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.

1 files changed, 7 insertions, 3 deletions

diff --git a/source/blender/blenlib/intern/jitter.c b/source/blender/blenlib/intern/jitter.c
index 3fe0ef158df..7141bedcf05 100644
--- a/source/blender/blenlib/intern/jitter.c
+++ b/source/blender/blenlib/intern/jitter.c
@@ -139,6 +139,7 @@ void BLI_jitterate2(float *jit1, float *jit2, int num, float rad2)
 void BLI_jitter_init(float *jitarr, int num)
 {
 	float *jit2, x, rad1, rad2, rad3;
+	RNG *rng;
 	int i;
 
 	if (num == 0) return;
@@ -148,15 +149,18 @@ void BLI_jitter_init(float *jitarr, int num)
 	rad2 = 1.0f / ((float)num);
 	rad3 = sqrtf((float)num) / ((float)num);
 
-	BLI_srand(31415926 + num);
+	rng = BLI_rng_new(31415926 + num);
+
 	x = 0;
 	for (i = 0; i < 2 * num; i += 2) {
-		jitarr[i] = x + rad1 * (float)(0.5 - BLI_drand());
-		jitarr[i + 1] = ((float)i / 2) / num + rad1 * (float)(0.5 - BLI_drand());
+		jitarr[i] = x + rad1 * (float)(0.5 - BLI_rng_get_double(rng));
+		jitarr[i + 1] = ((float)i / 2) / num + rad1 * (float)(0.5 - BLI_rng_get_double(rng));
 		x += rad3;
 		x -= floorf(x);
 	}
 
+	BLI_rng_free(rng);
+
 	for (i = 0; i < 24; i++) {
 		BLI_jitterate1(jitarr, jit2, num, rad1);
 		BLI_jitterate1(jitarr, jit2, num, rad1);