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.

10 files changed, 61 insertions, 40 deletions

diff --git a/source/blender/blenkernel/BKE_particle.h b/source/blender/blenkernel/BKE_particle.h
index b6a87ae333e..4820f0173bf 100644
--- a/source/blender/blenkernel/BKE_particle.h
+++ b/source/blender/blenkernel/BKE_particle.h
@@ -439,8 +439,8 @@ void psys_particle_on_dm(struct Mesh *mesh_final, int from, int index, int index
 /* particle_system.c */
 void distribute_particles(struct ParticleSimulationData *sim, int from);
 void initialize_particle(struct ParticleSimulationData *sim, struct ParticleData *pa);
-void psys_calc_dmcache(struct Object *ob, struct Mesh *mesh_final, struct Mesh *mesh_deformed, struct ParticleSystem *psys);
-int psys_particle_dm_face_lookup(struct Mesh *mesh_final, struct Mesh *mesh_deformed, int findex, const float fw[4], struct LinkNode **poly_nodes);
+void psys_calc_dmcache(struct Object *ob, struct Mesh *mesh_final, struct Mesh *mesh_original, struct ParticleSystem *psys);
+int psys_particle_dm_face_lookup(struct Mesh *mesh_final, struct Mesh *mesh_original, int findex, const float fw[4], struct LinkNode **poly_nodes);
 
 void reset_particle(struct ParticleSimulationData *sim, struct ParticleData *pa, float dtime, float cfra);
 
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);
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index e74f82dfb6d..bc4b8daf0d3 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -5230,7 +5230,7 @@ static void direct_link_modifiers(FileData *fd, ListBase *lb)
 			ParticleSystemModifierData *psmd = (ParticleSystemModifierData *)md;
 			
 			psmd->mesh_final = NULL;
-			psmd->mesh_deformed = NULL;
+			psmd->mesh_original = NULL;
 			psmd->psys= newdataadr(fd, psmd->psys);
 			psmd->flag &= ~eParticleSystemFlag_psys_updated;
 			psmd->flag |= eParticleSystemFlag_file_loaded;
diff --git a/source/blender/editors/physics/particle_edit.c b/source/blender/editors/physics/particle_edit.c
index 5210ff76491..b8a5c138a57 100644
--- a/source/blender/editors/physics/particle_edit.c
+++ b/source/blender/editors/physics/particle_edit.c
@@ -2963,7 +2963,7 @@ static void PE_mirror_x(
 			}
 			else {
 				newpa->num_dmcache = psys_particle_dm_face_lookup(
-				                         psmd->mesh_final, psmd->mesh_deformed, newpa->num, newpa->fuv, NULL);
+				                         psmd->mesh_final, psmd->mesh_original, newpa->num, newpa->fuv, NULL);
 			}
 
 			/* update edit key pointers */
@@ -3557,7 +3557,7 @@ static int brush_add(const bContext *C, PEData *data, short number)
 		mesh = psmd->mesh_final;
 	}
 	else {
-		mesh = psmd->mesh_deformed;
+		mesh = psmd->mesh_original;
 	}
 	BLI_assert(mesh);
 
@@ -3591,11 +3591,11 @@ static int brush_add(const bContext *C, PEData *data, short number)
 				add_pars[n].num = add_pars[n].num_dmcache;
 				add_pars[n].num_dmcache = DMCACHE_ISCHILD;
 			}
-			else if (mesh == psmd->mesh_deformed) {
+			else if (mesh == psmd->mesh_original) {
 				/* Final DM is not same topology as orig mesh, we have to map num_dmcache to real final dm. */
 				add_pars[n].num = add_pars[n].num_dmcache;
 				add_pars[n].num_dmcache = psys_particle_dm_face_lookup(
-				                              psmd->mesh_final, psmd->mesh_deformed,
+				                              psmd->mesh_final, psmd->mesh_original,
 				                              add_pars[n].num, add_pars[n].fuv, NULL);
 			}
 			else {
diff --git a/source/blender/editors/physics/particle_object.c b/source/blender/editors/physics/particle_object.c
index cb7c90a6c3d..55f518a2a8c 100644
--- a/source/blender/editors/physics/particle_object.c
+++ b/source/blender/editors/physics/particle_object.c
@@ -680,7 +680,7 @@ static bool remap_hair_emitter(
 		mesh = target_psmd->mesh_final;
 	}
 	else {
-		mesh = target_psmd->mesh_deformed;
+		mesh = target_psmd->mesh_original;
 	}
 	target_mesh = target_psmd->mesh_final;
 	if (mesh == NULL) {
diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index 4371172f236..93ab7a035bc 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -739,7 +739,7 @@ typedef struct ParticleSystemModifierData {
 
