OpenSubdiv: Commit of OpenSubdiv integration into Blender

This commit contains all the remained parts needed for initial integration of
OpenSubdiv into Blender's subdivision surface code. Includes both GPU and CPU
backends which works in the following way:

- When SubSurf modifier is the last in the modifiers stack then GPU pipeline
  of OpenSubdiv is used, making viewport performance as fast as possible.

  This also requires graphscard with GLSL 1.5 support. If this requirement is
  not met, then no GPU pipeline is used at all.

- If SubSurf is not a last modifier or if DerivesMesh is being evaluated for
  rendering then CPU limit evaluation API from OpenSubdiv is used. This only
  replaces the legacy evaluation code from CCGSubSurf_legacy, but keeps CCG
  structures exactly the same as they used to be for ages now.

This integration is fully covered with ifdef and not enabled by default
because there are several TODOs to be solved first:

- Face varying data interpolation is not really cleanly implemented for GPU
  in OpenSubdiv 3.0. It is also not implemented for limit evaluation API.

  This basically means we'll have really hard time supporting UVs.

- Limit evaluation only works with adaptivly subdivided meshes so far, which
  basically means all the points of CCG are pushed to the limit. This gives
  different result from old code.

- There are some serious optimizations possible on the topology refiner
  creation, which would speed up initial OpenSubdiv mesh creation.

- There are some hardcoded asumptions in the GPU and DerivedMesh areas which
  could be generalized.

  That's something where Antony and Campbell can help, making it so the code
  is structured in a way which is reusable by all planned viewport projects.

- There are also some workarounds in the dependency graph to make sure OpenGL
  buffers are only freed from the main thread.

Those who'll be wanting to make experiments with this code should grab dev
branch (NOT master) from

  https://github.com/Nazg-Gul/OpenSubdiv/tree/dev

There are some patches applied in there which we're working on on getting
into upstream.

1 files changed, 94 insertions, 4 deletions

diff --git a/source/blender/blenkernel/intern/CCGSubSurf.c b/source/blender/blenkernel/intern/CCGSubSurf.c
index a60e1fa3076..9ac6166606e 100644
--- a/source/blender/blenkernel/intern/CCGSubSurf.c
+++ b/source/blender/blenkernel/intern/CCGSubSurf.c
@@ -37,6 +37,11 @@
 #include "CCGSubSurf_intern.h"
 #include "BKE_subsurf.h"
 
+#ifdef WITH_OPENSUBDIV
+#  include "opensubdiv_capi.h"
+#  include "opensubdiv_converter_capi.h"
+#endif
+
 #include "GL/glew.h"
 
 /***/
@@ -299,6 +304,23 @@ CCGSubSurf *ccgSubSurf_new(CCGMeshIFC *ifc, int subdivLevels, CCGAllocatorIFC *a
 		ss->tempVerts = NULL;
 		ss->tempEdges = NULL;
 
+#ifdef WITH_OPENSUBDIV
+		ss->osd_evaluator = NULL;
+		ss->osd_mesh = NULL;
+		ss->osd_topology_refiner = NULL;
+		ss->osd_mesh_invalid = false;
+		ss->osd_coarse_coords_invalid = false;
+		ss->osd_vao = 0;
+		ss->skip_grids = false;
+		ss->osd_compute = 0;
+		ss->osd_uvs_invalid = true;
+		ss->osd_subsurf_uv = 0;
+		ss->osd_uv_index = -1;
+		ss->osd_next_face_ptex_index = 0;
+		ss->osd_coarse_coords = NULL;
+		ss->osd_num_coarse_coords = 0;
+#endif
+
 		return ss;
 	}
 }
@@ -307,6 +329,24 @@ void ccgSubSurf_free(CCGSubSurf *ss)
 {
 	CCGAllocatorIFC allocatorIFC = ss->allocatorIFC;
 	CCGAllocatorHDL allocator = ss->allocator;
+#ifdef WITH_OPENSUBDIV
+	if (ss->osd_evaluator != NULL) {
+		openSubdiv_deleteEvaluatorDescr(ss->osd_evaluator);
+	}
+	if (ss->osd_mesh != NULL) {
+		/* TODO(sergey): Make sure free happens form the main thread! */
+		openSubdiv_deleteOsdGLMesh(ss->osd_mesh);
+	}
+	if (ss->osd_vao != 0) {
+		glDeleteVertexArrays(1, &ss->osd_vao);
+	}
+	if (ss->osd_coarse_coords != NULL) {
+		MEM_freeN(ss->osd_coarse_coords);
+	}
+	if (ss->osd_topology_refiner != NULL) {
+		openSubdiv_deleteTopologyRefinerDescr(ss->osd_topology_refiner);
+	}
+#endif
 
