Random number generator: replace a bunch of usage of the global random number

generator with a local one. It's not thread safe and will not give repeatable
results, so in most cases it should not be used.

Also fixes #34992 where the noise texture of a displacement modifier was not
properly random in opengl animation render, because the seed got reset to a
fixed value by an unrelated function while for final render it changed each
frame.

7 files changed, 83 insertions, 51 deletions

diff --git a/source/blender/blenkernel/intern/anim.c b/source/blender/blenkernel/intern/anim.c
index 6fa33e8d3c5..1f54da402ab 100644
--- a/source/blender/blenkernel/intern/anim.c
+++ b/source/blender/blenkernel/intern/anim.c
@@ -1263,6 +1263,7 @@ static void new_particle_duplilist(ListBase *lb, ID *id, Scene *scene, Object *p
 	ChildParticle *cpa = NULL;
 	ParticleKey state;
 	ParticleCacheKey *cache;
+	RNG *rng = NULL;
 	float ctime, pa_time, scale = 1.0f;
 	float tmat[4][4], mat[4][4], pamat[4][4], vec[3], size = 0.0;
 	float (*obmat)[4], (*oldobmat)[4];
@@ -1293,14 +1294,9 @@ static void new_particle_duplilist(ListBase *lb, ID *id, Scene *scene, Object *p
 	totpart = psys->totpart;
 	totchild = psys->totchild;
 
-	BLI_srandom(31415926 + psys->seed);
-
 	if ((psys->renderdata || part->draw_as == PART_DRAW_REND) && ELEM(part->ren_as, PART_DRAW_OB, PART_DRAW_GR)) {
 		ParticleSimulationData sim = {NULL};
-		sim.scene = scene;
-		sim.ob = par;
-		sim.psys = psys;
-		sim.psmd = psys_get_modifier(par, psys);
+
 		/* make sure emitter imat is in global coordinates instead of render view coordinates */
 		invert_m4_m4(par->imat, par->obmat);
 
@@ -1332,6 +1328,12 @@ static void new_particle_duplilist(ListBase *lb, ID *id, Scene *scene, Object *p
 
 		psys_check_group_weights(part);
 
+		sim.scene = scene;
+		sim.ob = par;
+		sim.psys = psys;
+		sim.psmd = psys_get_modifier(par, psys);
+		sim.rng = BLI_rng_new(0);
+
 		psys->lattice = psys_get_lattice(&sim);
 
 		/* gather list of objects or single object */
@@ -1378,6 +1380,8 @@ static void new_particle_duplilist(ListBase *lb, ID *id, Scene *scene, Object *p
 			obcopy = *ob;
 		}
 
+		rng = BLI_rng_new_srandom(31415926 + psys->seed);
+
 		if (totchild == 0 || part->draw & PART_DRAW_PARENT)
 			a = 0;
 		else
@@ -1417,7 +1421,7 @@ static void new_particle_duplilist(ListBase *lb, ID *id, Scene *scene, Object *p
 
 				/* for groups, pick the object based on settings */
 				if (part->draw & PART_DRAW_RAND_GR)
-					b = BLI_rand() % totgroup;
+					b = BLI_rng_get_int(rng) % totgroup;
 				else
 					b = a % totgroup;
 
@@ -1561,6 +1565,8 @@ static void new_particle_duplilist(ListBase *lb, ID *id, Scene *scene, Object *p
 		}
 		else
 			*ob = obcopy;
+
+		BLI_rng_free(sim.rng);
 	}
 
 	/* clean up */
@@ -1573,6 +1579,9 @@ static void new_particle_duplilist(ListBase *lb, ID *id, Scene *scene, Object *p
 		end_latt_deform(psys->lattice);
 		psys->lattice = NULL;
 	}
+
+	if (rng)
+		BLI_rng_free(rng);
 }
 
