Blender Git Loki

UI: rename various nodes

- RoughnessU = Roughness
- RoughnessV = Radial Roughness
- Primary Reflection Roughness = Undercoat Roughness

This rename does **not** affect the existing Hair node.

Remove unused closure

Update signatures to use Lukas's new linear_rgb_to_gray

Merge branch 'master' into soc-2018-hair-shader

Week 5 final merge: update submodules

(I'm doing this extra merge to pull some CUDA fixes.)

Merge branch 'master' into soc-2018-hair-shader

Fix discrepancy between RNG in CPU and GPU

The second random sample is reordered between devices,
which causes a divergence if using both at the same time.
Thanks to nirved on irc for finding this out!

Fix a precision issue in the coord frame with low roughness

Merge branch 'master' into soc-2018-hair-shader

Use the latest Week 5 commits for build

Cleanup: store and retrieve parameters consistently

Randomization is (currently) only available for melanin

Merge branch 'master' into soc-2018-hair-shader

Week 4's merge: two formatting issues fixed

Separate the randomized factors into new variables

This makes it easier to disable in code.

Cleanup: get rid of compiler warnings

Ty nirved!

Remove unnecessary cast to float

Fix double casting error in Linux

Fix interpolation in melanin randomization

It seems lerp =/= OSL's linearstep. Will revise this later.

Ref T54796

Add color and roughness randomization

Set 0.0 to not randomize anything. The value represent how much (less) of the feature you want to add to your hair, in percentage.

Ref T54796

Add random number socket

This is not yet used, but I wanted to get it in place first.

Ref T54796

Cleanup: formatting

Add hair dye to Melanin concentration mode

This lets you dye the hair after the melanin, using d'Eon's mapping.
Set white (default) to apply no dye, and any other color to apply dye.
Inspired in V-Ray's new hair shader (https://www.chaosgroup.com/blog/v-ray-next-the-science-behind-the-new-hair-shader)

Ref T54796