Subdiv: CCG, store edge adjacency information

This information is stored for each non-loose edge.

For each of such edge we store:

- List of CCG faces it is adjacent to.

  This way we can easily check whether it is adjacent to
  any face which is tagged for update or so.

- List of boundary elements from adjacent grids.

  This allows to traverse along the edge and average all
  adjacent grids.

1 files changed, 17 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_subdiv_ccg.h b/source/blender/blenkernel/BKE_subdiv_ccg.h
index cbdc32e319b..f8dbd2092f1 100644
--- a/source/blender/blenkernel/BKE_subdiv_ccg.h
+++ b/source/blender/blenkernel/BKE_subdiv_ccg.h
@@ -68,6 +68,17 @@ typedef struct SubdivCCGFace {
 	int start_grid_index;
 } SubdivCCGFace;
 
+/* Definition of an edge which is adjacent to at least one of the faces. */
+typedef struct SubdivCCGAdjacentEdge {
+	int num_adjacent_faces;
+	/* Indexed by adjacent face index. */
+	SubdivCCGFace **faces;
+	/* Indexed by adjacent face index, then by point index on the edge.
+	 * points to a grid element.
+	 */
+	struct CCGElem ***boundary_elements;
+} SubdivCCGAdjacentEdge;
+
 /* Representation of subdivision surface which uses CCG grids. */
 typedef struct SubdivCCG {
 	/* This is a subdivision surface this CCG was created for.
@@ -123,6 +134,12 @@ typedef struct SubdivCCG {
 	/* Indexed by grid index, points to corresponding face from `faces`. */
 	SubdivCCGFace **grid_faces;
 
+	/* Edges which are adjacent to faces.
+	 * Used for faster grid stitching, in the cost of extra memory.
+	 */
+	int num_adjacent_edges;
+	SubdivCCGAdjacentEdge *adjacent_edges;
+
 	struct DMFlagMat *grid_flag_mats;
 	BLI_bitmap **grid_hidden;