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.

2 files changed, 33 insertions, 22 deletions

diff --git a/source/blender/render/intern/source/convertblender.c b/source/blender/render/intern/source/convertblender.c
index 6b033a4eb3c..76179b25871 100644
--- a/source/blender/render/intern/source/convertblender.c
+++ b/source/blender/render/intern/source/convertblender.c
@@ -176,6 +176,7 @@ void RE_make_stars(Render *re, Scene *scenev3d, void (*initfunc)(void),
 	Scene *scene;
 	Object *camera;
 	Camera *cam;
+	RNG *rng;
 	double dblrand, hlfrand;
 	float vec[4], fx, fy, fz;
 	float fac, starmindist, clipend;
@@ -244,14 +245,16 @@ void RE_make_stars(Render *re, Scene *scenev3d, void (*initfunc)(void),
 	if (re) /* add render object for stars */
 		obr= RE_addRenderObject(re, NULL, NULL, 0, 0, 0);
 	
+	rng = BLI_rng_new(0);
+	
 	for (x = sx, fx = sx * stargrid; x <= ex; x++, fx += stargrid) {
 		for (y = sy, fy = sy * stargrid; y <= ey; y++, fy += stargrid) {
 			for (z = sz, fz = sz * stargrid; z <= ez; z++, fz += stargrid) {
 
-				BLI_srand((hash[z & 0xff] << 24) + (hash[y & 0xff] << 16) + (hash[x & 0xff] << 8));
-				vec[0] = fx + (hlfrand * BLI_drand()) - dblrand;
-				vec[1] = fy + (hlfrand * BLI_drand()) - dblrand;
-				vec[2] = fz + (hlfrand * BLI_drand()) - dblrand;
+				BLI_rng_seed(rng, (hash[z & 0xff] << 24) + (hash[y & 0xff] << 16) + (hash[x & 0xff] << 8));
+				vec[0] = fx + (hlfrand * BLI_rng_get_double(rng)) - dblrand;
+				vec[1] = fy + (hlfrand * BLI_rng_get_double(rng)) - dblrand;
+				vec[2] = fz + (hlfrand * BLI_rng_get_double(rng)) - dblrand;
 				vec[3] = 1.0;
 				
 				if (vertexfunc) {
@@ -281,7 +284,7 @@ void RE_make_stars(Render *re, Scene *scenev3d, void (*initfunc)(void),
 					
 					
 					if (alpha != 0.0f) {
-						fac = force * BLI_drand();
+						fac = force * BLI_rng_get_double(rng);
 						
 						har = initstar(re, obr, vec, fac);
 						
@@ -290,9 +293,9 @@ void RE_make_stars(Render *re, Scene *scenev3d, void (*initfunc)(void),
 							har->add= 255;
 							har->r = har->g = har->b = 1.0;
 							if (maxjit) {
-								har->r += ((maxjit * BLI_drand()) ) - maxjit;
-								har->g += ((maxjit * BLI_drand()) ) - maxjit;
-								har->b += ((maxjit * BLI_drand()) ) - maxjit;
+								har->r += ((maxjit * BLI_rng_get_double(rng)) ) - maxjit;
+								har->g += ((maxjit * BLI_rng_get_double(rng)) ) - maxjit;
+								har->b += ((maxjit * BLI_rng_get_double(rng)) ) - maxjit;
 							}
 							har->hard = 32;
 							har->lay= -1;
@@ -321,6 +324,8 @@ void RE_make_stars(Render *re, Scene *scenev3d, void (*initfunc)(void),
 
 	if (obr)
 		re->tothalo += obr->tothalo;
+
+	BLI_rng_free(rng);
 }
 
 
diff --git a/source/blender/render/intern/source/rayshade.c b/source/blender/render/intern/source/rayshade.c
index 88c0719fa59..387004527c0 100644
--- a/source/blender/render/intern/source/rayshade.c
+++ b/source/blender/render/intern/source/rayshade.c
@@ -935,15 +935,14 @@ void init_jitter_plane(LampRen *lar)
 	
 	/* if 1 sample, we leave table to be zero's */
 	if (tot>1) {
+		/* set per-lamp fixed seed */
+		RNG *rng = BLI_rng_new_srandom(tot);
 		int iter=12;
 
