OpenSubdiv: Support for multiple materials in solid shading mode

Implementation is less optimal compared to non-opensubdiv drawing but
it is now as good as we can do it without affecting on how patches are
being created by OpenSubdiv.

3 files changed, 94 insertions, 16 deletions

diff --git a/source/blender/blenkernel/intern/CCGSubSurf.h b/source/blender/blenkernel/intern/CCGSubSurf.h
index e9ad4c52531..a825cffe7a0 100644
--- a/source/blender/blenkernel/intern/CCGSubSurf.h
+++ b/source/blender/blenkernel/intern/CCGSubSurf.h
@@ -215,6 +215,12 @@ bool ccgSubSurf_prepareGLMesh(CCGSubSurf *ss, bool use_osd_glsl);
 void ccgSubSurf_drawGLMesh(CCGSubSurf *ss, bool fill_quads,
                            int start_partition, int num_partitions);
 
+/* Get number of base faces in a particular GL mesh. */
+int ccgSubSurf_getNumGLMeshBaseFaces(CCGSubSurf *ss);
+
+/* Get number of vertices in base faces in a particular GL mesh. */
+int ccgSubSurf_getNumGLMeshBaseFaceVerts(CCGSubSurf *ss, int face);
+
 /* Controls whether CCG are needed (Cmeaning CPU evaluation) or fully GPU compute
  * and draw is allowed.
  */
diff --git a/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c b/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c
index eb7c3bf6ffd..fcc46308efa 100644
--- a/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c
+++ b/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c
@@ -308,6 +308,31 @@ void ccgSubSurf_drawGLMesh(CCGSubSurf *ss, bool fill_quads,
 	}
 }
 
+int ccgSubSurf_getNumGLMeshBaseFaces(CCGSubSurf *ss)
+{
+	const OpenSubdiv_TopologyRefinerDescr *topology_refiner;
+	if (ss->osd_topology_refiner != NULL) {
+		topology_refiner = ss->osd_topology_refiner;
+	}
+	else {
+		topology_refiner = openSubdiv_getGLMeshTopologyRefiner(ss->osd_mesh);
+	}
+	return openSubdiv_topologyRefinerGetNumFaces(topology_refiner);
+}
+
+/* Get number of vertices in base faces in a particular GL mesh. */
+int ccgSubSurf_getNumGLMeshBaseFaceVerts(CCGSubSurf *ss, int face)
+{
+	const OpenSubdiv_TopologyRefinerDescr *topology_refiner;
+	if (ss->osd_topology_refiner != NULL) {
+		topology_refiner = ss->osd_topology_refiner;
+	}
+	else {
+		topology_refiner = openSubdiv_getGLMeshTopologyRefiner(ss->osd_mesh);
+	}
+	return openSubdiv_topologyRefinerGetNumFaceVerts(topology_refiner, face);
+}
+
 void ccgSubSurf_setSkipGrids(CCGSubSurf *ss, bool skip_grids)
 {
 	ss->skip_grids = skip_grids;
diff --git a/source/blender/blenkernel/intern/subsurf_ccg.c b/source/blender/blenkernel/intern/subsurf_ccg.c
index e38d62cd9bc..867065b060d 100644
--- a/source/blender/blenkernel/intern/subsurf_ccg.c
+++ b/source/blender/blenkernel/intern/subsurf_ccg.c
@@ -2622,24 +2622,72 @@ static void ccgDM_drawFacesSolid(DerivedMesh *dm, float (*partial_redraw_planes)
 #ifdef WITH_OPENSUBDIV
 	if (ccgdm->useGpuBackend) {
 		CCGSubSurf *ss = ccgdm->ss;
-		DMFlagMat *faceFlags = ccgdm->faceFlags;
-		int new_matnr;
-		bool draw_smooth;
+		const DMFlagMat *faceFlags = ccgdm->faceFlags;
+		const int level = ccgSubSurf_getSubdivisionLevels(ss);
+		const int face_side = 1 << level;
+		const int grid_side = 1 << (level - 1);
+		const int face_patches = face_side * face_side;
+		const int grid_patches = grid_side * grid_side;
+		const int num_base_faces = ccgSubSurf_getNumGLMeshBaseFaces(ss);
+		int i, current_patch = 0;
+		int mat_nr = -1;
+		bool draw_smooth = false;
+		int start_draw_patch = -1, num_draw_patches = 0;
 		if (UNLIKELY(ccgSubSurf_prepareGLMesh(ss, setMaterial != NULL) == false)) {
 			return;
 		}
-		/* TODO(sergey): Single matierial currently. */
-		if (faceFlags) {
-			draw_smooth = (faceFlags[0].flag & ME_SMOOTH);
-			new_matnr = (faceFlags[0].mat_nr + 1);
-		}
-		else {
-			draw_smooth = true;
-			new_matnr = 1;
+		if (setMaterial == NULL) {
+			ccgSubSurf_drawGLMesh(ss,
+			                      true,
+			                      -1,
+			                      -1);
+			return;
 		}
-		if (setMaterial && setMaterial(new_matnr, NULL)) {
-			glShadeModel(draw_smooth ? GL_SMOOTH : GL_FLAT);
-			ccgSubSurf_drawGLMesh(ss, true, -1, -1);
+		for (i = 0; i < num_base_faces; ++i) {
+			const int num_face_verts = ccgSubSurf_getNumGLMeshBaseFaceVerts(ss, i);
+			const int num_patches = (num_face_verts == 4) ? face_patches
+			                                              : num_face_verts * grid_patches;
+			int new_matnr;
+			bool new_draw_smooth;
+			if (faceFlags) {
+				new_draw_smooth = (faceFlags[i].flag & ME_SMOOTH);
+				new_matnr = (faceFlags[i].mat_nr + 1);
+			}
+			else {
+				new_draw_smooth = true;
+				new_matnr = 1;
+			}
+			if (new_draw_smooth != draw_smooth || new_matnr != mat_nr) {
+				if (num_draw_patches != 0) {
+					bool do_draw = setMaterial == NULL ||
+					               setMaterial(mat_nr, NULL);
+					if (do_draw) {
+						glShadeModel(draw_smooth ? GL_SMOOTH : GL_FLAT);
+						ccgSubSurf_drawGLMesh(ss,
+						                      true,
+						                      start_draw_patch,
+						                      num_draw_patches);
+					}
+				}
+				start_draw_patch = current_patch;
+				num_draw_patches = num_patches;
+				mat_nr = new_matnr;
+				draw_smooth = new_draw_smooth;
+			}
+			else {
+				num_draw_patches += num_patches;
+			}
+			current_patch += num_patches;
+		}
+		if (num_draw_patches != 0) {
+			bool do_draw = setMaterial(mat_nr, NULL);
+			if (do_draw) {
+				glShadeModel(draw_smooth ? GL_SMOOTH : GL_FLAT);
+				ccgSubSurf_drawGLMesh(ss,
+				                      true,
+				                      start_draw_patch,
+				                      num_draw_patches);
+			}
 		}
 		return;
 	}
@@ -4528,8 +4576,7 @@ static void set_ccgdm_gpu_geometry(CCGDerivedMesh *ccgdm, DerivedMesh *dm)
 
 	for (index = 0; index < totface; index++) {
 		faceFlags->flag = mpoly ?  mpoly[index].flag : 0;
-		/* faceFlags->mat_nr = mpoly ? mpoly[index].mat_nr : 0; */
-		faceFlags->mat_nr = 0;
+		faceFlags->mat_nr = mpoly ? mpoly[index].mat_nr : 0;
 		faceFlags++;
 	}