Particles Hair system discution

Hi,

I post here to discust about the hair system, so please leave this post here.

The new hair sustem was planned for gooseberry and paused because it’s to much work.
Right now, it’s still planned, but there a no date or else.

So, I think it will be great to discust about that here and talk about how it should be for us, 3D artist.
Like that, the dev’s should be aware of waht they should do, what is it working and they could won a lot of time to make it the more usefull possible.

Due to my experience with other softwares, I tested a lot of hair solution, shave and haircut, Yeti, zbrush, Maya, Blender, Guerilla etc.
Right now my workflow is Blender for the creation of guides and Guerilla for the render.
That give me great results.

  • Blender because of the particle edit system who is really great, we can work our guide as we can, it’s easy and fast.
  • Guerilla because of the hair parameters, much more parameters than Blender for the hair and the render.

So I think we could talk about those two aspect of the hair system on Blender.

First, the particles edit system and the particles parameters.

What do you think ?

Google drive page : https://docs.google.com/document/d/1_hpjJr1KpVD6vToxFLj4fXIZ5LhcZEJ0VIeyrtCDrog/edit?usp=sharing

What is really missing imo is a way to change(locally) the orientation of the interpolated strand.
I’m thinking about fur work,where combing it’s not enought.
It could be great if a texture force(based on uv coordinates derived from the emitter object,with the possibility to choice the correct uv texture set)could be used to displace the fur direction(not the parent fur,but the children)along it’s own local x,y axis.
Blender has allready a texture force effector,but without the possibility to use the uv coordinates from the emitter is not much usefull.
Also a smart clumping feature could be cool,where you decide how big is the clump radius locally.

First of all the hair system need a big fixing, I recently filed a bug report about a bug involving hair that was introduced after 2.74, and the result was that it was archived because “Particles are broken, needs rewrite.” (bug tracker is full of particles bugs, BTW).

I hope they’ll put their hands on it ASAP.

paolo

Yep it’s better they don’t fix bug anymore because every fix breaks 10 other things. (like you see with your report for 2.75) But on the other hand, it makes that the rewrite should be done as fast as possible (no stress, no deadlines, but do it please). The “everything nodal” was meant for 2.8x, but I think it should be started much quicker to finally get the work Lukas has done 3 years long and start on a good base for the future. The best would be to have a transition period with both system available like for depsgraph to allow the new system to be light (without all the compatibility and corner case/workaround crap). It would also allow all those nice modifier patches in the tracker to be finally integrated (randomness modifier, fracture, openVDB mesher, etc.)
Otherwise for the functionality, I think the devs already know what we need with their todo list.

yeah, there needs to be a total particle system rewrite and it needs to be done soon. Thankfully the end of Gooseberry is going to free up Lukas´ hands. Question is, will the BF fund the work that needs to be done? Will there be any funds to begin with?

@pitiwazou you are a really good artists and you did a lot for the community, so please try to be a module owner for hair/particles to cooperate with Lukas. I already had the occasion to speak with him. Although he doesn’t come in this forum, he’s pretty open to suggestion and user needs when done correctly, like you do. So, don’t only post on this forum, it will just get lost.

Rewriting the broken hair/particle system sounds like a massive task in a program that has so many thing interwined (and probably it’s why so many new particles-related bugs are popping up with each new changes).

I hope there will be some founding left after that gooseberry movie.

Wazou, what’s your tools/workflow for getting your blender hair guides into maya? Im wanting to do exactly that. :slight_smile:

I think the hair system in blender has much more potential other than for creating fur or hair. The hair system used a lot in many grass tutorial I had watched. But mostly for still images.

There is a grass animation tutorial where the grass is completely using the hair system. But the grass doesn’t look realistic to me. It looks more like green hairs, planted into the ground. No offense to the creator of that tutorial. I do find the tutorial very informative and I hope he will continue making awesome tutorials. That’s just the impression I got after watching that tutorial.

Unless I’m missing something, the grass animation with hair system is not easy in blender, when the grass is modeled. I know there are workarounds like using soft body or cloth. But each workaround has its own pros and cons, and sometimes the cons can be difficult to deal with.
The best workaround I could think of right now is combining multiple workarounds, depends on the type of the grass, and the distance to the camera.

