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Adaptive subdivision texture distortion
I'm curious to know if the issue I'm experiencing in the included renders is the same as the issue described here.
My mesh is shown here:

Standard subdivision surface with texture here (what I expect to see):

When I change the subsurf modifier to "Adaptive", this happens (corners stretched):

It appears that the issue linked on the Blender dev site has been closed/archived.
My questions are:

Does this mean that textured models will need the double-subsurf approach described in the Blender ticket as a rule when adaptive subsurf is used?
Is my approach to "sharpening" the subsurfaced edges correct?  I followed this tutorial to implement the loop-cut-edge-slide technique and it's worked very well in the past.  Just wondering if there's an alternative approach with the introduction of the "adaptive" setting?

Adaptive doesn't work well so far with subdividing UVs so yes, likely one should apply usual Subsurf and then add another one with Adaptive turned on to bring amount of edges to the same quantity and avoid faces subdivision without UVs subdivision.
Although you can reduce the problem a bit (not all of it) by enabling Use Subsurf in the unwrap options while Subsurf modifier is present in modifier stack.

Then UV map will be changed accordingly to the level of subdivisions at the moment of unwrapping (you can unwrap with Subsurf at level 4 and then bring it back to 2, like is done in the example below):

First one from the left is original object with Wire turned on (with Subsurf modifier changing it).
Those 2 to the right are rendered copies - second from the left is its copy unwrapped with Use Subsurf, roundish defromations are almost only in the corners. Third one is usual unwrap without Use Subsurf with some strong deformations only except for the middle parts of faces.
If you aren't searching for some good looking subdivisions you can use Crease to make hard corners and avoid supporting loopcuts altogether (or crease supporting loopcuts thus leaving deformation between them and avoiding it in other areas). Working with UVs for Subsurf will become much easier.

Interesting suggestion about using creases in addition to supporting loops.  Hadn't considered that.  Thanks!


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How well does Blender handle multiple instalations side by side?
I have Blender (latest stable version) installed on my workstation.  I want to install the nightly build so that I can have the stereo 3D features for a project that I am working on.
Are there any known problems that I could have by having both installed/running at the same time?

I tried to run nightly builds along stable versions and never experienced problems with that.

As long as they are installed in different folders under Blender Foundation, there really shouldn't be any issues

I have never actually "installed" blender, I just use the zips archives. I have never had a problem with having multiple version of blender.

You don't really install Blender, you download it, and uncompress it (unzip), and that's an intentional design model, it should run just fine from a flash drive (haven't tried myself though).

multiple blender versions on one system should be fine.
Personally, I don't update Blender builds more than 2 times a week, often less. Of course if some needed feature is broken and has been fixed in a recent build then i'll update asap. There's no right or wrong way here, it's more about how much effort you want to stick into being on the cutting edge.
Let's assume you are downloading from Builder bot
The simplest way to do avoid potential collisions is to take control of where your new blender files go. This means not using the installers, but instead unpacking the builds manually and putting them in separate folders.
You can make short-cuts to different Blenders and put them on your desktop, that way loading different instances of blender is easy. Remove the short-cuts of the Blender versions that you don't think you'll need for a while. Use unique icons to quickly identify the Blender (maybe using 3d glasses for the icon in the viewport branch)
Add-ons
Add-ons are an easy issue to get wrong, both locating them and installing.  But it doesn't have to be hard. Each version of Blender will look in several locations for /scripts/addon.
If you have a core of preferred addons, the way to only worry about those once is to make a custom add-ons folder, and tell Blender to also look there for addons. In:

User Preferences > File > Scripts

In this example I have a folder on that path called scripts, inside scripts i have:
scripts/addons
scripts/addons_contrib

This is where I stick the addons (manually) that I always want to have. And this manually setting of the scripts folder is one reason I don't update every day. It could be scripted of course.. :)

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UV's not updated in Textured view when in GLSL material mode
When Viewport Shading is set to Texture and I set the Shading section's material mode to GLSL instead of Multitexture, the UV's are incorrect and do not update when I adjust them. But when I set it to Multitexture, the material properties are incorrect (normal maps ignored, etc.)
Only when I set Viewport Shading to Rendered does everything appear correctly.
Am I missing something about GLSL mode? I created a UV sphere, and it always shows the original UV's from before I did my own unwrap on them.

Blender behaves in a way designed to help make UV Editing/Texturing easy. Which can be a bit confusing at first.
When using Blender Render and the 3DView's draw mode is set to Solid and Textured Solid shading is enabled both Multitexture and GLSL behave as follows -

When you are in edit mode, you can select one of an objects UV Maps, then select an image in the UV Image Editor to associate with that UV Map. While still in edit mode selecting another UV Map will also switch the image displayed in the UV Image Editor to show the image associated with it, which will also be the UV Map and image used for display in the 3DView.
In object mode selecting a UV Map will still switch the UV Map and image used in the 3DView but not the image shown in the UV Image Editor.
When unwrapping objects this is helpful but it does override the texture setup for the material. So for the texture shown may not be the same as what gets rendered.
When the 3DView shading is set to Texture, multitexture continues to behave this way but GLSL will use the image set to be used in the texture. If multiple image textures are defined then the image used in the texture lowest in the texture list will be used and if the UV Map to use is also defined in the same texture then it will be used instead of the selected UV Map in the UV Map list.
For a material with one texture and UV Map then GLSL will look closer to the rendered result, but using multiple textures will still vary from the rendered result.
When using Cycles it can seem a bit trickier. With Texure shading it uses the UV Map selected but uses an image from the active Image Texture node (the selected -or last selected- image node in the node editor) from the objects material.
When using Material shading it gets an approximation of the images used in the material, that is image nodes connected to the output with other nodes mixed in also altering the appearance but they don't give the same result as when rendered. Any uvmapping adjustments being fed into the image nodes also effect the result seen in the 3dView.

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How coould I scale a bone to fit inside the models body?
the bone is too wider than the models body(hand) and it is giving me a trouble while weight painting(the model shrinks). And when I try to resize/scale the bones it doesn't go as I needed it(unable to make it thiner with out affecting the length). I don't get the problem on vertical bones. only when adding horizontally the bone gets wider than needed.

You cannot scale the default armature but if you change the bone display type to B-Bone, you can use CtrlAltS to scale it and make it thicker or thinner. It's also fairly easy to have the default armature display type fit inside any model by scaling it down in Edit mode and making it longer and thinner.

You cannot reduce the thickness of bones but you can change the type of bone and choose the most suitable ones for you like this :
Go to Properties> Armature> Display> change the type of bone(Octahedral, stick, B-bone, Envelope, Wire ).

Thanks! but if the bone in the Octahedral display does not fit inside the body, changing the display to the other's does not solve the problem while painting. I am considering to increase the size of the model and to re add the bones again. But I will be looking for a better solution if exist.

@user3576 can you post a screenshot of it ?

By the way Its o.k. if a little portion of the bones stick out of your model because it is not going to be a problem. after weight painting once you finish the rigging part you won't need those bones on the viewport .

The problem arises when I make weight painting. the body just shrinks if respective bone is larger than the body.

can u give a screenshot?


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toon shadder problems
Currently, I'm having a lighting error with a toon shader I'm trying to build. My goal was to try and make a stepped honeycomb effect on a toon shader, however the light is not reacting how I hoped it would, and I can't seem to find a fix.
What the shader currently looks like.

What I'm hoping to make. (example from Photoshop)

Current node setup.
[The problem does not stem from my janky honeycomb pattern, if I plug lets say a voronoi texture into the setup instead I will still get the same weird artifacting.]

blend file

Nothing too wrong, here.. you've just got to make your Pluses and Minuses consistent across the piece (you could do everything the other way round; just not some of it):

The Length nodes above do the same as your Dot-Products, no problem. The added 'Cell Center' branch might help you get a circular patch of hex-cells. The fields showing 0.866 are typed in as sqrt(3)/2.

Your node setup is working great, however I'm still failing to get the nodes it to react to a light source properly, sorry to take more of your time. Also, I have edited the post to include the blend file if you need it.

@Dickhead_Jones   Ahh! OK, I'll have a look when I can.

@Dickhead_Jones Could be tricky.. I'll try and get ahead anyway tomorrow am , but a query....  Do you want the hexes in the plane's space, or the lamp's? (should they look flat on the floor, or as if projected from the lamp). Is the floor always flat? Is the floor always in XY?

My goal was to use this on some weird objects (Ex: Suzanne), so it probably should look flat on the floor, however. If the other one (projected from a lamp), is easier, please don't hesitate to go with that version since I'm taking so much of your time.

Don't worry, I don't need this immediately by any means.

@Dickhead_Jones.. stuck on this one... :(

@Dickhead_Jones  You could shade the lamp instead, or make a physical gobo for it?  Not quite the same...

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daisy chaining map range nodes
Currently, I have run into a problem in my understanding of how to create a node set up using the map range nodes.
What I'm attempting to achieve is creating a stepped map range shader similar to this example that utilizes a color ramp node instead.

The problem The map range node does have a stepped option. However, this is just not suitable for what I'm attempting to do. I need direct control over every layer for adjusting each layer's color, size, and texture. Not to mention, I need to make this gradient have 7+ controllable layers, while at most the map range only allows 4 controllable inputs.
The solution idea involves creating a daisy chain of map range nodes to make an infinitely adjustable stepped gradient. I'm envisioning something akin to this image below to achieve results similar to image 1. However, no matter what I try, I can't seem to achieve this desired effect. Many thanks if someone knows how to do this.

Why don't you use the color ramp?

I think you should provide more context to increase the chance of getting more precise answers. What exactly are you trying to create? What kind of control do you need for size and texture?

@MartynasŽiemys The context to this is a toon wood shader https://imgur.com/a/oiVjFtj. Currently, I'm just using a basic color ramp, but this method doesn't allow for different textures on each layer of the wood. So I'm planing to use a map range node instead. However, the final product will have more layers than inputs on the map range node, so I'm looking for a way to add as many inputs to the map range as possible. Hence, the daisy-chaining.

If you want to have different step sizes and different textures for each layer, I would use a Math > Greater than node with a Mix Color node to create the stepped layers.

