Particles tangent rotation control by vertex group missing #35103

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Anna Celarek · 2013-04-27T01:39:33+02:00

Anna Celarek commented

2013-04-27 01:39:33 +02:00

%%%--- Operating System, Graphics card ---
Win 7 x64
Nvidia GTX 550Ti

- Blender version with error, and version that worked ---

problem in 2.66a and perhaps in most versions since 2.5x
worked in 2.49b and earlier

- Short description of error ---

"Forgotten" feature (see the screenshot):
Controlling of particle tangent rotation by a vertex group.
Must have gone missing during the big changes from 2.4x to 2.5x.
I know about the workaround by rotating UV chunks, but the workaround is incredibly inconvenient and doesn't work at all if I need a second UV set for the texture, because the particles don't know which UV to chose for their rotation.
Vertex group control was more intuitive, simpler to use and more reliable than the UV thing.

- Steps for others to reproduce the error (preferably based on attached .blend file) ---

I'm attaching test files for both 2.49b and 2.66a.
When you open the 2.49b file in 2.66a, initially the hair is rotated following the vertex group, so some code must still be there. But they lose that rotation as soon as you move the object or go into edit mode.

%%%

%%%--- Operating System, Graphics card --- Win 7 x64 Nvidia GTX 550Ti - Blender version with error, and version that worked --- problem in 2.66a and perhaps in most versions since 2.5x worked in 2.49b and earlier - Short description of error --- "Forgotten" feature (see the screenshot): Controlling of particle tangent rotation by a vertex group. Must have gone missing during the big changes from 2.4x to 2.5x. I know about the workaround by rotating UV chunks, but the workaround is incredibly inconvenient and doesn't work at all if I need a second UV set for the texture, because the particles don't know which UV to chose for their rotation. Vertex group control was more intuitive, simpler to use and more reliable than the UV thing. - Steps for others to reproduce the error (preferably based on attached .blend file) --- I'm attaching test files for both 2.49b and 2.66a. When you open the 2.49b file in 2.66a, initially the hair is rotated following the vertex group, so some code must still be there. But they lose that rotation as soon as you move the object or go into edit mode. %%%

Anna Celarek commented

2013-04-27 01:39:33 +02:00

Changed status to: 'Open'

ronan ducluzeau commented

2013-04-27 09:53:12 +02:00

%%%"Vertex group control was more intuitive, simpler to use and more reliable than the UV thing."
I have to say that the more intuitive and more reliable way to control hairs is particle mode.

Are you aware of what you can do with new particles children ?
http://youtu.be/k8FLJik6-Lw?t=3m
%%%

%%%"Vertex group control was more intuitive, simpler to use and more reliable than the UV thing." I have to say that the more intuitive and more reliable way to control hairs is particle mode. Are you aware of what you can do with new particles children ? http://youtu.be/k8FLJik6-Lw?t=3m %%%

ronan ducluzeau commented

2013-04-27 10:15:31 +02:00

%%%I tweaked your blend in Particle Mode to show what you can do.
You are not forced to use brushes, you can simply grab and rotate selected tips or points and change pivot point.%%%

%%%I tweaked your blend in Particle Mode to show what you can do. You are not forced to use brushes, you can simply grab and rotate selected tips or points and change pivot point.%%%

Anna Celarek commented

2013-04-27 11:12:14 +02:00

%%%I am aware of this, but in some situations vertex groups are just easier to handle than particle mode. Especially for relatively short fur.
And the other groups are there despite particle mode (density, length etc.), so why not Tangent Rotation? %%%

%%%I am aware of this, but in some situations vertex groups are just easier to handle than particle mode. Especially for relatively short fur. And the other groups are there despite particle mode (density, length etc.), so why not Tangent Rotation? %%%

ronan ducluzeau commented

2013-04-27 12:03:56 +02:00

%%%I think the problem is that weight groups can be animated in 2.66. So, what is guided by a weight group should be animatable.

But Tangent Rotation can not be animated for Hair, it is why it is hidden in an advanced panel.

