Vertex Paint: Alpha Support

GSOC 2017 by Darshan Kadu, see: D2859.

This is a partial merge of some of the features from
the soc-2017-vertex_paint branch.

- Alpha painting & drawing.
- 10 new color blending modes.
- Support for vertex select in vertex paint mode.

1 files changed, 14 insertions, 0 deletions

diff --git a/source/blender/editors/mesh/mesh_data.c b/source/blender/editors/mesh/mesh_data.c
index 3294490d5b1..737c8ac665d 100644
--- a/source/blender/editors/mesh/mesh_data.c
+++ b/source/blender/editors/mesh/mesh_data.c
@@ -464,6 +464,20 @@ int ED_mesh_color_add(Mesh *me, const char *name, const bool active_set)
 	return layernum;
 }
 
+bool ED_mesh_color_ensure(struct Mesh *me, const char *name)
+{
+	BLI_assert(me->edit_btmesh == NULL);
+
+	if (!me->mloopcol && me->totloop) {
+		CustomData_add_layer_named(&me->ldata, CD_MLOOPCOL, CD_DEFAULT, NULL, me->totloop, name);
+		BKE_mesh_update_customdata_pointers(me, true);
+	}
+
+	DAG_id_tag_update(&me->id, 0);
+
+	return (me->mloopcol != NULL);
+}
+
 bool ED_mesh_color_remove_index(Mesh *me, const int n)
 {
 	CustomData *ldata = GET_CD_DATA(me, ldata);