For clarity, you can put the two nodes in one group and pass the factor through so that you can daisy-chain the groups easily.

The values for the Threshold must increase from node group to node group and are similar to the slider positions of a Color Ramp node.

The context to this is a toon wood shader

Well then why don't you avoid the XY problem kind of situation and ask about wood?..
Wood texture comes from the way a tree grows. The trunk grows outwards and environment conditions change in a similar way through the year and that's why the trunk is made out of layers of rings:

We can see this one is around 7 years old. The seasons are similar so what happens in every ring is similar and there aren't that many extremely distinct types of texture, probably not over 7 especially not in a simplified toon style anyway... ...maybe in a photorealistic texture you can go crazy and make some years very distinct, maybe especially cold winter or a draught...
You can take some extremely useful insight from this regarding how you could make wood textures procedurally. You can make a volume with a cylinder with rings inside procedurally so the surface of your object could be inside it and the texture would be sort of where the piece is cut out of that cylinder:

Then you can deform the volume in various ways to give it variation and randomness manipulating the coordinates of the volume. It will also later have grain - tubes going along the rings that transport water and nutrients up from the ground. It's also possible to introduce distortions given by branches, but that gives me nightmares so let's not go there yet...
Let's start with randomness in the volume with some noise and let's make the center wider since the tree has to grow bigger amounts of wood volume every year as the trunk gets wider so probably the rings get narrower:

Grain can be made with Voronoi deformed in the same way the rest of the tree(well maybe you want to add something grain specific to that later):

And so like this you can add more and more stuff to it in terms of volume deformations and then various noises on top to make the wood realistic. The start of this process still has the waves where it goes from 0 to 1 so you can worry about remapping that to something more interesting.
Here is one (somewhat)photorealistic made this way, but cutting parts out and putting them together(with many UV planes and baking):

Hopefully it should be possible to go into the other direction then photorealism once you have the basic pattern.
This is not a complete answer, but hopefully it could give you a start/example or a way to look at the problem, that might lead to something.


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Curvature Dependent Treshold Fresnel Effect
While reading a paper titled Line Drawing from 3D Models I came across a unique technique on page 6 that creates a Fresnel like effect that would be cool to recreate in blender. I have attempted this myself, however nodes never have been my strong suit and I failed to replicate it. here is the relevant equation n · v < ε √ Kᵣ and Below, I've detailed the parts I believe I've correctly equated.
n = Geometry (Normal)
· = Vector Math (Dot Droduct)
v = Geometry (incoming)
ε = Threshold Value
I've found myself quite lost with Kᵣ and what it represents, If anyone could provide guidance on how I can achieve the effects, I would welcome the assistance.

I'm not going to read the complete paper, but since you said you have read it: is this graphic the only time the variables $n$, $v$, $\varepsilon$ and $\kappa_r$ are ever mentioned in all these pages? //Edit: I just saw that below the image, the text says $\sqrt{\kappa_r}$ is the square root of radial curvature. So, I don't know how you calculate it, but that's what it is.

Lets re-visit the variables:
$\textbf{n}$ = Geometry (Normal) Yes, the normal of the surface point.
$·$ = Vector Math (Dot Droduct)  Yes.
$\textbf{v}$ = Geometry (incoming) I believe you mean the right thing. It's the view vector from the camera to the surface point.
$\epsilon$ = Threshold Value  Yes.
$\kappa$ (small kappa) the common character for curvature. There are different definitions of curvature, but in general it describes how strongly the surface is "not flat" at some surface point. Depending on the complexity of the definition one can express properties like convex/elliptic ($\kappa > 0$), concave/hyperbolic ($\kappa < 0$) and flat ($\kappa = 0$), see Gaussian curvature for example. The radial curvature is never negative ($\kappa_r \geq 0$) because the radius of a sphere (circle in 2D), which approximates the surface point's surrounding is used. For a flat spot the sphere would have infinite radius, thus $\kappa_r = \frac{1}{r = \infty} = 0$. For a very bend surrounding the sphere would be very small and $\kappa_r \gg 0$.
To implement this effect in Blender, i found this very nice post which sets the curvature value of every vertex as its weight. These values can then be accessed in shaders ultimatively, like demonstrated in another very nice post. Use the Camera Data and Geometry node to get $\textbf{v}$ and $\textbf{n}$ in the shader. With all the data at hand, you should be able to implement the formula and achieve the effect. But well, this will be a bit of work.


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how to combine a toon shader a voronoi texture
Currently, I'm trying to find a way to combine a toon shader and voronoi texture to create something like the example below, but I'm unaware of how to make this possible anyone know how I might achieve this?

I would use the Object output of a Texture Coordinate node with a Separate XYZ node to generally create the black/white border in X, Y or Z direction depending on which separate output you choose.
The Object coordinates can be mixed with a Voronoi Texture by a Mix RGB node. And to finally get a pure black and white result I would put at a Math node set to Greater Than at the end.
To get your final desired look you can play around with the settings of the Mix RGB node, scale of the Voronoi Texture, the Threshold in the Math node (or switch it from Greater Than to Less Than maybe). Here's a quick example - in this case the mix factor is set to 1, which means it only uses the Voronoi Texture thus making the Texture Coordinate irrelevant. I chose this because I think it's closest to what you show in your question, but I'll leave the Mix RGB there so you can experiment with different settings:

PS: You could also set the Voronoi Texture to 4D, so that you can change the W value as a kind of seed to change the look. Also a Mapping node after the Texture Coordinate can be used to manipulate the orientation etc. of the original coordinates.
//EDIT: After your comment I suppose you're looking for something like this, although it's basically the same as before. I use a Math node (this time with Less Than) to create the general black/white mask and use it as mix between two colors. To get a third color, I just plug the resulting two into another mix node with a mix created by a different Threshold in the Math node. You could of course even use different Voronoi Texture nodes. The only crucial thing is creating the mask with a Math node.

Sorry for the confusion, my example was not entirely accurate to what I'm trying to do, I just couldn't think of a good way to visualize it. Here is a better example of what I'm trying to do [ https://imgur.com/a/8bKZHZB ]. (sorry again, I cannot seem to find a way to attach an image)
Basically, I'm attempting to create a toon shader that only shades the tiles generated from the voronoi texture.

@Dickhead_Jones Since you have a better example image, why don't you add this to the question? It's always better to have resources here instead of external sites.

@Dickhead_Jones I edited my answer to better fit your demands.

Thank you for helping me, and sorry for being an idiot.

@Dickhead_Jones Don't worry for being an idiot, I mean you have to live up to your nickname and that's okay :) Jokes aside, best way to thank on this site is accepting an answer if it solves your problem.


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How do I fix this weird cloth simul issue?

I tried following a tutorial where he says that after making a denser mesh he got his creases right, when I tried, I got it in a irregular place, I want it to go, any help appreciated!

I don't know what you are trying to achieve and what the problem is.

I am trying to achieve a effect as mentioned in this video:
https://www.youtube.com/watch?v=p2iloupX7S8&t=1636s
at around 35:54, the folds that he get, I am trying to achieve just that, but somehow it's not working


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Why does my glass reflection turn black when I play animation?

Trying this new glass tutorial by polyfjord.
Why does my glass animation suddenly turn all black when I am a couple of frames into the animation, does this has to do with my drivers??

i just tested it...i never see "all black" so i just can assume it's your graphic driver....did u try updating? [1]: https://i.sstatic.net/gmZ08.jpg

Hey Chris, it usually happens only in the viewport, the render animation works fine, can it be just only a blender glitch??


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how do I create glass material and lens material similar to the glass camera panel in image?

Hi, I am trying to create a glass material that is similar to the one I posted below...
How do I achieve a similar effect, in eevee?

Hi Please use a title that reflects the content of the question. It should be descriptive but succinct, unique and identifying, summarizing the issue so that users can at a glance understand what your post is about. Use the [edit] link below your post and avoid anything not strictly essential to the post. Remember, your title is the first thing potential visitors will see, and makes your question findable for future users. See "What is the problem with posting an image or link and asking “How do I do this?""

What part are you talking about, and have you tried to set the Transmission to 1, switch from Opaque to Alpha Blend and so on?

I am trying to get the camera frame glass for the iphone to look as close as possible to the one in the image....


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How to add triangle crevices to the bottom of my bulb model like the 2D image?

I am trying to get the above model to look something like the vector image below, but in 3D, I am not able to picture how I can get the below look without making the mesh get weird shading.

i think i would use image as plane of the shape, then extrude vertices (just for one side) and then use the screw modifier. If that result is ok, apply screw modifier and delete the triangle faces at top and bottom and make one ngon face and inset that a few times. Then subdiv modifier.

Hi Please use a title that reflects the content of the question. It should be descriptive but succinct, unique and identifying, summarizing the issue so that users can at a glance understand what your post is about. Use the [edit] link below your post and avoid anything not strictly essential to the post. Remember, your title is the first thing potential visitors will see, and makes your question findable for future users. See "What is the problem with posting an image or link and asking “How do I do this?""

It's hard to guess how you imagine that in 3D, maybe tell a bit more

@moonboots so in front view, I want the model to be able to show the triangle crevices going up as in the vector image for both front and back, same for the bottom sections of the bulb, somehow I am not able to correctly model that for the curved surface

Your model is almost fine. Just that the face orientation is inverted which caused your shading issues. To resolve that, select the red object and tab into Edit Mode then press A to select all vertices and go to menu Mesh > Normals > Recalculate Outside or shortcut Shift+N to fix the normals so it appears blue.

Then you could try to get rid of some edge loops or try to space the edge loops a bit to give the subdivision more room to smoothen things out by selecting an edge loop with Alt+LMB and pressing GG to move the edge loops around. Then maybe add another level of subdivision.

Then you have non-manifold geometry in this selected faces area which causes the weird shading. Delete these faces:

And you have duplicate overlapping vertices in this object which causes weird shading. Go tab into Edit Mode and press A > Merge By Distance.


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How do I fix this weird shading on my eevee render?