 	struct ParticleSystem *psys;
 	struct Mesh *mesh_final;  /* Final Mesh - its topology may differ from orig mesh. */
-	struct Mesh *mesh_deformed;  /* Deformed-only Mesh - its topology is same as orig mesh one. */
+	struct Mesh *mesh_original;  /* Original mesh that particles are attached to. */
 	int totdmvert, totdmedge, totdmface;
 	short flag, pad;
 } ParticleSystemModifierData;
diff --git a/source/blender/modifiers/intern/MOD_particlesystem.c b/source/blender/modifiers/intern/MOD_particlesystem.c
index c2493e6d8f3..72bdcc779ea 100644
--- a/source/blender/modifiers/intern/MOD_particlesystem.c
+++ b/source/blender/modifiers/intern/MOD_particlesystem.c
@@ -42,6 +42,7 @@
 
 
 #include "BKE_cdderivedmesh.h"
+#include "BKE_editmesh.h"
 #include "BKE_mesh.h"
 #include "BKE_library.h"
 #include "BKE_modifier.h"
@@ -55,7 +56,7 @@ static void initData(ModifierData *md)
 	ParticleSystemModifierData *psmd = (ParticleSystemModifierData *) md;
 	psmd->psys = NULL;
 	psmd->mesh_final = NULL;
-	psmd->mesh_deformed = NULL;
+	psmd->mesh_original = NULL;
 	psmd->totdmvert = psmd->totdmedge = psmd->totdmface = 0;
 }
 static void freeData(ModifierData *md)
@@ -65,9 +66,9 @@ static void freeData(ModifierData *md)
 	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->totdmvert = psmd->totdmedge = psmd->totdmface = 0;
@@ -88,7 +89,7 @@ static void copyData(const ModifierData *md, ModifierData *target)
 	modifier_copyData_generic(md, target);
 
 	tpsmd->mesh_final = NULL;
-	tpsmd->mesh_deformed = NULL;
+	tpsmd->mesh_original = NULL;
 	tpsmd->totdmvert = tpsmd->totdmedge = tpsmd->totdmface = 0;
 }
 
@@ -129,9 +130,9 @@ static void deformVerts(
 	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;
 		}
 	}
 	else if (psmd->flag & eParticleSystemFlag_file_loaded) {
@@ -156,20 +157,40 @@ static void deformVerts(
 	BKE_mesh_tessface_ensure(psmd->mesh_final);
 
 	if (!psmd->mesh_final->runtime.deformed_only) {
-		/* XXX Think we can assume here that if current DM is not only-deformed, ob->deformedOnly has been set.
-		 *     This is awfully weak though. :| */
-		if (ctx->object->derivedDeform) {
-			DM_to_mesh(ctx->object->derivedDeform, psmd->mesh_deformed, ctx->object, CD_MASK_EVERYTHING, false);
+		/* Get the original mesh from the object, this is what the particles
+		 * are attached to so in case of non-deform modifiers we need to remap
+		 * them to the final mesh (typically subdivision surfaces). */
+		Mesh *mesh_original = NULL;
+
+		if (ctx->object->type == OB_MESH) {
+			BMEditMesh *edit_btmesh = BKE_editmesh_from_object(ctx->object);
+
+			if (edit_btmesh) {
+				/* In edit mode get directly from the edit mesh. */
+				psmd->mesh_original = BKE_bmesh_to_mesh_nomain(edit_btmesh->bm, &(struct BMeshToMeshParams){0});
+			}
+			else {
+				/* Otherwise get regular mesh. */
+				mesh_original = ctx->object->data;
+			}
 		}
-		else {  /* Can happen in some cases, e.g. when rendering from Edit mode... */
-			BKE_id_copy_ex(NULL, &mesh_src->id, (ID **)&psmd->mesh_deformed,
+		else {
+			mesh_original = mesh_src;
+		}
+
+		if (mesh_original) {
+			/* Make a persistent copy of the mesh. We don't actually need
+			 * all this data, just some topology for remapping. Could be
+			 * optimized once. */
+			BKE_id_copy_ex(NULL, &mesh_original->id, (ID **)&psmd->mesh_original,
 			               LIB_ID_CREATE_NO_MAIN |
 			               LIB_ID_CREATE_NO_USER_REFCOUNT |
 			               LIB_ID_CREATE_NO_DEG_TAG |
 			               LIB_ID_COPY_NO_PREVIEW,
 			               false);
 		}
-		BKE_mesh_tessface_ensure(psmd->mesh_deformed);
+
+		BKE_mesh_tessface_ensure(psmd->mesh_original);
 	}
 
 	if (mesh_src != psmd->mesh_final && mesh_src != mesh) {