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Child hair clump length not affected by 'Length' vertex group
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OS: Windows 7 x64
Blender version: 2.74 (although it shows up in .73 and possibly earlier)

The clumping of child hairs does not take into account the length of the parent hair as defined by the Length vertex group.


Steps to reproduce:

  1. Add a new particle system to an object, and set its type to 'Hair.'
  2. Enable either simple or interpolated children (the bug shows up with both).
  3. Set 'Clump' to 1.
  4. Switch to Weight Paint mode on the emitter object, and paint an area with a low weight.
  5. Under the Vertex Groups panel of the particle settings, select the newly created group for Length.
  6. Note that in the areas where the hair is shorter (i.e. the low-weight areas), the tips of the children do not converge at the ends.

Sample .blend:



Event Timeline

RSchr (rookie1024) added a project: BF Blender.
RSchr (rookie1024) set Type to Bug.
RSchr (rookie1024) created this task.
RSchr (rookie1024) raised the priority of this task from to Needs Triage by Developer.

Okay, so for whatever reason I can't edit the task description now, but I forgot to mention that the coloring on that cube is a visual representation of the vertex group.

Bastien Montagne (mont29) triaged this task as Normal priority.Apr 3 2015, 10:23 AM

Also, depending on how complicated it would be to do this, it might be useful for users (though I don't think I'd personally need it in the near future) to have some kind of control over how the length affects the clump length. Some way to switch (or fade, again depending on complexity) between "cutting" the hairs (where short clumps don't converge) and "de-growing" them (where short clumps converge).

Particles are broken, needs rewrite.