This means the diffuse and specular shaders don't use the normal
for hair (which is actually undefined, a hair is micro cylinder) but
it uses the tangent vector (vector in direction of hair).
For Diffuse, it computes a fake normal now, representing the optimal
hair normal pointing towards the light. All current builtin shaders
work with this, including ramps.
For Specular, it uses another formula to remap dot products for all
lines that now use the tangent vector instead of the normal:
dot = vector * tangent
dot = sqrt(1.0 - dot*dot)
Gives better results than using the 'fake' normal for diffuse. Officially
(according the papers) this could be used for diffuse too, but then hair
becomes very flat. Now you can control the flatness easily with ramps or
using Oren-Nayer for example.
Example image (disappears in some weeks)
http://www.blender.org/bf/rt9.jpg
- Added new texture channel "Strand" to apply textures on hairs over the
length of hair (1 dimensional). Orco now gives 1 fixed coordinate for
the entire hair, based on where it starts.
Note; UV doesn't work yet. Nor vertexcolor.
http://www.blender.org/bf/rt10.jpg
03e1ec988b
