Improvements for particle grid distribution:

* Particles that aren't shown are now actually deleted (huge memory savings for flat objects).
* Grid distribution for flat objects is now done on the surface object surface without offset.
* Invert grid option wasn't in ui and it didn't work for non-volume grids.
* New parameter to randomize the grid point locations.
* Resolution soft/hard limits changed to even 50/250.

4 files changed, 87 insertions, 15 deletions

diff --git a/release/scripts/ui/properties_particle.py b/release/scripts/ui/properties_particle.py
index 9cde2891177..596d0381f43 100644
--- a/release/scripts/ui/properties_particle.py
+++ b/release/scripts/ui/properties_particle.py
@@ -190,8 +190,10 @@ class PARTICLE_PT_emission(ParticleButtonsPanel, bpy.types.Panel):
         row.prop(part, "emit_from", expand=True)
 
         row = layout.row()
-        row.prop(part, "use_emit_random")
-        if part.distribution != 'GRID':
+        if part.distribution == 'GRID':
+            row.prop(part, "invert_grid")
+        else:
+            row.prop(part, "use_emit_random")
             row.prop(part, "use_even_distribution")
 
         if part.emit_from == 'FACE' or part.emit_from == 'VOLUME':
@@ -206,6 +208,7 @@ class PARTICLE_PT_emission(ParticleButtonsPanel, bpy.types.Panel):
                 row.prop(part, "jitter_factor", text="Jittering Amount", slider=True)
             elif part.distribution == 'GRID':
                 row.prop(part, "grid_resolution")
+                row.prop(part, "grid_random", text="Random", slider=True)
 
 
 class PARTICLE_PT_hair_dynamics(ParticleButtonsPanel, bpy.types.Panel):
diff --git a/source/blender/blenkernel/intern/particle_system.c b/source/blender/blenkernel/intern/particle_system.c
index a0948e61708..4d3a908edb0 100644
--- a/source/blender/blenkernel/intern/particle_system.c
+++ b/source/blender/blenkernel/intern/particle_system.c
@@ -137,9 +137,9 @@ static int tot_particles(ParticleSystem *psys, PTCacheID *pid)
 	if(pid && psys->pointcache->flag & PTCACHE_EXTERNAL)
 		return pid->cache->totpoint;
 	else if(psys->part->distr == PART_DISTR_GRID && psys->part->from != PART_FROM_VERT)
-		return psys->part->grid_res * psys->part->grid_res * psys->part->grid_res;
+		return psys->part->grid_res * psys->part->grid_res * psys->part->grid_res - psys->totunexist;
 	else
-		return psys->part->totpart;
+		return psys->part->totpart - psys->totunexist;
 }
 
 void psys_reset(ParticleSystem *psys, int mode)
@@ -439,9 +439,14 @@ static void distribute_particles_in_grid(DerivedMesh *dm, ParticleSystem *psys)
 	size[(axis+1)%3] = MIN2(size[(axis+1)%3],res);
 	size[(axis+2)%3] = MIN2(size[(axis+2)%3],res);
 
-	min[0]+=d/2.0f;
-	min[1]+=d/2.0f;
-	min[2]+=d/2.0f;
+	size[0] = MAX2(size[0], 1);
+	size[1] = MAX2(size[1], 1);
+	size[2] = MAX2(size[2], 1);
+
+	/* no full offset for flat/thin objects */
+	min[0]+= d < delta[0] ? d/2.f : delta[0]/2.f;
+	min[1]+= d < delta[1] ? d/2.f : delta[1]/2.f;
+	min[2]+= d < delta[2] ? d/2.f : delta[2]/2.f;
 
 	for(i=0,p=0,pa=psys->particles; i<res; i++){
 		for(j=0; j<res; j++){
@@ -497,7 +502,7 @@ static void distribute_particles_in_grid(DerivedMesh *dm, ParticleSystem *psys)
 
 					pa=psys->particles + a1*a1mul + a2*a2mul;
 					VECCOPY(co1,pa->fuv);
-					co1[a]-=d/2.0f;
+					co1[a]-= d < delta[a] ? d/2.f : delta[a]/2.f;
 					VECCOPY(co2,co1);
 					co2[a]+=delta[a] + 0.001f*d;
 					co1[a]-=0.001f*d;
@@ -553,6 +558,18 @@ static void distribute_particles_in_grid(DerivedMesh *dm, ParticleSystem *psys)
 			}
 		}
 	}
+
+	if(psys->part->grid_rand > 0.f) {
+		float rfac = d * psys->part->grid_rand;
+		for(p=0,pa=psys->particles; p<psys->totpart; p++,pa++){
+			if(pa->flag & PARS_UNEXIST)
+				continue;
+
+			pa->fuv[0] += rfac * (PSYS_FRAND(p + 31) - 0.5f);
+			pa->fuv[1] += rfac * (PSYS_FRAND(p + 32) - 0.5f);
+			pa->fuv[2] += rfac * (PSYS_FRAND(p + 33) - 0.5f);
+		}
+	}
 }
 
 /* modified copy from rayshade.c */
@@ -1554,8 +1571,51 @@ static void initialize_all_particles(ParticleSimulationData *sim)
 	ParticleSystem *psys = sim->psys;
 	PARTICLE_P;
 
