text:
multiple smoke simulations - independent of each other
it's more like a general question:
I made a smoke simulation, one domain + one emitter -> baked that, worked fine.
Then i added another domain + emitter, where the domain is that big, that the emitter of the already baked domain is in it.
I hoped, that the baked smoke + emitter wouldn't influence the new domain, but it did.
Question: how do i prevent that from happening? or how can i have overlapping domains which are "just" reacting to "special" emitters? Is there a trick i am missing?

You can control which emitters and effectors are used in each domain by placing each domains grouping of those objects into different collections and then specifying to only use that collection in the domain's Field Weights Effector Collection field:

For fun I offer a free sample that I call "dual smoking skulls", a nice Halloween treat!


text:
how to build mutiple targets in a loop in animation nodes?
so i have made this nice animation within a loop. But if i put the curve object output in the loop, the target is the same. I want to create these columns in one loop and create a target for each column. is this possible with animation nodes?

Yes. You can create multiple targets using object instancer and simplify this process using loop.

great thank you!!!!!

source: Stack Exchange

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

sort: votes


text:
Why are the objects in ParticleSystems clipping through mesh?
I recalculate the normels on "All" the objects to make sure they were facing outwards on the meshes, while that fixed the scattering effect it causes another issue. The three branch objects are all placed in collections which I have in "Render As", but they seem to be clipping in through the mesh surface causing those white dots you see. This happen when I clicked on "Object Rotation" I only did that because the branches were twisting weirdly around the tree stem. Do I just uncheck "Object Rotation" and tweak the settings until I get it right if so, how? Or is there a way to push the objects out of the mesh?

In Edit mode rotate branches in +Z direction
under Particle Properties enable Rotation > Normal
under Particle Properties > Collection uncheck Object Rotation

Note: One of the confusion with particles is object orientation, where the particle object should be oriented in positive Y direction to be used in emitter's Normal direction. That looks weird even more in situations like if instance is something like a tree model to be emitted as a forest ... correctly orientated mesh tree looks like it is laying on a ground. I'm not sure what is behind this ... probably it comes from unification with other apps (that is not natural for  blender concepts :) ...where +Y is used for up direction and +Z for depth ... but blender is using +Y for depth direction and +Z for height.

The first two I understand but the last one I couldn't get can you please explain further?

Edited ... I hope it is more clear now :)

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


text:
In Shading how do I make lighting physics from Cycles work in Eevee?
I was following this YouTube video that teaches you how to make stylized trees using a simple shading build that can react to lighting efficiently. Unfortunately, this trick only works in Cycles, I was hoping to make a flexible build that can work on both engines just in case if I need to switch between them. The image on the top is in Cycles while the one on the bottom is in Eevee, I think it's pretty clear which one's better but, in any case, how do I achieve that same level of detail in Cycles?

Eevee manage the light differently than Cycles, maybe that's what you've noticed, but there's no real way to avoid that, or please be more specific?

Well how do I match the color from Cycles to Eevee because it doesn't look bright or lush in Eevee.

That's how Eevee works and it has nothing to do with your material, you need to find tricks to correct that if you don't like the current result, like for example adding lights, etc


text:
Is there a tool in blender that is similar to the 'blend' tool in Illustrator?
I'm a graphic designer who's been using blender for fun and making mockups for my projects, and I'm looking to make a textbook model. Now I know there are other convincing ways to model a book, but while working I became curious if it would be possible to use curves to make each individual page, then convert them to mesh and extrude each page individually (this tutorial shows this process in the first few seconds https://www.youtube.com/watch?v=aDOxTniM0Wg ).
Instead of individually placing and shaping 200+ curves I was wondering if there was a way to shape one curve at one extreme, and another at the other extreme, and have the software create steps in between?
The closest tool I can think of is the blend tool in illustrator, which does virtually exactly what I'm looking for, but in 2d.

May I ask you why do you need all pages real 3D?

I don't need the pages to be separate, but I'm trying to create something as convincing as possible as it is a mockup for showcasing some client work. I suppose I could also just use bump or displacement maps if I really needed the 3d look, but they tend to look less realistic under close scrutiny in my limited experience.

Sometimes is better to ask "How to create ...", because in your case there are a bunch of ways to get desired result, eg. to get a lot of pages you can try a Cloth Simulation.

Cloth Simulation

Add Plane, switch into Edit Mode move along X to side, add few Loops (Ctrl+R) along longer side
Add an Empty
Select Plane add Array Modifier > Relative Offset > 0, Object Offset > Empty and rotate the Empty in Y axis
Apply the modifier
In Edit Mode select the first and the last page as well as all central vertices of all pages and add them to a Vertex Group
Add Cloth Simulation, use the newly created vertex group for Pinning, enable Self Collision, adjust parameters as you like

@brockman Thank you for text polishing :)

At around 1:10 in the video, the person applies a mirror modifier. Instead of entering edit mode and extruding down to make the book, select the curve in object mode and add an Array Modifier. Change the Z offset to something very small, and increase the iterations (although 200 makes a very thick book, even at .01 offset).

Hopefully this is close to what you're looking for.

I managed to use this method along with proportional editing to achieve something very close to what I'm looking for! thanks!


text:
How can I have a strong emission object without it turning white?
For my project, I need a light source with powerful light, and I need it to take a shape, or at least appear to. Currently I have this :
This is emitting teal-ish light, but with the perfect strength it turns white. Is there a way I can keep its teal appearance, or at least make it look that way?

Unfortunately, thats just how things work in real life: as they get really bright, they turn white. Increasing the saturation can help, but another strategy is to make it just bright enough you can still see the colors, and then adding point lights of the same color around it to fake extra emission.

Forgot to come back to this, but @person132 I thought of this but wasn't sure if it would work, but it did, perfectly really, thanks!

Read: Make the flame of a candle more yellow

Technically, Cycles is correct in making it look white.  Because it's so bright, the camera is overexposed and it comes out as white.  If you try to take a real picture of a light bulb, depending on how you set the exposure, the light will appear white instead of yellow.  If you put your light in an actual scene, it will cast a teal glow.

If you want to make it appear teal, the most accurate way to do that would be to use a glare on the fog glow setting in the compositor to make a teal halo around the light.

Also, unless the entire object is glowing, it might look more realistic if you just set a small portion of the light (such as a filament in an incandescent light) to actually glow, it will cast bright teal light on the rest of the light and make it clear that the light is teal in color. (Just note that Cycles doesn't do a very good job if the light is inside a glass bulb)

If the entire thing is supposed to be glowing, depending on what look you're going for, you could try using the Principle Volume shader to make the emission rather than an emission shader (i.e. turn it into a glowing volume rather than a glowing surface).  That way, places on the edge would be duller and glow teal rather than white.  Note that this may negatively affect render times, and the effect honestly didn't look as nice as I was hoping in my example.  But maybe you could try it.

One final "cheating" way to make it look teal is to give it a week, teal emission for any rays coming from the camera but a strong, teal emission for all other rays so that it looks teal to the camera but still gives off the same amount of brightness as before.  The way you could do that is by mixing a strong and a week emission shader together with a factor dictated by the Light Path node "Is Camera Path" option.


text:
Help with bridging on a curve, and using multiple edges
So currently, this is what I have

My goal is to get the middle of the sides to meet in the middle, I used some photoshop to portray what I mean

Though when i do bridge, I have 2 issues

As you can see, there are many edges. When I go and properly select them all before the bridge, they all bridge to each other as well, so only one of them is actually accomplishing the goal.

When I did accidentally get it to work, each one took the shortest path possible, so rather than the curve I was looking for, I got a pavilion type look.

I am doing this one side at a time, but I just need a small bit of help with this. If bridge isn't the right tool to use, or if there is a better tool to use, please let me know. Any help is appreciated!

so you would like a topology like that? https://zupimages.net/up/20/41/92x9.jpg ... why do you need a so dense topology, or why at least don't you begin with a much lighter one?

you could create a cylinder, delete the half (x-axis) and the half (y-axis), add some loop cuts, and then use the knife (k) to cut in the hole. Then add a mirror modifier (x & y) to re-create the object.


text:
Particle system not working with geometry nodes
I was working on a scene, and I wanted to try the new geometry nodes with rocks. I already had a particle system on the same plane. The problem is, when I enabled the geometry nodes modifier, the particles (grass) didn't show up any more. I think the the reason why it doesn't work is because the particle system isn't part of the mesh. I could convert the particle system to mesh, but that will just kill my computer and the pebbles will probably also go on top of the grass. So I want to know if there's a way to add the particle system in the geometry node modifier, or maybe you have another way!
So my question in short: "how can I add the particle system to the object while also having a geometry node modifier active?"
Thanks in advance!
Ravi

The particle system is a modifier. Make sure it happens after the geometry nodes modifier. Then check the box under the 'source' expander of particle nodes tab that says "Use Modifier Stack"


text:
How to make topology smooth in Blender for rounded object (helmet modeling)
I have managed to make a relatively spherical object using plane extrude technique. I use Blender 2.9. Just to be more specific, I use Schuberth RF1 helmet model as a refernce. So far, this is what I have come up with.

However, since modeled using this technique, I have struggled to smoothen the surface of the helmet I modeled to appear in a uniform flat surface of a sphere. You can see on the below pictures that the top part of the helmet is a bit uneven.

Do we have an option in blender to smoothen the top part so it looks really even?

You could try selecting all the vertices in the area in edit mode and then select Smooth Vertices from the Vertex menu. Also Shade Smooth from the right-click menu in Object Mode might help.

@JohnEason The Smooth Vertices worked really well. Thank you for your prompt reply!

Good! Glad it helped!

See the comments from John Eason under my question and AsianMario's answers. In this case, the Smooth Vertices worked really well to polish the topology that I already have

Have you tried shade smoothing the whole object? If you start having problems with the normals go to: Object Data Properties > Normals > Autosmooth.

Yes, I have tried to apply the suggestions on the comment from my question above and it worked really well for me. What I need is to make the topology smooth, not just the shading for the jagged edges. Thank you for your answer!

