surfaces 'face's so you're looking to create faces.  Are you sure there are no faces in the model?  To create a face, select a group of vertices and type the f key.  That will fill the vertices with a face.  Unfortunately if your model has no faces at all you'll have to do that for every face.  Can you share your blend file?

Thanks for your response.  I'm reasonably sure there are no faces, this is a unmodified .stl file.  In Daz it was a single "surface", I'm not sure if that means it's a single face in Blender. In any case, when I try to create a face from the selection, I get an error, "Could not create merged face".

If the model has no faces, you will see nothing but black dots and lines.

Check out docs.blender.org -> Modeling

Yes, exactly, the model in question, when I bring it in, has only lines and dots, I'm not sure how that helps, can you clarify (without referring me to the documentation).

maybe you should add your blend file to your question - because it does NOT look like you have no faces....

what @ZargulTheWizard is trying politely saying to you is that your Blender knowledge could be a little bit more advanced. You are assuming too much with too less knowledge.
"A common object type used in a 3D scene is a mesh." (from Blender docs). A mesh consists of vertices (points), edges (connections between points) and faces.
"face
A closed set of edges, in which a triangle face has three edges, and a quad face has four edges. A polygon is a coplanar set of faces. In systems that support multi-sided faces, polygons and faces are equivalent. However, most rendering hardware supports only 3- or 4-sided faces, so polygons are represented as multiple faces. Mathematically a polygonal mesh may be considered an unstructured grid, or undirected graph, with additional properties of geometry, shape and topology." (from wikipedia)
With "F"

you can create an edge between two selected vertices
you can create a single(!) face between more than two selected vertices

Answer to your assumption: "I would expect to see something new in my Scene Collection, nope. When I pop over to the Shading pane, nothing new to see, in fact, the disappearance of the geometry is the only indication that something (who knows what) happened.":
But if you created edges or faces, you just change the mesh of an object, you do not create new objects at all which you could see in the outliner (scene collection).
If you just see points as in your last posted picture you just have vertices. Nobody ever would then press "F" to create one single face because that are way too many vertices and it would look like shit.
Next to your sentence:
"In the Modeling pane I've selected the first part of the model that I want to isolate and I believe I want to create a Surface so that it can then be shaded."
-> in the picture you posted to that you already have a surface (which is called faces in Blender -> try to use the right terms, else there will be lots of misunderstandings). You can "see" the faces by the gray color. The dots are the vertices and the "lines" are the edges.
Hopefully this helps you a bit. Maybe you should watch some beginner tutorials like here...
they are free:
https://www.blender.org/support/tutorials/

Thank you for those who responded but I found the answer on my own.
To solve the problem, the first thing I had to do after importing the mesh is to put a material on the whole model.  This, evidently (implicitly?) automatically puts faces on all of the triangles.
It is after doing this, I can select faces (very easy now that the model has some to select) and apply the material(s) is desire.
Finally, with respect, please do not respond to a question and point someone to the documentation.  It is in no way helpful (and quite frustrating) unless you are pointing to a very specific example of the problem or solution.

No need to assign any materials to be able to select the faces of a model.

As @Chris said, you probably should make yourself more familiar with terms in Blender and basic modeling. Your first image clearly shows your model has faces. You never have to put a material on an object just to be able to select faces. And if your object wouldn't have faces, putting a material on it won't create any. The first image looks like all those vertices are unconnected (because the edges between them are not highlighted), seems like all vertices are doubled (second image, now vertices and edges are highlighted), one set unconnected vertices, the second set connected.

Another thing is, you should make yourself familiar with the different selection types in Edit Mode. If you're on Vertex Select or Edge Select then you can't select a face (only if you select all its bounding vertices or edges). And if you add a material on an object and in the material settings you hit "Select", then of course faces will be selected, because a default material (not assigned to certain faces) automatically applies to all faces. But these loose unconnected twin vertices cannot have a material be assigned to - because materials apply to faces, not single vertices or edges.

Sorry, another addition: since it looks like you have a twin set of vertices lying over the ones connected with each other, when you select them with Circle or Box Select you almost only select those vertices that are on top of the others - to also select the underlying ones you have to turn Xray on or be in Wireframe Mode. But when you have a model like this, it's best to hit 'A' to select all vertices/edges/faces, then hit 'M' to Merge > By Distance. This usually merges the vertices that are in the same space as others.