-	LOOP_PARTICLES
+	psys->totunexist = 0;
+
+	LOOP_PARTICLES {
 		initialize_particle(sim, pa, p);
+		if(pa->flag & PARS_UNEXIST)
+			psys->totunexist++;
+	}
+
+	/* Free unexisting particles. */
+	if(psys->totpart && psys->totunexist == psys->totpart) {
+		if(psys->particles->boid)
+			MEM_freeN(psys->particles->boid);
+
+		MEM_freeN(psys->particles);
+		psys->particles = NULL;
+		psys->totpart = psys->totunexist = 0;
+	}
+
+	if(psys->totunexist) {
+		int newtotpart = psys->totpart - psys->totunexist;
+		ParticleData *npa, *newpars;
+		
+		npa = newpars = MEM_callocN(newtotpart * sizeof(ParticleData), "particles");
+
+		for(p=0, pa=psys->particles; p<newtotpart; p++, pa++, npa++) {
+			while(pa->flag & PARS_UNEXIST)
+				pa++;
+
+			memcpy(npa, pa, sizeof(ParticleData));
+		}
+
+		if(psys->particles->boid)
+			MEM_freeN(psys->particles->boid);
+		MEM_freeN(psys->particles);
+		psys->particles = newpars;
+		psys->totpart -= psys->totunexist;
+
+		if(psys->particles->boid) {
+			BoidParticle *newboids = MEM_callocN(psys->totpart * sizeof(BoidParticle), "boid particles");
+
+			LOOP_PARTICLES
+				pa->boid = newboids++;
+
+		}
+	}
 	
 	if(psys->part->type != PART_FLUID) {
 #if 0 // XXX old animation system
@@ -4091,6 +4151,9 @@ void particle_system_update(Scene *scene, Object *ob, ParticleSystem *psys)
 	if(psys->recalc & PSYS_RECALC_TYPE)
 		psys_changed_type(&sim);
 
+	if(psys->recalc & PSYS_RECALC_RESET)
+		psys->totunexist = 0;
+
 	/* setup necessary physics type dependent additional data if it doesn't yet exist */
 	psys_prepare_physics(&sim);
 
diff --git a/source/blender/makesdna/DNA_particle_types.h b/source/blender/makesdna/DNA_particle_types.h
index f009f3a9eb0..9ead2a3f572 100644
--- a/source/blender/makesdna/DNA_particle_types.h
+++ b/source/blender/makesdna/DNA_particle_types.h
@@ -168,8 +168,8 @@ typedef struct ParticleSettings {
 
 	/* general values */
 	float sta, end, lifetime, randlife;
-	float timetweak, jitfac, eff_hair;
-	int totpart, userjit, grid_res;
+	float timetweak, jitfac, eff_hair, grid_rand;
+	int totpart, userjit, grid_res, rt;
 
 	/* initial velocity factors */
 	float normfac, obfac, randfac, partfac, tanfac, tanphase, reactfac;
@@ -247,7 +247,7 @@ typedef struct ParticleSystem{				/* note, make sure all (runtime) are NULL's in
 	float imat[4][4];	/* used for duplicators */
 	float cfra, tree_frame;
 	int seed, child_seed;
-	int flag, totpart, totchild, totcached, totchildcache;
+	int flag, totpart, totunexist, totchild, totcached, totchildcache, rt;
 	short recalc, target_psys, totkeyed, bakespace;
 
 	char bb_uvname[3][32];					/* billboard uv name */
diff --git a/source/blender/makesrna/intern/rna_particle.c b/source/blender/makesrna/intern/rna_particle.c
index cbf8c7093d7..82e2eb96002 100644
--- a/source/blender/makesrna/intern/rna_particle.c
+++ b/source/blender/makesrna/intern/rna_particle.c
@@ -1289,7 +1289,7 @@ static void rna_def_particle_settings(BlenderRNA *brna)
 
 	prop= RNA_def_property(srna, "invert_grid", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_sdna(prop, NULL, "flag", PART_GRID_INVERT);
-	RNA_def_property_ui_text(prop, "Invert", "Invert what is considered object and what is not");
+	RNA_def_property_ui_text(prop, "Invert Grid", "Invert what is considered object and what is not");
 	RNA_def_property_update(prop, 0, "rna_Particle_reset");
 
 	prop= RNA_def_property(srna, "apply_effector_to_children", PROP_BOOLEAN, PROP_NONE);
@@ -1684,11 +1684,17 @@ static void rna_def_particle_settings(BlenderRNA *brna)
 	prop= RNA_def_property(srna, "grid_resolution", PROP_INT, PROP_UNSIGNED);
 	RNA_def_property_int_sdna(prop, NULL, "grid_res");
 	RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
-	RNA_def_property_range(prop, 1, 215); /* ~10M particles in a cube */
-	RNA_def_property_ui_range(prop, 1, 46, 1, 0); /* ~100k particles in a cube */
+	RNA_def_property_range(prop, 1, 250); /* ~15M particles in a cube (ouch!), but could be very usable in a plane */
+	RNA_def_property_ui_range(prop, 1, 50, 1, 0); /* ~100k particles in a cube */
 	RNA_def_property_ui_text(prop, "Resolution", "The resolution of the particle grid");
 	RNA_def_property_update(prop, 0, "rna_Particle_reset");
 
+	prop= RNA_def_property(srna, "grid_random", PROP_FLOAT, PROP_NONE);
+	RNA_def_property_float_sdna(prop, NULL, "grid_rand");
+	RNA_def_property_range(prop, 0.0f, 1.0f);
+	RNA_def_property_ui_text(prop, "Grid Randomness", "Add random offset to the grid locations");
+	RNA_def_property_update(prop, 0, "rna_Particle_reset");
+
 	/* initial velocity factors */
 	prop= RNA_def_property(srna, "normal_factor", PROP_FLOAT, PROP_NONE);
 	RNA_def_property_float_sdna(prop, NULL, "normfac");//optional if prop names are the same