Ah alright, can't really help you word-by word on that but here's a video that might help you. Good luck! link


text:
Significant digits in Measure Tool
I would like to set the number of significant digits given by the Measure tool.
While measuring I obtain values with 5 significant digits (as seen in the image).

Could you please tell me how to set Blender to round the number to only 2 significant digits?
I would like to get for this case something like 3.05 mm, instead of 3.05158 mm ...
Thanks a lot!

go to view -> measureit tools -> precision

UPDATE: Measure

Move one end with cursor, then hold CTRL and let go on one edge of default cube. Same to other end.
Result:

Thanks, this is an excelent walkaround if you are working in Edit mode, using the Measurelt Tool Add-on.

However, do know how to do it in the Object Mode, using the standard Measure Tool (second icon from the bottom in the the left tool bar)? Thanks a lot.

first - this tool also show measurements in object mode. "Your tool" cannot do this (AFAIK), but does it automatically, if the value e.g. is 2m it shows 2m. Just get the end of your newly created measurement, hold CTRL and draw it to one edge of the default cube. Do the same to the other end -> voila -> 2m

i updated my answer

Perfect. Thanks a lot!

you are welcome. would be nice if you would tap on the checkmark left to my answer ;) -> this means: this solution is ok for you


text:
Eevee disable receiving light for an object
Im currently working on a Wormhole tunnel effect like this:
https://www.youtube.com/watch?v=K2WTH016rfk
Problem is in my scene I got objects which are flying through it and those emit light too. So if they fly through it, the tunnel gets lightened up.
The Wormhole in itself is more of a special effect and its own shadermaterial emits light already, but I dont want it to accept other lights... any ideas how to disable this in eevee?

Can you post a screenshot with your Nodesetup and a render? The Node Wranglers Viewer Node is just an Emission Shader and should not receive light anyway, so this shouldn't be a problem in theory...

For me, I just use an emission node with a default value of 1.0.
As you can see in the screenshot, the emission only affects the self object and not other objects.

I think in blender you have to use the compositor to do that. Blender doesn't have a light excluder see this tut.
https://www.youtube.com/watch?v=PByGtB_ahmw


text:
Remove light ball from reflection in TV
I have created a scene where there is a TV screen on the wall, in the final render there are what I can only describe as "light balls" on the glass material within the tv. (extruded plane with glass texture on it).
The lights are Point lights with a IES node on them. Is there a way to make the "balls" not be there?

Try increasing the roughness to a point those ball are not visible and then add clearcoat in the material setting. Might help.

@Rajjaiswal He says he's got a "glass texture" on it, so I guess he means a Glass BSDF shader. To add the clearcoat he first has to switch to Principled BSDF. But that's useless, because then the clearcoat will reflect the light balls. But I'll think about it.

The light balls are the point lights reflected on the glossy surface, the size depends on which radius you have set in the Point Lamp properties. Reducing the radius will make the reflection smaller (but presumably the shadows also sharper, I'm not sure about IES lights because I don't use them).
To get completely rid of the reflections (no matter if you're using a Glass BSDF or a Principled BSDF), select the Point Lamp and go to the Object Properties tab, there you will find Visibilty > Ray Visibility. Disable Glossy and the light will not show up in reflections.


text:
does blender care what GPU I use?
When supplies are more available, I'll be building a new PC and am wondering if Blender works better with NVidia or AMD GPUs or if it even cares. Is it more important to have a card with more RAM?
Thanks!
--ted

This is really too general for stack exchange, but typically Blender supports NVIDIA GPUs better than others; although AMD support is improving.

This is a very general question and the answer varies over time.  You can always check the open data benchmarks to see what the current status is:  https://opendata.blender.org/
Historically, Blender has worked better with NVIDIA GPUs, but a lot of effort is being currently spent on improving AMD performance.
Yes, more RAM is better, but even that statement has exceptions.

Thanks for the reply. I realize this is broad question, but one I need help with as I weigh my purchasing decisions for this app and my others. As long as there are no strong reasons one way or another, that's helpful.

Short answer: It doesn't really matter since blender works with both.
Longer Answer: Blender has better support with Nvidia GPU's rather than AMD GPU's, along with this Nvidia's Developer Program has many more Nvidia-Optimized add-ons for Nvidia GPU's using blender. Such as the Optix denoiser which allows Nvidia GPU's to have clear images even with a low render sample count, along with the Optix Render Engine (which is still in WIP). Due to the GPU shortages now, it's more just a matter of availability.

You should get an Nvidia GPU. OpenCL kernel is losing support in 3.0, so you may not be able to use a AMD GPU for rendering in Cycles. The blender Dev team is working with AMD to get other kernels to work, but they said it would most likely not happen until after 3.0 is released. You can read more about this in the last paragraph here


text:
Can Blender use color id maps to texture the same object with different materials?
I have an object I want to texture with different materials. I'm using ZBrush to create the object and have a color ID map made.
Can this be imported into Blender for texturing or do I need to select the faces in Blender first and assign it a different material there?
Thanks!

As long as your geometry has a color attribute, you can assign different materials based on different attribute values in Blender.


text:
Slow lagging Blender
I'm fairly new to Blender. I'm working on a sculpted character. Since I have started using the dyntopo and resolution I get the wheel of death at almost every command! So I can't really continue! I'm using version 2.92.My pc otherwise works fine, so it's just Blender that is frustratingly slow!

Hi, this really isn't a question anyone can answer.  Would you like to edit it to make it into such a question?

It could be that your sculpted character has too many vertices and your PC can't handle it. But it's impossible to tell without more information/screenshots.

After some figuring out, I now think that is the problem. Too much detail. Thanks!


text:
What causes the mesh to look like there is another mesh underneath?

I don't know, what causes my objects to look like they are torn.

Does this answer your question? Why Faces eat each other? https://blender.stackexchange.com/a/1386/32374

They will go away if you tweak the viewport clipping start and end value.


text:
Armature is resetting it's y position every time I open the blend file
For whatever reason, the armature ends up pinging off downwards whenever I open up the blend file, applying transformations, setting origin point, does nothing. The armature is where it needs to be in edit mode, however
Here's the blend file https://drive.google.com/file/d/1hp4gV7TZas9mHoBjiBhDD1f62L0QtY3x/view?usp=sharing I really don't want to close the file incase I want to add anything else

Bones are keyframed down there.  Select your rig, then select all keyframes on your timeline with 'a' and delete.  Now you can reset position etc on your bones and it'll preserve through save/load, render, frame change, etc.

Thank you so much, I didn't even realize there were any keyframes


text:
Attempted relative import with no known parent package
I'm new to python and attempting to split off my executes for my panels buttons into a new .py file. However, when I try to run the script I receive the following error :
init.py line 27 in
"ImportError: attempted relative import with no known parent package"
the related init.py lines are :
if "bpy" in locals():
    import importlib
    importlib.reload(xmlhandler)
    importlib.reload(zokfunctions)
else:
    from bl_wep_export import xmlhandler
    from bl_wep_export import zokfunctions

    if "bpy" in locals():
    import importlib
    importlib.reload(xmlhandler)
    importlib.reload(zokfunctions)
else:
    from bl_wep_export import xmlhandler
    from bl_wep_export import zokfunctions

import bpy

from math import radians
from .zokfunctions import execute

The zokfunctions.py file has a simple
def execute(self, context):
print("TEST")
return {'FINISHED'}

I've tried several solutions, like removing the period before zokfunctions or using a class in zokfunctions called Hello and registering it, which throws an attribute error if I remember correctly..
I do my editing in VScode and the files itself are in my blender addons folder installed as an addon, so it is addons/myaddon/the init file and zokfunctions file.

To the future me if I make more addons and to newer programmers when it comes to blender, the issue isn't actually the scripts at all. Blenders in-house text editor cannot edit multi file addons, if you try it will throw this error. I was going insane trying to figure out what was wrong with my addon and comparing it to other code.
To conclude, if you're making a multi file addon, it'll work if the syntax is right and it's installed, and you can still edit it this way..

It's not that text editor cannot edit multi-file addons, more so that relative imports may not work if from __main__ thread.   Related https://blender.stackexchange.com/questions/183773/trying-to-make-a-menu-using-multiple-modules/183817#183817  or in your case from myaddon.zokfunctions import execute will work both as an addon or from the text editor.


text:
How do I apply time remapping?
So, I have an animation which should be at half the speed that it originally was. So I time remapped it. But when I did this, the animation did what it was supposed to do, it played at half speed. But I wanted to animate it further at this new time-remapped speed, I came across the problem that the keyframes stayed as they originally were. So I wanted to find a way to "apply" or "bake" this new time-remapped animation. I couldn't find this anywhere, so I'm asking it here.
So my question in short,
How do I apply the time remapped animation to the keyframes?

I believe time remapping actually just changes the frame rate of the animation playback, so to permanently change how fast the animation runs, I would recommend selecting the key frames to be affected, and then scaling them with S. Have the time cursor at the start of the key frames that need to be scaled, as it will be used as an origin point.

Go to the timeline, move your cursor to the first frame of the animation, select all keyframes with "A", then press "S" to scale the keyframes relative to your cursor, and then enter the scaling factor.
If you want the animation speed to be halved, scale the keyframes by 2, if you want to double the speed, scale it by 0.5 and so forth.

scaling by 2 DO indeed work BUT scaling by a fraction like  0.5 DOESN'T - the scaled frames go "empty" - I'm loosing all the    animation information - the object DOES NOT animate any more!

@Ringger81 It's probably snapping to the nearest frame (nearest "real" frame.)  Turn off frame snapping in whatever viewport you're using.


text:
How to create a super fine wireframe with low poly?
https://www.youtube.com/watch?v=A2oPC4ytFrE
As you can see on the Ironman nanomachine suit, during the transformation, there is a very fine wireframe being formed before the shell forms around it. Currently, I don't have a way to increase the amount of wires without also increasing the resolution of the mesh, so I'm asking, is there a way to create a super fine wireframe using textures, or a way to create more edges without increasing the polycount, sort of like hair children.

Do you mean this part? - https://ibb.co/x5T99wL

You could try something like this - material only, no geometry.

