Vertex/Weight Paint: Use PBVH for painting

2016 GSOC project by @nathanvollmer, see D2150

- Mirrored painting and radial symmetry, like in sculpt mode.
- Volume based splash prevention,
  which avoids painting vertices far away from the 3D brush location.
- Normal based splash prevention,
  which avoids painting vertices with normals opposite the normal
  at the 3D brush location.
- Blur mode now uses a nearest neighbor average.
- Average mode, which averages the color/weight
  of the vertices within the brush
- Smudge mode, which pulls the colors/weights
  along the direction of the brush
- RGB^2 color blending, which gives a more accurate
  blend between two colors
- multithreading support. (PBVH leaves are painted in parallel.)
- Foreground/background color picker in vertex paint

1 files changed, 36 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_paint.h b/source/blender/blenkernel/BKE_paint.h
index f7e6ab59d20..88693600653 100644
--- a/source/blender/blenkernel/BKE_paint.h
+++ b/source/blender/blenkernel/BKE_paint.h
@@ -160,6 +160,14 @@ void paint_update_brush_rake_rotation(struct UnifiedPaintSettings *ups, struct B
 
 void BKE_paint_stroke_get_average(struct Scene *scene, struct Object *ob, float stroke[3]);
 
+/* Used for both vertex color and weight paint */
+struct SculptVertexPaintGeomMap {
+	int *vert_map_mem;
+	struct MeshElemMap *vert_to_loop;
+	int *poly_map_mem;
+	struct MeshElemMap *vert_to_poly;
+};
+
 /* Session data (mode-specific) */
 
 typedef struct SculptSession {
@@ -205,10 +213,38 @@ typedef struct SculptSession {
 
 	struct SculptStroke *stroke;
 	struct StrokeCache *cache;
+
+	union {
+		struct {
+			struct SculptVertexPaintGeomMap gmap;
+
+			/* For non-airbrush painting to re-apply from the original (MLoop aligned). */
+			unsigned int *previous_color;
+		} vpaint;
+
+		struct {
+			struct SculptVertexPaintGeomMap gmap;
+
+			/* Vertex aligned arrays of weights. */
+			/* For non-airbrush painting to re-apply from the original. */
+			float *previous_weight;
+			/* Keep track of how much each vertex has been painted (non-airbrush only). */
+			float *alpha_weight;
+		} wpaint;
+
+		//struct {
+		//ToDo: identify sculpt-only fields
+		//} sculpt;
+	} mode;
+	int mode_type;
+
+	/* This flag prevents PBVH from being freed when creating the vp_handle for texture paint. */
+	bool building_vp_handle;
 } SculptSession;
 
 void BKE_sculptsession_free(struct Object *ob);
 void BKE_sculptsession_free_deformMats(struct SculptSession *ss);
+void BKE_sculptsession_free_vwpaint_data(struct SculptSession *ss);
 void BKE_sculptsession_bm_to_me(struct Object *ob, bool reorder);
 void BKE_sculptsession_bm_to_me_for_render(struct Object *object);
 void BKE_sculpt_update_mesh_elements(struct Scene *scene, struct Sculpt *sd, struct Object *ob,