Blender Git Loki

Follicle generation function for hair systems.

Rename "Hair" modifier to "Fur" modifier.

This will be a simple testbed for generating hair geometry.

The plan here is to use different modifiers for different editing methods
for hair. Each of these will use a HairSystem instance, but vary
in the editable data used to generate guide curves. The hair system
underneath is agnostic to the editing method used.

Remove the guide_object pointer from HairSystem.

Scalp mesh now is passed explicitly to the hair API functions again.

The idea is that hair systems can be created in any object and use
another object as the scalp. Sharing the same hair pattern should be
implemented at a later time, pending a good design for assigning
follicles to specific hair systems.

Merge branch 'blender2.8' into hair_guides

Minor flag rename.

Free draw data when deleting a hair system.

Remove deprecated UI code for the hair modifier.

Fix null pointer reads when there are no hair follicles (which is allowed).

Parent indices and weights for hair follicles and a binding function.

Add fields for curve storage in hair systems and use it in draw code.

Implementation for BKE_hair_get_scalp.

Restructure the hair modifier so external tools define guide curves.

Remove the new hair edit mode.

The purpose of this branch is to create a new hair system with a dedicated
grooming tool, unlike the current direct editing of hair guide curves.

The modified bmesh-based strand edit mode is quite complex and distracts
from the main purpose of the branch, so its better to remove it for now
and implement a new tool.

Merge branch 'blender2.8' into hair_guides

DNA data for explicitly storing hair guide curves.

The idea is to separate guide curves from the various methods of
generating them. Guides could be created explicitly (as hair
strands), or automatically from vertices or external mesh data.

A guide then forms the basis for interpolating the render data
(fibers).

Simple CSV mesh loading for tests.

File paths are crude and preliminary.

Fix neighbor conflict checks for Poisson disk distribution.

The cell size is chosen as r/sqrt(3) (i.e. max. 1 sample per cell),
which means that the influence of each cell extends beyond the 1st
neighbor. a 5x5x5 box (except the center and corners) needs to be
examined to find collisions.

Added a 1-cell margin to the grid dimensions to simplify neighbor lookups.

Separate step for mesh sample generators to bind them to a specific mesh.

Initial implementation of Poisson disk sampling on meshes.

This is still buggy (uneven sample coverage) and needs changes to the
sampling system for better threading support.

The implementation is based on

Bowers, John, et al. "Parallel Poisson disk sampling with spectrum analysis on surfaces." ACM Transactions on Graphics (TOG). Vol. 29. No. 6. ACM, 2010.