I’ve been playing with the pre-release versions of the upcoming Blender release and the hair system is really amazing. One question I haven’t been able to figure out, however, is how to make patches of different colored fur or hair grow out of a mesh. Suppose I have a cube with different colors on each face, would it be possible to emit particle hairs that are colored the same way as the faces emitting them?
Looking at the fur library at the gallery. I think the workflow is to create the mesh, rig it if needed, duplicate the mesh and cut the duplicate into different pieces for different colored or fur type parts…
Would be nice if the fur system would emit differently for different material groups instead, though. Probably in the future, but I think I can make it do what I want to enough already. Lots of extra meshes, though…
Also, the curve guides seems to work on any fur they come into contact with. Might be a good idea if the influence can be defined as per material or vertex group…
I was wondering about that today actually, that way seems pretty damn aweful, perhaps it would be better if the hair was teated as a seperate object and we could have a color map applied to it.
https://blenderartists.org/forum/viewtopic.php?t=56625&start=15
It says how the sully fur patches were made.
The colors were from textures, not the diffuse color of the faces in the mesh. The current implementation seems to be using only the first material color. If you have 2 or more materials, for different faces on the same mesh, the next ones are ignored, so you only get one hair color even if the faces emitting them are colored differently. And for really dense fur on big objects, the rendertimes are very long. Not sure how one could animate furry creatures with these, unless you got a really big renderfarm…
One more drawback about particle hair is that if you have objects shrinking or going far back, they get furrier and furrier… or balder and balder if they were to grow big or move towards the camera… 
He says for controlling hair length you have to assign vertexe groups. What about density? What if I had a model and he has thick hair on his head, but his arm hair is thinner and shorter?
WeightPainting. Red is max and Blue is min.
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