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, 66 insertions, 7 deletions

diff --git a/source/blender/gpu/intern/gpu_draw.c b/source/blender/gpu/intern/gpu_draw.c
index 04441fc1b20..af8b2a0f806 100644
--- a/source/blender/gpu/intern/gpu_draw.c
+++ b/source/blender/gpu/intern/gpu_draw.c
@@ -71,6 +71,7 @@
 #include "BKE_node.h"
 #include "BKE_object.h"
 #include "BKE_scene.h"
+#include "BKE_subsurf.h"
 #include "BKE_DerivedMesh.h"
 
 #include "GPU_buffers.h"
@@ -82,6 +83,13 @@
 
 #include "smoke_API.h"
 
+#ifdef WITH_OPENSUBDIV
+#  include "DNA_mesh_types.h"
+#  include "BKE_editmesh.h"
+
+#  include "gpu_codegen.h"
+#endif
+
 extern Material defmaterial; /* from material.c */
 
 /* Text Rendering */
@@ -1357,7 +1365,7 @@ void GPU_free_images_old(void)
 {
 	Image *ima;
 	static int lasttime = 0;
-	int ctime = PIL_check_seconds_timer_i();
+	int ctime = (int)PIL_check_seconds_timer();
 
 	/*
 	 * Run garbage collector once for every collecting period of time
@@ -1433,6 +1441,7 @@ static struct GPUMaterialState {
 
 	int lastmatnr, lastretval;
 	GPUBlendMode lastalphablend;
+	bool is_opensubdiv;
 } GMS = {NULL};
 
 /* fixed function material, alpha handed by caller */
@@ -1519,6 +1528,27 @@ void GPU_begin_object_materials(View3D *v3d, RegionView3D *rv3d, Scene *scene, O
 	const bool gamma = BKE_scene_check_color_management_enabled(scene);
 	const bool new_shading_nodes = BKE_scene_use_new_shading_nodes(scene);
 	const bool use_matcap = (v3d->flag2 & V3D_SHOW_SOLID_MATCAP) != 0;  /* assumes v3d->defmaterial->preview is set */
+	bool use_opensubdiv = false;
+
+#ifdef WITH_OPENSUBDIV
+	{
+		DerivedMesh *derivedFinal = NULL;
+		Mesh *me = ob->data;
+		BMEditMesh *em = me->edit_btmesh;
+
+		if (em != NULL) {
+			derivedFinal = em->derivedFinal;
+		}
+		else {
+			derivedFinal = ob->derivedFinal;
+		}
+
+		if (derivedFinal != NULL && derivedFinal->type == DM_TYPE_CCGDM) {
+			CCGDerivedMesh *ccgdm = (CCGDerivedMesh *) derivedFinal;
+			use_opensubdiv = ccgdm->useGpuBackend;
+		}
+	}
+#endif
 
 #ifdef WITH_GAMEENGINE
 	if (rv3d->rflag & RV3D_IS_GAME_ENGINE) {
@@ -1541,6 +1571,7 @@ void GPU_begin_object_materials(View3D *v3d, RegionView3D *rv3d, Scene *scene, O
 
 	GMS.gob = ob;
 	GMS.gscene = scene;
+	GMS.is_opensubdiv = use_opensubdiv;
 	GMS.totmat = use_matcap ? 1 : ob->totcol + 1;  /* materials start from 1, default material is 0 */
 	GMS.glay = (v3d->localvd)? v3d->localvd->lay: v3d->lay; /* keep lamps visible in local view */
 	GMS.gscenelock = (v3d->scenelock != 0);
@@ -1572,7 +1603,7 @@ void GPU_begin_object_materials(View3D *v3d, RegionView3D *rv3d, Scene *scene, O
 	/* viewport material, setup in space_view3d, defaults to matcap using ma->preview now */
 	if (use_matcap) {
 		GMS.gmatbuf[0] = v3d->defmaterial;
-		GPU_material_matcap(scene, v3d->defmaterial);
+		GPU_material_matcap(scene, v3d->defmaterial, use_opensubdiv);
 