Do you have an example when vertex group is better than particle mode ?
Except to reuse an existing one, I don't see why vertex group should be needed.%%%

%%%I think the problem is that weight groups can be animated in 2.66. So, what is guided by a weight group should be animatable. But Tangent Rotation can not be animated for Hair, it is why it is hidden in an advanced panel. Do you have an example when vertex group is better than particle mode ? Except to reuse an existing one, I don't see why vertex group should be needed.%%%

Anna Celarek commented

2013-04-27 13:36:34 +02:00

%%%Using options of the weight paint mode such as blur. For smooth transistions between dense and sparse hair regions, for example.
Changing the hair count (Emission > Number) after editing the hair distribution.
Making sure two different parts of the body have the same hair density.
Uniform distribution. Adding or removing hair in particle mode can yield an irregular, patchy distribution very easily, which won't happen if I use vertex groups.
And reusing existing groups, yes, as you said. For example using the same group for density and lenght.

%%%

%%%Using options of the weight paint mode such as blur. For smooth transistions between dense and sparse hair regions, for example. Changing the hair count (Emission > Number) after editing the hair distribution. Making sure two different parts of the body have the same hair density. Uniform distribution. Adding or removing hair in particle mode can yield an irregular, patchy distribution very easily, which won't happen if I use vertex groups. And reusing existing groups, yes, as you said. For example using the same group for density and lenght. %%%

ronan ducluzeau commented

2013-04-27 14:02:17 +02:00

%%%I agree with your examples that are about density and length which is still available.
But your report is about rotation. And interpolated children have smoothed transition between hair that can not only be oriented but also combed differently.%%%

%%%I agree with your examples that are about density and length which is still available. But your report is about rotation. And interpolated children have smoothed transition between hair that can not only be oriented but also combed differently.%%%

Anna Celarek commented

2013-04-27 14:28:38 +02:00

%%%Combing freezes the vertex group options, so if I comb, and then change density by changing a vertex group, it has no effect unless I do Free Edit, which destroys the combing.
That means I can either use the particle mode options alone, or the vertex group options alone, but I can't use and edit both at the same time, because they exclude each other. Particle mode can be edited after vertex group editing, but not before. Which doesn't help when there are many little changes and tweaking.

If I have density and length set by vertex groups, then do combing, and then I notice that I have to edit the density vertex group, I'd have to redo all the combing. Which would be no issue, if I could replace the combing by a vertex group which controls tangent rotation (and perhaps tangent velocity, which is also missing), because a vertex group wouldn't be affected by changes in another vertex group.

%%%

%%%Combing freezes the vertex group options, so if I comb, and then change density by changing a vertex group, it has no effect unless I do Free Edit, which destroys the combing. That means I can either use the particle mode options alone, or the vertex group options alone, but I can't use and edit both at the same time, because they exclude each other. Particle mode can be edited after vertex group editing, but not before. Which doesn't help when there are many little changes and tweaking. If I have density and length set by vertex groups, then do combing, and then I notice that I have to edit the density vertex group, I'd have to redo all the combing. Which would be no issue, if I could replace the combing by a vertex group which controls tangent rotation (and perhaps tangent velocity, which is also missing), because a vertex group wouldn't be affected by changes in another vertex group. %%%

ronan ducluzeau commented

2013-04-27 16:44:42 +02:00

%%%I don't understand why combing freezes vertex group density.
I can tweak a density texture and go to particle mode. And I can do several switch without problems.
Length guided by a weight group is updated and doesn't seem to break combing.%%%

%%%I don't understand why combing freezes vertex group density. I can tweak a density texture and go to particle mode. And I can do several switch without problems. Length guided by a weight group is updated and doesn't seem to break combing.%%%

Anna Celarek commented

2013-04-27 17:23:54 +02:00

%%%Open the file that you sent (PM_266.blend).
Go to vertex groups in the particle settings. Chose Group for density.
Any change in the density? No.
Go to Weight paint mode. Paint anything on the vertex group.
Any change in the density? No.

Now go back to object mode, and do Free Edit of the particle system. NOW it changes density, but the combing you did is gone.

