Add tessellation data to DerivedMesh (LoopTri)

This stores loop indices into the loop array giving easier acess
to data such as vertex-colors and UV's,
removing the need to store an MFace duplicate of custom-data.

This doesn't yet move all internal code from MFace to LoopTri just yet.

Only applies to:
- opengl drawing
- sculpting (pbvh)
- vertex/weight paint

Thanks to @psy-fi for review, fixes and improvements to drawing!

1 files changed, 22 insertions, 3 deletions

diff --git a/source/blender/blenkernel/BKE_DerivedMesh.h b/source/blender/blenkernel/BKE_DerivedMesh.h
index 62c68380289..0a4cc7f543f 100644
--- a/source/blender/blenkernel/BKE_DerivedMesh.h
+++ b/source/blender/blenkernel/BKE_DerivedMesh.h
@@ -185,6 +185,15 @@ struct DerivedMesh {
 	int totmat; /* total materials. Will be valid only before object drawing. */
 	struct Material **mat; /* material array. Will be valid only before object drawing */
 
+	/**
+	 * \warning Typical access is done via #getLoopTriArray, #getNumLoopTri.
+	 */
+	struct {
+		struct MLoopTri *array;
+		int num;
+		int num_alloc;
+	} looptris;
+
 	/* use for converting to BMesh which doesn't store bevel weight and edge crease by default */
 	char cd_flag;
 
@@ -201,6 +210,12 @@ struct DerivedMesh {
 	/** Recalculates mesh tessellation */
 	void (*recalcTessellation)(DerivedMesh *dm);
 
+	/** Loop tessellation cache */
+	void (*recalcLoopTri)(DerivedMesh *dm);
+	/** accessor functions */
+	const struct MLoopTri *(*getLoopTriArray)(DerivedMesh * dm);
+	int (*getNumLoopTri)(DerivedMesh *dm);
+
 	/* Misc. Queries */
 
 	/* Also called in Editmode */
@@ -594,10 +609,14 @@ void DM_DupPolys(DerivedMesh *source, DerivedMesh *target);
 void DM_ensure_normals(DerivedMesh *dm);
 void DM_ensure_tessface(DerivedMesh *dm);
 
+void DM_ensure_looptri_data(DerivedMesh *dm);
+void DM_ensure_looptri(DerivedMesh *dm);
+
 void DM_update_tessface_data(DerivedMesh *dm);
 
 void DM_update_materials(DerivedMesh *dm, struct Object *ob);
 struct MTFace *DM_paint_uvlayer_active_get(DerivedMesh *dm, int mat_nr);
+struct MLoopUV *DM_paint_uvlayer_active_get_mloopuv(DerivedMesh *dm, int mat_nr);
 
 void DM_interp_vert_data(
         struct DerivedMesh *source, struct DerivedMesh *dest,
@@ -721,12 +740,12 @@ void DM_update_weight_mcol(
  * the DerivedMesh, with both a pointer for arrays and an offset for editmesh */
 typedef struct DMVertexAttribs {
 	struct {
-		struct MTFace *array;
+		struct MLoopUV *array;
 		int em_offset, gl_index, gl_texco;
 	} tface[MAX_MTFACE];
 
 	struct {
-		struct MCol *array;
+		struct MLoopCol *array;
 		int em_offset, gl_index;
 	} mcol[MAX_MCOL];
 
@@ -747,7 +766,7 @@ void DM_vertex_attributes_from_gpu(
         DerivedMesh *dm,
         struct GPUVertexAttribs *gattribs, DMVertexAttribs *attribs);
 
-void DM_draw_attrib_vertex(DMVertexAttribs *attribs, int a, int index, int vert);
+void DM_draw_attrib_vertex(DMVertexAttribs *attribs, int a, int index, int vert, int loop);
 
 void DM_add_tangent_layer(DerivedMesh *dm);
 void DM_calc_auto_bump_scale(DerivedMesh *dm);