@GordonBrinkmann The solution has already been posted.  My original post indicated the object was the result of an import of a .stl file.  I'm not sure what you call that (a mesh or something else) and I'm not sure what you would do to get this job done.  But I can tell you that I could do nothing with regard to isolating parts of the model and shading them.  However, once, a material was applied to the object as a whole (maybe that process does something as well with the vertices or edges), I was able to do exactly what I needed to do.

@GordonBrinkmann Another thing, I understand what Chris meant by referring me to the docs.  Obviously I need to be more familiar with the software, but reading documentation cold (especially Blender's) is not exactly helpful, especially when you have a task that is (obviously) out of band.  And when someone comes to a site like this looking for help, telling them to quit bothering you and go learn something is not the desired experience.

@StevenFrank That's not how he meant it. And for people giving answers it's frustrating to tell you how something works (and explaining things about faces for example) and then you tell them they are wrong but you found out yourself - and showing with your answer you still don't actually understand how it works. But I hope my comments made it a little clearer what's going on with your model.


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Mirroring rotated object

I'm attempting to mirror the orange cube to the other side, the rotation opposite, remaining the same dimensions. Any help?

Without knowing HOW you'r trying to mirror the object, not really! However, if you showed the whole screen with the mirror modifier settings and/or upload your blend file we might be able to help. - First thought (and the usual mistake lots of people make) is to make sure that the modifier is set to mirror on the Y axis rather than the X which is the default setting.

You can also use that large cube in the middle as a mirror target object, which will make your smaller one appear exactly the proportions you want.

https://drive.google.com/file/d/1maHk0lGHd4tj0qVBHPOTHsnBIygKwJti/view?usp=sharing here's my file - sorry I wasn't as descriptive - I'm fairly new to blender...

Ok. You don't actually have a mirror modifier on your object at the moment, just a Subdivision one. Add a mirror modifier to your 'eye' object, click the little white square in the modifier's 'Mirror Object' field and then 'Cube' (which is your head) in the dropdown that appears. That will mirror the 'eye' to the other side as you want. I find it's a good idea to rename your objects as you add them so that you can keep track of what's what in the outliner otherwise you'll have a whole list of 'Cube.00x' objects and won't know which to select.


text:
Nothing is unwraping in the UV window. As you can see below, i have everything selected and when i then select "unwrap" nothing happens
I dont know what´s happening. When i did it a cupple of minutes ago i at least got a map. (it was wrong and wierd looking though). Im following a tutorial (https://www.youtube.com/watch?v=xPoxqOcUzNQ) and i marked the exact seams they did and it looked sooo wrong. idk, everyting layed on top of eatchother and i couldn´t see what whas what. Then i deselected everyting and started ofer and now nothing works.
please help!
!!Update!!
It was the "show overlay" that was the problem. However it stil looks wierd to me. Why does it look like this? (it didn´t in the tutorial)

Hello :). You have no faces selected. You need to select the faces you want to unwrap.

thank you, that didn´t work either though

Your image shows that you have nothing selected in the edit window. With the mouse in that window, press 'A' then try unwrapping again.

everytig is selected. I tried to unwrap the apple again (witch have worked before) and it didn´t work either.

I highly recommended you to open a new topic for your second question seen that the original is already answered. and that will also help you to have a better answer. But basically it looks like overlapping faces.

You have "Show overlays" turn it Off"

Thank you so much! it worked :)


text:
How do I fix the unwrapped version of my knife?
The first picture below is the tutorial I´m following and the second one is mine.
Why do they look so different? And how do I fix it?
the tutorial: https://www.youtube.com/watch?v=xPoxqOcUzNQ&list=PL3UWN2F2M2C8-zUjbFlbgtWPQa0NXBsp0&index=6
update:
I unmarked everey seam and did it againg and it worked! I hav no idea what i did wrong but it works now. My guess is that i had marked some seams that you couldn´t see or someting
[]

It looks like you haven't marked exactly the same set of seams as the instructor and that when you unwrap  you didn't use exactly the same set of unwrap options.  Go back through the tutorial and make sure you have the seams the same as the instructor.  It looks like you've marked a lot more seams than they did, which is why there are so many more objects (islands) in your UV map

They don't look so different ; but some of your UVs are overlapping. You can fix that by using the "Pack Island" function (in the "UV" menu). Ifg you want a more precise answer, please provide the link to the tutorial !

or provide your blend file...

okey, i added a link to the tutorial but i caan´t figure out how i can provide my blend file. I did the "pack island" and have now updated tha image above

When you unwrap objects, there is a slider for the "Margin" that you could use. Another things is that even if you cut the same areas as in the tutorial, probably some parts will have a different orientation; that could be fixed manually with rotation
Example:

Hi, thanks. That madi it alot easier to ovrersee what it is.


