Fix T55207, fix T55208: hair not positioned correctly after subsurf.

The problem was that the particle system modifier was reading ob->derivedDeform
during modifier stack evaluation. Due to the mesh -> DM conversion this was no
longer set leading to wrong results.

In fact we don't really need the deformed mesh, just the original mesh topology
for face/poly index remapping. So the solution is to use that instead.

4 files changed, 16 insertions, 16 deletions

diff --git a/source/blender/blenkernel/intern/object.c b/source/blender/blenkernel/intern/object.c
index 39e190631ff..b8764f2c29d 100644
--- a/source/blender/blenkernel/intern/object.c
+++ b/source/blender/blenkernel/intern/object.c
@@ -379,9 +379,9 @@ void BKE_object_free_caches(Object *object)
 			if (psmd->mesh_final) {
 				BKE_id_free(NULL, psmd->mesh_final);
 				psmd->mesh_final = NULL;
-				if (psmd->mesh_deformed) {
-					BKE_id_free(NULL, psmd->mesh_deformed);
-					psmd->mesh_deformed = NULL;
+				if (psmd->mesh_original) {
+					BKE_id_free(NULL, psmd->mesh_original);
+					psmd->mesh_original = NULL;
 				}
 				psmd->flag |= eParticleSystemFlag_file_loaded;
 				update_flag |= OB_RECALC_DATA;
diff --git a/source/blender/blenkernel/intern/particle.c b/source/blender/blenkernel/intern/particle.c
index 26c822f5fef..a42826a1f89 100644
--- a/source/blender/blenkernel/intern/particle.c
+++ b/source/blender/blenkernel/intern/particle.c
@@ -1295,7 +1295,7 @@ static void psys_origspace_to_w(OrigSpaceFace *osface, int quad, const float w[4
  * \return the DM tessface index.
  */
 int psys_particle_dm_face_lookup(
-        Mesh *mesh_final, Mesh *mesh_deformed,
+        Mesh *mesh_final, Mesh *mesh_original,
         int findex_orig, const float fw[4], struct LinkNode **poly_nodes)
 {
 	MFace *mtessface_final;
@@ -1308,7 +1308,7 @@ int psys_particle_dm_face_lookup(
 	const int *index_mp_to_orig = NULL;
 
 	const int totface_final = mesh_final->totface;
-	const int totface_deformed = mesh_deformed ? mesh_deformed->totface : totface_final;
+	const int totface_deformed = mesh_original ? mesh_original->totface : totface_final;
 
 	if (ELEM(0, totface_final, totface_deformed)) {
 		return DMCACHE_NOTFOUND;
@@ -1318,8 +1318,8 @@ int psys_particle_dm_face_lookup(
 	index_mp_to_orig = CustomData_get_layer(&mesh_final->pdata, CD_ORIGINDEX);
 	BLI_assert(index_mf_to_mpoly);
 
-	if (mesh_deformed) {
-		index_mf_to_mpoly_deformed = CustomData_get_layer(&mesh_deformed->fdata, CD_ORIGINDEX);
+	if (mesh_original) {
+		index_mf_to_mpoly_deformed = CustomData_get_layer(&mesh_original->fdata, CD_ORIGINDEX);
 	}
 	else {
 		BLI_assert(mesh_final->runtime.deformed_only);
@@ -1329,8 +1329,8 @@ int psys_particle_dm_face_lookup(
 
 	pindex_orig = index_mf_to_mpoly_deformed[findex_orig];
 
