Particles: patch #35205 by Jakub Zolcik

The Emission panel now has a Use Modifier Stack option to emit particles from
the mesh with modifiers applied. Previously particles would only be emitted from
faces that exist in the original mesh. There are some caveats however:
http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.68/Tools#Particles

2 files changed, 55 insertions, 18 deletions

diff --git a/source/blender/blenkernel/intern/particle.c b/source/blender/blenkernel/intern/particle.c
index a95afe14a48..3ab535febb1 100644
--- a/source/blender/blenkernel/intern/particle.c
+++ b/source/blender/blenkernel/intern/particle.c
@@ -3636,6 +3636,8 @@ static void default_particle_settings(ParticleSettings *part)
 
 	if (!part->effector_weights)
 		part->effector_weights = BKE_add_effector_weights(NULL);
+
+	part->use_modifier_stack = false;
 }
 
 
diff --git a/source/blender/blenkernel/intern/particle_system.c b/source/blender/blenkernel/intern/particle_system.c
index eb95ca16fc3..81c7fc44715 100644
--- a/source/blender/blenkernel/intern/particle_system.c
+++ b/source/blender/blenkernel/intern/particle_system.c
@@ -341,6 +341,7 @@ void psys_calc_dmcache(Object *ob, DerivedMesh *dm, ParticleSystem *psys)
 	 *            each original elements can reference its derived elements
 	 */
 	Mesh *me= (Mesh*)ob->data;
+	bool use_modifier_stack= psys->part->use_modifier_stack;
 	PARTICLE_P;
 	
 	/* CACHE LOCATIONS */
@@ -351,17 +352,33 @@ void psys_calc_dmcache(Object *ob, DerivedMesh *dm, ParticleSystem *psys)
 
 		if (psys->part->from == PART_FROM_VERT) {
 			totdmelem= dm->getNumVerts(dm);
-			totelem= me->totvert;
-			origindex= dm->getVertDataArray(dm, CD_ORIGINDEX);
+
+			if (use_modifier_stack) {
+				totelem= totdmelem;
+				origindex= NULL;
+			}
+			else {
+				totelem= me->totvert;
+				origindex= dm->getVertDataArray(dm, CD_ORIGINDEX);
+			}
 		}
 		else { /* FROM_FACE/FROM_VOLUME */
 			totdmelem= dm->getNumTessFaces(dm);
-			totelem= me->totpoly;
-			origindex = dm->getTessFaceDataArray(dm, CD_ORIGINDEX);
-			/* for face lookups we need the poly origindex too */
-			origindex_poly = dm->getPolyDataArray(dm, CD_ORIGINDEX);
-			if (origindex_poly == NULL) {
-				origindex = NULL;
+
+			if (use_modifier_stack) {
+				totelem= totdmelem;
+				origindex= NULL;
+				origindex_poly= NULL;
+			}
+			else {
+				totelem= me->totpoly;
+				origindex= dm->getTessFaceDataArray(dm, CD_ORIGINDEX);
+
+				/* for face lookups we need the poly origindex too */
+				origindex_poly= dm->getPolyDataArray(dm, CD_ORIGINDEX);
+				if (origindex_poly == NULL) {
+					origindex= NULL;
+				}
 			}
 		}
 	
@@ -373,11 +390,16 @@ void psys_calc_dmcache(Object *ob, DerivedMesh *dm, ParticleSystem *psys)
 			node->link = SET_INT_IN_POINTER(i);
 
 			/* may be vertex or face origindex */
-			origindex_final = origindex ? origindex[i] : ORIGINDEX_NONE;
+			if (use_modifier_stack) {
+				origindex_final = i;
+			}
+			else {
+				origindex_final = origindex ? origindex[i] : ORIGINDEX_NONE;
 
-			/* if we have a poly source, do an index lookup */
-			if (origindex_poly && origindex_final != ORIGINDEX_NONE) {
-				origindex_final = origindex_poly[origindex_final];
+				/* if we have a poly source, do an index lookup */
+				if (origindex_poly && origindex_final != ORIGINDEX_NONE) {
+					origindex_final = origindex_poly[origindex_final];
+				}
 			}
 
 			if (origindex_final != ORIGINDEX_NONE) {
@@ -395,18 +417,27 @@ void psys_calc_dmcache(Object *ob, DerivedMesh *dm, ParticleSystem *psys)
 		/* cache the verts/faces! */
 		LOOP_PARTICLES {
 			if (pa->num < 0) {
-				pa->num_dmcache = -1;
+				pa->num_dmcache = DMCACHE_NOTFOUND;
 				continue;
 			}
 
 			if (psys->part->from == PART_FROM_VERT) {
-				if (nodearray[pa->num])
+				if (pa->num < totelem && nodearray[pa->num])
 					pa->num_dmcache= GET_INT_FROM_POINTER(nodearray[pa->num]->link);
+				else
+					pa->num_dmcache = DMCACHE_NOTFOUND;
 			}
 			else { /* FROM_FACE/FROM_VOLUME */
 				/* Note that sometimes the pa->num is over the nodearray size, this is bad, maybe there is a better place to fix this,
 				 * but for now passing NULL is OK. every face will be searched for the particle so its slower - Campbell */
-				pa->num_dmcache= psys_particle_dm_face_lookup(ob, dm, pa->num, pa->fuv, pa->num < totelem ? nodearray[pa->num] : NULL);
+				if (use_modifier_stack) {
+					if (pa->num < totelem && nodearray[pa->num])
+						pa->num_dmcache = GET_INT_FROM_POINTER(nodearray[pa->num]->link);
+					else
+						pa->num_dmcache = DMCACHE_NOTFOUND;
+				}
+				else
+					pa->num_dmcache= psys_particle_dm_face_lookup(ob, dm, pa->num, pa->fuv, pa->num < totelem ? nodearray[pa->num] : NULL);
 			}
 		}
 
@@ -419,7 +450,7 @@ void psys_calc_dmcache(Object *ob, DerivedMesh *dm, ParticleSystem *psys)
 		 * an invalid value, just in case */
 		
 		LOOP_PARTICLES
-			pa->num_dmcache = -1;
+			pa->num_dmcache = DMCACHE_NOTFOUND;
 	}
 }
 
@@ -1110,7 +1141,10 @@ static int distribute_threads_init_data(ParticleThread *threads, Scene *scene, D
 		distr = part->distr;
 		BLI_srandom(31415926 + psys->seed);
 		
-		dm= CDDM_from_mesh((Mesh*)ob->data, ob);
+		if (psys->part->use_modifier_stack)
+			dm = finaldm;
+		else
+			dm= CDDM_from_mesh((Mesh*)ob->data, ob);
 
 		/* BMESH ONLY, for verts we don't care about tessfaces */
 		if (from != PART_FROM_VERT) {
@@ -1118,7 +1152,8 @@ static int distribute_threads_init_data(ParticleThread *threads, Scene *scene, D
 		}
 
 		/* we need orco for consistent distributions */
-		DM_add_vert_layer(dm, CD_ORCO, CD_ASSIGN, BKE_mesh_orco_verts_get(ob));
+		if (!CustomData_has_layer(&dm->vertData, CD_ORCO))
+			DM_add_vert_layer(dm, CD_ORCO, CD_ASSIGN, BKE_mesh_orco_verts_get(ob));
 
 		if (from == PART_FROM_VERT) {
 			MVert *mv= dm->getVertDataArray(dm, CD_MVERT);