All it is really, is a mix of two separate Wave Textures (on different axes), clamped by ColorRamps to make sharper "ridges". I softened the effects of the procedural textures (noise and wave) in a few places using MixRGB nodes, mixed with white, and I ran the (multiplied) result of the 2 Wave textures through a Bump Node and into the Normal input of the Principled BSDF.
I slightly warped the input vector using a Noise Texture so the result isn't so "gridlike", and I mixed a bit of Ambient Occlusion shadow effect to make the ridges "pop" even more.


text:
Blender IK doesn't bend knee
https://youtu.be/5HBzaBwuUoA
In my rig, I have the IK constraint between the shin, the heel, and the knee, but the leg doesn't bend the way I want it to, any help?

do you have a pole bone

Yes, I followed https://www.youtube.com/watch?v=SBYb1YmaOMY tutorial, but my issue stands, the IK works when there is no pole bone, but obviously the knee bends the wrong way.

you may need to bend it a bit in Edit mode, if it still doesn't work, please share your file: https://blend-exchange.giantcowfilms.com/

Its as Moonboots says, you need to slightly bend the bones forwards before you use IK constraints


text:
Problem with Blender Guru Tutorial
I started to follow the Blender Guru Donut tutorial.
At this point in the video https://youtu.be/R2qjqqfkH6E?t=310 He talks about mesh intercepting other mesh.I was wondering if this is what he was talking about. Also when he told to Use Control + L
to select the mesh instead of selecting the top part it selected all the vertices.
https://i.sstatic.net/7FQAi.jpg
https://i.sstatic.net/HDmrl.jpg

Hi. Please make the title of your question specific to the problem you are having and not just the general topic. Thanks.

I think the blender guru course is very good, but I recommend you see the one on this page that I found if you handle Spanish, it is super complete and detailed.
Here you can find the course: Blender 3D I hope it helps you!

He's referring to a possible problem before the icing is properly separated from the donut.  The tutorial instructions are to:

Select the top half of the donut with the mouse in edit mode using X-ray
Use ShiftD to duplicate the selected part of the mesh only
Use Esc or right mouse-click to leave the duplicated part in its original position, overlapping the original full mesh of the donut.
Use P -> Selection to separate the still-selected, duplicated mesh from the donut, to create a separate icing object.

Judging from your videos, you already did this correctly and have successfully separated the donut and icing objects.  So, you should switch from Edit Mode to Object Mode and skip ahead to 6:05 to continue with the tutorial.
If you want to understand the problem he's talking about, some people make a mistake between steps 3 and 4 by clicking on another part of the donut, so they lose the selection on their duplicated future icing before separating it from the donut object.  Now, they discover that they have trouble selecting the icing again, particularly because it overlaps the original donut, and both meshes are part of the same object.
They can't use box-select, because it will select vertices from both the duplicated icing and the original donut.  They can't even select individual vertices of the icing, not only because it would take forever, but because the icing vertices and donut vertices overlap, and it's very difficult to figure out which one is being selected.
A solution is to select a single vertex.  If you're lucky, it might be an icing vertex.  If you're unlucky, it might be a donut vertex, since they overlap.  You can tell by paying careful attention to the edge highlighting, or grabbing it and moving it around.  If you select a donut vertex by accident, you can re-click on the same vertex position, and Blender will normally switch to the icing vertex.  Once you having an icing vertex selected, you can use CtrlL to select all linked vertices, re-selecting the entire icing mesh.
Note that this only works this way before the donut and icing meshes are separated into different objects.  In your case, you have already successfully separated the icing, and you are in edit mode with the donut object.  Because the icing vertices are in a separate object, you aren't able to select them at all, so any vertex you click on will be a donut vertex.  If you press CtrlL it will select the entire donut because the whole donut mesh is connected.  It won't select the icing, because it's in a different object.
Fortunately, you don't need to select the icing, because it's already been separated, so you should just continue with the rest of the tutorial.

Thanks but the Donut mesh is intersecting the icing mesh.
Here in this vid i took https://imgur.com/a/Q0fkuyy

That type of intersection is unrelated to what he's talking about with this Ctrl-L business.  Keep watching the tutorial after 6:05.  You haven't reached the part where he pulls the icing mesh away from the donut so they no longer "intersect" this way.


text:
Mesh with editing failures
I'm new to blender and I was interested in using it to develop game mods.
I started with a simple one and am having problems with the mesh of the personage's legs.
I edited the right side of the leg and then used Modifiers> mirror to mirror the other leg. But the other leg appeared with cuts in the mesh.
I used the remove double and the mesh has dark spots. How can I solve this?

You could try resetting the normals for the faces, in Edit Mode, select all the faces, go to Mesh at the top selection bar or press Alt + N, then set Normals from Face.

Thank you very much. Fixed it. I was having this problem a lot with all the mesh.

No problem, nice model by the way.


text:
Control MixShader value by shape key value
I have a Mix Shader mixing two textures and one shape key applied to an object.
I want to control the mix shader value from the shape key slider.
I think this is achievable by using drivers but i don't know how to do it.

You can insert keyframe for the Mix factor, if you move the mouse cursor above the slider and hit "i". After you can manage it in the dopesheet, or in the graph editor.

Select the mesh, in the node editor right click hovering the mix Shader slider and choose "Add driver-manually create later".
Then open a graph editor window and set it as "drivers" instead of "F-Curves".
Select the Fac driver you created, open the "N" tab, choose "Drivers" tab, set all thoose options:
Scripted expression,
var,
Type of var: single property,
Type of single property: Key property.

Lastly hover on the shapekey slider, right click on it and choose "Copy data path", then in the driver tab click on the empty path field and press Ctrl V to paste.
Enjoy (consider that in some cases the driver is not updated in the viewport, like in "material" kind of visualisation, but it will work in rendered mode, and you can always click the "Update dependencies" button to have it work).
This is the complete driver in my setup, and an highlight of a common mistake you may be missing.


text:
Double UV unwraps
I apparently accidentally made 2 UV layers and so the bottom UV layer is ghosting onto the second layer (see photo). Is there any way to delete the selected UV?

You can't make two UV faces for a mesh face on one UV map. Probably your mesh is duplicated. Delete one of them.

Your UVs are alright. It's just a basic logic of 3d Softwares to repeat the texture outside the texture.  So you just need to scale down the Uvs if you don't want them to repeat
.

Or change the Image Texture Node from Repeat to Clip


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Background image in blender 2.8
How do you set a Background image in blender 2.8?

It depends on the purpose of the background, but if you encounter this problem in 2.8, it means that you are confused by the loss of the sidebar, then you need a camera background


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Color management in blender 2.8
Color Management used to be in the "Scene" tab. But now it's gone. Where did it go?


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Blender won't respect video alpha
I've exported a video in Davinci Resolve (Container: Quicktime, Codec:DNxHR) which is a codec that is alpha approved. But when i import the alpha video into blender, blender for some reason doesn't show the alpha channel.
Then I exported another video (Container: Quicktime, Codec: Grass Valley)
And when I import the alpha video into blender, it has strange green clipping (see photo). Why is this happening?

If the documentation is correct Blender doesn't support alpha for DNxHR. (See: https://docs.blender.org/manual/en/latest/files/media/video_formats.html#ffmpeg-video-codecs)

Yeah, it seems that way. Thanks, Do you know what the deal is with the green clipping?

No sorry, I don't know.


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add a handle to curve
In this tutorial, Ian adds another vert onto his curve making now 3 adjusting handles. How do I add another handle?

(In 2.8) select the 2 control points at the ends of the segment of interest, Right-Click > 'Subdivide'


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Render showing nothing
I'm rendering a particle explosion in Cycles but the render shows nothing. When I hide the particle emitter it only shows only the emitter. Not the particles. What is going wrong? The camera clipping length is 500 & I don't have the particle emitter hidden (in the outliner) or disabled during renders.

Just wanted to clarify: what are you using for your particle renders? I know halo is not supported in Cycles. If it is an Object Instance, did you uncheck "Show Emitter" from both the Render panel and the Viewport Display panel of the Particle Settings?

It's a collection. Not an object instance. I guess cycles doesn't support a collection because, when I changed it to object, it rendered it. I just can't figure out how to change the "render as" to an object and still render out multiple objects. If I just rendered out a bunch of the same object, it would end up looking really stupid.

No unless of a bug it supports collections. Could you share your file with us so we can dig in ourselves?


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Glittery smoke in render and viewport
I'm rendering out this smoke sim and my smoke is glittery. Why?
My smoke's Resolution Division is 100 with a High Resolution Division of 2.
And it is a smoke sim based off of particles.

Here's a link to the material node setup.

Do you have denoising turned on?

I've never really used that so I don't know where it is. :)

Denoising will just remove all definition of the smoke... you need to have more samples in the cycles render.

If you are in 2.8, it's in View Layer Context > Denoising. For 2.79, Render Layers > Denoising. Just click the checkbox. :)

I think those are fireflies.  They are a common problem with blender.  Here's a link to help you reduce them.
https://www.blenderguru.com/articles/7-ways-get-rid-fireflies?rq=fireflies

Where is the "Multiple importance sample" setting for HDR's in blender 2.8? I think that may be the problem.

I'm pretty sure that's on by default now.  Try clamping, or turning off caustics, although caustics are more realistic.


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Scaling down texture
When building this building, when I add the brick texture, it's way too big (as should be expeted). And I know I should probably already know this but, how do you get it to scale down? I've triesd adding Texture Coordinate>Mapping>Image Texture and everything turns cream colored.

In your Mapping node, it looks like Texture increases the size of your image texture, instead of reducing it, so decrease it or use Point. Also, if you've unwrapped your object, use Texture Coordinate > UV output instead of Generated.

Thank so much! Now they're vertical. When I rotate it along an axis, it messes everything up. How do I fix this?

it depends what sort of mapping method you've chosen, if you didn't unwrap your object it won't be very controllable, you can try Box instead of Flat in your Image Texture, but if it doesn't give any good result you'll have to mark seam and unwrap your object, please follow some tutorials about that because it's a completely different topic  ;)


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Blender 2.8 Text Editor OSL Script Node Update Disabled
I found out what Open Shading Language was today and was excited to try it out, and it was working at first.  But at some point, I found that I could no longer press the "Script Node Update" button either in the Text Editor or in the Shader Editor's script node in order to actually use the scripts.  I've tried both Internal and External scripts, and I'm using the Templates, so it's not a syntax error in the OSL Script.  I also tried saving the file to see if that was the problem (as before, I was working just on new, unsaved files), but it still didn't work.
I just can't press the update button to actually use the Script node as the button is grayed out.  I can't figure out what I did to break it and how to fix it.

@RobinBetts Wow, okay, that should have been obvious.  Thanks, it's working now.  Feel free to post that as the answer.

OSL scripts will compile only if you are rendering in Cycles, on the CPU.
When both of those are true, an 'Open Shading Language' checkbox becomes available in the Properties region, Render tab, just under 'Device' (CPU)


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Pixelated smoke in render
Every time I render mmy smoke sim out, it looks pixelated. What setting do I need to change?

The resolution of your smoke domain is probably too low.

Resolution is 200 with a High Resolution division of 2


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Multiple objects to particles
Is there any way to add multiple objects to a particle simulation (emitter) without having to join the objects before adding them to the sim?

Is there a reason you've put rigid-body-simulation as tag on your question? Are those multiple objects you want to emit rigid bodies?

You can put all objects you want to emit in one collection. In the Render settings of the Particle System you can choose Collection which will use all the objects in this collection.
By default, it's picking single objects to be emitted as particle. But you can check Whole Collection which means, each emitted particle will then consist off all objects in this collection in their relative positions like they are placed to each other.
For emitting single objects of the collection you can also check Pick Random, although it already looks random to me without this enabled.
Another setting you might want to use is Use Count, there you can specify if some of those picked should appear more often than others from the collection.

When you create a particle system for the second emitter, click on where it says "ParticleSettings.002". It will bring up a menu, and you can select your other particle system. They will be linked, and have the same particle system without being connected.

I don't think that was the question. Adding multiple objects to a particle simulation is not adding a particle simulation to multiple objects.


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How to add Principled volume as default
Every time I add a material to a smoke domain, it always adds a "Principled BSDF" shader and not a "Principled Volume" shader. Is there something I should be doing to add the "Principled Volume" shader as default or should I just keep removing the "Principled BSDF" shader and adding a "Principled Volume" shader?

You could create a default smoke material and save it in your default Blender starting scene if you find yourself doing smoke sims really often. Or you could write a small python script that create a domain with the right material and node setup. At the end of the day it's just a few extra clicks, I wouldn't bother with it. Principled BSDF is just the default setup for all Blender materials (remember that materials are completely independent data from objects).

Okay, thanks. I wondered if it was the default or if I was doing something wrong.


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Mantaflow not going hires
I'm using the blender 2.81 mantaflow beta build and, I've set up a smoke scene and, as I understand it, the "Noise" setting is the equivalent of the "High Resolution" setting before so, when I check noise and bake the sim, the fire and smoke disappears and then when I uncheck it, it reappears. Why is it doing this?

Is mantaflow included with 2.80? are you using a plugin, or does blender 2.81 come included with mantaflow, finally?

You have to go to blender.org>download blender 2.80>get blender experimental(bottom of page)>then click on the "experimental branches" link below the blue "new features and changes" button.

Sorry guys, I figured out the answer but wanted to post this to help others. You need to bake the noise as well before you can see the result.


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How do I shatter rigid bodies on edges
So, I'm creating a rigid body that I am going to throw and I was wondering, is there any way to make the rigid bodies break apart on impact (Similar to the cell frac add-on) except on the edges?

You might want to consider ending the bounty as it does not show up in the bountied question section anymore.

There are a bunch of very good fracture add-ons out there. Some of them only support fracturing the entire object at one time, while others actually let you control the places that the object fractures. You may want to consider this add-on as it lets you do that kind of thing with objects. I am positive that there is no way to automatically generate fractured edges based off of the rigid-body simulation, but this add-on should help a lot.

What about the Explode modifier as used in CG Geek's tutorial here: https://www.youtube.com/watch?v=3dTcz5wWvVE&t=104s (Watch from about 14:45 minutes I think

This add-on improves a lot of that. I.e. makes it simpler.

Is it available for MACos? I use Mac. It says "Windows" on it.

Its says windows, but there is a Mac build download link on the page.


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Delete already existing animation
So, I got a .ABC file and it has an animation already on it. How do I delete this animation?

Can you delete the keyframes on the objects?

There are no keyframes. I don't know if that's inherent with a .abc file or what but the object is just moving.

Could you provide a picture of the setup?

You can freeze a frame in the modifier. Altering animations of alembic files isn't builtin.

Open the NLA editor, that will show the animation tracks for all objects. Just select them all and delete - that should remove any sort of animation.

What is the NLA editor? Is it the "Nonlinear Animation" timeline? because that doesn't have any keyframes in it.


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Light not effecting volumetrics
So I'm rendering a scene out and I'm using the world volumetrics with "volume scatter". Blender Guru has a tutorial on it. When I put a "sun" light in the scene, it doesn't effect the scene at all. Why? Is this a supposed to act this way? I know when I add a plane in with an emission material, it lights it.

Are you using cycles or eevee  andare you viewing this is material preview mode or rendered view

I'm rendering in cycles and I'm viewing it in rendered mode.

you can try increasing the strength of sun,or just deleting sun lamp and add it again and what is the density value for volume scatter node it should be low round to 0.1 and you can also try reducing color brightness for volume scatter node

Go to the top right and make sure this little guy is enabled other wise EEVEE just uses the Material Preview Settings, with preloaded HDRIs.


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Multiple colors on particles
So, I have a simple emission texture applied to a particle system and I was wondering, is there a way to make your particle emitter emit a random variety of colors?

It does! Thank you!


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renderman not installing
So, I've got the renderman engine from GitHub and, when I install it and enable it (as an add-on), it doesn't show up with the render engines. Why? (The add-on said it required a 2.8 blender update so the add-on is 2.8 ready)
Also, I'm trying it in blender 2.81 and blender 2.82a

Yeah, that is just not going to work. It is actually not compatible with 2.8 or many of the previous versions. Even though it may say. There are forums all over the place that say the same thing. No one has gotten it to work. But, it is probably for the best. Renderman is not near as capable in clarity of pixelization as cycles. 1080p in Cycles vs Rman is a pretty big difference. Plus, I would guess that alot of the modifiers in Blender would not work in Renderman. It also takes alot more time to Render especially in Windows. And a huge bug with Renderman that comes from what people like about it overcasting light, is that you will get pitch black shadows sometimes that you cannot get rid of.

Thanks!!!!!!!!!

The rendering addon space for Blender version 2.83 and higher is a confusing mess of outdated information and equally outdated addons. Renderman addon appears to be abandoned on Github and doesn't work for Blender 2.83 or higher. The only renderer addon other than the built-in Cycles that seems to be actively updating is Luxcore @ https://github.com/LuxCoreRender/BlendLuxCore, but that only officially supports Blender versions up to 2.83, so if you have anything higher like 2.90, you may have issues and must wait on updates.

Just your opinion... In fact: Renderman add-on development was on-hold as of Blender 2.8x release for many reasons: (1) Renderman's core is in heavy development in order to support GPU and CPU (2) OSL adaptation (3) Blender API changes, etc... Good news is that they are working on it, preview -> https://app.livestorm.co/pixar-animation-studios/new-bridge-tool?utm_source=Livestorm+company+page and it should be released soon (when stable). Also note, there are add-ons for other popular engines like Redshift or Octane too... and Luxcore should work on 2.9.


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Can I mirror backwards?
I want to mirror a building across the Y-axis, but I want the mirrored side to be flipped along the X-axis (I.E. be flipped). Is there a way to do that?

If you mirror/flip an object in two axis you get the same result as rotating it 180° around the other axis. Is that what you mean? Alt+D duplicates an object with linked data, so you can rotate the copy to where you want it and retain the possibility to edit both parts at the same time.

By the way - "...to be flipped along the X-axis (I.E. be flipped)" here I.E. or id est means “in other words” while "flipped" is the same word you already used - makes little sense.

My answer to a different question may help you here. https://blender.stackexchange.com/questions/163243/mirrored-object-is-misaligned-when-compared-to-its-source-object/163249#163249

The best way to do this is to make a  linked duplicate of your original object (ALT+D) and then rotate it 180 degrees on the z axis. They will technically be separate objects, unlike  a modifier, but editing one will change the other accordingly.

... which you could also do with a 180-rotated object-offset array modifier.


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How do you re-unwrap an object and have it be the same scale?
In this tutorial by Blender Guru, Andrew re-unwraps his plane (because he changes the UV to be a 2*1 aspect ratio and so it stretched his UV). He also mentions that with cycles, it won't re-unwrap it. You have to be in blender internal to re-unwrap it.
In Blender 2.8, there is no  blender internal anymore. (and with EEVEE and Workbench it doesn't sucessfully re-unwrap it either)
How do you re-unwrap an object and have it be the same scale?

UV's are squared. IMO this is a bad recommendation and there is no need to setup a 2:1 ratio (even for a plane like this). The more UV islands you have the better the resolution of the texture... And if you need more space, you can use UDIMs as of 2.82.

Well, this is a fun one.
What is going on
It seems, unwrapping depends on your shader's image texture, not the texture in the UV editor.
Again.  It's not about the UV editor, it's about the shader editor.

I have three textures with different aspect ratios. 1:1, 2:1, 3:1.
But the UV map ratio is always based on the image selected in the shader editor.

So, in some cases, there's no way to match the correct aspect ratio.
Example:
2:1 in UV editor, 3:1 in shader editor.  And no way to match the correct ratio.
Correct aspect ✔ doesn't work either - it only switches to 1:1 ratio.

Solution
Check what image is selected in the shader editor. That's what drives the UV map aspect ratio.
And then match it to the image in your UV editor.
Note
The above is a reason why it sometimes works, and sometimes doesn't.
Still not sure if it's a bug or not, but either way it's pretty messed up :).

Thank You for explaining!

Cycles CAN re-unwrap things. I don't know how old that video is, but if in edit mode you just select all the faces of your mesh, and press 'U', you can unwrap your object how you want to again. Try it, it should work.

Not with a distorted (2*1) aspect ratio. At least not with the plane in the video. (In my instance)

Hey there :). Don't feel bad if you solution doesn't work here, Blender's behavior is pretty messed up.

Now that's something I can agree with.


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Collection particles not working?
I have a plane with hair particles on it with the render set to "Collection". I have a collection made up of the tree and leaves on it's branches. When I set the collection particles to the tree collection, it only shows the tree. Why?

Probably duplication https://blender.stackexchange.com/questions/55659/hair-particles-on-hair-particles

... or here https://blender.stackexchange.com/questions/27818/is-it-possible-to-recursively-instance-object-particles?answertab=votes#tab-top

I don't think so. What I'm asking is, why doesn't it put the whole collection (tree and leaves) when I set the particle render settings as "Collection". I made it so that the leaves are no longer particles on the tree. The leaves are a separate object just put into a group with the tree.

Can you post simplified blend with that issue via https://blend-exchange.giantcowfilms.com? But if you have leaves as particles on a tree and you want this tree (with leaves) as particle on plane - thats the issue covered by posted links. Including leaves into collection does not solve the issue of missing leaves on trees as particles, I would say.


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Scale edge loops along edge
I have a 6 sided polygon and I'm adding loop cuts to one of the sides not even with either the X or the Y axis. I was wondering, is there a way to scale it along the edge that the loop cut is on?

Is this what you are looking for? https://blender.stackexchange.com/questions/74634/slide-two-edge-loops-away-from-each-other/74635#74635

Yes. Thank you so much!


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Remove particles with weight paint
So, I have a Plain Plane with a hair particle system on it. I want to control where my objects are instanced onto it with weight paint. But, when I draw the normal weight paint onto it, it takes all the other particles off of it and paints the particles on in the brush's path. How can I set the brush settings so that it only takes away the particles where I paint and leaves the rest?

Assign all verts to the Density Vertex Group then select the Subtract brush.

Thanks!!!!!!!!!


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is there an easy way to delete all dead tracks?
I have a tracked out video and a lot of tracks failed. Is there a button or something to delete all the dead tracking points? It's a long process to go through and find all of them and delete them.

Dead tracks are markers that have not been solved?

I mean, tracks that have lost their point somewhere in the track


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Is there a way to minimize my boolean modifiers?
I have a long corridor that I'm putting a bunch of windows in and, I have a cube put in where I want the windows with a simple boolean modifier setup to the object I'm wanting to penetrate  and it's working perfectly except I want to add a heap of windows to the wall and I don't want to have to add a billion boolean modifiers to the wall. Is there a way to do this?

Can't you use the Array modifier on the object used to create the hole in the window?

Yes sorry, I tried it before but apparently I didn't separate the two cubes enough lol

Use the Array modifier on the window cube. Make sure to increase the relative distance to be greater than 1.0 otherwise, your cubes won't separate.

You only need one boolean modifier if you are using the same object for all the windows, so you can go to edit mode of the cutting object and just duplicate the windows and move them around as a mesh of a single object from edit mode.


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Can I merge different edges
I have a lot of edges (pictured below) and, I want to merge them all together (which in turn would create extra vertices). Is there a way to merge all of these edges?

Have you tried "limited dissolve"?

The edges at the underside crossing each other do not have shared vertices right? That's only edges going in 2 different directions, right?

@Xylvier Correct!

@Leander Yes, I've tried but it doesn't work

Based on the comments and the question i take it that you want to close the bottom area of the object and at the same time reduce the number of vertices to a minimum.
In that regard, i would do the following:

Go in edit mode -> edge selection
Select the edges that go along the long side ending at each side at
the n-gon
Press X and Delete the Edges
Now switch to vertex selection
Select the vertices at each side at the bottom edge of the n-gon, where the previously deleted edges were connected.
Press X and Dissolve Vertices
Now the left over edges can be used to create faces along the bottom area by selecting two edges and pressing F to fill the area between those.

All this sounds stretched and long, but once you know the steps it's done in a jiffy.
Here a little visual of the procedure:

I didn't go through all faces at the end, as it is just rinse and repeat.
A tip at the end, i would suggest to use the "F2"-add-on, that comes with Blender:

Makes it easier and faster while modeling.
Happy Blending


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Floor in camera track flipped upside down
I have a 3d camera track and I have it solved perfectly but, when I set a floor, it looks like the floor would line up perfectly except, the camera is positioned upside down. Is there a way to flip the camera over and keep the position?

in the clip editor you can set origin, but also wall or floor. Or set X and Y axis. Then re-do Setup Tracking Scene.

Or you can manually re-orient the camera: https://blender.stackexchange.com/questions/10698/correct-tracked-camera-orientation/10708#10708


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Is there a way to spread a texture across each stone and not the whole thing?
I have a well model and I'm wanting to spread the texture across each little stone individually and not the whole well at once. Is there a way to do this?

The way I ended up doing this was to select all the edges and then marking a seam on all of them. But then, the texture will be blurred so you have to turn the scale up on the mapping node.


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How can I add a second colour to an object?
For the past month or so I have been learning how to pretty much learn blender from scratch so bear with me.
Currently I am trying to add a second colour to the objects I have created. I have worked out how to subdivide and select sections, then assign them two different materials/colours. But this process only allows me to change colours in straight lines corresponding to the subdivisions.
I would like to re create something like the provided image, where the second colour is very fluid and is more like a pattern. Thank you

Do you know how to use an image texture? You can create and draw an image texture in Blender, or load an image prepared in a separate program. You could also generate a material procedurally.

What you are doing at the moment (I think), is applying different materials with different colors to certains faces i.e. parts of the mesh. The example image you posted is using one material for the complete mesh and distributed by some texture which is used as mix factor between two colors. A simple example - very simple, you can do so much more complex things, but I would suggest you watch more tutorials on these things because this is too much to put in single answer here - you can see in the following screenshot:

FYI Musgrave Texture returns a range of -1 to 1, that's why your color ramp has to be put so close to 0.

You definitely hit the nail on the head with guessing my current process. Thank you for your answer, your example has been very helpful. What you have provided has gotten me very  close to what I was after. Thank you for pointing me in the right direction.

@AllenSimpson I know, I didn't think that this was important for a very basic information on how to mix two colors together... and I just used Musgrave because it resembled the example image pattern without closer investigation.

I recommend using a single material, generated procedurally.

Head to the Shading screen.
In your object material, Add a Textures -> Musgrave Texture node.
Now Add a Convert -> Math node, and set it from “Add” to “Greater than,” and pipe the Musgrave Texture node’s Height output into the Math node’s Value input.
Add a Color -> MixRGB node, and set its two colors as discovered.
Connect the Math node’s Value output to the MixRGB node’s Factor input.
Connect the MixRGB node’s Color output to the Principled BSDF’s Base Color input.
Adjust the Math node’s Threshold value as desired, probably to about zero.

PS: You can use Voronoi, Color Ramp, Mix Shader, and Normal Map to add glitter.

...or like that.

@GordonBrinkmann Yeah, I was already working on my answer when you posted yours, and while I was a bit disappointed that you got to one before me, I was happy to know that was the first thing someone else thought of as well. I would not have said using a math node, but I had just experimented with Musgrave this morning (and learned it is perfect for this ), and I discovered while working here that the center of the Musgrave gradient is actually zero.


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Why can I see the inside but not the outside of some objects?
I'm running into this weird problem on my model where some objects have only their inside mesh visible, with their outside being "invisible". You can see in the screenshots below that, from any point you see, my arm is only showing it's outline, like you can only see it's inside but not the outside. Does anyone know how to fix that? This is not happening in any of the other body elements, just on the arms and the legs.
I tried using the Solidify modifier and it worked but created issues later. Since Solidify creates a "second mesh", the problem is that when animating with bones the now created inside mesh gets really weird and goes outside of the character depending on it's position, as you can see in the 3rd scrrenshot, so I'm looking to a solution without adding this modifier. Thanks in advance!
The issue in my model's mesh:

The bug that solidify creates on my legs when animating it:

Could you upload a blend-file. The issue could be caused by several problems.

Seems like you have inverted normals.
Try selecting the affected object, going into edit mode, select all faces and hit alt+N, then select "recalculate outside".
(the hotkey might actually be ctrl+N, not sure right now)

Unfortunately I posted the original question as a Visitor, so I can't select an answer neither comment the original post, but Alexandre Marcati just solved my problem!
Thanks a lot! I'm going to paste his reply here in case anyone needs it: Seems like you have inverted normals. Try selecting the affected object, going into edit mode, select all faces and hit alt+N, then select "recalculate outside". Thanks again!

(@Felipe You need 15 reputation points to answer your own question. After 48 hours you could accept the answer. But right now your reputation is still too low)

In Edit Mode go to Overlays (top of your viewport, towards the right hand side) and check 'Face Orientation'. The parts with inverted normals will turn red. Then you can go to Mesh, Normals and Flip or Recalculate the affected parts of the model.

When I was importing an .fbx everything was flipped. Turns out that the material that was applied had Show Backface turned on under the Settings drop down inside the Materials tab.


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How to reduce mesh vertices to obtain homogenous density while maintaining manifoldness
in Blender 2.79 I used to have a technique to make meshes have an even/homogenous distribution of vertices. I would start to increase the number of vertices (if necessary) using the "subdivide" or the "remesh" tools. Then I would apply a "remove doubles" (in 2.79, now it's called "merge by distance") with a distance that corresponds to a density I wanted.
The issue is that using the "remove double" would work pretty well in version 2.79, however in recent versions (e.g., 2.92) using the "merge by distance" tends to produce a lot of non-manifold faces.
This can be demonstrated just by using the default cube scene:

Start with the default scene cube
Apply a default settings "voxel remesh" (usable from object mode, not from edit mode)
Apply a "triangulate faces" and a "shade smooth" (that will help visualise the issues in the next step)
Do a "merge by distance" at 0.2m
Deselect all and then "select all by trait" - "non-manifold"

As it can be seen, the mesh becomes all messed up.
For comparison here is the result of the equivalent operations in 2.79:
Is this a bug? Is there any workaround for this?
Is there a better way to achieve homogenous vertex density while maintaining manifoldness?
Thanks.

I think you want to use the "Decimate" modifier rather than "Merge by distance"

The issue with "Decimate" is that it doesn't let the mesh with a homogeneous density of vertices.

It does appear to be a bug.  Have you checked the bug data base? https://developer.blender.org/maniphest/ and query for the bug.  If there doesn't seem to be anything, perhaps you could file a new bug report. https://wiki.blender.org/wiki/Process/Bug_Reports gives a summary of how to do that.

It seems that it is not a bug, as Nathan has said in a comment to my answer https://blender.stackexchange.com/questions/223381/how-to-reduce-mesh-vertices-to-obtain-homogenous-density-while-maintaining-manif#comment377673_223384

Well, I think I may have found a nice way to solve my own issue using the remesh tool itself:
Using the "QuadriFlow Remesh" with the "Edge Length" mode set to the desired value, or using the "Vertex Remesh" with the "Voxel Size" set to the desired value, produces pretty and homogeneous meshes while maintaining manifoldness.
Example:

Starting with a UV Sphere, which has a vertex density not so homogeneous

Apply a "QuadriFlow Remesh" with the "Edge Length" mode

The mesh gets a more homogeneous vertex density

Using the "Vertex Remesh" with the "Voxel Size" set to the desired value

will result in an also nice mesh:

The other remesh settings, may also produce nice results.
(Anyway, I still think that the merge by distance has some kind of bug, or else it must be used carefully. Edit: it's not a bug, it's expected behavior)

Merge by distance does have to be used carefully, but it's not a bug-- it's doing exactly what it's supposed to do, merge by distance.  Whether that creates non-manifold geometry or not depends on where your vertices are and what distance you choose.  This was true with earlier versions' remove doubles as well-- you were probably just luckier in earlier versions.

In Blender 3.0, select all edges in Edit Mode, go to Edge > Unsubdivide, repeat until you're satisfied.
Then go to Mesh menu and then click Symmetrize.

As it’s currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center.


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Why does it change shape when i apply the scale?
I just noticed that the scale whas wrong on my canle. So i applyed the scale on it and it went fine. Then when i did the exact same thing on the wax it suddenly became a "muchroom". why does it do that and how do i fix it?

It's because your modifiers act on original mesh scale 1.
Say you have a 1m diameter pipe mesh with 0.1 m thickness with the Solidify Modifier.
If you make it 2m diameter (scale it to 2 without applying it), you now have a 2m diameter with a thickness of 0.2m despite the Solidify Modifier still showing a thickness of 0.1m. The new scale and thickness are shown in the Viewport, but the modifier shows the values valid for a scale of 1)
And if you now apply the scale, the new thickness would be 0.1m because that's what the modifier is set to.
NOTE:
Scale is for the object and the modifier values are for the mesh. Object is separate from mesh (you can change the mesh that is used in your object anytime)

Your last paragraph is a bit misunderstandable... it sounds like object scale and mesh are independent from each other, but of course they are not. If you scale an object in Object Mode the mesh is scale with it of course. And in the same way the modifier is scaled. But overall your answer is definitely correct and the solution for her problem.

@GordonBrinkmann Try this: get default cube (object 1) and copy it (object 2). now make the mesh of object 2 from Cube.001 to cube. now scale the object 1 and apply it. you will get an error. now on the object 2 change mesh to Cube.001 and apply the object 1 scale and after that change object 2 from Cube.001 to cube. see that the object 2 is now changed in scale?
As you see scale dose not affect the mesh unless it is applied to the mesh. a 1m tall mesh is always going to be in 1m tall mesh in every object even if the object is 10m tall.

But yes I see what you mean as user expect that what you see is what you get.

Thanks for explaining that, didn't know I could learn such a basic thing after 20+ years in 3D modeling :D No seriously, I know that. I just wanted to say that this can be misunderstood by users that don't have as much experience. Especially when they are scaling non-multiuser objects they might not get these errors. By the way, duplicating the cube with Alt+D makes the second cube automatically use the same mesh as the first one... no need to switch meshes or anything.

srry, was trying to clarify what I meant. No assumptions about you were made. but yeah I was going for manual change in mesh cause that way new user would change it manually and see that it is a different thing. it's my 3rd year into 3d and I did not know that 1-2 years ago and I wished I knew that sooner. hence the example.

thank you so mutch!


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All was fine and suddenly Out of memory?
quick question.
my laptop is gtx 1080 and i5 and he render any scene without any problem.
but when I got home to my stronger pc (rtx2080 ryzen3700) and opened the project, chose render view and tried to render it says " out of memory" and that it!
what is wrong ?

If the laptop has an ssd it is able to handle page-file operations better (at the cost of some drive lifetime) and that seems to let you render things that you are otherwise unable to with your page-file on a traditional spinning hard drive.

thanks for replying so quick . It's weird because the project is on external drive anyway..so what is the solution in that case?

It's not where the project file is stored, but rather the hard drive the operating system uses when RAM runs low.  In task manager under performance you can look at the amount of committed memory to see if it is going over the amount of RAM installed in your system.

Related: https://blender.stackexchange.com/a/208828/110840


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Bool Tool slice function
Bool tool slice function not working the way I want it to it's removing parts of the mesh instead of just slicing.
How I want it to work:

How it works:

Have you applied the scale to both parts before trying to slice?

Yeah i tried that getting the same result

It's difficult to see which part you're actually trying to slice as there are so many separate objects, but if it's the bit I think the geometry is quite ugly with extra edges and vertices which may well be confusing the boolean. Try isolating just the part you're trying to slice with the slash key on the numpad and look at it in edit mode. You can probably dissolve most of the edges on the sides for a start.


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images as sequence in image texture node doesn't work
I created 3 different oceans with ocean modifier with different displacement and used linear extrapolation to animate it.
I then baked the 3 simulations.
After that i created a new plane and applied the baked ocean sims as texture to animate it and apply the displacement. the problem is only one frame out of the 150 is being applied instead of the entire animation even though i use image as sequence option in image texture. Also in the blend file if u unhide the displacement collection you can see the different oceans.

Please add your blend file to your question.

Check if you have auto update enabled in the image sequence node. If it's disabled it won't update the frame in the viewport when you play or scrub the timeline. But even it's disabled it should play correctly when rendering.
If you want the texture to loop, also enable "cyclic" or the texture will pause on the last frame. And for good measure check if the 'Frames' number is correct (this number should be the number of frames in your image sequence).

I had the same problem that only the first image was loaded.
In my case the file names were not congruent (image_01, picture_02, photo_03, ...) Changing them to image_01, image_02, image_03, ... has fixed this problem


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Removing animation keyframes outside of a specified range
I have over 1000 animation files that I want to "crop" off keyframes outside of a specified range.
Keyframes all start at frame 1 instead of frame 0, as such I want to shift all keyframes by one frame such that the animations start at frame 0.
I have an int variable named "framelength" which stores the framenumber of the last good frame. I want to remove every keyframe after this value.
The most similar code I was able to find online was:
How to remove all only rotation keyframes from current action with Python?
and Editing fcurve.keyframe points in FAST mode?
Both were written by BatFINGER.
I tried using a combination of the two to achieve what I want, but am struggling with deleting only certain keyframes.
ob = context.object
ad = ob.animation_data
action = ad.action if ad else None
if action:
    for fc in action.fcurves:
        sel = list(bool(i > int(framelength)) for i in range(len(fc.keyframe_points)))
        for i in range(len(fc.keyframe_points)):
            if i>35:
                fc.pop()

Above is my attempt at solving the problem.

Here's another that may be useful,  creates a new sliced action.  To make the default start frame 0 change to _kfs[:,0] -= start_frame.   For when use shift is set.  https://blender.stackexchange.com/a/214899/15543

I got it working thanks to batFINGER's comment.
My final code looked like this:
import numpy as np
def action_slice(action, start_frame, end_frame, shift=True):
    copy = bpy.data.actions.new(action.name)
    copy.id_root = action.id_root

    for fcurve in action.fcurves:
        kfs = np.empty(len(fcurve.keyframe_points) << 1)
        fcurve.keyframe_points.foreach_get("co", kfs)
        kfs = kfs.reshape((-1, 2))
        _fc = copy.fcurves.new(
                fcurve.data_path,
                index = fcurve.array_index
                )
        _fc.keyframe_points.add(0)
        _kfs = kfs[
                np.logical_and(
                    kfs[:,0] >= start_frame,
                    kfs[:,0] <= end_frame
                    )
                ]
        if shift:
            _kfs[:,0] -= start_frame
        _fc.keyframe_points.add(_kfs.shape[0])
        _fc.keyframe_points.foreach_set("co", _kfs.ravel())
    return copy

def object_do_slice(string, endframe):
    ob = bpy.data.objects.get(string)#context.object
    ad = ob.animation_data
    action = ad.action if ad else None
    if action:
        ad.action = action_slice(action, 1, endframe, shift=True)

object_do_slice("Root",framelength+1)


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quicker way to damp track or track to a location?

If i am rigging/modelling, i often have the need to align (track to, rotate) an object to a location.
e.g. : the blue part track to the 3D cursor.
I solve this by giving the blue part an object constraint (damped to) the piston (with of course setting the origin of the piston to the 3d cursor), then apply.
But this sounds a bit complicated to me. Is there a quicker way (and i am pretty sure there is)?
Something like "track to 3D cursor" e.g.?

Something like "track to 3D cursor" e.g.?

Wouldn't that be nice?  At first sight, a 'Point ±XYZ at 3D Cursor' operator would  seem a great addition to the Snap menu.   And not so hard to implement? Maybe a rock-solid Pythonista will answer this question with one :)
In the mean time, there is an 'Insta-Track' to Active Object. It's in the K Track sub-menu of the Header > Object menu. It can be added, as here, to your Quick Favorites:

It adds an 'Auto-Track' in the constraints tab, where 'Up' and 'Axis' can be adjusted.

ok...this is nice, but if somebody has an even nicer solution, i will change my "right answer" flag ;)

@Chris Absolutely! Fair enough! I'm tempted to have a shot at writing the operator myself, but I'm very slow at it, and not fully acquainted with all the possible 'gotchas'.

Thank you for that Robin - it’s already an improvement for me anyway!


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how to insert text with multiple lines in string node in GN?
I want to display text with several lines in GN.
Especially my text is in the text editor, i copy paste it into the string node and i got...one line.
Is there a trick to insert more lines?
What am i missing?

I'm not at a Blender computer right now, but what actually happens when you type "\n" for a line break? ...you would need a special character here. somehow. ...there is a node for this special char, as far as i remember.

then i got this: [1]: https://i.sstatic.net/ll0dR.jpg

You could achieve the desired result by using each line as a separate string input, and linking them together with a Special Character as a Delimiter:

Another solution would be to write everything in one line, and set the width of the text field with Max Width. This would create automatic line breaks.

If you really want to write everything in a string value, you could use any character as a separator, and replace it with a Special Character:

That’s what I didn’t want to do because I am lazy…I hoped for a solution with one string node

@Chris I understand, you could of course replace any character with the Special Character (see updated answer)

@Chris I have now looked at the source code: Apparently there really is no other way, unfortunately, because the line break really cannot be interpreted from the text. This is probably exactly why the Special Character node exists.

that's totally ok for me!! thanks!

Is there roadmap for integration of multi-line input ? Currently, there is only text-editor editor, but it would be nice to have this feature in nodetree, or any developer wanting this ui feature to make addon that don't rely on the current text-editor.

I use the solution from the second image, One thing I also do is using \n for Line Break and \t for Tab, cause I'm hoping those will work someday in the future and they make the most sense.


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why is the color of my hat blue and not orange?
I made the hat by copying some vertices from the head and separating the mesh. Then i made the material single user and changed it to orange.
But still...my hat is not orange so i made some stupid mistake...

blend file:

and yes, i know and i want to be in viewport shading.

You are not in the material view, so that Viewport display color is used:


text:
why are all textures for all objects the same?
Beginner texture question:
I thought, if i took object coordinates, the noise textures etc. would have different values so that the material doesn't look the same.
Unfortunately they look the same.
So it looks like i misunderstood here something!?

material:

See what object texture coordinates are https://blender.stackexchange.com/questions/56610/how-to-tile-textures-in-cycles/56613#56613 Also see https://blender.stackexchange.com/questions/186953/what-does-this-stone-texture-node-group-do/186957#186957

thanks Duarte....i used now geometry position, that was what i wanted

Alternatively you can use an Object Info node's Random or Object Index values to create variations. Here's a contrived example where the Object Index is used to control the W value of a 4d Noise texture while a random value is added to its scale to change the scale slightly.
W is often used as a "seed" in Noise textures. The downside is that 4d noise is computationally expensive, but you can use the Random value to randomize any parameter.
This has a slight advantage in animation: Using Position means that textures will "swim" as you move objects.  On the other hand, if you want the swimming effect, then Position is exactly what you want.

you are right, i just wonder why in my "special" case my solution worked....but it was a more complicated material from a library. But in the easy case i tried you are totally right! thanks!


text:
how to use context in drivers with a function in python?
How do i use "context" in a driver function correctly? i know i shouldn't use "bpy.context".
This is my function:
 import bpy

    def getLeftVal():

        depsgraph = bpy.context.evaluated_depsgraph_get()

        return 69

I think drivers are supposed to work with animation and animation is supposed to be rendered, but rendering does not always have regular context for example when rendering from command line, so the way I see it, it might be that one just isn't supposed to use context in drivers at all. I would use handlers. They might suffer the same issues in some situations, but I think they would be more reliable than drivers if it's even possible to do with drivers.

good idea! thank you!


text:
texture a curve
I have a curve (and i don't wanna convert it to mesh) and i want to texture that curve:

Unfortunately my texture is getting stretched on the straight parts.
How can i have the same distance of the rings on the circle part and on the straight part?
shader nodes:

resampling curve via geo nodes seems to be the only solution :( or you can subdivide the straight parts to get a uniform vertex density (ok solution for simple curves)

no it isn't because then it is no curve anymore

It doesn't seem possible: https://blender.stackexchange.com/questions/1670/how-to-texture-a-beveled-curve-without-stretching ... maybe you can try to subdivide the straight part

wow, that's so sad :( is there maybe an add-on which resamples a curve geonode can do? so that the distances between control points are equal? or wouldn't that help at all?

https://gamedev.stackexchange.com/a/5427 see Mapping T evenly on the curve AKA arc-length parameterization

Generate cooridinates option ? https://blender.stackexchange.com/questions/9319/adding-a-texture-map-to-a-beveled-curve-or-path

there is no "use uv for mapping" checkbox anymore...and i don't get it working. If you can...i would appreciate it if you show me how

ok, i would also accept a geometry nodes solution... :D

...it is still possible to achieve the desired result. Guess what? With Geometry Nodes, hell yeah! https://blender.stackexchange.com/questions/43146

@Chris Is this the look you are after? a curve with this texture https://imgur.com/a/cWTTjVj

ok, this works for me now:

so i give the factor value to the group output and use that as uv value.

+1, the easiest way. In one direction. The other direction will not work like this, but for this purpose it is enough.

I still try to understand your solution


text:
How can I effectively create a full face mask?
So I am having some problems, especially with stupid covid messing up my search. I am trying to create a full face mask in Blender but can't as I there seems to be no way to set the circumference of an object like a cylinder and when I tried searching online for measurements to help it just showed me useless results of masks to help protect against covid, and I don't want that mask, even including full face mask does nothing.
So does anyone know any effective way to create a full face mask in Blender, an example would be a mask like a hacker's mask or the mask Jason Voorhees wears, the hockey mask. I got results from the hockey mask, such as the circumference but I can't see to find a way to set the circumference of an object in Blender.
Any help is appreciated, as the internet is no help. I mean, I pretty much need to learn how to set the circumference of an object, such as a cylinder and I am good, but if you got any other ideas, please share. I could also just manually set it with each ring, but that would literally take forever and to get it right, it will keep changing, then I would have to quickly reset it, and it will take forever.

The easiest way to make a face mask is to start with a face and then edit it.  But it sounds like your question here is less how to make a face mask than how to create a cylinder with a specific circumference.
Blender doesn't create cylinders on the basis of circumference, but it does create cylinders on the basis of radius, and the two are proportional-- circumference is equal to radius * 2 * pi, so radius is equal to circumference / (2 * pi).  If you want to create a cylinder with a specific circumference:

Create a cylinder.
Look at the operator panel (F6 for me, but our initial interface choices may have differed.)
In the radius field of the operator panel, type "c/(2*pi)", where "c" is the circumference you want.

Most fields in Blender allow entering simple math like this directly.

Thanks a bunch.

I actually never knew you could add in math equations to the fields, that is amazing.


text:
Exporting Blender into Unity rotation not working correctly for both animations and scripting
I asked over at Unity Answers, however no one answered yet so I am hoping to receive answers here.
I have this Kitchen Counter I made in Blender where I have it set up where the cabinet doors opens for my game. When I open my doors manually in Unity, it works find. However when I open them through a script or an animation it doesn't rotate correctly.
I recorded some videos and I have a Blender file available. I want to know what the problem is so I can prevent it in the future. Anyways, the video should help anyone who seeks to share knowledge get all the information needed. If you need more information although, just ask.
Here is a video of trying to open it through a script.
https://youtu.be/WTeIgeWAXc0
Here is a video of trying to animate it.
https://youtu.be/px6mY4YGIPU
My Blender file. Hopefully you don't mind me using Google Drive as this is where I originally uploaded to. I exported it to FBX as well as I use the normal Blender file inside of the Unity assets, both share same results. If you didn't guess already, it's best if you have Unity when fully testing it, but if you already know the problem then don't hesitate to share.
https://drive.google.com/file/d/14yVDs2qMRdAJVy_3rv5xx3FGopwWvVbx/view?usp=sharing

The first video is hard to see. From the second one, its looks like what you get wen in a gimbal lock situation. You can either go around it by baking your animation, or try to fix it by changing the object's rotation order/mode. But I don't know how that can be done in Unity.
Baking
In Blender, select what you want to bake, then you can open the search bar via F3 and search for the Bake Action operator:

Most of its settings are self-explanatory, make sure to bake the frame range you need, clear the constraints if you are baking a complex rig from which you need to export only its deform bones without outer influences. Save as a copy (so to not overwrite your original non-baked animation, which is easier to work with and modify) and export.
It is recommended to do this anytime you export any animation to begin with, because it allows to "hide" such issues.
Each software and format exchange have its own way of doing things, and here the biggest culprit is that Unity and Blender do not use the same coordinates system to begin with (Blender: +Zup +X left, Unity +Yup -Xdown).
Baking on every frame allows to "force" the animation you made in Blender to "remain as it looked in Blender" on every frame even after importing it elsewhere, instead of leaving most of your animation up to the software's interpolations which will be different from each other just because of how they work differently under the hood.
It will not make the issue go away, but it will allow you to ignore it most of the time when you animate in Blender and just want to export the result straight into Unity or anywhere else.
Changing the rotation mode
What are Euler Rotations in Blender? | How to Avoid Gimbal Lock (2021) - YouTube
In Blender, you can do it in the sidebar:

If exporting with a new rotation mode doesn't seem to work, it could be many things. From Blender's exporter who doesn't export that change, the exchange, to Unity's importer who ignores it. Look inside Unity, if you can change it there. It will at least remove the potential issues with exporting and importing. Otherwise, maybe some people on the Internet already figured out precisely which settings to use and what button to press specifically for that, but I don't.
If you do manage to find the right setting for the rotation mode and export/imports, do keep baking your animations. It might not have the rotation mode issues anymore (until you try a different animation that rotates in a way that inevitably gimbal locks that rotation mode), but you still may have other interpolation differences without baking.

Have you tried to change your rotation mode and export again?

I did do that. Did you test it yourself in Unity to ensure what you are telling me is accurate? If not, I do recommend you do. It could even be a gimbal lock inside Unity and not Blender.

I do not have Unity, sorry. And BSE being a Q&A about Blender only, I will keep it to Blender. Actually, I don't even know why I bother about rotation order, people have been avoiding this kind of issues for decades just by baking their animations, I should have started with that. I edited my answer.


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Rotating instances in geometry nodes causes it to stretch
I've been stuck on this for hours. Internet hasn't helped me and I seem to be a unique case and need to finish this today.
Trying to create a Minecraft scene with arrows scattered all over the place from a battle. However, when trying to rotate the arrow instances, it stretches as I rotate it. I thought it was because I hadn't applied the transforms to the original arrow so I did that to no avail.
Here is the result.

I have seen that it is connected to the origin of the plane I am using for the geometry nodes as when changing the origin point, the stretching goes into different directions.
Here are my geometry nodes

I am using the MCPrep Blender addon to add in the arrows.
Please, can someone help me with this? I need help with this ASAP.

After a few hours of trying to fix it and just asking the question myself, I managed to fix it and that was to ensure I applied the transformation on the plane, not the arrow. I completely forgot the plane exists.
If anyone comes across the same problem as me, always make sure you apply transformations. Also, ensure you do it with the geometry nodes off as it will make your Blender software stop responding.


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Problem creating mirror in X, Y axes
I'm trying to create a mirror in X and Y axes with a circle like this:

But I can't fill all the circle, there are some edges that doesn't create. I've looked many manuals and it is supposed to work well as I'm doing. What am I doing wrong?

can you add a link of your reference manual.

Mirror's axes are specified by the object, not by the world. So the transforms what you do in object mode don't count, only what you do in edit mode. You generated the circle in object mode, then rotated, then went to edit mode. You are supposed to go in edit mode, then rotate with 22,5°.
All the transforms must be 0. You can apply the transforms by hit CTRL-a and select rotate and scale.


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How do I bake both the paint texture and sculpted effects into one normal?
Right now I have a sculpted texture that I used a method I learned on youtube to bake. You have a low poly version of your object and a high poly sculpted version right on top and bake the high poly effects onto the low poly which gives you a normal map. Now I want to begin painting my object however have a question.
How would I go about baking the paint texture part of my object (like effect of wood or stone)?

if i understood you, i think you have to bake both as normal maps separately, and then save the images that you got and then open a image editor like photoshop or gimp and then set to overlay mode the first layer and then join them and export it to png or other image format, and then setup the normal in your node editor.

Overlay mostly works but is not mathematically correct.  There are better (but also more complicated) ways to combine normal maps.  Also, you can do Overlay (and the other methods) directly in Blender if you're ok with the hassle of additional nodes.

complicated ways like?

https://blender.stackexchange.com/questions/38298/how-to-combine-two-normal-maps - if I understood it all myself I'd make it a full answer, but this is probably a good place to start.


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Is it possible to get a proper terrain-like height map?
So I've been working with a displacement map through the shader editor in 2.8 because I need to create a terrain, I need it in Unreal but given I don't have the means to something like World Machine it seemed like Blender would be able to do it, but I haven't had that much luck, I've got a height map but it really looks nothing like the displacement I have in Blender so I'll cut to my question. Can I get a proper terrain height map in blender?
Can I get this

Out of this? Or is Blender or any plugin not capable of getting that kind of definition out of a displacement map or modifier?


text:
Fading Colours in Blender Render
I'm trying to fade one colour into another colour in blender render without using cycles render. Someone please tell me there's a way.

...and what you tried until now?

You can animate the Diffuse color parameter :
Put your mouse over the color selector, press I to insert a key. The color selector should be highlighted in yellow to show that a key is present.
Move a few frames forward, change the color, then insert a new key.
(You can do the same with almost every parameter)

Im sorry I worded that wrong. Say I have a plane and one side is black and the other side is green. I want the 2 colours to fade into each other with no animation. I hope you understand cause this is driving me nuts lol

I didn't use blender render for a while, but you can do that with a Blend texture and a Green/Black color ramp.

where do I find blender texture? node editor?

In the Properties editor, "checker" icon, close to material icon. Add a new texture, in "type" select Blend. In "Color" tick "Ramp", then edit the ramp to choose your colors.

Thanks to you I got it the way I want it to look! I really appreciate your help.


text:
Why is the bone Tip and Root separated from the body of the bone in blender 2.8.Kindly assist
When I add a bone in blender 2.8 the bone body happens not to be connected to the Tip and Root of the bone. How can I solve this problem?Kindly assist. I have also included a screenshot.

I experienced the same thing while using windows 7, I tried it on windows 10, and the problem was solved.
Also tried on Linux(Ubuntu) it works fine. It might be a bug associated with windows seven on certain hardwares.


text:
How would I be able to set one vertices the same y axis as another one?
I'm new to use blender and the current version I'm using in 2.8 and I want to get used to learning this software.

I assume "setting a vertex to the same y axis as another vertex" means that they both should be on the same line perpendicular to Y axis.
Snapping
You can use snapping for that. You can constrain to the other two axis by pressing shift+x,y or z so that transform operations are constrained to a plane and then hold ctrl while in transform operation to temporarily enable snapping. Your snapping settings need to be set to Vertex mode:

Scaling
You can also use scaling to 0 while using active element as transform pivot and constraining to the XZ axis plane the same way as with snapping. The active vertex will be the one you select the last.

Nice solution and very easy to follow. I knew about snapping and the combination of multiple restrictions sure does the trick. Learning more ways every day. Even for some seemingly simple situations.

Thanks, I am really glad to hear this is easy to follow, that's exactly what I aim to make it. :)

It sure is, while i tried to go with a simple way to follow, you made the use of shortcuts easy to follow which sooner or later ends up being the way to go to be efficient anyways. I need to learn how to make those gif animations, as they do show so much information (more then a dozen pictures you would have to scroll through) in a compact way.

There is this ScreenToGif tool if you are on Windows.

Great tool, thanks for pointing me in the right direction, i'm sure that a lot answers can profit from tools like this.

Welcome to the Blender world, and yes 2.8 is a good start.
So you want to set one vertex of an object to the same y-axis (value).
I'll go by example then:
We need to see the coordinates, so in the Viewport press "n" to open the "Transform" tab.
In vertex edit mode, i selected one vertex and moved it a bit in the y direction to build an example.
The vertex has the y-coordinate of -0.55815m, as marked in the picture below.

In the second picture we have the vertex on the other side selected.

This time the y-coordinate is -1m, means we have 2 vertices that have different y coordinates and can correct the cube the following way.
You can click on the value behind the "Y:" and it should look like this.

The y-value is now marked and you can copy it by "ctrl-c" to then select the other vertex again and override the value like this.

By clicking on the value, in this case -0.55815m it will be selected and you can "ctrl-v" paste the value you copied from the other vertex. The picture shows the already pasted new value of -1m. After which you press enter and confirm thus the new value.
Now the starter cube looks fine again.

While there are a lot shortcuts you can and may want to learn, start with the basics and if you need to set values precise, this is a good start. There are a lot tutorials to get used to Blender, well worth the time to watch and especially with the new 2.8+ version, it's fun, so i hope you enjoy yourself with Blender.

There are many different ways to do this: which one you choose will be the one you can reach most quickly, and which disrupts the settings for everything else you're doing at the time the least.
Typically for me it would be:

Keyboard . > set the Pivot point to 'Active Element'
Select the vertices you want to move, and lastly the one you want to move to, making it active.. and ..
SY0 Scale all the selected vertices to 0 in the Y axis (of whichever orientation you're working in).

or, if you want to move all the vertices on to the same axis, rather than flatten them along it:  SShiftY0, scaling in all axes except Y.

In edit mode select the vertex you want to move, hit 'G', and then hit 'Y' to lock the movement to the Y axis, then just match it, you can press num 1 to align your viewport properly so you will see the y axis in a more precise manner, and you can also hold shift to move it with less speed.


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Is there a way to split a flat multi-poly face into squares and triangles easily?
I'm relatively new to blender (previous game was 2d) but I know the basic rules like making your mesh out of rectangle/squares and triangles. Due to a city block being mostly flat I've disregarded that rule for the top face which has worked until this particular shape. I've tried removing doubles and recalculating normals, and all vertices on the face have the same z-co-ordinate. This means it's due to the shape and I don't want to spend time joining these vertices into squares/triangles in order to fix it, is there any way to do it easy/automatically?

I don't get the idea behind this question. If it's about how to convert Ngon into tris then press Ctrl+T with it selected. If it's about converting it to quads then try to delete the face and fill with Grid Fill. If clean quads are needed it might be required to convert into quads manually. Also depending on the purpose of the mesh converting might not be needed at all

These functions can be useful for you. Hit ctrl+e or ctrl+f in edit mode.


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Textures looking different in texture paint vs render/export
I'm trying to texture a mesh and I manage to have it looking fine in texture paint:

But then when I switch to any other viewport that isn't texture paint it looks super blurry, like this:

It's worth nothing that when I import it to Unreal it looks like the second, blurry version.
Can somebody tell me what I'm doing wrong please? I've tried looking at similar issues from other people but I haven't had luck with the suggestions in those (smooth shading, recreate the materials, change resolutions...)
Thanks :)

What does the image look like in the 2d image editor? Is it blurry there as well, or finely detailed as you expect? Is there a setting on your texture that uses mipmap/ Gaussian blur or something like that in the game engine? In Blender, is your scene set to simplify textures? Maybe show a screen from blender on these settings if you can.

Do you mind sharing the file? It's hard to reproduce this issue.

Hey guys, I found the issue. My UV was wrong (I automated it), when I made it manually the problem went away. Why it appeared ok in texture paint but not in the final render I don't get though, but anyways it's solved.
Thank you very much for your attention though :)