-		/* set per-lamp fixed seed */
-		BLI_srandom(tot);
-		
 		/* fill table with random locations, area_size large */
 		for (x=0; x<tot; x++, fp+=2) {
-			fp[0]= (BLI_frand()-0.5f)*lar->area_size;
-			fp[1]= (BLI_frand()-0.5f)*lar->area_sizey;
+			fp[0]= (BLI_rng_get_float(rng)-0.5f)*lar->area_size;
+			fp[1]= (BLI_rng_get_float(rng)-0.5f)*lar->area_sizey;
 		}
 		
 		while (iter--) {
@@ -952,6 +951,8 @@ void init_jitter_plane(LampRen *lar)
 				DP_energy(lar->jitter, fp, tot, lar->area_size, lar->area_sizey);
 			}
 		}
+
+		BLI_rng_free(rng);
 	}
 	/* create the dithered tables (could just check lamp type!) */
 	jitter_plane_offset(lar->jitter, lar->jitter+2*tot, tot, lar->area_size, lar->area_sizey, 0.5f, 0.0f);
@@ -1727,12 +1728,12 @@ static int UNUSED_FUNCTION(ray_trace_shadow_rad)(ShadeInput *ship, ShadeResult *
 }
 
 /* aolight: function to create random unit sphere vectors for total random sampling */
-static void RandomSpherical(float v[3])
+static void RandomSpherical(RNG *rng, float v[3])
 {
 	float r;
-	v[2] = 2.f*BLI_frand()-1.f;
+	v[2] = 2.f*BLI_rng_get_float(rng)-1.f;
 	if ((r = 1.f - v[2]*v[2])>0.f) {
-		float a = 6.283185307f*BLI_frand();
+		float a = 6.283185307f*BLI_rng_get_float(rng);
 		r = sqrt(r);
 		v[0] = r * cosf(a);
 		v[1] = r * sinf(a);
@@ -1770,6 +1771,8 @@ static void DS_energy(float *sphere, int tot, float vec[3])
 /* and allocates threadsafe memory */
 void init_ao_sphere(World *wrld)
 {
+	/* fixed random */
+	RNG *rng;
 	float *fp;
 	int a, tot, iter= 16;
 
@@ -1777,14 +1780,12 @@ void init_ao_sphere(World *wrld)
 	tot= 2*wrld->aosamp*wrld->aosamp;
 	
 	wrld->aosphere= MEM_mallocN(3*tot*sizeof(float), "AO sphere");
-	
-	/* fixed random */
-	BLI_srandom(tot);
+	rng = BLI_rng_new_srandom(tot);
 	
 	/* init */
 	fp= wrld->aosphere;
 	for (a=0; a<tot; a++, fp+= 3) {
-		RandomSpherical(fp);
+		RandomSpherical(rng, fp);
 	}
 	
 	while (iter--) {
@@ -1795,6 +1796,8 @@ void init_ao_sphere(World *wrld)
 	
 	/* tables */
 	wrld->aotables= MEM_mallocN(BLENDER_MAX_THREADS*3*tot*sizeof(float), "AO tables");
+
+	BLI_rng_free(rng);
 }
 
 /* give per thread a table, we have to compare xs ys because of way OSA works... */
@@ -1823,17 +1826,20 @@ static float *sphere_sampler(int type, int resol, int thread, int xs, int ys, in
 	tot= 2*resol*resol;
 
 	if (type & WO_AORNDSMP) {
+		/* total random sampling. NOT THREADSAFE! (should be removed, is not useful) */
+		RNG *rng = BLI_rng_new(BLI_thread_rand(thread));
 		float *sphere;
 		int a;
 		
 		/* always returns table */
 		sphere= threadsafe_table_sphere(0, thread, xs, ys, tot);
 
-		/* total random sampling. NOT THREADSAFE! (should be removed, is not useful) */
 		vec= sphere;
 		for (a=0; a<tot; a++, vec+=3) {
-			RandomSpherical(vec);
+			RandomSpherical(rng, vec);
 		}
+
+		BLI_rng_free(rng);
 		
 		return sphere;
 	}