Fix T47038: Particles in Particle Edit Mode get added in completely wrong location.

It also fixes another issue (crash) related to symmetric editing.

Quite involved, we (try to!) fix complete broken logic of parts of particle code, which would use poly index
as tessface one (or vice-versa). Issue most probably goes back to BMesh integration time...

This patch mostly fixes particle editing mode:
  - Adding/removing particles when using generative modifiers (like subsurf) should now work.
  - Adding/removing particles with a non-tessellated mesh (i.e. one having ngons) should also mostly work.
  - X-axis-mirror-editing particles over ngons does not really work, not sure why currently.
  - All this in both 'modes' (with or without using modifier stack for particles).

Tech side:
  - Store a deformed-only DM in particle modifier data.
  - Rename existing DM to make it clear it's a final one.
  - Use deformed-only DM's tessface2poly mapping to 'solve' poly/tessface mismatches.
  - Make (part of) mirror-editing code able to use a DM instead of raw mesh, so that we can mirror based on final DM
    when editing particles using modifier stack (mandatory, since there is no way currently to find orig tessface
    from an final DM tessface index).

Note that this patch is not really nice and clean (current particles are beyond hope on this side anyway),
it's more like some urgency bandage. Whole crap needs complete rewrite anyway,
BMesh's polygons make it really hard to work with current system (and looptri would not help much here).

Also, did not test everything possibly affected by those changes, so it needs some users' testing & validation too.

Reviewers: psy-fi

Subscribers: dfelinto, eyecandy

Maniphest Tasks: T47038

Differential Revision: https://developer.blender.org/D1685

1 files changed, 16 insertions, 12 deletions

diff --git a/source/blender/editors/mesh/editface.c b/source/blender/editors/mesh/editface.c
index e5b4e661773..01be8f848aa 100644
--- a/source/blender/editors/mesh/editface.c
+++ b/source/blender/editors/mesh/editface.c
@@ -632,12 +632,16 @@ static int mirrtopo_vert_sort(const void *v1, const void *v2)
 	return 0;
 }
 
-bool ED_mesh_mirrtopo_recalc_check(Mesh *me, const int ob_mode, MirrTopoStore_t *mesh_topo_store)
+bool ED_mesh_mirrtopo_recalc_check(Mesh *me, DerivedMesh *dm, const int ob_mode, MirrTopoStore_t *mesh_topo_store)
 {
 	int totvert;
 	int totedge;
 
-	if (me->edit_btmesh) {
+	if (dm) {
+		totvert = dm->getNumVerts(dm);
+		totedge = dm->getNumEdges(dm);
+	}
+	else if (me->edit_btmesh) {
 		totvert = me->edit_btmesh->bm->totvert;
 		totedge = me->edit_btmesh->bm->totedge;
 	}
@@ -659,11 +663,11 @@ bool ED_mesh_mirrtopo_recalc_check(Mesh *me, const int ob_mode, MirrTopoStore_t
 
 }
 
-void ED_mesh_mirrtopo_init(Mesh *me, const int ob_mode, MirrTopoStore_t *mesh_topo_store,
+void ED_mesh_mirrtopo_init(Mesh *me, DerivedMesh *dm, const int ob_mode, MirrTopoStore_t *mesh_topo_store,
                            const bool skip_em_vert_array_init)
 {
-	MEdge *medge;
-	BMEditMesh *em = me->edit_btmesh;
+	MEdge *medge = NULL, *med;
+	BMEditMesh *em = dm ?  NULL : me->edit_btmesh;
 
 	/* editmode*/
 	BMEdge *eed;
@@ -692,7 +696,7 @@ void ED_mesh_mirrtopo_init(Mesh *me, const int ob_mode, MirrTopoStore_t *mesh_to
 		totvert = em->bm->totvert;
 	}
 	else {
-		totvert = me->totvert;
+		totvert = dm ? dm->getNumVerts(dm) : me->totvert;
 	}
 
 	topo_hash = MEM_callocN(totvert * sizeof(MirrTopoHash_t), "TopoMirr");
@@ -708,10 +712,11 @@ void ED_mesh_mirrtopo_init(Mesh *me, const int ob_mode, MirrTopoStore_t *mesh_to
 		}
 	}
 	else {
-		totedge = me->totedge;
+		totedge = dm ? dm->getNumEdges(dm) : me->totedge;
+		medge = dm ? dm->getEdgeArray(dm) : me->medge;
 
-		for (a = 0, medge = me->medge; a < me->totedge; a++, medge++) {
-			const unsigned int i1 = medge->v1, i2 = medge->v2;
+		for (a = 0, med = medge; a < totedge; a++, med++) {
+			const unsigned int i1 = med->v1, i2 = med->v2;
 			topo_hash[i1]++;
 			topo_hash[i2]++;
 		}
@@ -736,8 +741,8 @@ void ED_mesh_mirrtopo_init(Mesh *me, const int ob_mode, MirrTopoStore_t *mesh_to
 			}
 		}
 		else {
-			for (a = 0, medge = me->medge; a < me->totedge; a++, medge++) {
-				const unsigned int i1 = medge->v1, i2 = medge->v2;
+			for (a = 0, med = medge; a < totedge; a++, med++) {
+				const unsigned int i1 = med->v1, i2 = med->v2;
 				topo_hash[i1] += topo_hash_prev[i2] * topo_pass;
 				topo_hash[i2] += topo_hash_prev[i1] * topo_pass;
 				tot_unique_edges += (topo_hash[i1] != topo_hash[i2]);
@@ -782,7 +787,6 @@ void ED_mesh_mirrtopo_init(Mesh *me, const int ob_mode, MirrTopoStore_t *mesh_to
 		}
 	}
 
-
 	for (a = 0; a < totvert; a++) {
 		topo_pairs[a].hash    = topo_hash[a];
 		topo_pairs[a].v_index = a;