Blender Git Loki

Merge branch 'hair_guides' into hair_guides_grooming

Merge branch 'blender2.8' into hair_guides

Merge branch 'hair_guides' into hair_guides_grooming

Merge branch 'blender2.8' into hair_guides

Add surface drawing to groom geometry.

Merge branch 'hair_guides' into hair_guides_grooming

Merge branch 'blender2.8' into hair_guides

Merge branch 'hair_guides' into hair_guides_grooming

Backport hair drawing improvements and workbench support from the grooming branch.

Use the taper factor to modulate influence of parent hairs.

This way the hair becomes influenced only by the primary guide curve
after tapering fully. Especially for long hair having secondary influences
is unnatural and creates weird effects. Full interpolation can be achieved
still by just setting a long taper length.

Use correct notifiers to get immediate 3D view redraw.

Calculate and store length for each vertex in the guides texture.

This allows accurate and consistent deformation based on hair length,
rather than relying on the relative parameterization.

Nicer return value for interpolation function in a struct.

Fix stupid copy/paste error, was using the same parent index when interpolating.

Fix incorrect strand data offset due to added taper attributes.

Set shape parameters per region and use them as per-guide attributes.

Eventually should also support scalp textures/vgroups as factors for
fine-grained control.

Reenable clump feature for fibers with a simpler taper function.

Using the smoothstep function for taper means the hair stay parallel
after a certain distance, which seems a bit more realistic as well as
giving more control.

Add commonly used strand draw settings to the hair system draw settings.

Move calculation of section rotations out of curve caching and into constraints function.

Move parent interpolation shader to common_hair_guides_lib.glsl