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Why do i paint on the wrong side of my object?
i am trying to paint my cat. However when i try to paint where the cursor is in the first picture the colour ends up on the neck. It does this where ever i paint regardless witch way i´m facing. How do i fix this?

What does your active UV map look like?

I added a picture :) i have no idea why it looks like that

Your normals are inverted, meaning when you paint the front of the head, you are hitting the neck with your spray can. In edit mode, select everything, and go shift N or Mesh > Normals > Recalculate outside

Thank you! it worked :)

Hi Clara.. this seems to have been cleared up OK, and it's a duplicate, so it's fair to 'close the case'


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How to script the motion blur shutter curve?
I am trying to script the motion blur shutter curve (image below) for each frame of a render. I want to control the "openness" of the shutter curve with a list of values between 0 and 1. Ideally I would also like to be able to change this from one frame to the next within a single animation. I believe the variable I need to change is bpy.context.scene.render.motion_blur_shutter_curve. How do I convert a list of values to a curve and pass it to this variable?

Learned a LOT from both answers. Super helpful y'all, thanks a bunch.

I'd suggest read the values and create a dictionary out of point positions per frame, which allows to structure as well as access the values in a reasonable way:
dict = {
    frame_number : [
        (LOC_X, LOC_Y),
        (LOC_X, LOC_Y),
        (LOC_X, LOC_Y),
        ...
    ]
    frame_number : [
        (LOC_X, LOC_Y),
        (LOC_X, LOC_Y),
        (LOC_X, LOC_Y),
        ...
    ]
}

One pitfall is that the minimum point count for a curve is 2, means that you can not remove all the points of any existing curve.
The following demo sets the shutter curve based on custom data. Notice that set_curve() is a slightly modified version of the reset_curve() function from this Q&A:
import bpy

frame_dict = {
    1: [(0.0, 0.0), (0.07, 0.5), (0.25, 0.9), (0.5, 1.0), (0.75, 0.9), (0.92, 0.5),  (1.0, 0.0)],
    2: [(0.0, 0.0), (0.125, 0.44), (0.375, 0.95), (0.5, 1.0), (0.625, 0.95), (0.875, 0.44), (1.0, 0.0)]
}

# Based on 'reset_curve()' from https://blender.stackexchange.com/a/64461/
def set_curve(curvemap, custom_points):

    curve = curvemap.curves[0] # Get the curve
    # Remove redundant points
    if len(curve.points) > len(custom_points):
        n = 0
        while len(curve.points) > len(custom_points):
            curve.points.remove(curve.points[n])
            n += 1
    # Generate missing points
    if len(curve.points) < len(custom_points):
        n = 0
        while len(curve.points) < len(custom_points):
            curve.points.new(0.1, 0.5)
            n +=1
    # Set the values and update UI
    for c, point in enumerate(curve.points):
        point.location = custom_points[c]
    curvemap.update() # Optional call

C = bpy.context
shutter_curve = C.scene.render.motion_blur_shutter_curve

# test call
set_curve(shutter_curve, frame_dict.get(2))

In order to set the curve and render each frame, go through the key-value pair of the dict and call Scene.frame_set(your_frame) per iteration to update the scene:
for frame, points in frame_dict.items():
    # Set the curve
    set_curve(shutter_curve, points)
    # Set the frame
    C.scene.frame_set(frame)
    # Render the frame
    bpy.ops.render.render(write_still=True)

Alternatively you can setup a frame_change_post handler which allows to preview and set your values on the fly, when changing the frame in the timeline (before rendering):

def set_curve_frame(scene):
    shutter_curve = scene.render.motion_blur_shutter_curve
    if scene.frame_current in frame_dict:
        set_curve(shutter_curve, frame_dict.get(scene.frame_current))

bpy.app.handlers.frame_change_post.append(set_curve_frame)

Related:

Can python access control points of Hue modifier?
Python Render Specific Frames

I think this works (after running, a new text block should appear with a script restoring the curves):
import bpy, json

save_name = "load_blur_curve.py"