-	if (mesh_deformed == NULL) {
-		mesh_deformed = mesh_final;
+	if (mesh_original == NULL) {
+		mesh_original = mesh_final;
 	}
 
 	index_mf_to_mpoly_deformed = NULL;
@@ -1349,7 +1349,7 @@ int psys_particle_dm_face_lookup(
 			return DMCACHE_NOTFOUND;
 		}
 	}
-	else if (findex_orig >= mesh_deformed->totface) {
+	else if (findex_orig >= mesh_original->totface) {
 		return DMCACHE_NOTFOUND;  /* index not in the original mesh */
 	}
 
diff --git a/source/blender/blenkernel/intern/particle_distribute.c b/source/blender/blenkernel/intern/particle_distribute.c
index e85a3f15022..846afd48064 100644
--- a/source/blender/blenkernel/intern/particle_distribute.c
+++ b/source/blender/blenkernel/intern/particle_distribute.c
@@ -847,7 +847,7 @@ static int psys_thread_context_init_distribute(ParticleThreadContext *ctx, Parti
 		/* Simple children */
 		if (part->childtype != PART_CHILD_FACES) {
 			BLI_srandom(31415926 + psys->seed + psys->child_seed);
-			distribute_simple_children(scene, ob, final_mesh, sim->psmd->mesh_deformed, psys, use_render_params);
+			distribute_simple_children(scene, ob, final_mesh, sim->psmd->mesh_original, psys, use_render_params);
 			return 0;
 		}
 	}
@@ -1233,7 +1233,7 @@ static void distribute_particles_on_dm(ParticleSimulationData *sim, int from)
 	
 	BLI_task_pool_free(task_pool);
 	
-	psys_calc_dmcache(sim->ob, final_mesh, sim->psmd->mesh_deformed, sim->psys);
+	psys_calc_dmcache(sim->ob, final_mesh, sim->psmd->mesh_original, sim->psys);
 	
 	if (ctx.mesh != final_mesh)
 		BKE_id_free(NULL, ctx.mesh);
diff --git a/source/blender/blenkernel/intern/particle_system.c b/source/blender/blenkernel/intern/particle_system.c
index 6c454cfa0b1..cba0721ab3f 100644
--- a/source/blender/blenkernel/intern/particle_system.c
+++ b/source/blender/blenkernel/intern/particle_system.c
@@ -311,7 +311,7 @@ int psys_get_tot_child(Scene *scene, ParticleSystem *psys, const bool use_render
 /*			Distribution						*/
 /************************************************/
 
-void psys_calc_dmcache(Object *ob, Mesh *mesh_final, Mesh *mesh_deformed, ParticleSystem *psys)
+void psys_calc_dmcache(Object *ob, Mesh *mesh_final, Mesh *mesh_original, ParticleSystem *psys)
 {
 	/* use for building derived mesh mapping info:
 	 *
@@ -350,7 +350,7 @@ void psys_calc_dmcache(Object *ob, Mesh *mesh_final, Mesh *mesh_deformed, Partic
 				origindex_poly= NULL;
 			}
 			else {
-				totelem = mesh_deformed->totface;
+				totelem = mesh_original->totface;
 				origindex = CustomData_get_layer(&mesh_final->fdata, CD_ORIGINDEX);
 
 				/* for face lookups we need the poly origindex too */
@@ -414,7 +414,7 @@ void psys_calc_dmcache(Object *ob, Mesh *mesh_final, Mesh *mesh_deformed, Partic
 						pa->num_dmcache = DMCACHE_NOTFOUND;
 				}
 				else { /* FROM_FACE/FROM_VOLUME */
-					pa->num_dmcache = psys_particle_dm_face_lookup(mesh_final, mesh_deformed, pa->num, pa->fuv, nodearray);
+					pa->num_dmcache = psys_particle_dm_face_lookup(mesh_final, mesh_original, pa->num, pa->fuv, nodearray);
 				}
 			}
 		}
@@ -3242,7 +3242,7 @@ static void hair_step(ParticleSimulationData *sim, float cfra, const bool use_re
 
 	if (psys->recalc & PSYS_RECALC_RESET) {
 		/* need this for changing subsurf levels */
-		psys_calc_dmcache(sim->ob, sim->psmd->mesh_final, sim->psmd->mesh_deformed, psys);
+		psys_calc_dmcache(sim->ob, sim->psmd->mesh_final, sim->psmd->mesh_original, psys);
 
 		if (psys->clmd)
 			cloth_free_modifier(psys->clmd);