 static Object *find_family_object(Object **obar, char *family, char ch)
diff --git a/source/blender/blenkernel/intern/boids.c b/source/blender/blenkernel/intern/boids.c
index b6f1b88c912..dfffb7c795e 100644
--- a/source/blender/blenkernel/intern/boids.c
+++ b/source/blender/blenkernel/intern/boids.c
@@ -234,9 +234,9 @@ static int rule_avoid_collision(BoidRule *rule, BoidBrainData *bbd, BoidValues *
 			if (dot_v3v3(col.pce.nor, pa->prev_state.ave) < -0.99f) {
 				/* don't know why, but uneven range [0.0, 1.0] */
 				/* works much better than even [-1.0, 1.0] */
-				bbd->wanted_co[0] = BLI_frand();
-				bbd->wanted_co[1] = BLI_frand();
-				bbd->wanted_co[2] = BLI_frand();
+				bbd->wanted_co[0] = BLI_rng_get_float(bbd->rng);
+				bbd->wanted_co[1] = BLI_rng_get_float(bbd->rng);
+				bbd->wanted_co[2] = BLI_rng_get_float(bbd->rng);
 			}
 			else {
 				copy_v3_v3(bbd->wanted_co, col.pce.nor);
@@ -558,9 +558,9 @@ static int rule_average_speed(BoidRule *rule, BoidBrainData *bbd, BoidValues *va
 
 	if (asbr->wander > 0.0f) {
 		/* abuse pa->r_ave for wandering */
-		bpa->wander[0] += asbr->wander * (-1.0f + 2.0f * BLI_frand());
-		bpa->wander[1] += asbr->wander * (-1.0f + 2.0f * BLI_frand());
-		bpa->wander[2] += asbr->wander * (-1.0f + 2.0f * BLI_frand());
+		bpa->wander[0] += asbr->wander * (-1.0f + 2.0f * BLI_rng_get_float(bbd->rng));
+		bpa->wander[1] += asbr->wander * (-1.0f + 2.0f * BLI_rng_get_float(bbd->rng));
+		bpa->wander[2] += asbr->wander * (-1.0f + 2.0f * BLI_rng_get_float(bbd->rng));
 
 		normalize_v3(bpa->wander);
 
@@ -586,9 +586,9 @@ static int rule_average_speed(BoidRule *rule, BoidBrainData *bbd, BoidValues *va
 
 		/* may happen at birth */
 		if (dot_v2v2(bbd->wanted_co, bbd->wanted_co)==0.0f) {
-			bbd->wanted_co[0] = 2.0f*(0.5f - BLI_frand());
-			bbd->wanted_co[1] = 2.0f*(0.5f - BLI_frand());
-			bbd->wanted_co[2] = 2.0f*(0.5f - BLI_frand());
+			bbd->wanted_co[0] = 2.0f*(0.5f - BLI_rng_get_float(bbd->rng));
+			bbd->wanted_co[1] = 2.0f*(0.5f - BLI_rng_get_float(bbd->rng));
+			bbd->wanted_co[2] = 2.0f*(0.5f - BLI_rng_get_float(bbd->rng));
 		}
 		
 		/* leveling */
@@ -663,7 +663,7 @@ static int rule_fight(BoidRule *rule, BoidBrainData *bbd, BoidValues *val, Parti
 
 		/* attack if in range */
 		if (closest_dist <= bbd->part->boids->range + pa->size + enemy_pa->size) {
-			float damage = BLI_frand();
+			float damage = BLI_rng_get_float(bbd->rng);
 			float enemy_dir[3];
 
 			normalize_v3_v3(enemy_dir, bbd->wanted_co);
@@ -1164,9 +1164,9 @@ void boid_body(BoidBrainData *bbd, ParticleData *pa)
 			/* choose random direction to turn if wanted velocity */
 			/* is directly behind regardless of z-coordinate */
 			if (dot_v2v2(old_dir2, wanted_dir2) < -0.99f) {
-				wanted_dir[0] = 2.0f*(0.5f - BLI_frand());
-				wanted_dir[1] = 2.0f*(0.5f - BLI_frand());
-				wanted_dir[2] = 2.0f*(0.5f - BLI_frand());
+				wanted_dir[0] = 2.0f*(0.5f - BLI_rng_get_float(bbd->rng));
+				wanted_dir[1] = 2.0f*(0.5f - BLI_rng_get_float(bbd->rng));
+				wanted_dir[2] = 2.0f*(0.5f - BLI_rng_get_float(bbd->rng));
 				normalize_v3(wanted_dir);
 			}
 
diff --git a/source/blender/blenkernel/intern/effect.c b/source/blender/blenkernel/intern/effect.c
index 9e8693e957e..3fbbc484169 100644
--- a/source/blender/blenkernel/intern/effect.c
+++ b/source/blender/blenkernel/intern/effect.c
@@ -619,6 +619,7 @@ int get_effector_data(EffectorCache *eff, EffectorData *efd, EffectedPoint *poin
 			sim.scene= eff->scene;
 			sim.ob= eff->ob;
 			sim.psys= eff->psys;
+			sim.rng= NULL;
 