D = bpy.data
curves = {}
for name, scene in D.scenes.items():
    curve = scene.render.motion_blur_shutter_curve.curves[0]
    curves[name] = [(p.location.x, p.location.y, p.handle_type) for p in curve.points]

out = "curves = " + json.dumps(curves, indent=4)
out += '''

import bpy
from itertools import zip_longest

for scene_name, source in curves.items():
    curve_wrapper = bpy.data.scenes[scene_name].render.motion_blur_shutter_curve
    target = curve_wrapper.curves[0].points
    for i in range(len(target) - len(source)):
        target.remove(target[-1])
    for oldp, newp in zip_longest(target, source):
        if not oldp:
            oldp = target.new(*newp[:2])  # probably can init with just 0, 0
        oldp.location.x, oldp.location.y, oldp.handle_type = newp
    curve_wrapper.update()
'''

text = D.texts.get(save_name)
if not text:
    text = D.texts.new(save_name)
text.from_string(out)  # OVERWRITE!

Funny, I understood the question in a completely different way. We'll see, UV'd.

@brockmann when you run this script, it basically generates your script, though it seems your script uses old solutions that are battle-tested, while mine is fresh and perhaps buggy.

OH and I didn't put anything for the animation. Also I noticed there's an option to add drivers, will test later if it actually works.


text:
Bevel modifier is glitching my object
I am a noobie but im really trying to learn here and this modifier is not letting me. When i apply the bevel to the object it kinds of glitches and makes a weird outline. I`ve watched tons of videos and read a lot of solutions but i can´t seem to get it right. The thing that bothers me the most is that there is two objects, the small one i managed to make it work but the big one just doesn´t want to cooperate.

Here's my file.

You have duplicate objects in the scene.

Maybe share your object: https://blend-exchange.com/

If the problem your'e talking about is fixed by hiding Cube.001, then Gordon is on it.


text:
Animation in Blender 3.4 renders only he first frame
I am currently running into a problem where it only renders the first frame of my animation. I have checked most of my settings but nothing seems to work.
I am running Blender on a Mac Studio M1 Ultra Desktop computer fully spec'd.

MY FILE - https://blend-exchange.com/b/YOnxdQNd

Can you show an image of your R/H panel Output Properties in Blender and are you using F12 (Render > Image) or Ctrl-F12 (Render Animation) to do the render?

Hi , I have tried using both ways of Rendering , from the top panel , and CTRL F12. Both lead to the same issue where I get an error Image should be closer to 1920 X 1088 ? I seem to be able to Render Stills but not Animations I set up unfortanely. Can anyone provide an Email where I can send you my Sample file for Inspection ? Thanks a Million , I am a Designer trying to create a building that Moves. I'm also running Blender on a Mac Studio M1 Ultra if that helps. I can't seem to attach any type of file in here , I would be more than willing to send it to you for your Help . TIA

We don't do email here but you can share your file via https://blend-exchange.com/ following the instructions on that page as long as your Blend file isn't too large.

Thanks my Friend ! I surely attached the file , please if someone can figure out why my Computer doesn't want to render out an animation , I would be very Thankful for your help on This. Thats unfortunate that I can't email somebody about this. Anyways , Thanks again and I look forward to your Help

You didn't add the link to your file so we can't download it!

Hi. Please don't post essential information like links, file downloads or additional details in the comments section where it can be easily missed. Instead edit them into your original post with the [Edit] button above. Comments are transitory by nature, are hard to index or search for, and may be erased at any moment.

I apologize for not adding the link , but I think I got it right this time. The animation plays out , but won't render Out when I hit "Render Animation" something is not right. I hope the attached file and screenshots will help make things more clear. But Overall , I Love Blender and want to get this issue resolved soon. TIA

I just changed the Output path to my desktop in your file and rendered 30  frames without issues here. Do you have a GPU in your machine because I see that your render device is set to CPU rather than GPU. GPU would be much faster if you have a resonable one.

Wow , Yes I think I have a decent GPU , 64 core. Let me see if that's the Problem , Thank you so much for your insight. I hope this works out , Thanks again my friend.

Just tried rendering with GPU , I still get only 1 frame and that's it , I get an error that the Image needs to be closer to 1920 x 1088 ?? I'm clueless as to why

It's set to 1920x1080 (not 1088) under Output Properties > Format in the file you uploaded so I don't know where that error is coming from.


text:
Blender-GIS Get SRTM python error
I'm running Blender 3.4.1, and I am following this video tutorial to generate a 3D map.
The Basemap function works fine.
I got a valid API key from OpenTopography but when I try to get the elevation data (either through the option "OpenTopography SRTM 30m" or "OpenTopography SRTM 90m" I get an error message including:
'URL can't contain control characters':

Does anyone know waht's wrong??
Thank you in advance!!

