Collision of hairs doesn't works properly #39219

New Issue

Jan-Niklas Bogatka · 2014-03-16T21:11:43+01:00

2014-03-16 21:11:43 +01:00

System Information
Win7 Ultimate 64bit , Nvidea GTX 460 SE Direct CU

Blender Version
Broken: 2.70 RC2 2525f9c
Worked: 2.69

Short description of error
The hair particle system doesn't reacts properly on collisions.
E.g. the hairs go through the emmiting object even if a collision modifier is applied.
Same with other objects, when enabling the kill particles option in the collision modifier only a few of the particles are killed.

Exact steps for others to reproduce the error
Open the appended file and play the animation. collision_problem_hair.blend

**System Information** Win7 Ultimate 64bit , Nvidea GTX 460 SE Direct CU **Blender Version** Broken: 2.70 RC2 2525f9c Worked: 2.69 **Short description of error** The hair particle system doesn't reacts properly on collisions. E.g. the hairs go through the emmiting object even if a collision modifier is applied. Same with other objects, when enabling the kill particles option in the collision modifier only a few of the particles are killed. **Exact steps for others to reproduce the error** Open the appended file and play the animation. [collision_problem_hair.blend](https://archive.blender.org/developer/F81470/collision_problem_hair.blend)

Jan-Niklas Bogatka commented

2014-03-16 21:11:44 +01:00

Changed status to: 'Open'

Jan-Niklas Bogatka commented

2014-03-16 21:11:44 +01:00

Added subscriber: @Jan-NiklasBogatka

Fasit commented

2014-03-17 05:10:34 +01:00

Added subscriber: @ygtsvtr

Fasit commented

2014-03-17 05:10:34 +01:00

collision_problem_hair_edited.blend Try this file.

If you subdivide your mesh or add a subdivision modifier the particle collision friction will activate more quickly.

But this is not true surface collision.
There is no collision system for hairs outside "Particle Edit Mode".

There is a way to make fake collisions but it doesn't solve the problem for characters or complex behaviours (like brushing hair with a object).

Here is the work around :

Add a force field to the object you would like it to collide with the hair system.

Set force type as "Force" and set shape as "Surface".

Now if your collision object comes in close proximity of the hairs they will get pushed.

note: Even if the hair object has this force field it wont collide with it self. The hair emitter object and collision object must be separate.

Hopefully gooseberry project will improve/solve these problems.

Good luck.

[collision_problem_hair_edited.blend](https://archive.blender.org/developer/F81544/collision_problem_hair_edited.blend) Try this file. If you subdivide your mesh or add a subdivision modifier the particle collision friction will activate more quickly. But this is not true surface collision. There is no collision system for hairs outside "Particle Edit Mode". There is a way to make fake collisions but it doesn't solve the problem for characters or complex behaviours (like brushing hair with a object). Here is the work around : Add a force field to the object you would like it to collide with the hair system. Set force type as "Force" and set shape as "Surface". Now if your collision object comes in close proximity of the hairs they will get pushed. note: Even if the hair object has this force field it wont collide with it self. The hair emitter object and collision object must be separate. Hopefully gooseberry project will improve/solve these problems. Good luck.

Sergey Sharybin commented

2014-03-18 11:55:09 +01:00

Added subscriber: @Sergey

Sergey Sharybin commented

2014-03-18 11:55:09 +01:00

Don't see the difference in behavior between 2.69 and 2.70RC2 really. And Blender 2.70 project is only about regressions which are stoppers for 2.70 release.

Sergey Sharybin commented

2014-04-10 18:48:10 +02:00

Added subscriber: @LukasTonne

Sergey Sharybin commented

2014-04-10 18:48:10 +02:00

@LukasTonne, is it something known to you?

Lukas Tönne commented

2014-04-11 08:26:06 +02:00

Don't think this can be made to work properly, needs complete refactor anyway. Close as todo?

Sergey Sharybin commented

2014-05-19 18:33:55 +02:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2014-05-19 18:33:55 +02:00

Sergey Sharybin self-assigned this 2014-05-19 18:33:55 +02:00

Sergey Sharybin commented

2014-05-19 18:33:55 +02:00

Marking as a TODO. Added it there http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Tools#Cloth so it'll be a nice reference for the hair/physics works we're gonna to do for gooseberry.

Thanks for the report anyway!

Marking as a TODO. Added it there http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Tools#Cloth so it'll be a nice reference for the hair/physics works we're gonna to do for gooseberry. Thanks for the report anyway!

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Collision of hairs doesn't works properly #39219