 			/* TODO: time from actual previous calculated frame (step might not be 1) */
 			state.time = cfra - 1.0f;
diff --git a/source/blender/blenkernel/intern/ocean.c b/source/blender/blenkernel/intern/ocean.c
index 695ac7da792..94dbe7b87c2 100644
--- a/source/blender/blenkernel/intern/ocean.c
+++ b/source/blender/blenkernel/intern/ocean.c
@@ -144,12 +144,12 @@ typedef struct Ocean {
 
 
 
-static float nextfr(float min, float max)
+static float nextfr(RNG *rng, float min, float max)
 {
-	return BLI_frand() * (min - max) + max;
+	return BLI_rng_get_float(rng) * (min - max) + max;
 }
 
-static float gaussRand(void)
+static float gaussRand(RNG *rng)
 {
 	/* Note: to avoid numerical problems with very small numbers, we make these variables singe-precision floats,
 	 * but later we call the double-precision log() and sqrt() functions instead of logf() and sqrtf().
@@ -765,6 +765,7 @@ void BKE_init_ocean(struct Ocean *o, int M, int N, float Lx, float Lz, float V,
                     float alignment, float depth, float time, short do_height_field, short do_chop, short do_normals,
                     short do_jacobian, int seed)
 {
+	RNG *rng;
 	int i, j, ii;
 
 	BLI_rw_mutex_lock(&o->oceanmutex, THREAD_LOCK_WRITE);
@@ -825,12 +826,12 @@ void BKE_init_ocean(struct Ocean *o, int M, int N, float Lx, float Lz, float V,
 			o->_k[i * (1 + o->_N / 2) + j] = sqrt(o->_kx[i] * o->_kx[i] + o->_kz[j] * o->_kz[j]);
 
 	/*srand(seed);*/
-	BLI_srand(seed);
+	rng = BLI_rng_new(seed);
 
 	for (i = 0; i < o->_M; ++i) {
 		for (j = 0; j < o->_N; ++j) {
-			float r1 = gaussRand();
-			float r2 = gaussRand();
+			float r1 = gaussRand(rng);
+			float r2 = gaussRand(rng);
 
 			fftw_complex r1r2;
 			init_complex(r1r2, r1, r2);
@@ -890,6 +891,7 @@ void BKE_init_ocean(struct Ocean *o, int M, int N, float Lx, float Lz, float V,
 
 	set_height_normalize_factor(o);
 
+	BLI_rng_free(rng);
 }
 
 void BKE_free_ocean_data(struct Ocean *oc)
@@ -1188,13 +1190,14 @@ void BKE_bake_ocean(struct Ocean *o, struct OceanCache *och, void (*update_cb)(v
 	int res_x = och->resolution_x;
 	int res_y = och->resolution_y;
 	char string[FILE_MAX];
+	//RNG *rng;
 
 	if (!o) return;
 
 	if (o->_do_jacobian) prev_foam = MEM_callocN(res_x * res_y * sizeof(float), "previous frame foam bake data");
 	else prev_foam = NULL;
 
-	BLI_srand(0);
+	//rng = BLI_rng_new(0);
 
 	/* setup image format */
 	imf.imtype = R_IMF_IMTYPE_OPENEXR;
@@ -1232,7 +1235,7 @@ void BKE_bake_ocean(struct Ocean *o, struct OceanCache *och, void (*update_cb)(v
 						pr = prev_foam[res_x * y + x];
 					}
 
-					/* r = BLI_frand(); */ /* UNUSED */ /* randomly reduce foam */
+					/* r = BLI_rng_get_float(rng); */ /* UNUSED */ /* randomly reduce foam */
 
 					/* pr = pr * och->foam_fade; */		/* overall fade */
 
@@ -1311,10 +1314,12 @@ void BKE_bake_ocean(struct Ocean *o, struct OceanCache *och, void (*update_cb)(v
 
 		if (cancel) {
 			if (prev_foam) MEM_freeN(prev_foam);
+			//BLI_rng_free(rng);
 			return;
 		}
 	}
 