Hey guys while making a phone model, reference to this tutorial :
https://www.youtube.com/watch?v=lZPedlX6CMw&t=2182s
Why is this showing me such weird shading, is it because of the two seperate objects or edges or something else, I am a beginner to blender and my first time working with eevee so any help is appreciated.

Try changing the shadowmap resolution.

Try changing the shadow bias on the area light.

You could do either one of these or both at the same time, depending on the desired result.

Wow, Thanks.
It did fixed it. Thanks

@AtharvaDeodhar Enabling Contact Shadows on the area light "Area" also fixes it.


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How do I create smooth, realistic ribbon cloth?

Hey Guys I want to replicate the ribbons in this photograph in blender. So far I know how to create thin tubes using curve modifier with a circle as the offset. but I don't know how to create the smooth waves that naturally occur in a velvet ribbon like in the picture above. Can y'all help guide me through this, thanks!

I basically used a cloth sim to make this ribbon, but I want to know the different ways I can achieve this ribbon mesh, and also how to create the middle knot in the ribbon and to create and edit the ribbon for different objects/bottles.

Hello could you please highlight the small waves you're talking about and also maybe show what you've done so far?

@moonboots I have added a answer that might help you understand my situation

Please don't use the Your Answer field to add precisions, instead edit your original post, what you've done seems pretty good no?

Just did, thanks for the clarification @moonboots


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Animating the trajectory of solutions to ordinary differential equations
Hello Blender Community,
I am new to the software and I am looking for some advice on the following problem.
Suppose that we are given the position and orientation of a rigid object in Euclidean space $(x,y,z)$ which are represented by the coordinates $(\boldsymbol{r},\Lambda)$ respectively. Further, let us assume that the evolution of the position and orientation is governed by an ordinary differential equation of the form
$$(\dot{\boldsymbol{r}},\dot{\Lambda}) = f(\boldsymbol{r},\Lambda) $$ where dot's refer to time derivatives $\frac{d}{dt}$.
We then can solve this ODE numerically using, say, the Runge-Kutta algorithm. This then gives us a time indexed sequence of vectors and matrices, namely,
$$\boldsymbol{r}_i = \begin{bmatrix}x_i\\y_i \\ z_i \end{bmatrix}  $$ for the object's position and
$$\Lambda_i = \begin{bmatrix}\Lambda_{11}^i& \Lambda_{12}^i & \Lambda_{13}^i\\\Lambda_{21}^i& \Lambda_{22}^i & \Lambda_{23}^i\\
\Lambda_{31}^i& \Lambda_{32}^i & \Lambda_{33}^i \end{bmatrix} $$ for it's orientation. If one were to take enough points $i$, then this sequence approximates the trajectory of the object (its position and orientation in space) by applying these sets of transformations to a chosen $(x,y,z)$ coordinate system.
I would like to animate the trajectory but I need some help/examples as to how to implement. I think a possible solution is as follows:
Step 1: Either solve the ODE in Python and import an array of solution points as a csv file OR set up the problem using C# (I think this is what Blender uses though I am at loss as to how to interface with it), implement Runga-Kutta and get an time indexed array of state-points.
Step 2: Interpolate the missing points to obtain a smooth trajectory.
Step 3: Fix a coordinate system to the animated object
Step 4: Somehow apply coordinate transformations $(\boldsymbol{r},\Lambda)$ to the object
Step 5: run the simulation from which we obtain an animation the trajectory of a rigid body in space.
I know how to solve ODE's in Python or MATLAB (Step 1) but I am at a loss as to how to complete steps 2-5. If anyone has any expertise with such a problem or can suggest any reading material/resources that would be greatly appreciated. Thank you.
Let me give an example. Let us consider the motion of a free rigid body. Euler tells us that the evolution of the body's motion is governed by $$\dot{\Omega} = \mathbb{I}\Omega\times\Omega$$ $$\dot{\Lambda} = \widehat{\Omega}\Lambda $$ where $\widehat{\Omega} = \Omega\times = \epsilon_{ijk}\Omega_k$, the antisymmetic tensor. To solve this equation we use the following routine in python:
from scipy.integrate import odeint
import numpy as np
# define the hat map
# takes in 3 vector and returns anti symmetric matrix
def hat(x):
    hat = np.array([[0,-x[2],x[1],[x[2],0,-x[0]],[-x[1],x[0],0]])
    return hat

# define vector field
# x[0] - x[2] Omega1-3
# x[3] - x[11] Lambda
# I moment of inertia

def f(x,t,I):
    dfdt = np.zeros(12)
    Om1 = x[0]
    Om2 = x[1]
    Om3 = x[2]
    La11 = x[3]
    La12 = x[4]
    La13 = x[5]
    La21 = x[6]
    La22 = x[7]
    La23 = x[8]
    La31 = x[9]
    La32 = x[10]
    La33 = x[11]
    Om = np.array([Om1,Om2,Om3])
    La = np.array([[La11,La12,La13],[La21,La22,La23],[La31,La32,La33]])
    Pi = np.matmult(I,Om)
    X = np.cross(Pi,Om)
    # Dynamics
    dfdt[0:4] = X
    # Reconstruction equations
    hatOm = hat(Om)
    Y = np.matmul(hatOm,La)
    Ry = np.reshape(Y,(9))
    dfdt[4:12] = Ry
    return dfdt

# simulate rigid body
# time interval
tspan = np.linspace(0,1,100)
# initial conditions
IC = np.zeros(12)
IC[0] = 1
# moment of inertia
I = np.array([[1,0,0],[0,1,0],[0,0,1]])
x = odeint(f,IC,tspan,args=(I))
Omega1 = x[0:,0]
Omega2 = x[0:,1]
Omega3 = x[0:,2]
La11 = x[0:,3]
La12 = x[0:,4]
La13 = x[0:,5]
La21 = x[0:,6]
La22 = x[0:,7]
La23 = x[0:,8]
La31 = x[0:,9]
La32 = x[0:,10]
La33 = x[0:,11]

My question is how to attach these simulated values to an object to be animated. I have tried the following code, yet the animation it produces does not seem realistic. I am not sure where the issue is.
# lets look at the motion in velocity space
import bpy
ob = bpy.data.objects["Sphere"]
start_position = (1,0,0)
frame_num = 0
t0 = len(tspan)
for i in range(t0-1):
    bpy.context.scene.frame_set(frame_num)
    ob.location = (Omega1[i],Omega2[i],Omega3[i])
    ob.keyframe_insert(data_path='location',index = -1)
    frame_num +=20

Good question, the first part of your code has errors. Could you fix them please? Or even better, could your replace it with a simpler equation?

What I don't understand is, that you have timesteps of 0.01 but jump 20 frames when settings keyframes.

As for the motion path, simple create a new object and populate it with your samples, then connect the vertices. Bmesh.


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Simple Python script not moving objects away from center
Warning: I am a complete noob at Python Scripting :P
What I want to achieve is that all of the selected objects are moved away from the center randomly, so I have created a simple script that (should) do just that.
Problem: It is not moving moving parts around the scene.
import bpy
from random import randint

for obj in bpy.context.selected_objects:
    rand = (randint(0, 20) / 20) + 1
    obj.location.x = obj.location.x * rand
    obj.location.y = obj.location.y * rand
    obj.location.z = obj.location.z * rand

EDIT: Because the parts were centered at (0, 0, 0), they would not move at all; a.k.a. anything times 0 is 0!

please create an answer with your EDIT and set it as accepted, so the question will register as closed

If the initial position is (0, 0, 0) then multiplying by a random number wouldn't change the position. Try adding or setting the position with a random number.


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Indices font size & color
Does anyone know how to increase the  indices (e.g. for vertex ids) font size and/or color in the viewport. Currently its a '2 pixel navy colored font on a dark grey backdrop' which can only be read by nocturnal species.
I'm using blender 2.93

I wonder why they chose this color and size. It's really hard to see. Ridiculous lol. Good question!

You can change it in your preferences->themes->3D Viewport

color: Face Angle text
point size: vertex size
font size: you can change it here:

but....it will change more than you want...i guess ;)

Perfect! Solved! Thank you so much

you are welcome


text:
Toggle selectable, enable in viewport
I wrote a small script that should:

unhide
enable in viewport
enable in render
enable selectable

for ALL objects in the scene

import bpy
from bpy import context
from bpy import data

# all objects
all_objects = data.objects

for ob in data.objects:
    ob.select_set(True)
    ob.hide_set(False)
    ob.hide_render = False
    ob.hide_select = False

However it wont toggle everything on, there are still objects or collections turned off.
Before:

After:

Is it perhaps not selecting everything with data.objects? Maybe i'm misunderstanding it.
Update:
I updated my script to include collections but it gives me an error

import bpy
from bpy import context
from bpy import data

for collection in bpy.data.collections:
    collections.hide_viewport = False

    for obj in collection.all_objects:
       obj.select_set(True)
       obj.hide_set(False)
       obj.hide_render = False
       obj.hide_select = False

Error: AttributeError: 'list' object has no attribute 'hide_viewport'

It is not selecting the nested collections.  You need to iterate over scene collections as well.

@MartyFouts thanks, ive updated my initial message with an updated script but its giving me an error.

Not all collection properties are in collection itself. hide_viewport for example depends on view layer, so it located in the view layer. You can find it like this (for the first collection):
 bpy.context.view_layer.layer_collection.children[0].hide_viewport
 bpy.context.view_layer.layer_collection.children[0].exclude

For nested list like this, you have to write recursion, there is no complite list of it

Sorry, this goes way above my head.  I think I understand it partially because there is the [scenes] and the [view layer] so i would have to iterate over both layers? Could I perhaps get an ELI5?


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Blender .DXF export object color information
I have the same models in blender and 3d max that I export to .dxf files.
MAX scene (3d max 2012 design)

Blender scene (Blender 3.6)

If I open both files in either Autodesk Viewer Online or DWG Trueview software, the .dxf files from MAX shows colors while the Blender files do not.
Autodesk Viewer Online (dxf from max)

Autodesk Viewer Online (dxf from blender)

DWG Trueview (dxf from max)

DWG Trueview (dxf from blender)

I realize that export settings in both softwares are different but with blender I have tried ALL export settings and I have even tried dxf exporter plugins but to no avail.
Is there any way to make blender push out color information for objects in dxf format at all?
Please also kindly let me know if there is perhaps another stack community or website where I could also ask for more information regarding this issue?
Thank you.
Edit: Adding additional information to make my question more understandable.
In 3d max, you can set an objects "wireframe" color, this is not the diffuse color but a separate setting. I want to be able to export the wireframe/object color from blender IF its possible. Currently that is probably the Object Properties >> View layer >> Object Color information what im talking about.