 		/* do material 1 too, for displists! */
 		memcpy(&GMS.matbuf[1], &GMS.matbuf[0], sizeof(GPUMaterialFixed));
@@ -1590,7 +1621,7 @@ void GPU_begin_object_materials(View3D *v3d, RegionView3D *rv3d, Scene *scene, O
 
 			if (glsl) {
 				GMS.gmatbuf[0] = &defmaterial;
-				GPU_material_from_blender(GMS.gscene, &defmaterial);
+				GPU_material_from_blender(GMS.gscene, &defmaterial, GMS.is_opensubdiv);
 			}
 
 			GMS.alphablend[0] = GPU_BLEND_SOLID;
@@ -1604,7 +1635,7 @@ void GPU_begin_object_materials(View3D *v3d, RegionView3D *rv3d, Scene *scene, O
 			if (ma == NULL) ma = &defmaterial;
 
 			/* create glsl material if requested */
-			gpumat = glsl? GPU_material_from_blender(GMS.gscene, ma): NULL;
+			gpumat = glsl? GPU_material_from_blender(GMS.gscene, ma, GMS.is_opensubdiv): NULL;
 
 			if (gpumat) {
 				/* do glsl only if creating it succeed, else fallback */
@@ -1708,7 +1739,7 @@ int GPU_enable_material(int nr, void *attribs)
 	/* unbind glsl material */
 	if (GMS.gboundmat) {
 		if (GMS.is_alpha_pass) glDepthMask(0);
-		GPU_material_unbind(GPU_material_from_blender(GMS.gscene, GMS.gboundmat));
+		GPU_material_unbind(GPU_material_from_blender(GMS.gscene, GMS.gboundmat, GMS.is_opensubdiv));
 		GMS.gboundmat = NULL;
 	}
 
@@ -1735,7 +1766,7 @@ int GPU_enable_material(int nr, void *attribs)
 
 			float auto_bump_scale;
 
-			gpumat = GPU_material_from_blender(GMS.gscene, mat);
+			gpumat = GPU_material_from_blender(GMS.gscene, mat, GMS.is_opensubdiv);
 			GPU_material_vertex_attributes(gpumat, gattribs);
 
 			if (GMS.dob)
@@ -1802,7 +1833,7 @@ void GPU_disable_material(void)
 			glDisable(GL_CULL_FACE);
 
 		if (GMS.is_alpha_pass) glDepthMask(0);
-		GPU_material_unbind(GPU_material_from_blender(GMS.gscene, GMS.gboundmat));
+		GPU_material_unbind(GPU_material_from_blender(GMS.gscene, GMS.gboundmat, GMS.is_opensubdiv));
 		GMS.gboundmat = NULL;
 	}
 
@@ -2108,3 +2139,31 @@ void GPU_state_init(void)
 	gpu_multisample(false);
 }
 
+#ifdef WITH_OPENSUBDIV
+/* Update face-varying variables offset which might be
+ * different from mesh to mesh sharing the same material.
+ */
+void GPU_draw_update_fvar_offset(DerivedMesh *dm)
+{
+	int i;
+
+	/* Sanity check to be sure we only do this for OpenSubdiv draw. */
+	BLI_assert(dm->type == DM_TYPE_CCGDM);
+	BLI_assert(GMS.is_opensubdiv);
+
+	for (i = 0; i < GMS.totmat; ++i) {
+		Material *material = GMS.gmatbuf[i];
+		GPUMaterial *gpu_material;
+
+		if (material == NULL) {
+			continue;
+		}
+
+		gpu_material = GPU_material_from_blender(GMS.gscene,
+		                                         material,
+		                                         GMS.is_opensubdiv);
+
+		GPU_material_update_fvar_offset(gpu_material, dm);
+	}
+}
+#endif