Blender Git Loki

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.

Thread-safe implementation of the volume bounding-box raycast sampler.

Include other sample generators in tests.

Volume bbray method is currently excluded because the implementation
is not yet thread-safe.

New gtests for the mesh sampling system.

This should test general functionality and consistency of different methods
for generating samples. In particular it shoud ensure that threaded variants
produce the same samples as unthreaded variants when using the same generator
and seeds.

Use a consistent number of RNG steps in both sample generation and skipping.

This is to ensure that threaded generator usage creates the exact same results
as the non-threaded base version. Further improvements and testing will be
needed.

Multithreading support for the mesh sampling library.

Samples can be generated either one-by-one using the existing "make_sample"
function (which uses a default context), or use the more efficient batch
generation functions. These optionally support threading via the task scheduler
now.

Fix hair follicle array write/read.

Merge branch 'blender2.8' into strand_editmode