Fix unstable particle jittered distribution.

This was never working for threaded distribution.

1 files changed, 6 insertions, 8 deletions

diff --git a/source/blender/blenkernel/intern/particle_distribute.c b/source/blender/blenkernel/intern/particle_distribute.c
index 6cc42e85a12..245c2432105 100644
--- a/source/blender/blenkernel/intern/particle_distribute.c
+++ b/source/blender/blenkernel/intern/particle_distribute.c
@@ -467,10 +467,9 @@ static void distribute_from_faces_exec(ParticleTask *thread, ParticleData *pa, i
 					psys_uv_to_w(1.0f / 3.0f, 1.0f / 3.0f, mface->v4, pa->fuv);
 			}
 			else {
-				ctx->jitoff[i] = fmod(ctx->jitoff[i],(float)ctx->jitlevel);
-				if (!isnan(ctx->jitoff[i])) {
-					psys_uv_to_w(ctx->jit[2*(int)ctx->jitoff[i]], ctx->jit[2*(int)ctx->jitoff[i]+1], mface->v4, pa->fuv);
-					ctx->jitoff[i]++;
+				float offset = fmod(ctx->jitoff[i] + (float)p, (float)ctx->jitlevel);
+				if (!isnan(offset)) {
+					psys_uv_to_w(ctx->jit[2*(int)offset], ctx->jit[2*(int)offset+1], mface->v4, pa->fuv);
 				}
 			}
 			break;
@@ -512,10 +511,9 @@ static void distribute_from_volume_exec(ParticleTask *thread, ParticleData *pa,
 					psys_uv_to_w(1.0f / 3.0f, 1.0f / 3.0f, mface->v4, pa->fuv);
 			}
 			else {
-				ctx->jitoff[i] = fmod(ctx->jitoff[i],(float)ctx->jitlevel);
-				if (!isnan(ctx->jitoff[i])) {
-					psys_uv_to_w(ctx->jit[2*(int)ctx->jitoff[i]], ctx->jit[2*(int)ctx->jitoff[i]+1], mface->v4, pa->fuv);
-					ctx->jitoff[i]++;
+				float offset = fmod(ctx->jitoff[i] + (float)p, (float)ctx->jitlevel);
+				if (!isnan(offset)) {
+					psys_uv_to_w(ctx->jit[2*(int)offset], ctx->jit[2*(int)offset+1], mface->v4, pa->fuv);
 				}
 			}
 			break;