Removing ParticleSystem->frand arrays to avoid memory corruption issues

in threaded depgraph updates and effector list construction.

Gathering effectors during depgraph updates will call the
psys_check_enabled function. This in turn contained a DNA alloc call
for the psys->frand RNG arrays, which is really bad because data must be
immutable during these effector constructions.

To avoid such allocs the frand array is now global for all particle
systems. To avoid correlation of pseudo-random numbers the psys->seed
value is complemented with random offset and multiplier for the actual
float array. This is not ideal, but work sufficiently well (given that
random numbers were already really limited and show repetition quite
easily for particle counts > PSYS_FRAND_COUNT).

1 files changed, 31 insertions, 35 deletions

diff --git a/source/blender/blenkernel/intern/particle.c b/source/blender/blenkernel/intern/particle.c
index edf902e0eb5..48db07d45eb 100644
--- a/source/blender/blenkernel/intern/particle.c
+++ b/source/blender/blenkernel/intern/particle.c
@@ -85,6 +85,17 @@
 
 #include "RE_render_ext.h"
 
+void psys_init_rng(void)
+{
+	int i;
+	BLI_srandom(5831); /* arbitrary */
+	for (i = 0; i < PSYS_FRAND_COUNT; ++i) {
+		PSYS_FRAND_BASE[i] = BLI_frand();
+		PSYS_FRAND_SEED_OFFSET[i] = (unsigned int)BLI_rand();
+		PSYS_FRAND_SEED_MULTIPLIER[i] = (unsigned int)BLI_rand();
+	}
+}
+
 static void get_child_modifier_parameters(ParticleSettings *part, ParticleThreadContext *ctx,
                                           ChildParticle *cpa, short cpa_from, int cpa_num, float *cpa_fuv, float *orco, ParticleTexture *ptex);
 static void do_child_modifiers(ParticleSimulationData *sim,
@@ -260,16 +271,6 @@ int psys_in_edit_mode(Scene *scene, ParticleSystem *psys)
 {
 	return (scene->basact && (scene->basact->object->mode & OB_MODE_PARTICLE_EDIT) && psys == psys_get_current((scene->basact)->object) && (psys->edit || psys->pointcache->edit) && !psys->renderdata);
 }
-static void psys_create_frand(ParticleSystem *psys)
-{
-	int i;
-	float *rand = psys->frand = MEM_callocN(PSYS_FRAND_COUNT * sizeof(float), "particle randoms");
-
-	BLI_srandom(psys->seed);
-
-	for (i = 0; i < 1024; i++, rand++)
-		*rand = BLI_frand();
-}
 int psys_check_enabled(Object *ob, ParticleSystem *psys)
 {
 	ParticleSystemModifierData *psmd;
@@ -285,14 +286,6 @@ int psys_check_enabled(Object *ob, ParticleSystem *psys)
 	else if (!(psmd->modifier.mode & eModifierMode_Realtime))
 		return 0;
 
-	/* perhaps not the perfect place, but we have to be sure the rands are there before usage */
-	if (!psys->frand)
-		psys_create_frand(psys);
-	else if (psys->recalc & PSYS_RECALC_RESET) {
-		MEM_freeN(psys->frand);
-		psys_create_frand(psys);
-	}
-	
 	return 1;
 }
 
@@ -579,9 +572,6 @@ void psys_free(Object *ob, ParticleSystem *psys)
 
 		pdEndEffectors(&psys->effectors);
 
-		if (psys->frand)
-			MEM_freeN(psys->frand);
-
 		if (psys->pdd) {
 			psys_free_pdd(psys);
 			MEM_freeN(psys->pdd);
@@ -787,7 +777,7 @@ void psys_render_restore(Object *ob, ParticleSystem *psys)
 		PARTICLE_P;
 
 		LOOP_PARTICLES {
-			if (PSYS_FRAND(p) > disp)
+			if (psys_frand(psys, p) > disp)
 				pa->flag |= PARS_NO_DISP;
 			else
 				pa->flag &= ~PARS_NO_DISP;
@@ -2680,7 +2670,7 @@ static void psys_thread_create_path(ParticleThread *thread, struct ChildParticle
 	/* get different child parameters from textures & vgroups */
 	get_child_modifier_parameters(part, ctx, cpa, cpa_from, cpa_num, cpa_fuv, orco, &ptex);
 
-	if (ptex.exist < PSYS_FRAND(i + 24)) {
+	if (ptex.exist < psys_frand(psys, i + 24)) {
 		child_keys->steps = -1;
 		return;
 	}
@@ -2996,7 +2986,7 @@ void psys_cache_paths(ParticleSimulationData *sim, float cfra)
 	LOOP_SHOWN_PARTICLES {
 		if (!psys->totchild) {
 			psys_get_texture(sim, pa, &ptex, PAMAP_LENGTH, 0.f);
-			pa_length = ptex.length * (1.0f - part->randlength * PSYS_FRAND(psys->seed + p));
+			pa_length = ptex.length * (1.0f - part->randlength * psys_frand(psys, psys->seed + p));
 			if (vg_length)
 				pa_length *= psys_particle_value_from_verts(psmd->dm, part->from, pa, vg_length);
 		}
@@ -3832,8 +3822,8 @@ static void get_cpa_texture(DerivedMesh *dm, ParticleSystem *psys, ParticleSetti
 	ptex->gravity = ptex->field = ptex->time = ptex->clump = ptex->kink =
 	ptex->effector = ptex->rough1 = ptex->rough2 = ptex->roughe = 1.0f;
 
