Mesh Batch Cache: Refactor + Multithread

For clarity sake, the batch cache now uses exclusively per Loop attributes.
While this is a bit of a waste of VRAM (for the few case where per vert
attribs are enough) it reduces the complexity and amount of overall VBO
to update in general situations.

This patch also makes the VertexBuffers filling multithreaded. This make
the update of dense meshes a bit faster. The main bottleneck is the
IndexBuffers update which cannot be multithreaded efficiently (have to
increment a counter and/or do a final sorting pass).

We introduce the concept of "extract" functions/step.
All extract functions are executed in one thread each and if possible,
using multiple thread for looping over all elements.

Reviewed By: brecht

Differential Revision: http://developer.blender.org/D5424

1 files changed, 18 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/mesh_evaluate.c b/source/blender/blenkernel/intern/mesh_evaluate.c
index e28d50cbde4..2ea275cdfb0 100644
--- a/source/blender/blenkernel/intern/mesh_evaluate.c
+++ b/source/blender/blenkernel/intern/mesh_evaluate.c
@@ -2378,6 +2378,24 @@ float BKE_mesh_calc_poly_area(const MPoly *mpoly, const MLoop *loopstart, const
   }
 }
 
+float BKE_mesh_calc_poly_uv_area(const MPoly *mpoly, const MLoopUV *uv_array)
+{
+
+  int i, l_iter = mpoly->loopstart;
+  float area;
+  float(*vertexcos)[2] = BLI_array_alloca(vertexcos, (size_t)mpoly->totloop);
+
+  /* pack vertex cos into an array for area_poly_v2 */
+  for (i = 0; i < mpoly->totloop; i++, l_iter++) {
+    copy_v2_v2(vertexcos[i], uv_array[l_iter].uv);
+  }
+
+  /* finally calculate the area */
+  area = area_poly_v2((const float(*)[2])vertexcos, (unsigned int)mpoly->totloop);
+
+  return area;
+}
+
 /**
  * Calculate the volume and volume-weighted centroid of the volume
  * formed by the polygon and the origin.