Refactor: Merge non-functional-change part of 'edit normals' 2017 GSoC.

This merges changes in internals, runtime-only of existing custom
normals code, which make sense as of themselves, and will make diff of
soc branch easier/lighter to review.

In the details, it mostly changes two things:

* Now, smooth fans (aka MLoopNorSpaceArray) can store either loop
indices, or pointers to BMLoop themselves. This makes sense since in
BMesh, it's relatively easy to get index from a BMElement, but nearly
impracticable to go the other way around.

* First change enforces another, now we cannot rely anymore on `loops`
being NULL in MLoopNorSpace to detect single-loop fans, so we instead
store that info in a new flag.

Again, these are expected to be totally non-functional changes.

1 files changed, 11 insertions, 8 deletions

diff --git a/source/blender/blenkernel/intern/mesh.c b/source/blender/blenkernel/intern/mesh.c
index 81a06ff17cc..16017d8c250 100644
--- a/source/blender/blenkernel/intern/mesh.c
+++ b/source/blender/blenkernel/intern/mesh.c
@@ -2165,6 +2165,8 @@ static int split_faces_prepare_new_verts(
 	MLoop *ml = mloop;
 	MLoopNorSpace **lnor_space = lnors_spacearr->lspacearr;
 
+	BLI_assert(lnors_spacearr->data_type == MLNOR_SPACEARR_LOOP_INDEX);
+
 	for (int loop_idx = 0; loop_idx < num_loops; loop_idx++, ml++, lnor_space++) {
 		if (!BLI_BITMAP_TEST(done_loops, loop_idx)) {
 			const int vert_idx = ml->v;
@@ -2174,7 +2176,15 @@ static int split_faces_prepare_new_verts(
 
 			BLI_assert(*lnor_space);
 
-			if ((*lnor_space)->loops) {
+			if ((*lnor_space)->flags & MLNOR_SPACE_IS_SINGLE) {
+				/* Single loop in this fan... */
+				BLI_assert(GET_INT_FROM_POINTER((*lnor_space)->loops) == loop_idx);
+				BLI_BITMAP_ENABLE(done_loops, loop_idx);
+				if (vert_used) {
+					ml->v = new_vert_idx;
+				}
+			}
+			else {
 				for (LinkNode *lnode = (*lnor_space)->loops; lnode; lnode = lnode->next) {
 					const int ml_fan_idx = GET_INT_FROM_POINTER(lnode->link);
 					BLI_BITMAP_ENABLE(done_loops, ml_fan_idx);
@@ -2183,13 +2193,6 @@ static int split_faces_prepare_new_verts(
 					}
 				}
 			}
-			else {
-				/* Single loop in this fan... */
-				BLI_BITMAP_ENABLE(done_loops, loop_idx);
-				if (vert_used) {
-					ml->v = new_vert_idx;
-				}
-			}
 
 			if (!vert_used) {
 				BLI_BITMAP_ENABLE(verts_used, vert_idx);