Blender Git Loki

Intermediate commit: switching strand edit data to BMesh.

Hair/Strand editing will only use a subset of the bmesh topology and
expect a specific topology that needs to be verified and enforced.
However, this extra requirement is much less work than reimplementing a
whole edit data system with the same feature set as bmesh and avoids
much redundant code.

Fix for verts-of-strand iterator: This requires a second pointer in
addition to the edge, otherwise the last point is omitted.

New customdata type for mesh surface samples.

Switched the hair edit data to a bmesh-like structure for consistency.

This means using mempools to store curve and vertex data, which allows
arbitrary addition and removal of data more easily. Also this includes
an iterator system similar to bmesh iterators (although the simpler
topology makes it a lot less complex).

Reconstruct most basic particle data when applying the hair edit, so
particle hairs remain visible.

Note that currently the hair root location (num/num_dmcache, fuv, foffset)
is not stored from edit data, so all hairs end up in a default location.

Store hair edit data in particle systems and manage it in the operator
for entering/exiting the edit mode.

Finished the particle-to-edit conversion function.

Moved code for the hair edit data structures to blenkernel.

This makes it work more like editmesh, and avoid the awkward and
basically bad-level approach in particles, where the edit data is an
anonymous pointer in particle systems together with a callback for
freeing.

New edit mode for hair.

More work on particle conversion methods for hair edit mode.

Minor syntax fix.

Usable random distribution algorithm.

Does not include area weighting yet.

Shifted the dispatch from the algorithm side to the storage side of the
sampling system to keep the code simple.

Now there is a MSurfaceSampleStorage struct that encodes the storage
details, which the algorithms don't have to care about.

Added generalized method for creating an array of mesh samples with
arbitrary stride.

New editor library for hair edit mode.

Eval function to get a location and normal vector from mesh samples.

Normalize the normal vector after sample eval to account for
interpolation.

Added a bool return to the eval function to give feedback on invalid
samples.

Changed mesh sample definition to use 3 vertex weights instead of a
face index. This is easier to sample uniformly and avoids the need for
tesselation for evaluating.

Skeleton code for sampling meshes.