Since that's an external addon not included in Blender, you should report the error to the author, but it doesn't appear to have been updated since May 2021 (v2.28) and there are various recent error reports on the github issues page for it

I had to go back to Blender 2.9 to get it to work.


text:
UV unwrapping issue, UV map appears as cube
https://i.sstatic.net/eExpP.jpg

I am working on modeling a Formula 1 car. I am almost done modeling the car, but I am running into a problem with UV unwrapping.
The body of the car is modeled off of a cube that has been extruded, cut, shaped, etc. with Blender's modeling. The wheels are modeled off of cylinders. It can be seen in the image I put here that when UV unwrapping the car, the UV map is not clean with lots of overlaps and extremely bad crowding and you can't tell which vertices in the map correspond to which vertices on the model. Interestingly you can clearly see the outline of an unwrapped cube, assumedly the body of the car, while the wheels are pretty clear.
Wondering how I can get a cleaner UV map which I can work with for texturing. Thank you for any help!

You'll need to apply the scale to your model in Object mode (Ctrl-A) and mark some seams before unwrapping it. Plenty of YT tutorials on UV unwrapping online.

Looks good! John Eason is right, you just need some seams for your unwrapping to go right. With a model like this that shouldn't be too hard, there are many edges that can be used as seams. To make a seam, make a selection of edges and press ctrl+E, then select 'Mark Seam'. This will mark those edges in red and tell Blender that when UV-unwrapping the faces that share this edge cannot be connected in the UV-map. That way you can separate the UV-map into islands, like you're looking for. Here's this short video by Royal Skies who has done lots of tutorials on Blender. Or "Blendeh", as he likes to call it.
Good luck!


text:
Why are two exported FBX files with the same nodes and property values rendering differently?
I've built a 3D environment that looks like this (I'm using the game engine Monogame; but I don't think the game engine plays a part in this problem)

I'm using external assets for the terrain tiles, given as FBX files (in the graphics shown there are 4 such tiles). The way the FBX files come; they need their path to their texture updated. To get around this I import them into Blender (v3.4), make necessary fixes, and re-export them as new FBX files (producing a version that the game engine is able to deal with).
Essentially, I found two ways to convert the FBX files, (1) by updating the texture file reference, or (2) removing and recreating the material. While between these options 1. is more direct and obvious, I just assumed it shouldn't be a problem to do 2. by copying over any material properties.
But I'm not able to do this perfectly, getting a slightly darker render. It looks like I'm missing a configuration somewhere; possibly expressing something interesting. Whatever it is, I'm curious to know what is wrong with this idea, or where the hidden settings are.

Method 1
I import the external fbx from a new Blender document deleting all existing objects, then File > Import > FBX (.fbx), choosing CPT_Terrain_M_f_13.fbx. Showing

I change the file reference of the existing Image Texture node (in the Shader Editor) to point to my own copy of the terrain texture CPT_Terrain_Texture_Atlas_01.png (located in my game-engine folder, the same directory that I export to below). It is also necessary to turn the Alpha up, for some reason the import comes with Alpha = 0 (perhaps it has something to do with the problem?). The only other change I make is 'Apply all transforms' (written into the export script).
I complete the export by running this script (saving the terrain-tile directly to the game engine folder). Without any change to the game engine itself, if I now run my game it will show the top render.
import bpy
def exportFbx(filenamepath):
    bpy.ops.object.transform_apply(location=True, rotation=True, scale=True)
    bpy.ops.export_scene.fbx(filepath = filenamepath, path_mode = 'STRIP', axis_up = 'Z')
exportFbx('Z:\\github\\LSystemsMG\\LSystemsMG\\Content\\terrain-tiles\\CPT_Terrain_M_f_13.fbx')

Method 2
I start in the same way, (i) open a new Blender file (ii) delete all objects (iii) import the same FBX file. Now, instead of changing the existing texture I delete and replace the existing material; effecting a new Principled BSDF node and Material Output node, I add to this a new Image Texture node and Normal Map node so that they are the same as observed (i.e. I set Normal Map to 'Tangent Space' and draw a connection to the BSDF). With this only the Specular and Roughness components in the Principled BSDF are different, otherwise all settings are the same.
I then export the FBX using the same Python script. This leads my game to producing the second darker render.
Properties seen
All the Material properties and properties in the Shader Editor are the same in both cases at time of export.

