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, 11 insertions, 6 deletions

diff --git a/source/blender/bmesh/operators/bmo_edgenet.c b/source/blender/bmesh/operators/bmo_edgenet.c
index a4af570ded0..b6d6af1e6da 100644
--- a/source/blender/bmesh/operators/bmo_edgenet.c
+++ b/source/blender/bmesh/operators/bmo_edgenet.c
@@ -362,6 +362,7 @@ static void init_rotsys(BMesh *bm, EdgeData *edata, VertData *vdata)
 	BMEdge **edges = NULL;
 	BLI_array_staticdeclare(edges, BM_DEFAULT_NGON_STACK_SIZE);
 	BMVert *v;
+	RNG *rng;
 	/* BMVert **verts = NULL; */
 	/* BLI_array_staticdeclare(verts, BM_DEFAULT_NGON_STACK_SIZE); */ /* UNUSE */
 	int i;
@@ -427,7 +428,7 @@ static void init_rotsys(BMesh *bm, EdgeData *edata, VertData *vdata)
 			copy_v3_v3(vdata[BM_elem_index_get(v2)].sco, vec1);
 		}
 
-		BLI_srandom(0);
+		rng = BLI_rng_new_srandom(0);
 
 		/* first, ensure no 0 or 180 angles between adjacent
 		 * (and that adjacent's adjacent) edges */
@@ -471,7 +472,7 @@ static void init_rotsys(BMesh *bm, EdgeData *edata, VertData *vdata)
 				copy_v3_v3(cent, v->co);
 
 				for (j = 0; j < 3; j++) {
-					float fac = (BLI_frand() - 0.5f) * size;
+					float fac = (BLI_rng_get_float(rng) - 0.5f) * size;
 					cent[j] += fac;
 				}
 
@@ -488,6 +489,8 @@ static void init_rotsys(BMesh *bm, EdgeData *edata, VertData *vdata)
 			}
 		}
 
+		BLI_rng_free(rng);
+
 		copy_v3_v3(vdata[BM_elem_index_get(v)].offco, cent);
 		//copy_v3_v3(v->co, cent);
 
diff --git a/source/blender/bmesh/operators/bmo_subdivide.c b/source/blender/bmesh/operators/bmo_subdivide.c
index aaa2914e6ae..8df52c3a6ae 100644
--- a/source/blender/bmesh/operators/bmo_subdivide.c
+++ b/source/blender/bmesh/operators/bmo_subdivide.c
@@ -831,11 +831,13 @@ void bmo_subdivide_edges_exec(BMesh *bm, BMOperator *op)
 	params.origkey = skey;
 
 	if (params.use_fractal) {
-		BLI_srandom(seed);
+		RNG *rng = BLI_rng_new_srandom(seed);
 
-		params.fractal_ofs[0] = (float)BLI_drand() * 200.0f;
-		params.fractal_ofs[1] = (float)BLI_drand() * 200.0f;
-		params.fractal_ofs[2] = (float)BLI_drand() * 200.0f;
+		params.fractal_ofs[0] = BLI_rng_get_float(rng) * 200.0f;
+		params.fractal_ofs[1] = BLI_rng_get_float(rng) * 200.0f;
+		params.fractal_ofs[2] = BLI_rng_get_float(rng) * 200.0f;
+
+		BLI_rng_free(rng);
 	}
 	
 	BMO_slot_map_to_flag(bm, op->slots_in, "custom_patterns",