T88352: Use threaded ibo.tris extraction for single material meshes.

This patch adds a specific extraction method when the mesh has only
one material. This method is multi-threaded.

There is a trade-off in this patch as the ibo isn't compressed (it adds
restart indexes for hidden faces). So it depends if threading is faster
than the additional GPU buffer upload.

# Subdivided cube
I used a cube subdivided 7 times, modifiers applied. that gives around 400000 faces.

The test is selecting some vertices and move them. During this test the next buffers are updated on each frame:
* vbo.pos_nor
* vbo.lnor
* vbo.edit_data
* ibo.tris
* ibo.points

System info:
|platform| Linux-5.11.0-7614-generic-x86_64-with-glibc2.33|
| renderer|      AMD SIENNA_CICHLID (DRM 3.40.0, 5.11.0-7614-generic, LLVM 11.0.1)|
|vendor|         AMD|
|version|        4.6 (Core Profile) Mesa 21.0.1|
|cpu|              Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz|
|compiler|     gcc version 10.3.0|

Timing have been measured using DEBUG_TIME in `draw_cache_extract_mesh`.

master: `rdata 8ms iter 45ms (frame 153ms)`
this patch `rdata 6ms iter 36ms (frame 132ms)`

Reviewed By: mano-wii

Maniphest Tasks: T88352

Differential Revision: https://developer.blender.org/D11290

1 files changed, 1 insertions, 1 deletions

diff --git a/source/blender/draw/intern/draw_cache_extract.h b/source/blender/draw/intern/draw_cache_extract.h
index 0b6dffa9073..304cae1d2dc 100644
--- a/source/blender/draw/intern/draw_cache_extract.h
+++ b/source/blender/draw/intern/draw_cache_extract.h
@@ -90,7 +90,7 @@ ENUM_OPERATORS(eMRDataType, MR_DATA_TAN_LOOP_NOR)
 extern "C" {
 #endif
 
-BLI_INLINE int mesh_render_mat_len_get(Mesh *me)
+BLI_INLINE int mesh_render_mat_len_get(const Mesh *me)
 {
   /* In edit mode, the displayed mesh is stored in the edit-mesh. */
   if (me->edit_mesh && me->edit_mesh->mesh_eval_final) {