+	//BLI_rng_free(rng);
 	if (prev_foam) MEM_freeN(prev_foam);
 	och->baked = 1;
 }
diff --git a/source/blender/blenkernel/intern/particle.c b/source/blender/blenkernel/intern/particle.c
index 4e78ab52499..b0ef6715382 100644
--- a/source/blender/blenkernel/intern/particle.c
+++ b/source/blender/blenkernel/intern/particle.c
@@ -264,11 +264,12 @@ 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);
+	RNG *rng = BLI_rng_new_srandom(psys->seed);
 
 	for (i = 0; i < 1024; i++, rand++)
-		*rand = BLI_frand();
+		*rand = BLI_rng_get_float(rng);
+
+	BLI_rng_free(rng);
 }
 int psys_check_enabled(Object *ob, ParticleSystem *psys)
 {
@@ -3302,8 +3303,11 @@ void psys_cache_edit_paths(Scene *scene, Object *ob, PTCacheEdit *edit, float cf
 		sim.ob = ob;
 		sim.psys = psys;
 		sim.psmd = psys_get_modifier(ob, psys);
+		sim.rng = BLI_rng_new(0);
 
 		psys_cache_child_paths(&sim, cfra, 1);
+
+		BLI_rng_free(sim.rng);
 	}
 
 	/* clear recalc flag if set here */
@@ -4660,6 +4664,7 @@ void psys_apply_hair_lattice(Scene *scene, Object *ob, ParticleSystem *psys)
 	sim.ob = ob;
 	sim.psys = psys;
 	sim.psmd = psys_get_modifier(ob, psys);
+	sim.rng = BLI_rng_new(0);
 
 	psys->lattice = psys_get_lattice(&sim);
 
@@ -4687,4 +4692,6 @@ void psys_apply_hair_lattice(Scene *scene, Object *ob, ParticleSystem *psys)
 		/* protect the applied shape */
 		psys->flag |= PSYS_EDITED;
 	}
+
+	BLI_rng_free(sim.rng);
 }
diff --git a/source/blender/blenkernel/intern/particle_system.c b/source/blender/blenkernel/intern/particle_system.c
index 5124cb1da26..f131e7297ed 100644
--- a/source/blender/blenkernel/intern/particle_system.c
+++ b/source/blender/blenkernel/intern/particle_system.c
@@ -423,7 +423,7 @@ void psys_calc_dmcache(Object *ob, DerivedMesh *dm, ParticleSystem *psys)
 	}
 }
 
-static void distribute_simple_children(Scene *scene, Object *ob, DerivedMesh *finaldm, ParticleSystem *psys)
+static void distribute_simple_children(Scene *scene, Object *ob, DerivedMesh *finaldm, ParticleSystem *psys, RNG *rng)
 {
 	ChildParticle *cpa = NULL;
 	int i, p;
@@ -440,9 +440,9 @@ static void distribute_simple_children(Scene *scene, Object *ob, DerivedMesh *fi
 					
 			/* create even spherical distribution inside unit sphere */
 			while (length>=1.0f) {
-				cpa->fuv[0]=2.0f*BLI_frand()-1.0f;
-				cpa->fuv[1]=2.0f*BLI_frand()-1.0f;
-				cpa->fuv[2]=2.0f*BLI_frand()-1.0f;
+				cpa->fuv[0]=2.0f*BLI_rng_get_float(rng)-1.0f;
+				cpa->fuv[1]=2.0f*BLI_rng_get_float(rng)-1.0f;
+				cpa->fuv[2]=2.0f*BLI_rng_get_float(rng)-1.0f;
 				length=len_v3(cpa->fuv);
 			}
 
@@ -872,7 +872,7 @@ static void distribute_threads_exec(ParticleThread *thread, ParticleData *pa, Ch
 						pa->foffset *= ctx->jit[p % (2 * ctx->jitlevel)];
 						break;
 					case PART_DISTR_RAND:
-						pa->foffset *= BLI_frand();
+						pa->foffset *= BLI_rng_get_float(ctx->sim.rng);
 						break;
 				}
 			}
@@ -1065,15 +1065,15 @@ static int distribute_threads_init_data(ParticleThread *threads, Scene *scene, D
 	if (from == PART_FROM_CHILD) {
 		/* Simple children */
 		if (part->childtype != PART_CHILD_FACES) {
-			BLI_srandom(31415926 + psys->seed + psys->child_seed);
-			distribute_simple_children(scene, ob, finaldm, psys);
+			BLI_rng_srandom(ctx->sim.rng, 31415926 + psys->seed + psys->child_seed);
+			distribute_simple_children(scene, ob, finaldm, psys, ctx->sim.rng);
 			return 0;
 		}
 	}
 	else {
 		/* Grid distribution */
 		if (part->distr==PART_DISTR_GRID && from != PART_FROM_VERT) {
-			BLI_srandom(31415926 + psys->seed);
+			BLI_rng_srandom(ctx->sim.rng, 31415926 + psys->seed);
 			dm= CDDM_from_mesh((Mesh*)ob->data, ob);
 			DM_ensure_tessface(dm);
 			distribute_grid(dm,psys);
@@ -1085,7 +1085,7 @@ static int distribute_threads_init_data(ParticleThread *threads, Scene *scene, D
 	/* Create trees and original coordinates if needed */
 	if (from == PART_FROM_CHILD) {
 		distr=PART_DISTR_RAND;
-		BLI_srandom(31415926 + psys->seed + psys->child_seed);
+		BLI_rng_srandom(ctx->sim.rng, 31415926 + psys->seed + psys->child_seed);
 		dm= finaldm;
 