 	if (ss->syncState) {
 		ccg_ehash_free(ss->oldFMap, (EHEntryFreeFP) _face_free, ss);
@@ -467,6 +507,9 @@ CCGError ccgSubSurf_initFullSync(CCGSubSurf *ss)
 	ss->tempEdges = MEM_mallocN(sizeof(*ss->tempEdges) * ss->lenTempArrays, "CCGSubsurf tempEdges");
 
 	ss->syncState = eSyncState_Vert;
+#ifdef WITH_OPENSUBDIV
+	ss->osd_next_face_ptex_index = 0;
+#endif
 
 	return eCCGError_None;
 }
@@ -607,6 +650,9 @@ CCGError ccgSubSurf_syncVert(CCGSubSurf *ss, CCGVertHDL vHDL, const void *vertDa
 			ccg_ehash_insert(ss->vMap, (EHEntry *) v);
 			v->flags = 0;
 		}
+#ifdef WITH_OPENSUBDIV
+		v->osd_index = ss->vMap->numEntries - 1;
+#endif
 	}
 
 	if (v_r) *v_r = v;
@@ -789,6 +835,15 @@ CCGError ccgSubSurf_syncFace(CCGSubSurf *ss, CCGFaceHDL fHDL, int numVerts, CCGV
 				}
 			}
 		}
+#ifdef WITH_OPENSUBDIV
+		f->osd_index = ss->osd_next_face_ptex_index;
+		if (numVerts == 4) {
+			ss->osd_next_face_ptex_index++;
+		}
+		else {
+			ss->osd_next_face_ptex_index += numVerts;
+		}
+#endif
 	}
 
 	if (f_r) *f_r = f;
@@ -797,7 +852,18 @@ CCGError ccgSubSurf_syncFace(CCGSubSurf *ss, CCGFaceHDL fHDL, int numVerts, CCGV
 
 static void ccgSubSurf__sync(CCGSubSurf *ss)
 {
-	ccgSubSurf__sync_legacy(ss);
+#ifdef WITH_OPENSUBDIV
+	/* TODO(sergey): This is because OSD evaluator does not support
+	 * bilinear subdivision scheme at this moment.
+	 */
+	if (ss->meshIFC.simpleSubdiv == false || ss->skip_grids == true) {
+		ccgSubSurf__sync_opensubdiv(ss);
+	}
+	else
+#endif
+	{
+		ccgSubSurf__sync_legacy(ss);
+	}
 }
 
 CCGError ccgSubSurf_processSync(CCGSubSurf *ss)
@@ -1128,15 +1194,39 @@ CCGError ccgSubSurf_stitchFaces(CCGSubSurf *ss, int lvl, CCGFace **effectedF, in
 
 int ccgSubSurf_getNumVerts(const CCGSubSurf *ss)
 {
-	return ss->vMap->numEntries;
+#ifdef WITH_OPENSUBDIV
+	if (ss->skip_grids) {
+		return ccgSubSurf__getNumOsdBaseVerts(ss);
+	}
+	else
+#endif
+	{
+		return ss->vMap->numEntries;
+	}
 }
 int ccgSubSurf_getNumEdges(const CCGSubSurf *ss)
 {
-	return ss->eMap->numEntries;
+#ifdef WITH_OPENSUBDIV
+	if (ss->skip_grids) {
+		return ccgSubSurf__getNumOsdBaseEdges(ss);
+	}
+	else
+#endif
+	{
+		return ss->eMap->numEntries;
+	}
 }
 int ccgSubSurf_getNumFaces(const CCGSubSurf *ss)
 {
-	return ss->fMap->numEntries;
+#ifdef WITH_OPENSUBDIV
+	if (ss->skip_grids) {
+		return ccgSubSurf__getNumOsdBaseFaces(ss);
+	}
+	else
+#endif
+	{
+		return ss->fMap->numEntries;
+	}
 }
 
 CCGVert *ccgSubSurf_getVert(CCGSubSurf *ss, CCGVertHDL v)