Fix: jittered brushes are not jittered, reported by kursad karatas.

Issue is sharing using global random generator which is shared with
particle system which resets the seed due to some scene/option
combination. Since it may be desirable to get predictable results with
particles, made sure brushes allocate their own random number generator
on startup and use that for jittering.

4 files changed, 25 insertions, 2 deletions

diff --git a/source/blender/blenkernel/BKE_brush.h b/source/blender/blenkernel/BKE_brush.h
index 4dfc70db952..e0afb1929a5 100644
--- a/source/blender/blenkernel/BKE_brush.h
+++ b/source/blender/blenkernel/BKE_brush.h
@@ -42,6 +42,11 @@ struct Scene;
 struct wmOperator;
 // enum CurveMappingPreset;
 
+
+/* globals for brush execution */
+void BKE_brush_system_init(void);
+void BKE_brush_system_exit(void);
+
 /* datablock functions */
 struct Brush *BKE_brush_add(struct Main *bmain, const char *name);
 struct Brush *BKE_brush_copy(struct Brush *brush);
diff --git a/source/blender/blenkernel/intern/blender.c b/source/blender/blenkernel/intern/blender.c
index fa6aafabe05..b3c94beba93 100644
--- a/source/blender/blenkernel/intern/blender.c
+++ b/source/blender/blenkernel/intern/blender.c
@@ -66,6 +66,7 @@
 
 #include "BKE_blender.h"
 #include "BKE_bpath.h"
+#include "BKE_brush.h"
 #include "BKE_context.h"
 #include "BKE_depsgraph.h"
 #include "BKE_displist.h"
@@ -120,6 +121,8 @@ void free_blender(void)
 	IMB_exit();
 	BKE_images_exit();
 
+	BKE_brush_system_exit();
+
 	BLI_callback_global_finalize();
 
 	BKE_sequencer_cache_destruct();
diff --git a/source/blender/blenkernel/intern/brush.c b/source/blender/blenkernel/intern/brush.c
index c594e19b960..819d20d4770 100644
--- a/source/blender/blenkernel/intern/brush.c
+++ b/source/blender/blenkernel/intern/brush.c
@@ -55,6 +55,18 @@
 #include "RE_render_ext.h" /* externtex */
 #include "RE_shader_ext.h"
 
+static RNG *brush_rng;
+
+void BKE_brush_system_init(void) {
+	brush_rng = BLI_rng_new(0);
+	BLI_rng_srandom(brush_rng, 31415682);
+}
+
+void BKE_brush_system_exit(void) {
+	BLI_rng_free(brush_rng);
+}
+
+
 static void brush_defaults(Brush *brush)
 {
 	brush->blend = 0;
@@ -877,8 +889,8 @@ void BKE_brush_jitter_pos(const Scene *scene, Brush *brush, const float pos[2],
 		int diameter;
 
 		do {
-			rand_pos[0] = BLI_frand() - 0.5f;
-			rand_pos[1] = BLI_frand() - 0.5f;
+			rand_pos[0] = BLI_rng_get_float(brush_rng) - 0.5f;
+			rand_pos[1] = BLI_rng_get_float(brush_rng) - 0.5f;
 		} while (len_v2(rand_pos) > 0.5f);
 
 
diff --git a/source/creator/creator.c b/source/creator/creator.c
index d7b2d87ffe8..ba6cc728eca 100644
--- a/source/creator/creator.c
+++ b/source/creator/creator.c
@@ -84,6 +84,7 @@
 #include "BLI_blenlib.h"
 
 #include "BKE_blender.h"
+#include "BKE_brush.h"
 #include "BKE_context.h"
 #include "BKE_depsgraph.h" /* for DAG_on_visible_update */
 #include "BKE_font.h"
@@ -1486,6 +1487,8 @@ int main(int argc, const char **argv)
 	IMB_init();
 	BKE_images_init();
 
+	BKE_brush_system_init();
+
 #ifdef WITH_FFMPEG
 	IMB_ffmpeg_init();
 #endif