 		/* BMESH ONLY */
@@ -1108,7 +1108,7 @@ static int distribute_threads_init_data(ParticleThread *threads, Scene *scene, D
 	}
 	else {
 		distr = part->distr;
-		BLI_srandom(31415926 + psys->seed);
+		BLI_rng_srandom(ctx->sim.rng, 31415926 + psys->seed);
 		
 		dm= CDDM_from_mesh((Mesh*)ob->data, ob);
 
@@ -1264,7 +1264,7 @@ static int distribute_threads_init_data(ParticleThread *threads, Scene *scene, D
 
 		for (p=0; p<totpart; p++) {
 			/* In theory element_sum[totelem] should be 1.0, but due to float errors this is not necessarily always true, so scale pos accordingly. */
-			pos= BLI_frand() * element_sum[totelem];
+			pos= BLI_rng_get_float(ctx->sim.rng) * element_sum[totelem];
 			particle_element[p] = distribute_binary_search(element_sum, totelem, pos);
 			particle_element[p] = MIN2(totelem-1, particle_element[p]);
 			jitter_offset[particle_element[p]] = pos;
@@ -2916,9 +2916,9 @@ static void basic_force_cb(void *efdata_v, ParticleKey *state, float *force, flo
 
 	/* brownian force */
 	if (part->brownfac != 0.0f) {
-		force[0] += (BLI_frand()-0.5f) * part->brownfac;
-		force[1] += (BLI_frand()-0.5f) * part->brownfac;
-		force[2] += (BLI_frand()-0.5f) * part->brownfac;
+		force[0] += (BLI_rng_get_float(sim->rng)-0.5f) * part->brownfac;
+		force[1] += (BLI_rng_get_float(sim->rng)-0.5f) * part->brownfac;
+		force[2] += (BLI_rng_get_float(sim->rng)-0.5f) * part->brownfac;
 	}
 
 	if (part->flag & PART_ROT_DYN && epoint.ave)
@@ -3497,7 +3497,7 @@ static int collision_detect(ParticleData *pa, ParticleCollision *col, BVHTreeRay
 
 	return hit->index >= 0;
 }
-static int collision_response(ParticleData *pa, ParticleCollision *col, BVHTreeRayHit *hit, int kill, int dynamic_rotation)
+static int collision_response(ParticleData *pa, ParticleCollision *col, BVHTreeRayHit *hit, int kill, int dynamic_rotation, RNG *rng)
 {
 	ParticleCollisionElement *pce = &col->pce;
 	PartDeflect *pd = col->hit->pd;
@@ -3506,7 +3506,7 @@ static int collision_response(ParticleData *pa, ParticleCollision *col, BVHTreeR
 	float f = col->f + x * (1.0f - col->f);				/* time factor of collision between timestep */
 	float dt1 = (f - col->f) * col->total_time;			/* time since previous collision (in seconds) */
 	float dt2 = (1.0f - f) * col->total_time;			/* time left after collision (in seconds) */
-	int through = (BLI_frand() < pd->pdef_perm) ? 1 : 0; /* did particle pass through the collision surface? */
+	int through = (BLI_rng_get_float(rng) < pd->pdef_perm) ? 1 : 0; /* did particle pass through the collision surface? */
 
