Particle system removal for 4.0 #105316

New Issue

Convert hair particle system combs to curves objects with versioning
Remove explode modifier
Remove particle instance modifier
Remove non-hair particles

Needs agreement

Decide how much of simulation and non-hair particle systems to replace with versioning vs. remove

- [ ] Convert hair particle system combs to curves objects with versioning - [ ] Remove explode modifier - [ ] Remove particle instance modifier - [ ] Remove non-hair particles **Needs agreement** - [ ] Decide how much of simulation and non-hair particle systems to replace with versioning vs. remove

Just to note, I have an old patch to add support for PointCloud as input to fluid simulations, without replacing particles. I guess this would be part of this task. It's simple enough that it could be in for next version, then particles support removed by 4.0.

Not sure if this the right place to discuss, but I'm not sure if it's a good idea to remove the particle hair system in Blender 4.0.

The new geo-node based hair system is lacking some important things, which makes it e.g. for me to use the new geo-node based system.

And I'm not talking about simulation (I'm aware of that there is work going on).

What I have in mind is:

Performance. I cant use the new node/curved based hair on a character with 16k+ faces. It's becomes incrediable slow. The old particle base system can handle this with no efforts.
I'm using currently a DAZ Genesis 8.1 figure with 16k faces. And Genesis 9 has even more faces (around 32k).
I think there is still no "Deflect Emitter" feature the new curved based hair?

I really don't think that we should remove the old hair system until there is a solution for those. And after Blender 4.0 is target for end of 2023 I doubt that this is realstic.

Not sure if this the right place to discuss, but I'm not sure if it's a good idea to remove the particle hair system in Blender 4.0. The new geo-node based hair system is lacking some important things, which makes it e.g. for me to use the new geo-node based system. And I'm not talking about simulation (I'm aware of that there is work going on). What I have in mind is: - Performance. I cant use the new node/curved based hair on a character with 16k+ faces. It's becomes incrediable slow. The old particle base system can handle this with no efforts. I'm using currently a DAZ Genesis 8.1 figure with 16k faces. And Genesis 9 has even more faces (around 32k). - I think there is still no "Deflect Emitter" feature the new curved based hair? I really don't think that we should remove the old hair system until there is a solution for those. And after Blender 4.0 is target for end of 2023 I doubt that this is realstic.

Performance. I cant use the new node/curved based hair on a character with 16k+ faces. It's becomes incrediable slow. The old particle base system can handle this with no efforts.
I'm using currently a DAZ Genesis 8.1 figure with 16k faces. And Genesis 9 has even more faces (around 32k).

You need to really be sure that there is a performance problem. In that case, it would be nice if you just reported it as a bug, then it would be fixed.

I think there is still no "Deflect Emitter" feature the new curved based hair?

You can still do whatever you want with the new node groups, you just have to do it.

> - Performance. I cant use the new node/curved based hair on a character with 16k+ faces. It's becomes incrediable slow. The old particle base system can handle this with no efforts. > I'm using currently a DAZ Genesis 8.1 figure with 16k faces. And Genesis 9 has even more faces (around 32k). You need to really be sure that there is a performance problem. In that case, it would be nice if you just reported it as a bug, then it would be fixed. > - I think there is still no "Deflect Emitter" feature the new curved based hair? You can still do whatever you want with the new node groups, you just have to do it.

You need to really be sure that there is a performance problem. In that case, it would be nice if you just reported it as a bug, then it would be fixed.

I did this 7 month ago, but it was closed because they don't consider performance issues as bugs. I hardly disagree here. I could handle such meshes with the old particle system without any issues, but the new one fails on it. So, for me it's a valid issue.
#100805

I think there is still no "Deflect Emitter" feature the new curved based hair?

You can still do whatever you want with the new node groups, you just have to do it.

I think that should be a toggle for the curves, like in the old system.
However, I think there should be an offical solution from Blender before releasing version 4.0. And even if that means that there is a node group for it in the Blender Essentials.

> You need to really be sure that there is a performance problem. In that case, it would be nice if you just reported it as a bug, then it would be fixed. I did this 7 month ago, but it was closed because they don't consider performance issues as bugs. I hardly disagree here. I could handle such meshes with the old particle system without any issues, but the new one fails on it. So, for me it's a valid issue. https://projects.blender.org/blender/blender/issues/100805 > > - I think there is still no "Deflect Emitter" feature the new curved based hair? > > You can still do whatever you want with the new node groups, you just have to do it. I think that should be a toggle for the curves, like in the old system. However, I think there should be an offical solution from Blender before releasing version 4.0. And even if that means that there is a node group for it in the Blender Essentials.

Thank you @mod_moder for creating issue #106713 which takes care about the slowness.

However, my second point is already fixed. I just found out that a replacement for "Deflect Emitter" is already implemented. It's a little bit hidden and called "Use Sculpt Collision".

Despite everything, I still think it's very bold to remove the old hair node system at the end of the year. Even if the hair simulations is added and the slowness fixed until end of year, I think the system should get more time until is really stable and working perfectly.

What's wrong with leaving the old hair system in 4.0 and giving users enough time to migrate slowly?

Thank you @mod_moder for creating issue #106713 which takes care about the slowness. However, my second point is already fixed. I just found out that a replacement for "Deflect Emitter" is already implemented. It's a little bit hidden and called "Use Sculpt Collision". Despite everything, I still think it's very bold to remove the old hair node system at the end of the year. Even if the hair simulations is added and the slowness fixed until end of year, I think the system should get more time until is really stable and working perfectly. What's wrong with leaving the old hair system in 4.0 and giving users enough time to migrate slowly?

I found an addtional reason why I think the removal of the old particle hair should be delayed.

The old particle system is added in the modifier stack of a mesh. This allows me to add the hair before the geometry is changed, e.g. by subdivsion. This is pretty usefully, because the hair is than not affacted by geometry changes through modifier e.g. the subdivision modifier:

blender_E00u7jTZpS.mp4

But the new system is bound to the surface. That means, if I sculpt my hair without any sudivision, or increase the subdivision level later, I get a different result of my hair sculp:

blender_sOOVP63Kol.mp4

This is for me a step backwards, compared to the old particle hair.

I found an addtional reason why I think the removal of the old particle hair should be delayed. The old particle system is added in the modifier stack of a mesh. This allows me to add the hair before the geometry is changed, e.g. by subdivsion. This is pretty usefully, because the hair is than not affacted by geometry changes through modifier e.g. the subdivision modifier: [blender_E00u7jTZpS.mp4](/attachments/d8d5490c-3369-4a28-97ba-9bfc1fb3385d) But the new system is bound to the surface. That means, if I sculpt my hair without any sudivision, or increase the subdivision level later, I get a different result of my hair sculp: [blender_sOOVP63Kol.mp4](/attachments/48cc786b-0788-477c-b476-3f0e7c1c4939) This is for me a step backwards, compared to the old particle hair.

blender_sOOVP63Kol.mp4

2.7 MiB

blender_E00u7jTZpS.mp4

1.3 MiB

Use a previous version if you need. Some things may just not happen all in one release.

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Particle system removal for 4.0 #105316