At least it's what happens here. Do you have different behaviour? %%%

%%%Open the file that you sent (PM_266.blend). Go to vertex groups in the particle settings. Chose Group for density. Any change in the density? No. Go to Weight paint mode. Paint anything on the vertex group. Any change in the density? No. Now go back to object mode, and do Free Edit of the particle system. NOW it changes density, but the combing you did is gone. At least it's what happens here. Do you have different behaviour? %%%

ronan ducluzeau commented

2013-04-27 17:45:02 +02:00

%%%I don't have a different behaviour.
I am just saying that the problem does not exist with an UV mapped texture. %%%

%%%I don't have a different behaviour. I am just saying that the problem does not exist with an UV mapped texture. %%%

Anna Celarek commented

2013-04-27 18:07:51 +02:00

%%%What does it have to do with an UV mapped texture?
%%%

%%%What does it have to do with an UV mapped texture? %%%

ronan ducluzeau commented

2013-04-27 18:29:24 +02:00

%%%What is influenced by a vertex group ( Density, Length ...) can be influenced by an UVmapped particle texture.
I did a previous test and it worked. But I forgot, I had enabled children.

So if you use children, you can switch between particle mode and weight paint mode without worries.

%%%

%%%What is influenced by a vertex group ( Density, Length ...) can be influenced by an UVmapped particle texture. I did a previous test and it worked. But I forgot, I had enabled children. So if you use children, you can switch between particle mode and weight paint mode without worries. %%%

Anna Celarek commented

2013-04-27 19:03:08 +02:00

%%%Didn't know about the texture option, thanks.
However, there's no direct feedback with textures, which makes it hard to work again.
When I set up a texture for the density, and go to texture paint mode, and paint it, the hair doesn't change. I have to go back to object mode to see the changes.
Also working with a black and white texture (which is needed if I want densities between 0 and 1) is like working blind in the viewport (hair and model is hardly visible in the hairless and almost hairless dark parts).

When I changed density with a vertex group in weight paint mode, I saw the result immediately.

I don't get what is the problem with adding those two vertex group controls?
Other vertex groups are there, and the 2.49 file opens with hair in the right direction controlled by the group, so I would guess it's already implemented somehow, just the input field missing?
%%%

%%%Didn't know about the texture option, thanks. However, there's no direct feedback with textures, which makes it hard to work again. When I set up a texture for the density, and go to texture paint mode, and paint it, the hair doesn't change. I have to go back to object mode to see the changes. Also working with a black and white texture (which is needed if I want densities between 0 and 1) is like working blind in the viewport (hair and model is hardly visible in the hairless and almost hairless dark parts). When I changed density with a vertex group in weight paint mode, I saw the result immediately. I don't get what is the problem with adding those two vertex group controls? Other vertex groups are there, and the 2.49 file opens with hair in the right direction controlled by the group, so I would guess it's already implemented somehow, just the input field missing? %%%

Brecht Van Lommel commented

2013-04-29 02:24:47 +02:00

%%%The implementation of this feature is missing, the hair is loaded in the same state as it was in 2.49 and only recalculated when changing settings.

It seems this code got lost in some big particle code refactoring in 2009. I don't see any particular reason this feature couldn't work anymore, but will have to look into it closer.%%%

%%%The implementation of this feature is missing, the hair is loaded in the same state as it was in 2.49 and only recalculated when changing settings. It seems this code got lost in some big particle code refactoring in 2009. I don't see any particular reason this feature couldn't work anymore, but will have to look into it closer.%%%

Sergey Sharybin commented

2014-02-03 15:19:15 +01:00

Added subscribers: @LukasTonne, @Sergey

Sergey Sharybin commented

2014-02-03 15:19:15 +01:00

@brecht, any verdict here? Or maybe @LukasTonne have some ideas? :)

Sergey Sharybin commented

2014-05-22 10:11:34 +02:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2014-05-22 10:11:34 +02:00

Sergey Sharybin self-assigned this 2014-05-22 10:11:34 +02:00

Sergey Sharybin commented

2014-05-22 10:11:34 +02:00

Moving to TODO list http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Tools#Particles

We're gonna to re-work particle system from scratch for the Gooseberry project.

Moving to TODO list http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Tools#Particles We're gonna to re-work particle system from scratch for the Gooseberry project.

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Particles tangent rotation control by vertex group missing #35103