 	/* calculate exact collision location */
 	interp_v3_v3v3(co, col->co1, col->co2, x);
@@ -3531,8 +3531,8 @@ static int collision_response(ParticleData *pa, ParticleCollision *col, BVHTreeR
 		float v0_tan[3];/* tangential component of v0 */
 		float vc_tan[3];/* tangential component of collision surface velocity */
 		float v0_dot, vc_dot;
-		float damp = pd->pdef_damp + pd->pdef_rdamp * 2 * (BLI_frand() - 0.5f);
-		float frict = pd->pdef_frict + pd->pdef_rfrict * 2 * (BLI_frand() - 0.5f);
+		float damp = pd->pdef_damp + pd->pdef_rdamp * 2 * (BLI_rng_get_float(rng) - 0.5f);
+		float frict = pd->pdef_frict + pd->pdef_rfrict * 2 * (BLI_rng_get_float(rng) - 0.5f);
 		float distance, nor[3], dot;
 
 		CLAMP(damp,0.0f, 1.0f);
@@ -3740,7 +3740,7 @@ static void collision_check(ParticleSimulationData *sim, int p, float dfra, floa
 
 			if (collision_count == COLLISION_MAX_COLLISIONS)
 				collision_fail(pa, &col);
-			else if (collision_response(pa, &col, &hit, part->flag & PART_DIE_ON_COL, part->flag & PART_ROT_DYN)==0)
+			else if (collision_response(pa, &col, &hit, part->flag & PART_DIE_ON_COL, part->flag & PART_ROT_DYN, sim->rng)==0)
 				return;
 		}
 		else
@@ -4100,6 +4100,7 @@ static void dynamics_step(ParticleSimulationData *sim, float cfra)
 {
 	ParticleSystem *psys = sim->psys;
 	ParticleSettings *part=psys->part;
+	RNG *rng;
 	BoidBrainData bbd;
 	ParticleTexture ptex;
 	PARTICLE_P;
@@ -4126,7 +4127,7 @@ static void dynamics_step(ParticleSimulationData *sim, float cfra)
 		return;
 	}
 
-	BLI_srandom(31415926 + (int)cfra + psys->seed);
+	rng = BLI_rng_new_srandom(31415926 + (int)cfra + psys->seed);
 
 	psys_update_effectors(sim);
 
@@ -4143,6 +4144,7 @@ static void dynamics_step(ParticleSimulationData *sim, float cfra)
 			bbd.cfra = cfra;
 			bbd.dfra = dfra;
 			bbd.timestep = timestep;
+			bbd.rng = rng;
 
 			psys_update_particle_tree(psys, cfra);
 
@@ -4326,6 +4328,7 @@ static void dynamics_step(ParticleSimulationData *sim, float cfra)
 	}
 
 	free_collider_cache(&sim->colliders);
+	BLI_rng_free(rng);
 }
 static void update_children(ParticleSimulationData *sim)
 {
@@ -4822,6 +4825,8 @@ void particle_system_update(Scene *scene, Object *ob, ParticleSystem *psys)
 	if (!sim.psmd->dm)
 		return;
 
+	sim.rng = BLI_rng_new(0);
+
 	if (part->from != PART_FROM_VERT) {
 		DM_ensure_tessface(sim.psmd->dm);
 	}
@@ -4962,5 +4967,7 @@ void particle_system_update(Scene *scene, Object *ob, ParticleSystem *psys)
 	/* save matrix for duplicators, at rendertime the actual dupliobject's matrix is used so don't update! */
 	if (psys->renderdata==0)
 		invert_m4_m4(psys->imat, ob->obmat);
+	
+	BLI_rng_free(sim.rng);
 }
 
diff --git a/source/blender/blenkernel/intern/smoke.c b/source/blender/blenkernel/intern/smoke.c
index 6b8f0348e16..ba6e8fe0a3a 100644
--- a/source/blender/blenkernel/intern/smoke.c
+++ b/source/blender/blenkernel/intern/smoke.c
@@ -969,6 +969,7 @@ static void emit_from_particles(Object *flow_ob, SmokeDomainSettings *sds, Smoke
 		sim.scene = scene;
 		sim.ob = flow_ob;
 		sim.psys = psys;
+		sim.rng = BLI_rng_new(sim.rng);
 
 		if (psys->part->type == PART_HAIR)
 		{
@@ -1055,6 +1056,8 @@ static void emit_from_particles(Object *flow_ob, SmokeDomainSettings *sds, Smoke
 			MEM_freeN(particle_pos);
 		if (particle_vel)
 			MEM_freeN(particle_vel);
+
+		BLI_rng_free(sim.rng);
 	}
 }