Blender Git Loki

Removed unused utility function.

Fix for calculation of the view vector in strand shading.

The product with the model-view matrix must take translation into account.

Augmentation of the strand shader with a debugging shader.

The debug shader shares most code with the regular shader. It uses a
geometry shader pass to create extra vector lines.

Cleanup for nicer code structure in the strand vertex shader.

Use a converter class for handling differences between DNA and BMesh strands data.

This moves most of the data access logic for this data out of the GPU code and into
the respective BKE files. The concept is similar to how DerivedMesh is used in other
GPU code.

Deduplication of strand drawing functions.

The two variants for object and edit mode are the same, except for
setting the edit data in the parameters.

Removed deprecated editmode drawing code.

The only real missing feature from this code is drawing points and
selection state, which can be reimplemented quite easily.

New option for selecting a fiber rendering primitive.

Currently lines and ribbons (triangle strips) are supported.
The ribbon width can be controlled with a parameter. Ribbons are
oriented toward the camera, similar to billboards, but shaded like lines
with the Kajiya shader imitating a reflective tube.

Removed a couple of unused fiber curve attribute buffers.

More detailed invalidation function for strand draw data.

Currently only used in its broadest form for freeing the whole buffer,
but could be used in the future to selectively invalidate parts of the
data, to avoid costly uploading of large but static buffers.

Cleanup: Move code for strand drawing buffers into its own file.

The gpu_buffers.c file is becoming too large, and incorporates all the logic
from meshes and now strands, which should be separate from the API.

Making the strands buffer code separate also allows much more control,
e.g. for partially invalidating draw data and avoiding unnecessary buffer
uploads to the GPU.

Merge branch 'strand_editmode' into strand_gpu

Merge branch 'mesh_samples' into strand_editmode

Merge branch 'master' into strand_editmode

Merge branch 'master' into mesh_samples

Replace the deprecated TessFace usage for mesh sampling by LoopTri.

Also make sure a valid generator instance for random sampling is always
returned, regardless of triangle counts.

Fix crashes when generating fibers without any control curves present.

Fix crash when adding a strands modifier and the fiber vertex/edge buffer is NULL.

The NULL buffer pointer is expected, just needs a sanity check.

Merge branch 'strand_editmode' into strand_gpu

Merge branch 'master' into strand_editmode