So, I think it will be great if the hair strand in the hair system, can drive the deformation of the modeled grass. Currently we already have a hair system that can distribute grass objects very nicely, and make the children of the grass. The only missing feature is to have the hair strands driving the animation of the grass particle.

Have you considered creating a vertex group to control the length of the hairs?

Then in vertex paint mode you can use a gradient to gradually increase or decrease the length on the transition area.

Yep, there is some way to do this, but it will be great to have a brush to do this when painting the particles.

I agree it would be nice to do it in the particle edit view.

I love the way Blender take care of brushing hair, but yes, maybe a node based edit could be a solution to achive a flexible worflow.

Yep I think it’s the best way for that.

Honnesly, I started this post, but I don’t know how to help the devs on this part of Blender.

I know what we can use, what we need and how to work with hair and fur, but I don’t know how to put all of this together.

Maybe by adding a list of what we need to work correctly on fur and long hair.

For example :

  • The capability to copy a hair system with guides, right now, if we add guides, we cannont copy them to a new hair system
  • The capability to use maps for clumping, right now, the clumping works with the guides, but it’s not usefull at all
  • Having a lot more controls for the hair
  • etc

@pitiwazou

The hair tools do need some upgrade. MeanWhile did you try >

  • You can choose “Particle Select Mode : Tip " and press x and choose " Delete key” this will remove those points in the hair curve so get trimmed to same height.

  • You can also create a bezier curve and make it a “Curve Guide” then based on the settings and curve length your hair particles will be aligned to curve normals (also changes length).

Yes I tried that but one more time, it’s not as usefull that a brush who can do that in no time ^^
After, the goal of this post is not to find other way to fix my problem, but to talk about the futur hair system.

Blender have good tools to create particle shapes. Particles shapes can be edited halfway as we do in sculpt mode and halfway as in mesh edit mode.
Problems are appearing when we must use a huge amount of particles, use children and animate all this stuff.

When we are talking about a better clumping, we are talking about variability in children settings.
Since 2.74, we have a clumping curve and new spiral kink but these settings are still applied to the whole particles system.
Although we can modify kink frequency or kink mplitude by a texture; it is still same kink shape that is shared between all particles of system.
There is no way to have an interpolation between a curl and a braid.

So if we choose to create a particle system for each lock, we are still missing a transition between these numerous particle systems.
For animation, initially modelled haircut is lost. Weighting is broken by unsastisfying Deflect Emitter feature (interesting for modelling, but not for weighting).
It should be considered has an armature rest pose. But there is no real tool to guess physics properties adaptation to keep shape at equilibria state.
Maybe physicist would llike a shape created by physics rules. But artists will prefer physics properties found from shape.
Children settings are not transformed by dynamics of their parents.
Deformation follows parent curve line but it is not coherent with expected physic of a kink.

I think that children should not be considered as simply a multiplier of particles but as a level of edition.
It would be like starting with a subdivision modifier and ending with a multiresolution modifier.

I made a little video to show you my workflow and the fur parameters on Guerilla, with the clump.


As you can see, blender for the guides, guerilla for the parameters and the result is great !
We can use maps for everything, it’s very powerfull and in blender with vertex painting or normal painting we could have this kind of controls in real time.


supercool video :slight_smile:
I hope in future we can see some of these procedural nodebased controller in blender too :slight_smile:

  1. For long hair it is anything but optimal to add hairs 1 at a time (+ very carefully positioning and twisting them…) Instead artist should be enabled to create hair guides using all the tools in the toolbox yielding optimal control (curves, mesh editing, zbrush fibremesh import). It is vital in such workflow to be able to transfer data from 1 form to another (Hair->Curves->Mesh->Curves->Hair). So at very least Hair system should have a “recomb from splines” function simialar to 3ds max Shave and Haircut // We have Hairnet but it’s not quite there.

  2. FUR. Texture driven parameters such with VrayHair (e.g length, thickness, Vector(tri color) based Direction etc) will give tremendous control.

  3. Few more brushes wouldnt hurt e.g Clump, Twist.