I found the answer; there are hidden properties in the materials not used by Blender but are still exported with FBX and, evidently, used by external parties such as my game engine's shaders (Monogame). Searching with scripts I found quite a few obscure values, but there was only one that I needed to change in my case, namely, the default value for the pincipled BSDF Base Color

Yes, there's a hidden value behind the texture node that is exported with FBX. The value can be read
bsdf = bpy.data.objects[0].data.materials[0].node_tree.nodes['Principled BSDF']
hidden_color_value = bsdf.inputs['Base Color'].default_value

In my case the new material I created needed to be updated from (0.8,0.8,0.8,1) to (1,1,1,1) to behave the same as the other
def setPrincipledBsdfBaseColorDefaultValue(r, g, b, a):
    bsdf = bpy.data.objects[0].data.materials[0].node_tree.nodes['Principled BSDF']
    bsdf.inputs['Base Color'].default_value = (r, g, b, a)
setPrincipledBsdfBaseColorDefaultValue(1,1,1,1)


text:
Baking a normal map on to two (seemingly) identical cubes is producing different results
I'm experimenting with baking normal maps. In my setup I've used the default cube with some notches cut out along the edges for the high resolution object (cube-high-res), and the default cube without any changes as the low resolution target (cube-low-res1). Things were going fine, but at some point I think I must have changed something on cube-low-res1, whatever it was it started messing up the normal map result. I brought in a new default cube (cube-low-res2) as the new target and the normal map produced good results again. To find out what happened I checked everything I could between cube-low-res1 and cube-low-res2 and found no differences in them. So my question is why are the normal maps generated between then different, did something happen to cube-low-res1 that is causing the difference or is it something else?
Here is a screenshot of my 3D Viewport and object hierarchy.

The objects shown from left to right are cube-high-res, cube-low-res1 and cube-low-res2. There is also a cage object (hidden from view) which is another default cube that is scaled by 1.01 on each axis and shares an origin with cube-high-res. Now, if I in turn bring in cube-low-res1 and cube-low-res2 and bake their normal map in the Scene properties (with Cycles), I get the following two different results.

The left image is the result of baking on to cube-low-res1 which is the messed up result. The right image is the result of baking on to cube-low-res2, this result seems to be a good normal map.
To ensure alignment while doing the baking I've set the origin on cube-low-res1 and cube-low-res2 by choosing Set Origin > Origin to Geometry, I make them coincide with cube-high-res by opening the Snap Menu (shift+S) and choosing Selection to Cursor, like shown here

I've done the following checks between cube-low-res1 and cube-low-res2 to determine what can be wrong.

Both object have the same vertices (8), edges (12) and faces (6). And they have the same dimensions (2x2x2m). I.e. they are both the default cube.
Rotation and scale have been applied to both objects.
I've recalculated the normals on both objects.
I've UV unwrapped both objects in the same way. I.e. using Smart UV project with an island margin of 0.09.
All seams have been cleared
Both objects use the same material, and therefore also use the same Image Texture node in the Shader Editor
The Bake settings are the same, I've set these to Bake Type: Normal, Selected to Active: checked, Cage: checked and set to cage object, Extrusion: 0.1m

The Blender version is 2.82a

Hello :). Since it's a really simple scene, consider sharing the .blend.

That's a good tip, thanks! I added the file :-)

The two lowres cubes are not the same. You may have rotated them or changed the vertices in Edit mode somehow... Here are the vertices IDs shown using the MeasureIt Addon (also possible by enabling developer mode in settings somehow).

Also the UV unwrap are not the same either for probably the same reason. If you split the seemingly same quad face into two triangles, they appear at different positions in the UV, meaning the quad faces are in different orientations to begin with.

Finally, simply duplicating the first lowres and baking the texture with the dup produces the same result as its source.

In essence, you have to add proper UV's to your low-res geometry to avoid artefacts and you have to make sure that the dimensions of both geometries are roughly the same, then it will bake fine:

Few seconds too late... so I added my result and the blend to your answer, hope that's fine @bruno

Good answer thanks, I didn't know about vertex IDs! I also discovered if I rotate the cage in the same way as cube-low-res1 then it will bake a good normal map

Excellent @brockmann, thanks.


text:
I have a problem with Blender, it bakes the textures to different images

I have 6 materials each have an image because my model have different textures and i solved it with material image texture. But Blender bakes the textures into different images. Because in the UV editor there are 6 images.
The UV map is on every image but i want it to be only on the Untitled.001

Each of them have this node

Welcome to Blender Stack Exchange! Just to clarify, you have a model with 6 materials, each with a unique texture, and you want to bake them into a single texture? Any chance you can edit your question and add an image of what you've tried so far?