However I would also be satisfied if it was base color

of a (principled BDSF) material. In fact I think that information would be more likely to be exported within a DXF file.

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

Does this answer your question? .fbx export why there are no materials or textures?

@HarryMcKenzie & John Eason, unfortunately this does not answer my question. I have no problems with the textures. I want to be able to export the wireframe (3d max specific)/object color from blender IF its possible to assign and export that information from blender. Ill edit my initial question.

Looking at Export - AutoCAD DXF — Blender Manual, it does not seem to be documented. So unless the developer who made that exporter intentionally programmed a way to export a data (that Blender doesn't have to begin with) by using another data, I guess this isn't supported.

@L0Lock ah thanks, I should've checked there. Okay I guess this is not supported yet then. Thank you.


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How to create accurate RBD simulations that are perfectly synced to sound and collide with each sound beats?
Hey Blender Community!,
I recently stumbled upon this youtube short by this famous artist using rigid body sims to create this amazing animation with the sim reacting with music notes. I was wondering how is it possible to create such an effect, especially making the rbd sim collide with objects in tune to music at the exact second. I tried it myself but couldn't exactly match up the sync between the physics and the music. Would really love the input and expertise from you lot!
https://www.youtube.com/shorts/nAGIh5NymL8
This is what I've tried so far, without much luck I can't get them to perfect sync.

AFAIK it is just tedious work. Play the sound (e.g. by speaker) and start your rigid body sim with e.g. a sphere. If the first note hits, stop the animation and add your first rigid body object exactly on that place. Then start rigid body from start again and keep going until music finishes.

It is most likely not even a rigid body simulation, just a keyframed animation made to look like rigid body simulation. Or tedious work. Or both. But I doubt that a real simulation could be looped so seamlessly. Maybe with a sim as a starting point, then baked to keyframes and tweaked to fit perfectly. You should ask the creator.

yeah, you are right, might be even just animated.


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Rounded Caps for Blender Geo Node Hair Curves?
I am trying to recreate this cloth.

And have used the set hair profile geo nodes to achieve this till now:

I just want to add rounded caps to the end of the strands so they look like the cloth above and I can proceed with the rest of the scene. I tried making round caps in blender following some tutorials but to implement it for every single strand is above my current geo nodes understanding. I appreciate all the help and energy for helping me solve this. Thanks

After following quellenform's advice, I've come this close:

I don't think there is a simple way. You could add half of a sphere at the end of each hair. With the correct orientation and resolution, you could merge it into one hair mesh. That being said, I've never used hair with geometry nodes.

Try the following: Curve to Points (Count:2) > Instance on Points (with Rotation of Curve to Points and a hemisphere as Instance). Also helpful: https://blender.stackexchange.com/questions/254598/ and https://blender.stackexchange.com/questions/309859/

@quellenform Hi, thanks for the reply. Yes, I've got very close, but the sphere caps and the tubes are not matching together, i.e their radius are a bit off. Can you please help me with that?

Do you use Cycles or Eevee to render? The 2nd screenshot looks like Cycles because of the rounded ribbons.

Look at the screenshot of your nodetree: there is an error message on the Curve to Mesh node. I guess it is because you instance spheres on the points - a sphere is a mesh object and not a suitable input for the Curve to Mesh node. You have to use the Join Geometry node after converting the curve to a mesh. Apart from that, I guess there are some discrepancies between the radii so they differ in the end. But I cannot check it because the file in your question does not have the nodetree shown in the screenshot.

@GordonBrinkmann Hi, just updated the file, yes I just made the changes now after seeing this. Please help me with the radii, I tried using a same value node but I don't know where to put it so the strands are also the same radii as the spheres


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How to correctly import FBX, OBJ, Max files with right materials?
I tried to import this couch model from 3D Sky. I got a lot of formats for the same model, Vray FBX, Corona FBX, OBJ, Max etc. I wanted the model to display in it's correct materials in blender. I also went ahead to reassign those materials in the texture folder provided with the model. But somehow I am lacking a certain material or the materials are just not showing the way it should in the original model. Here are images for reference.
Left one is FBX and Right one is OBJ.

Also, why are the models low poly:

The Original Folder:
https://easyupload.io/jd1z03

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

Please do not ask two different in the same post. But just a quick remark to second question: What do you mean by low poly? First of all, why that screenshot to this question, there is no mesh visible? Then, the OBJ and FBX files have over 339,000 triangles which is not exactly low poly, the MAX files have over 180,000 triangles. Only the 3DS file has "just" over 60,000 triangles, but still not exactly low poly. How many polygons did you expect the model to have, was there a number given somewhere which was higher?


text:
Import FBX file doesn't appear
I'm trying to import this fbx file in blender but the armature doesn't appear (no bones,...) Any idea please why this is happening?

My problem with with my blender version, I've updated to the latest and it works perfect now! Many Thanks to @cegaton for the answer it helped me out figuring out the cause of the problem.


text:
Control the location of my IK bone
I've created an IK bone for my left arm of my armature. I wonder how I can control it's location to be beside the armature around the hand. As shown below, when I grab it all the way it goes far from the armature and I want to avoid this? because I don't want the cube to be far from the armature once I grab then press left click.

with a  limit distance constraint?

@batFINGER thank you so much, that did it. Do you want to post an answer so I accept?


text:
Set x-ray of two objects inside another object
I have a mesh 'Suzanne' parented to an armature 'Armature'. Both are located inside another mesh 'Cube'. I want both 'Suzanne' and it's armature 'Armature' to be visible in the 3D view through 'Cube'. I tried setting the x-ray of 'Suzanne' and it's armature 'Armature' to True in Python, but then 'Suzanne'only appears through 'Cube'. I wonder how I can make both 'Suzanne' and it's armature 'Armature' appear through 'Cube'.
The .blend file can be found here in this Link

Considering this is just for display anyways, could you get rid of the xray on Suzanne and instead add transparency to the cube?

To see your armature, check X-Ray for the armature as shown below. Then set the Maximum Draw Type of the cube to Wire or Bounds depending on how much detail you want (wire gives more).

This is the result:

No. X-ray can't work that as as far as I know. Once you put both the armature and the monkey in x-ray, its like they are on the same "layer". The only way I can think of close to this is to invert the normals of the cube, but I don't think that meets what you're trying to do.

sorry, but inverting the normals didn't solve the problem

You also only want x-ray only on the armature.


text:
Open export file window using my operator
I want to know how I can call and open the bvh export menu from my python operator (button)? I've looked into it and I found that the class INFO_MT_file_export(Menu): is located in the space_info.py but I couldn't find except the collada no bvh.
So first, I want to know how I can call and open the bvh export as shown below from my operator?

Also, I've used  Blender's operator_file_export template for this and edited it to export bvh instead, and it also adds a menu item to the export menu, I wonder how I can add the Rotation dropdown list and the Root Translation Only shown below to my menu item created?

So to wrap it up, I want to know how to open the bvh export window from my operator, and also want to know how I can get the bvh export parameters to add them to my panel menu.

It's basically the same as this one: http://blender.stackexchange.com/a/31852/3710. Supply your properties in a draw method or raw in the operator itself. Just let me know what you do not understand, then I will write an answer...

@poor thank you very much for your comment. I've just checked the answers to the link you sent, and the other one included in your answer there as well. These are customized import/export scripts. I want to know how I can call an already existing one, like in my case I want when I press on a button in my script labeled "Import bvh", to open the import bvh form, and same with "export bvh", "import fbx" and export "fbx", and I don't want customization in them or anything, just being able to call them from the four buttons operators I'm going to create in my script. Is it clearer now? let me know

@poor so don't want the user to do this: 1-open the file menu 2- go to export or import 3- select bvh, fbx,... I want these three steps to be done through my operators supplied in my script, so for example, when my "import bvh" button operator is clicked, I want steps 1,2,3 to be done so that the export or import view of the chosen file type (bvh, fbx,..) will show up. Regarding the other part of my question, was how I can through my script write these properties in my panel, but I think the link you referenced will allow me to do so, I hope :)

That's the only way @Tak since we can't overwrite (not easily) existing export operators. Simplified my obj export operator with a enum and a bool: https://gist.github.com/p2or/07638b457053d674a018a69a452fefc1 (It also appends the operator to the file menu)

@poor thank you very much. Just to clarify, I don't want to overwrite, I want to just call them, is that possible?

Let us continue this discussion in chat.


text:
Run modal timer depending on a condition
I have a button for a modal time operator, when I press on it the modal time operator starts and the button is dimmed/disabled (as I wanted, depending on some conditions in the poll function) and everything works fine. But if I saved the file (with the button dimmed) then closed blender and opened it again the button will still be dimmed (As I wanted in the poll function) but the modal time is not running. How I can get it running? There is a certain condition in the poll function which is when it's True I want the modal timer to starts even if the button is dimmed. Any advice please?
Below is a sample code:
class modaltimeoperator(bpy.types.Operator):
        """Start modaltimeoperator"""
        bl_idname = "wm.modaltimeoperator"
        bl_label = "Start modaltimeoperator"

        _timer = None

        @classmethod
        def poll(cls, context):
                # depending on some conditions in my scene the visibility
                #  is turned on/off. One of these conditions satisfies the
                #  modal timer to be run again

                return on_off

        def modal(self, context, event):
                scene = context.scene

                if event.type == 'LEFTMOUSE' and event.value == 'RELEASE':
                        print('entered correct event')

                return {'PASS_THROUGH'}

        def execute(self, context):
                print('entered execute')

                wm = context.window_manager
                self._timer = wm.event_timer_add(0.1, context.window)
                wm.modal_handler_add(self)

                return {'RUNNING_MODAL'}

        def cancel(self, context):
                wm = context.window_manager
                wm.event_timer_remove(self._timer)

Running timers based on the file you have open can be done by defining a handler on bpy.app.handlers.load_post.
This handler can check the state of the blend file and start executing based on this.


text:
What is the best way to join two sculpted objects?
I have just finished a sculpt of my first head and neck in Blender which I did as two separate objects to be able to reposition at will.  As you can see in the wireframed pic the neck has quite some excess and unwanted mesh which I would like to eliminate to improve on the overall poly count.

Which would be the best way to proceed to join the two sculpted objects and eliminate the excess mesh?
I tried deleting the excess vertices in the neck's mesh and then simply join the two objects.  Once joined the deleted part was not visible at all. However, with this method I cannot smooth the line between the neck and head. Keep in mind that I plan to simply paint the objects with marble texture and the main aim is to finally 3d print the face.

Why did I get this result when I did a Boolean Operation on the Neck and chose the head as the second object?
The unwanted mesh on the neck was cut off as I wanted but the rest of the mesh resulted in a lot of disturbance.

You should be able to do this with the Boolean modifier. Add a Boolean modifier to one of the objects you want to join, and set the operation to union. This will join the two meshes into non-overlapping meshes. You can then join the mesh without overlapping, disconnected vertices.

Thanks for your help but the result of the Boolean operation I tired was not so encouraging as you can see in my edited question above.

@ronin074 This is because your Head object is there twice. There's one rendered by the boolean modifier, and there's also the original one underneath. You need to disable it in outliner (uncheck the eye and camera icon). Then it will work just fine ;).


text:
After Boolean union operation - correcting imperfections in joined mesh?
I have joined this hand with the main body with a Boolean Union modifier.  However, the union has produced some mesh imperfection along the joined lines as you can see in the second photo.

The joined line in between the mesh seems to be quite fuzzy and the only way I can find to partially correct it is with a creese and smooth brush in sculpting mode.   The result is never totally smooth.
Is there a better way to do it?
Here is a pics of the mesh as requested.

Could you post image with wireframe visible?

Mesh pic posted.

Shading artifacts is a common problem using the Boolean workflow. Using the bevel modifier with a very small width can help mitigate the problem. After that, consider marking any edges surrounding flat surfaces as sharp.
Finally, tab into Edit Mode and look for any double vertices or incorrectly shaded n-gons and fix these issues manually. Double vertices can be merged together (try selecting one, then pressing G twice to slide it along the edge into another vertex and Merge by Distance AltM).
Incorrectly shaded n-gons can be broken up, and you can add supporting edges for the merge point in the local geometry.


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Blender Flame Smoke animation rendering
I am playing around with my first fire animation attempt.  Settings are done but I have the following 2 difficulties,

I would like the flame animation to be a constant one.  As it is it starts from nothing at frame 0, develops into a flame at frame 66 and stays constant till frame 100.
I would like it as in the part from frame 66 to 100.  I tried starting the animation at frame 66 but it did not work.

The flame is not rendering, only the smoke is.  I tried to enable the volumetrics as in the tutorial I saw but there is not enabling button.

Here I uploaded the file I am working on.

Thanks for any help given.

To display the flame, connect the Volume Info/ Flame socket to the Blackbody intensity socket of your Principled Volume shader

As regards having a sustained flame, without the moment when it "ramps up", I believe the easiest way is to just bake your simulation cache for many frames, then remove the first 66 frames from the animation (Render > Start > 67). It's impossible to skip the baking of the phase where the flames develop, because you can't easily create an already-burning starting condition.
You could in principle move the smoke cache 66 frames forward, but it's hacky (requires moving several files manually) and I wouldn't suggest it.

Thanks for the help.  If I understood I would bake the simulation normally from frame one to hundred.  Then after removing frame 1 to 66.  Still my first noobish try.

If you want a 100 frame long animation, bake from 1 to 167. Then only render your animation frames 67 to 167!

I just tried to add the volume info as you said but when I drop down the input menu  Volume info is not present.  Am I in a different setting then yours?   Photo added in main post.


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Why is my viewport glitching in orthographic view and not in perspective view
Video Link

The Viewport is glitching after I was rapidly switching to and fro between my opera and blender and now I am getting this weird glitch everytime I am trying to model. Pls help.
I am trying to model a ring and this has started to happen. It has never happened to me before so I don't know what's causing it.

Your View Clip Start and End values are currently set to fairly extreme values (.001 m and 9999999 m) Right-clicking on each value and choosing Reset to Default cures the problem here.

Thanks John, yes this did it!

No problem. Make sure they haven't been set that way in your startup file by starting Blender and checking them immediately or you might have the same problem again!


text:
Why are the textures being distorted in final render vs in viewport
So I have two objects:

A Uv Unwrapped Object (Arrow Buttons) with the arrow texture.
A duplicate of the same object, but fattened (alt+s edit mode) and applied a
transmission texture with clearcoat.

Viewport Render
In the viewport everything is fine and dandy, all the arrows are appearing visible and positive, but as soon as I try to render this same frame out:

This is what I get.
I have tried:

Changing of HDRIs
Increasing Light Samples
Messing with the plastic material on top to see if that's an issue
Messed with noise settings in render to see if that's causing it.

But to conclude, nothing's been helping me and I want to just complete this part to finish my animation.
Really Appreciate your help in advance!

modifiers settings that are not the same in viewport and render, maybe... or some objects that are hidden in viewport but not in render

@lemon as far as the buttons are concerned there are no extra modifiers applied to them and there are no objects hidden or in between them

so Z fighting, as the two surfaces are very close

The object "White Controller Plastic" has a child object "controller_white.012" which is hidden in the viewport, but not disabled in render, this interferes with the controller button:

I have been stressing so much for this lol this is gold,
How would you find out in future in case you have this similar case, I was so busy in animation that this completely caught me off guard

@AtharvaDeodhar Depending on how many objects, I sometimes just look for them, or with all unselected I press Alt+H to unhide everything. By default settings, when the objects get unhidden they are selected. If there is an object where there should not be one like where the buttons are, I select specifically this, go to the Outliner, press Numpad . and the object gets exposed. Now that I know where it is I undo until the objects are hidden again (because some should stay hidden), then I deal with issue. Objects in disabled collections are not revealed, so they are no problem.


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How to fix improper AO shadow issue? Trying to bake Ambient Occlusion map on a shoe model

Hey guys, so I am trying to model this shoe, but while baking the AO texture, while I am supposed to get decent AO shadows, I am getting this black patchy shadows all over the botton shoe model, how do I make it so it renders properly without this, I have edge sharps all over the bottom mesh, could that be contributing towards the problem???

(Node tree to bake the AO map, I used the Diffuse method for baking it on a blank image file)
Any help to solve this will be appreciated!
Thanks in Advance!
https://drive.google.com/file/d/1qIC3FULVsymfDdh55_6ejYJptfjIXkPE/view?usp=sharing

might be that the resolution of the texture is too small, or might have to do with the UV island being too close to another UV island

Actually before baking the AO map ( I use the diffuse baking method with a node tree that I will share, it shows the node tree's AO material properly, only gives me issue when I try to bake it, also I am not able to upload the blend file, because it's over 100 mb

added the google drive link incase anyone wants to try a different technique

Hi, your share isn't public, and would be much better on https://blend-exchange.com/ . You don't need to share the whole thing.. a failing section would do.

Hey @RobinBetts, I tried to cut down on the objects, still the file is going beyond 100mbs, do you have any tips on how I can share it?

I think it makes sense that it only becomes an issue after baking. Before baking, the AO node has nothing to do with texture resolution or UV map. But when baking, you're baking the result of the AO into a texture that has a resolution, using the UVs. So if the texture resolution is to low or the UVs are not good, issues will arise after baking, not before.

I tried a 2K resolution, so it works now

Hi, @AtharvaDeodhar, all... could someone post a brief answer to this, to mark it as solved?

When you have intersecting meshes, you're going to have discontinuous AO.  When you use an image texture to represent that AO, you're limited to discrete samples of that AO, spread across the face.  And so you'll have bleed, including bleed across any discontinuities that exist.
Let's apply modifiers to see what we're dealing with.  Think about this face:

What is the AO on the bottom edge of that face?  Probably, close to 1.0, no ambient occlusion, because of the slight angle to the next surface.  But what is the AO on the top edge of that face?  It is completely occluded, black, 0.0, because it lies inside of the mesh with which it intersects.
Meanwhile, how big are our texels?  With a 1024^2 texture, we can see that they are very large, and that the entire line of intersection is going to include area both inside (fully occluded) and outside (barely occluded) in individual texels:

Of course, we can increase the size of that texture; if we use a 2048^2 texture, then each texel will become a quarter of the size they were before.  This will reduce the size of any artifacts and so improve the AO.  We could increase the texture size further.  However, we're not getting rid of the artifacts; we're just making them smaller.
And there's something else worth worrying about here, which is texture filtering.  When we use texture filtering on lookups from this image, we'll find that as we zoom out, the texture will get darker, as more and more fully occluded texels blur further and further onto the visible part of the mesh.  (And unfortunately, not using texture filtering is not really an option-- it's important to prevent other artifacts.)
Is there anything we could do that wouldn't just minimize the artifacts?  Yes, we could make meshes that didn't intersect.  We could do this with boolean operations, or we could retopo to a single, manifold mesh.  If there is no mesh intersection, then there is no discontinuity in AO-- there will be no black to bleed out.

Hehe.. if not a brief  answer, then maybe even a proper answer :D


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Trapezopid shaped face to square UV coordinates has unfavourable skewing
When I map a trapezoid shaped face to square shaped uv coordinates it doesnt skew how I would expect it to. I want it to go to from fat to slim pixels. Instead it seems to skew based on triangles maybe?
(object scale is applied btw)

Yes, that is exactly correct.  If you manually triangulate that face and inspect the texture + viewport, I think it will make more sense that this is actually what it has to do.  There are different ways to map trapezoids to rectangles (perspective mapping does exactly that after all), but they have their own (significant!) drawbacks and aren't available in Blender.  Your only solutions are some combination of remap, make more verts to minimize the issue, and/or live with it.