-	ptex->length = 1.0f - part->randlength * PSYS_FRAND(child_index + 26);
-	ptex->length *= part->clength_thres < PSYS_FRAND(child_index + 27) ? part->clength : 1.0f;
+	ptex->length = 1.0f - part->randlength * psys_frand(psys, child_index + 26);
+	ptex->length *= part->clength_thres < psys_frand(psys, child_index + 27) ? part->clength : 1.0f;
 
 	for (m = 0; m < MAX_MTEX; m++, mtexp++) {
 		mtex = *mtexp;
@@ -3995,7 +3985,7 @@ float psys_get_child_time(ParticleSystem *psys, ChildParticle *cpa, float cfra,
 			w++;
 		}
 
-		life = part->lifetime * (1.0f - part->randlife * PSYS_FRAND(cpa - psys->child + 25));
+		life = part->lifetime * (1.0f - part->randlife * psys_frand(psys, cpa - psys->child + 25));
 	}
 	else {
 		ParticleData *pa = psys->particles + cpa->parent;
@@ -4024,7 +4014,7 @@ float psys_get_child_size(ParticleSystem *psys, ChildParticle *cpa, float UNUSED
 	size *= part->childsize;
 
 	if (part->childrandsize != 0.0f)
-		size *= 1.0f - part->childrandsize * PSYS_FRAND(cpa - psys->child + 26);
+		size *= 1.0f - part->childrandsize * psys_frand(psys, cpa - psys->child + 26);
 
 	return size;
 }
@@ -4036,7 +4026,7 @@ static void get_child_modifier_parameters(ParticleSettings *part, ParticleThread
 	get_cpa_texture(ctx->dm, psys, part, psys->particles + cpa->pa[0], i, cpa_num, cpa_fuv, orco, ptex, PAMAP_DENS | PAMAP_CHILD, psys->cfra);
 
 
-	if (ptex->exist < PSYS_FRAND(i + 24))
+	if (ptex->exist < psys_frand(psys, i + 24))
 		return;
 
 	if (ctx->vg_length)
@@ -4091,11 +4081,17 @@ static void do_child_modifiers(ParticleSimulationData *sim, ParticleTexture *pte
 	if (rough1 > 0.f)
 		do_rough(orco, mat, t, rough1, part->rough1_size, 0.0, state);
 
-	if (rough2 > 0.f)
-		do_rough(sim->psys->frand + ((i + 27) % (PSYS_FRAND_COUNT - 3)), mat, t, rough2, part->rough2_size, part->rough2_thres, state);
+	if (rough2 > 0.f) {
+		float vec[3];
+		psys_frand_vec(sim->psys, i + 27, vec);
+		do_rough(vec, mat, t, rough2, part->rough2_size, part->rough2_thres, state);
+	}
 
-	if (rough_end > 0.f)
-		do_rough_end(sim->psys->frand + ((i + 27) % (PSYS_FRAND_COUNT - 3)), mat, t, rough_end, part->rough_end_shape, state);
+	if (rough_end > 0.f) {
+		float vec[3];
+		psys_frand_vec(sim->psys, i + 27, vec);
+		do_rough_end(vec, mat, t, rough_end, part->rough_end_shape, state);
+	}
 }
 /* get's hair (or keyed) particles state at the "path time" specified in state->time */
 void psys_get_particle_on_path(ParticleSimulationData *sim, int p, ParticleKey *state, int vel)
@@ -4358,7 +4354,7 @@ int psys_get_particle_state(ParticleSimulationData *sim, int p, ParticleKey *sta
 				}
 			}
 
-			state->time = (cfra - (part->sta + (part->end - part->sta) * PSYS_FRAND(p + 23))) / (part->lifetime * PSYS_FRAND(p + 24));
+			state->time = (cfra - (part->sta + (part->end - part->sta) * psys_frand(psys, p + 23))) / (part->lifetime * psys_frand(psys, p + 24));
 
 			psys_get_particle_on_path(sim, p, state, 1);
 			return 1;
@@ -4567,7 +4563,7 @@ void psys_get_dupli_path_transform(ParticleSimulationData *sim, ParticleData *pa
 			float q_phase[4];
 			float phasefac = psys->part->phasefac;
 			if (psys->part->randphasefac != 0.0f)
-				phasefac += psys->part->randphasefac * PSYS_FRAND((pa - psys->particles) + 20);
+				phasefac += psys->part->randphasefac * psys_frand(psys, (pa - psys->particles) + 20);
 			axis_angle_to_quat(q_phase, vec, phasefac * (float)M_PI);
 
 			mul_qt_v3(q_phase, side);