Based on what i can see, there are 6 images available in Blender, but the one that is supposed to be baked on, is black, means most likely the backing did not succeed yet. The dds files are most certainly not baked by Blender.

I solved it with asign uv map in nodes for the untitled 001 node

Btw thak you very mutch!


text:
how to apply texture paint

I drawn his eyes and mouth in texture paint and saved the image as png file

However when I go to layout, my drawing disappears.
How do I apply texture paint to my character?

Is this Texture Paint or Grease Pencil? You don't appear to have a texture on your object, but the strokes look like Grease Pencil object.

You first need to create the UVs
Than you need to unwrap your UVs
Than enter Enter Edit-Mode
Than select  the base of the neck in a loop at the base using edges
Than press CTRL+E > Edge Data > Mark Seam
Than Unselect All all selections
Now make an edge selection starting from the base of the neck (in the middle of the loop you just selected but starting at the middle of the neck, and select edges all the way up to the top of the head)
Than CTRL+E > Mark Edges
Select All all selections
CTRL+U > Unwrap while still in Edit-Mode. Now you have a UV map.
Finally apply the texture you created. You should than get distorted paintings.
Start to re-painting again, only this time you should see your UVs and your material and Your textures.

BFCT_Schiller

Hi. I would like to suggest not asking people to accept your answer (when they have not indicated that the answer has helped them) as asking encourages people to accept the first answer, not the best one. If they comment or indicate the answer has helped, then teach them about how accepting works (see: https://meta.stackexchange.com/questions/88535/asking-for-someone-to-accept-your-answer). Also, regarding adding sign-offs to your question: https://meta.stackexchange.com/questions/5029/are-taglines-signatures-disallowed

I'll link on images, all posts where it is demostrated clearly that new users do not know how voting works. I've explained this over and over. I'll include and IF answer works for them, next time.


text:
adding surface (F) adds vertices, massing up subdivision surface
I am totally new to blender, so please forgive me if it is a dumb question.
When I add a face by pressing 'F', I found out it adds an vertices to
where it seems to be middle position of selected points.
It doesn't show up in vertex select mode, but I can see it on Face select mode.
Because it doesn't show up in vertex select mode, I tried to delete it but I can't.
and it mess up subdivision surface.
I am so confused why it is happening, please help.
Thank you!

I select vertices to add face.

Pressed F and looks perfect.

But when I change to face select mode, yellow dot appears inside a circle with green and red arrows on it.

end up with weird shape because of that dot. :(

That orange square you see is not a vertex, but a "control point" that represents your face in Face selection mode (it's placed outside the actual face because the face is concave!). Also, it is not the reason your Subsurf looks odd.
Subdivision surface looks bad in general with faces with high number of edges, especially if they are concave.
The particular case of the base of an anvil has been asked dozen of times. Not all of them have the exact same issue (though they are similar), but the first one definitely is like your case:

Subdivision surface modifier issue
Anvil, extra lines thingies
Subdivision Surface not making things smooth as they are in the tutorial I am following
and many more

Unfortunately, using subdivision on a mesh like that one, wont usually work if you work off edges and vertices, blender doesn't like that.
start from the top and work to the base, that's the way I like to work, and it allows me to scale things better.
work off what you have though, perhaps don't subdivide, but use the cut tool in editor mode and smooth it yourself, to make it look more human.
also the dot is the center of the entire thing? if it's yellow and you've selected the mesh.
using F to make faces and subdivision aren't good friends!
( i'm not a pro, take what I say with a grain of salt, it might not work! )


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Cycles pearl-like material
Is there a way in Cycles to make pearl-like material using material nodes, something like this LEGO brick surface (I am adding more cos it might be hard to see what it is actually)?

You see, it is not metallic but rather like slightly "rainbowish" overtone variations depending on angle one is looking at it (that's my best description of it) with very tiny metallic shine maybe. Literally pearl surface from a shell in different colors, not just white. :-)

Check this material out.. (actually the rotations in the Anisotropic BSDF components should be 0-1, not 0-360) But it's a great starting-point.