If you have a seam down one side and around the circumferences top and bottom, then you can:

Align the approximately cylindrical region in an orthographic view (minus the caps)
U unwrap the tube with 'Cylinder Projection'

I believe that only looks okay because of the vert density.  Take a look at https://pasteboard.co/JTFqeYg.png .  On the left, I have a simply subdivided copy to demonstrate how you get better mapping by using more verts, but the problem never actually goes away.  The real solution is, don't try to map trapezoids to quads; if you need your texture to shrink, change the texture.

@Nathan You're  right. Am I right with this reasoning? This answer kind of misses the point, that barycentric interpolation from the corners of  triangles will never match Cartesian interpolation along X and Y of a quad? This answer  just increases accuracy by increasing samples. Does linearly changing the texture actually help with that? (Besides all, you can always mark every edge as a seam, and just U unwrap, which projects down the normal of every face?)

The problem is that the per-sample texture coordinates are actually generated after the (invisible) triangulation of the mesh.  When we have UV distortion, that matters.  (Try triangulating the mesh in both ways and see how it changes the mapping.)  You can compensate for the distortion in the texture if you need to, but you won't end up with a square UV grid image.  Texture baking or texture painting are both methods that can be used to create textures that compensate for the distortion.  (In this case, consider baking the texture, selected-to-active, from the subdivided mesh.)

@Nathan Yes. So the problem is the UV -> shaded surface interpolation, not the Geometry -> UV mapping.


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How do I bake a Bent Normal Map in Blender
The bent normal is the direction where most ambient light comes from. The median ray that did not intersect the mesh.
It is not the same as object space normals. A bent normal map could be baked in object space or in tangent space.
Bent normal maps are used to for more realistic realtime shading (GI approximation, specular occlusion)
Some links of where I got the info:

https://blender.stackexchange.com/a/137061/83384
https://github.com/keijiro/BentNormalTest
https://docs.unrealengine.com/en-US/Engine/Rendering/LightingAndShadows/BentNormalMaps/index.html
https://polycount.com/discussion/102351/minitut-bent-normals

So how would I bake a bent normal map using Blender (with Cycles)?

Probably the solution is to create an OSL script node.

I managed to write an Open Shading Language script that provides an ambient amount output (AO) and a direction vector from which the most ambient light came from. This can be used to create the bent normal map.
To use it, switch render engine to Cycles in CPU mode and enable the Open Shading Language checkbox.
For the object from which you want to bake the Bent Normals add a material if there isn't one yet. In the Material Node Editor add a Script Node and select this script:
AmbientOcclusionDirection.osl
Make sure the input Normal node is connected to the Normal from a Geometry input node. And the output NonOccludedDirection node to the Normal node of the shader.

Then bake as you would bake a normal normal map :-)
To check if the Distance and Samples settings are reasonable before baking, connect the AmbientAmount to the color and make sure the AO gradient is nice.

To quote on; "Then bake as you would bake a normal normal map", There are so many ways to bake a normal map. To start in tangent and in object space. How can I get a normal map out of this in object space?


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how to make one way glass
I'm trying to make one-way glass like the one used in interrogation rooms. if you look at it from one side, it's a solid color and from the other it's clear glass, so only one side can see the other.
Is there a way to do so in blender?
Thanks in advance.

Use the Geometry node and its Backfacing output as factor in a Mix Shader:

If you are in Eevee don't forget to enable the Alpha Blend option to have transparency:

If you give it thickness, select one face and invert it with AltN > Flip:

Thanks for the help.

of course it can be a bit more complicated setup than just transparency (Glass, Glossy, etc)

is there a way to do it if I wanted to add thickness instead of just a plane

I've edited, if you are in Eevee don't forget to enable Alpha Blend

If you give it thickness, select one face and invert it with Alt N > Flip

Thank you a lot.

Let us continue this discussion in chat.


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How can I replicate this image of a tied-up balloon?
I want to make a picture of the balloon tied with a string like in the picture.
Is there any useful function for that?
Should I reduce the scale of the dots that the string passes by and sculpture them?

Hi Please use a title that reflects the content of the question. It should be descriptive but succinct, unique and identifying, summarizing the issue so that users can at a glance understand what your post is about. Use the [edit] link below your post and avoid anything not strictly essential to the post. Remember, your title is the first thing potential visitors will see, and makes your question findable for future users. See "What is the problem with posting an image or link and asking “How do I do this?""

You could do it with a cloth simulation: Create a cube, subdivide it (put the Smoothness value at 1 in the Operator Box), cut several edge loops with the knife (K to activate, C to cut through), assign them to a vertex group (CtrlG):

Give your object a Cloth simulation, choose the group as Pin Group, enable the Pressure option, choose the pressure strength:

After a bit of sculpting (Cloth Filter brush in Pinch mode, with the Cavity option enabled):


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Namespacing imported assets
I'm looking at pipelining Blender and I'm wondering about namespacing.
It seems that Blender is pretty strict about node names and that no two geo/transform nodes in a scene can have the same name. If that's the case, it seems like there should be a formal way to namespace hierarchies of nodes (like Maya allows by prefixing "< N A M E S P A C E >:")
Currently if I import the same model asset twice, Blender just renames all nodes for the second import with a ".001" postfix.
Does anyone know how this is intended to be handled?
Thanks in advance
In response to vklidu's request for more info; indeed blender is adding the ".001" postfix to make the objects unique, which makes sense. However it would be preferable to have formal control over the renaming, ideally at the point of import.
Maya's namespacing is formalised, in that you can pass the namespace you want to use at the point of import. So in our pipeline we might import the exact same rig file multiple times (e.g. "Soldier" asset). We assign each one a "cast member name" ("Soldier_1", "Soldier_2" etc.) and use those as namespaces. This will prefix each object in the imported hierarchy with "Soldier_1:".
It just means everything is named uniquely but also predictably. Right now I'm just doing the Blender import and renaming programmatically with a similar type of "cast member name" prefix after the fact, which is fine. I just thought I'd sanity check it here, see if there's anything I'm missing, what other studios are doing etc.

Your Q is probably confusing in name convention for blender user. When I went to search Maya's prefix ":" I found this article -namespacing doesn't seem to be  useful at some point ... blender's .001 suffix is simply to distinguish objects (make unique) ... so I think I didn't get your goal here - what are you looking for? Do you need a name of source file be a part of imported object's name as prefix? Thanks for some details (if none answer here).

there are renaming tools like this [1]: https://i.sstatic.net/xvp9Y.png maybe this helps you? you can find it by search "batch rename"

in response to vklidu (I'm not permitted to comment yet); indeed blender is adding the ".001" postfix to make the objects unique, which makes sense. However it would be preferable to have formal control over the renaming, ideally at the point of import. Maya's namespacing is formalised, in that you can pass the namespace you want to use at the point of import. So in our pipeline we might import the exact same rig file multiple times (e.g. "Soldier" asset). We assign each one a "cast member name" ("Soldier_1", "Soldier_2" etc.) and use those as namespaces. This will prefix each object in the im

Thanks for edit ... You can delete comment above (partly copying extended Q) if you have privilege ... Sadly I haven't heard about such feature even used by some studio (with their own build version) ... But it doesn't mean it doesn't exist. It seems Chris's suggestion with Batch Rename is a way or store versions in Collections, but right it is just an organizer.


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Vertex group no longer recognized when a mesh primitive is added
I am trying to make a focus control in geometry nodes for a LOD (limit of detection). I have one vertex in the object "plane". This vertex is in a vertex group named: "DOF". I have move it in order to control the location of an empty (copy location, Vertex group : DOF). That's work well but when I had a Grid mesh in geometry nodes the empty jump to the object location...
I cant understand why, is there a way to resolve this?

PS: I have had a switch just to show the difference when the Grid is added and I am using blender 3.5a.
Thank you.

TL;DR When new geometry generated inside GN is involved, vertex groups get converted to an attribute type older modifiers can't read. You'll have to work around this limitation until those modifiers get updated. Sorry about the long-winded reply below, just wanted to put down a clear explanation for posterity.
This is one of the growing pains of Blender's gradual switch to a more generalized everything-nodes system. Vertex Groups are a somewhat specialized attribute type (a combination of boolean and float) and older modifiers expect that exact structure to function. In your case it's Copy Location, but it's the same with any other that employs them.
Geometry Nodes does not create specialized attributes like vertex groups and when nodes that create new geometry (like Join Geometry) encounter these, they convert them into generic float attributes. In simple language: Blender used to say "these vertices are a in vertex group, use that info where you need a selection", when now it's switching to saying "these vertices have a value of $1.0$, use that info wherever you want, however you want". That generalization is bringing much more power and flexibility to the system overall, but other parts of that system need to be updated to take advantage of that.
From the manual:

Due to ongoing development in the area of attributes, many areas of Blender can not yet work with the generic (identified with a name, stored on any domain with any data type) attributes used by geometry nodes.

In short, it's not that the vertex selection is getting lost at all (you can still see it listed in the Spreadsheet under a column named "DOF", in your case), it's just that older modifiers don't know how to read them. You can test this yourself: add another Geometry Nodes after your current one and, for example, use an Extrude Mesh on your vertex group. It'll work fine, because Geometry Nodes just reads the generic "DOF" attribute, and in this case, uses it as a selection for extrusion—it doesn't care if it was created specifically as a "vertex group" or not, or if there exists other geometry along with the original:

Whereas Solidify modifier doesn't know how to read the "DOF" attribute if it has been converted to generic float values:

This will get resolved as the older modifiers get replaced with new, Geometry Nodes-based versions, but that will take some time.

Thanks a lot Kuboå That's a very complete response, more than I expected, on a very specific problem. I hope this problem of level of interpretation will be solved.


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Mirror shape keys does not work
I'm trying to model a bird following a tutorial and I'm freezed on the shape keys tool. I would like to mirror the left eyelid so that I can open the right one using the secret entry mirror shape keys but the problem is that it doesn't work. The right eyelid doesn't open. Infact it says that 1 vertices mirrored,12075 vertices failed. Do you have any suggestion to give me why it does not work ? thanks. As usually you can check the attached screenshots to better understand the problem.

Your blender is too old. Make sure you always use the latest version. Maybe that'll fix.

I'm using blender 2.76b. The version of blender used on the tutorial is too old,not mine.

So download the version on tutorial and open your *.blend file, if that worked, report a bug to developers, if still not working, then maybe you did something wrong.

I have tried to follow this tutorial : https://www.youtube.com/watch?v=Nlf959QT9VI ; he used blender 2.73. It did not work cause the same error : 1 vertices mirrored and 12075 vertices failed.

maybe I found the solution by deleting half of the bird's body and then applying the mirror modifier...

You really didn't do that? O_o


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Eyeball doesn't rotate well while rigging eyes
I'm trying to make the tutorial called "Eye Rigging in Blender" found here :
https://www.youtube.com/watch?v=CCGekumdLLU
From minute 3.56 to minute 4.27 he links the bone to the left eye. I tried to do the same with my character. So,In object mode I selected the middle of my eyeball by pressing SHIFT+CTRL+ALT+C > Origin to Center of Mass and then,with SHIFT + A I created a new bone and then I have selected the eye and with SHIFT I selected also the bone,finally I linked the bone with the center of the eye pressing CTRL + P and then Parent to Bone. The problem is that my eyeball doesn't rotate like the one on the video. Which keys he pressed on minute 5:07 to rotate the eyeball in that way ? I rotate my eyeball using R + x ; R + y ; R + z but it does only in one direction.
This is how my eyeball rotates :
http://psychonews.it/dati/2016-04-14_16-54-46.mp4
you can see there is something wrong. Thanks.

Your pivot point is the 3D Cursor and and it's not in the center of the eye.Shift + S > Cursor to selected. minute 3:17 in your tutorial

Did it,but I don't know if the problem is fixed because I still don't know which keys the author of the tutorial pressed to move the eye in all directions,since I have to press R + x or R + y or R + z separately to move the eye in these different directions.

he rotates with the 3D Transform Manipulator

it does not work. I activated the "3d transform manipulator",In Pose mode I selected the bone and then I rotated the eye,but it didn't rotate like one on the tutorial,check this : http://psychonews.it/dati/2016-04-14_18-39-01.mp4

here also does not work with the corrected pivot point ? --> http://psychonews.it/dati/2016-04-14_18-46-02.mp4

Consider .... http://blender.stackexchange.com/questions/31711/how-can-i-make-an-object-face-or-locate-to-the-active-camera/31715#31715

Please place a screen image in your question to clarify your question.  The armature Jorge created has bone to control the head with other attached bones to control the eye. The location of the eyebone was constrained by the whole structure.  Copy his whole armature structure.  In your video you seem to be moving a single bone around freely in and out of the socket which is a defect and problem.  That will cause you, and viewer, and the eyeball hardship.  The attempted short cut has become the long extension of work.  You need the whole head armature to allow the eyebone to ONLY rotate.

Jorge didn't use neither bone constraint nor he disabled the "deform" checkbox when he linked the bone to the left eye !

If I have to build the whole armature to constrain the location of the eyebome,why it is constrained before completing its construction?


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How to bring always the front of view of a 2D animated character?
What can I do to animate a character showing only its front of view ? The problem is that it is done in two dimensions and when the camera shows it obliquely, is not good. how can I configure the x and y axys ? Even the duke nukem 3D character always shows only the front of view. thanks.

Do you mean the effect like this: http://blender.stackexchange.com/questions/31564/how-can-i-make-a-plane-always-look-at-camera ?

yes,I wanted to do something like that,but the latest thread on the blendercommunity says : " it doesn't work in 2,76, while plane is created, all vertices are stuck in the pivot point "..and I'm using blender 2.76

Could you post a link to this BA thread, cause I am using 2.76 and it still works fine for me. Just put your camera perfectly in front of your plane/model (as in my duplicated answer), then add a constraint and it should work well.


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Wrong bone placement on object and pose mode during the eyes rigging
I'm trying to learn how to rig eyes and I realized that while I'm on edit mode,the bones are placed correctly,but if I switch under object and pose mode,they aren't. Why ? How can I fix that ? I attached 3 pictures to show you...

This is likely due to a scaled Parent bone.
Like objects, each bone may have a parent bone that it follows by default. This parent is indicated in the Relations panel of the Bone Properties:

As noted in the properties, the default behavior for Child bones is to inherit the Rotation and Scale of the parent. The effect of this, as you've seen, is for some bones to seemingly move in Pose Mode from their original location in Edit Mode.
To fix this simply select all bones in Pose Mode and press ALT+R and ALT+S to reset their scale and rotation.
You can easily find the parent of any bone, if there is one, by selecting a bone in Edit Mode and then Select > Parent:

Anytime you extrude a bone the newly extruded bone is automatically parented, and connected to the bone it was extruded from.

Hello. Thanks. I did it,but the bones in pose mode are still placed in the wrong way. Check this picture : http://psychonews.it/dati/2016-04-25_19-07-20.png

Could you upload the .blend?

sure : get it here : http://psychonews.it/dati/Pierino87.blend

Ah ha, the issue is all the Track To constraints.

:) what should I do to fix the issue ?

Depends on your end goal. As it is right now the constraints are doing their job, tracking the tail of the bone to the Eye controller. The head (root) of the bone is not actually moving, so the bone location is not changing, just the rotation.

Hello man. I removed all the "track to constraints" and I selected all bones in Pose Mode and I pressed ALT+R and ALT+S to reset their scale and rotation,but it didn't work again. Check these pictures : http://psychonews.it/dati/2016-04-26_16-53-22.png and http://psychonews.it/dati/2016-04-26_16-53-40.png ; pressing ALT + R and ALT + S did nothing.


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Traceback - Attribute Error: 'SpaceView3D' object has no attribute 'context'
I'm kind of new to blender, so I don't know all there is to know about this software. Anyway I have a issue, I've been watching the tutorials for Blender 2.8 and I'm following the guide. But for some reason an error occurs when I select the selection tool after editing in edit mode.
I've tried to uninstall and reinstall the software but the same problem occurs.
Please help.

I had the same problem. I solved it By doing following steps:
Just go to Edit -> Prefrences. In the bottom left corner click on load factory  preferences. It will solve your problem.


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white outline around PNG
I have been stuck with this problem for a while now and cant move on.Im making sticker by applying PNG on object.Everything work just fine only the image have white outlines which i cant get rid off.Pls,any help would be much appreciate.

If you go into the UV editor for your object, can you try scaling down the UVs so that it fits on the image?

well i did it by method when I  applyed a subdivision modifyer and shrinkwrap the plane to the model

Try to change the shading (somewhere I don't remember now) from straight to multiplied.

please add that as the answer and include screen shots of the settings. Sounds like something other people will get stuck on and will value your answer.

I already figured it out.Changed the PNG options in shader editor from LINEAR to SMART.Outlines are gone –


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Importing second model just duplicates the first one
I have two models, the first one imports fine and I would like to import the second one to scale it to be the same size as the first. The issue arises when I try to import the second model, as soon as I click "Import FBX" it just copies the first model, nothing in the outliner or elsewhere to hint that the new one is in the project.
TLDR: I go to file > import > FBX, then see title happens, what am I doing wrong?

Welcome. Your question is a little vague. Could you improve it with some details?


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How to move selected vertices on Z axis by 1mm
I'm very new to Blender and I'm having difficult doing what I would of assumed to be a basic thing - yet I'm not finding how to do it. I have several vertices selected and I would like to move them up and down on the Z axis only WITHOUT using the mouse - super inaccurate. Is there a way to have the selected vertices be moved on the Z axis by entering the value somewhere? When I do so on the right in Object > Transform, it just moves the entire model/object.
Further more, I'd like to have these vertices be moved by 1mm increments.
Thanks
Edit: I figured out to do it by typing - very odd way. Push/Pull > Z > value. I assume there's a place to input the increments now to be mm, etc for the values entered?

You can type in your transforms if you call the transform using direct shortcuts to begin with (G to move/grab, R to rotate, S to scale).
Just hit the key for your transform, here G, then the key of the axis you want to move in, here Z, then you can type the amount of transform you want and press ⏎ Enter.
Unfortunately, you can't write "1mm" and press ⏎ Enter: it only takes numbers and simple maths operations, it uses the units set in your scene settings.
Blender is set to meters by default, so for moving by one millimeter you will have to write 0.001 (with a dot, not a comma) and hit ⏎ Enter.
You can also just type in the new global or local coordinates of your object in the Transform input in your viewport's sidebar. You can even let Blender make the maths operations for your by putting your cursor at the end of the value you want to edit and write simple maths like +0.01 or -1, ...
TL;DR type GZ 0.001 and ⏎ Enter.
If you will often need to type in millimeters, then it will be faster for you to set the units to milimeters so you don't have to convert millimeters to meters all the time.
Head over to the properties editor, Scene tab (white triangle icon), Units tab, and change the Length unit to millimeters. This just changes how units are displayed, it does'nt change any scale internally.

I figured out to do it by typing - very odd way. Push/Pull > Z > value.
For the increments, Scene > Units > Unit Scale (I think)


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black edges scatter around my imported mesh
I have recently imported my new base mesh for my model from maya. I tried to apply materials but even with the default mat, i could still see through my mesh. this happened with several quads around my model. i went on edit mode in blender and checked the mesh and i saw these unusual black edges in the areas the issue happened. i have no idea how to fix this, i just assume that my mesh has some problems with normal faces. last time i checked my mesh didnt have any overlapping verts or edges. Please help me resolve this problem.

Here's the mesh i just uploaded to blenderexchange:

are you 100% sure there are no double vertices, distorted edges, or maybe the mesh is open? Perhaps you could upload your .blend file here https://blend-exchange.giantcowfilms.com/ and [edit] the question to add the link.

@Luciano i have just uploaded the blender scene. please have a look to see the issue. i didn't include any material though

The black edges are normal edges, while all teal edges have the sharp flag set. So just select all edges, and open the edge menu with Ctrl+E. Select Clear Sharp, or Mark Sharp, depending of what you try to achieve.


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Find the tangent point automatically
I have a sin curve, I chose the center of this sin curve, the other curve is a parabola, I am able to displace the second curve on the tangent point by hand with the Sample Curve Factor.

I would like to know if there is a way to do it automatically, as I change the amplitude or frequency of the sin curve?
Edit: I would like to use only Translate on the parabola, and the reference point is the one chosen at the end of the sin Curve called : "Sin Center". Thank you for your help.

mainly this is more a mathematical problem than a geometry nodes problem. Unfortunately you didn't tell us all important informations to solve it because there are many ways to meet two points of two different functions. You can rotate, scale and move them. And i am pretty sure you don't want to rotate them. But you didn't tell us, whether the sin or the parabol should move to get a common point (or both) and should be the common point always at 0,0?

@ Chris: You are right this is certainly more  a mathematical problem than a geometry node one. It's true i don't want rotate or scale the parabola just translate it. The point of reference can should be chose by the Sample Curve Factor at the end of the sin curve. Thank you for your comment.

True, it's really a maths problem, not a Blender problem.. but since it's a quick one...

By the chain rule, it turns out that, (simplified by $cos0=1$), the derivative of $a\times sin(f\times x)$ at $0$ is $a\times f$
The derivative of $x^2$ is $2x$
So we have to find the point on the parabola such that $2x=a\times f$.
Calculate $(x=\frac {a\times f}{2},$ and $ y={whateverthatis^2})$  and offset the parabola by that:

.. with this sort of result:

Thanks Robin Betts, It's a very efficient mathematical approach. I just find a more GN one. I'll post it in a few minutes.

Thanks, @Kuboå, & Nathan .. Mathjax was never my thing.... I must start learning it :)

@RobinBetts Like RegEx, for me at least, it's one of those things you never really remember but copy from a cheat sheet whenever it comes up every other month or so :) I usually look here: https://jojozhuang.github.io/tutorial/mathjax-cheat-sheet-for-mathematical-notation/

I am agree that question could appear as pure math one but there is GN solution:
Edit:
So this approach is more physical than mathematical.

At first you must find the location of the point of touch on the sin curve. A Sample Curve and a Compare node will give you the index of this point. This Sample Curve will give the Position of all the points you just have to select the right one with a Attribute Statistic within the right selection (the output of the Compare node). With another Attribute Statistic you extract the Tangent at this point.

Now its time for the other curve. With a Sample Curve  and Compare node you will select the index of the point witch have the same tangent as the other point on the other curve. An Attribute Statistic will give the position of this point. Then you just have to subtract this value of a Position node and plug the out put in the Position input of a Set Position that will displace the curve in the way that this point is now the “origin” of the curve, then in the Offset input used the Set Position extracted from the first  Attribute Statistic node will displace it accordingly to the point you choose on the first curve.

\Edit:
The advantage of this method is that it will work for more than one type of curve (not everyone). But you will have to have a curve with a lot of point if not that jump.
For this specific question I do prefer the cleaner and simpler mathematical one.
Thanks Robin Betts.

I very much like that search-by-selection thing.. I'd never thought of that! And you're right, in principle, it would cope with any curve/surface.. Nothing wrong with numerical methods when they are reasonably efficient and the accuracy is as high as the resolution of your domain. I think maybe you should give yourself your tick :D


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Planes on Curves
My blend works, but when I wanted to respond to this post "Geometry Node: How would I convert a series of Curve Lines into a series of Planes", I proceeded using an empirical approach.

First I don't understand why the even faces and the odd faces are separated?
So a part of this blend is still very strange to me.
For what I know, when the number "Count" is odd the first face off the odd faces go directly from the start of the curve to the end. The second line of nodes (just under) is here to fix this problem. But as I tested lot of numbers, finally I came up with a solution, that doesn't mean that I understand how it works... I wish you can explain to me what I have done here:

And I have a second question is it possible to reorder the faces?

Thanks for your help.
Here is the blend:

Edit:
After the answer of Joel Reid, I will try to simplify and narrow down this question to a more simple problem and a more simple blend.
In fact my problem is to understand why those nodes produce only the evens faces and not the odds ones.

I hope this formulation is more likely to be understood, I am perfectly conscious that is a very different problem, and I am sorry for that. Thank you for your help.

Could you expand on the "empirical approach" in plain english ? I have no idea what you are trying to achieve, nor what these 10+ math nodes are doing.

@Lutzi, thank you, the purpose of these nodes is to order the indexes of each point of odd faces... I can't say more I don't understand what I have done... Sory.

What do you mean "order the indexes of each point of odd faces" ? Is your screenshot what you are trying to achieve, or an issue you have ? Please explain your goal clearly. I still have no idea what you want and where is the issue.

@Lutzi, Sorry I will try to be more clear and will edit my post. By "empirical approach" I mean that I have tested each step to see how it works (and find solutions) but for exemple I don't understand why the odd and even faces are separated... I thought that the simple Store Named Attribute Pos-Even was enough, it's not..

What?
We can examine the setup and perhaps gain some insight into what it is "trying" to accomplish.
In your Odd Face Index Calculation frame, let's follow the data left-to-right…

…and interrogate each in turn for "what is this node's output, conceptually?"

Truncated Modulo
This node uses the [Bezier Segment's, Curve's Points, Point Cloud's] Point Count (hereafter: "c"). The node's output Value is c mod 2.
Switch
A 0 or 1 subtrahend determined by c's oddness.
Add
The greatest odd int ≤ c
Subtract
The second-greatest odd int ≤ c

Add
Pardon my syntax from here forward, where curly braces indicate the two possible values.
{is c even? → 2c - 4,
 is c odd? →  2c - 2}
Index
"Points of Reference" Curve To Points, point index field
Subtract
index - 2c - {4,2}
Multiply
2c
Subtract
index - 2c - {6,4}
Subtract
2c - 4
Greater Than or Equal
bool answering, is 9's "index - 2c - {6,4}" ≥ 2 ?
Add
index - {10,8}

Switch

combined case
Output value
simplified

c even and index - 2c - 6 ≥ 2
index - 2c - 6

c odd and index - 2c - 4 ≥ 2
index - 2c - 4

c even and index - 2c - 6 < 2
index - 2c - 6 + 2c - 4
index - 10

c odd and index - 2c - 4 < 2
index - 2c - 4 + 2c - 4
index - 8

Why?
That node tree is many things; "working", reducible, intractable, baffling…
The above was all easy enough to work out. But then what does, say, "the index 6 less than double the input count of the current index" across the realized curve's points field mean to you? You're the user of this node arrangement.
I love Geometry Nodes, and love messing about with them as much as the next Blender-er, but I humbly submit that this method of throwing nodes at a problem is a horrible way to work and clearly no way to learn. If you're borrowing and adapting someone else's complex method of accomplishing something, you should…
go back and study what exactly they're accomplishing,
borrow the parts you understand,
adapt it only with new methods and nodes and workflows you also understand.
I hope the above breakdowns perhaps gave you some insight you can use to push forward. I think this is all that can be done with your question as asked, as Blender Stack Exchange is not for requesting tutorials and project autopsies, but for pointed technical questions and solving of clear problems—which is frankly not a fitting description for the situation you're in. Please ask another question if you reduce your tree to a clear technical question. Good luck.

[mods, I plead with you not to delete this answer for it's non-answer-ness and prose… GN node spaghetti is a common Blender problem and I think this is the "answer" this unanswerable question warrants.]

Has been acknowledged! Essentially agree with you too. Many thanks for your contribution!

@Joel Reid First thank you very much for your precise work. As I read you I can’t disagree that is an unanswerable question. And I am sorry for that. But please, let me try to narrow down what is my problem here. I will edit and let the previous question as it is in order to keep your answer as the most correct one. Once again thank You.

The answer was so evident that’s I am ashamed (as I should be), the first face is fixed on the 0, 1, 2 and 3 points then the second plan one 4, 5, 6, 7 points and so on…
So there is no plan between the points 2, 3, 4 ,5: there is no odd faces. With just another Sample Index plug on indexes plus 2, it makes the good indexes for the odd faces.

I am very sorry for the time you lost on this question. Thank you.

No time lost. There are several useful patterns in those trees (as you've seen—they work!). Even the point-count * 2 stuff makes sense… it's doubling the curve then working on it, and so forth. Alternating faces just falls out of this approach too. Glad you've cracked it—cheers!


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Importing a 3d model already texturized with substance painter in blender
I'm trying to learn the substance painter tool. So,I have a question to ask. So, I'm planning to texture a model using Substance Painter and will render it using the Cycles Render Engine. Is there a way to import the 3D model in the fbx format already texturized in substance painter directly in blender without applying the shaders and the textures within blender itself ? Thanks.

What @cegaton said. That said, the metalness/rough materials are pretty simple to setup with the principled shader, just plug the maps into the right slots. And remember to use OpenGl rather than directX normal maps (or flip the green channel)

Possible duplicate of .fbx export why there are no materials or textures?


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The proportional editing seems to be mirrored in some way?
I'm trying to move the vertices of the left leg of my character all around the armature (created by the Manuel Bastioni LAB) with the proportional editing tool,but when I press on G and then X,also the vertices of the right leg are moving. I thought that the X mirror option was enabled,but it isn't. So,why it happens ?

Instead,I have opened an old version of the same project and here you can see that it works as I want...

Use the mouse wheel to increase or decrease the range of the proportional editing (the white ring). In your first picture the range is too high, therefore it also affects the other leg.

Is the Proportional Editing type the same for both files? Or one of them has Connected type?

thanks,Carlo. I've just learnt something that I didn't know : the difference between the connected and the enable option on the proportional editing tool.


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An error prevented me from creating the final rig with rigify + pichipoi addon
I'm trying to use the rigify + pitchipoi in combination with the makewalk addon because I want to make the retargeting of a BVH file. So I cutted the bones of the METARIG armature that are responsible for the movements of the breasts (because otherwise it did not work) and then I loaded a BVH file with the makewalk addon and it has been accepted. Problem arose when I tried to create the final rig because there was an error that stopped my ambitions of glory...

Here you can find the blender file before pressing on "generate rig".