To me this approach is the correct one, very similar to what @GordonBrinkmann was proposing today.
In fact - as I commented under his approach - I created my final material design yesterday evening after seeing a YT video about making pearl surface in Blender that pushed me to the right direction: I basically just added mix shaders to mix that pearl effect with the actual BSDF material (I am not sure if I used the noise/bump from the @moonboots file or the one from the YT video or kind-of mix of them both).
Maybe the rainbow fx could be even less visible (I am calling it rainbow but it is more like oil spill in my case, haha), cos it is OK on the head but looks too intensive on the cockpit window, so if there is some sort of distinction how the fx should be strong according to, IDK, flatness of the surface, then it should be added so it would be less visible when the surface is more flat and/or bigger and more visible when the surface is smaller with lots of "angles" (I have no clue if there is something like that in the nodes for Cycles, I am amateur, really).
And this is how it looks (I added @GordonBrinkmann approach side by side for comparison):

It would have been nice (since you accepted this as the correct answer) if you would have uploaded the file or at least showed a screenshot your node setup... this site's intention to provide answers for all users who might have similar problems, and just showing comparison images is not really helping anyone. It's like posting the original pieces and saying: just make it look like that.  It would have been nice to know what you changed to make it its own answer. In your images it looks like just the color is different, but my goal was not the exact color but the metallic and pearl effect.

@GordonBrinkmann oh, sorry - I will later today, have some work at the moment...

Here is a proposition (without the iridescent effect though): Increase a bit the Specular value, decrease a bit the Roughness value, give it a Clearcoat effect with a rather low Clearcoat Roughness, also a bit of noise bump:

File:

Looks very good on your image, but although I guess I did everything as seen in the picture of the nodes I get nothing similar to your result: what I get is basically normal surface color. So would you be so kind and provided your example Blender file so I can test it?

Sure, here it is: https://blend-exchange.com/b/7pEbWOoS

I've tried to create something that might be helpful... the original color seems to be slightly metallic with some clearcoat over it. Also a bit of "glittering" effect like carpaint. I do not really see a rainbow coloring on the original pieces, but I've put some of that in there, too. This is far from perfect, but I'll upload the file so that you can play around with it.

Oh, now this is very nice and to me it resembles more accurately the real thing than the 1st initial approach above: there really is that rainbowishness on the surface if you look closely (on real LEGO brick), not that much of metallic, rather like a thicker lacquere and things going under it playing with the light tho not that much or strongly + I played with the @moonboots file seeing a Blender pearl video on YT achieving quite good result very similar to yours approach although not that advanced as yours as I am total amateur in this regard. Gonna test your file now, thank you.


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How to fix mesh topology to get bevel tool to work properly?
I have had this problem for a while, and have been kind of circumventing it while never finding a way to solve it. I am relatively new to blender, and have noticed that in some models, the bevel tool works differently on different edges. I can assume that this is due to different mesh topology, but I have yet to find a definitive fix to make the bevel modifier apply to the mesh evenly when it applies unevenly before. I'm no expert on 3d modeling, so any answers using relatively understandable terms for a novice would be nice.
Here is an example of the issue described; I have a crow's nest on a low-poly ship model I am making, and want certain edges to be beveled to add detail, only problem is that I end up with what is shown in the following picture when I try to bevel some of the outer edges:

and this is what it looked like beforehand:

I have already tried applying scale, toggling the bevel weight, and messing around with other various settings, but with no results.
Hope someone can help.

Hi. It might be more likely for you to get help if you could upload a .blend file with this problem part in it to https://blend-exchange.com/

From your second image, it looks as if you have overlapping edges as you can see with half of the right-hand line being hilighted orange and the other half in white. As @curious_1 says, we'll need to see your Blend file.  You can share it via https://blend-exchange.com/ following the instructions there to copy the link to it and then edit your question and paste the link into it. In future you can also create full-sized screenshots to upload via Blender's Window > Save Screenshot menu.

Please show us your topology, in Edit Mode, or with Wire-frame switched on in 'Properties > Object > Viewport Display' . One thing you may not have checked is Normals. Overlays > 'Face Orientation' .. everything should be blue.

here is the file for anyone who wants to diagnose the problem, I made the cuts that @Cornivius suggested, but the beveling is still wonky

I figured it out, and it's what responsible for 90% of my problems in blender which is the face normals. Turns out the upper and front rows of faces had outside facing normals while the lower and back facing rows of faces had inside facing normals, making the bevel tool a bit confused as to which side of the face's edge to bevel.

Bevels don't really work when you have edges connecting to an Ngon like that top face. For it to work properly you'd need edges here as well:

Alternatively, for this kind of low poly detail, you could just take the knife tool (K) And cut some edges on the red lines, then dissolve the green ones: