[Bf-blender-cvs] [b0271c6e408] master: Use golden ratio conjugate for Face Sets hue generation

[Pablo Dobarro]

Commit: b0271c6e408f66a7265dccc6e12ca21a9332a9dc
Author: Pablo Dobarro
Date:   Thu Mar 12 20:43:01 2020 +0100
Branches: master
https://developer.blender.org/rBb0271c6e408f66a7265dccc6e12ca21a9332a9dc

Use golden ratio conjugate for Face Sets hue generation

The face set ID is sequential, so implementing this was straightforward.
Suggested by Jeroen Bakker

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7123

===================================================================

M	source/blender/editors/sculpt_paint/sculpt.c
M	source/blender/gpu/intern/gpu_buffers.c

===================================================================

diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index 65cfcd1f8db..c14b9565c1b 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -11105,14 +11105,13 @@ static int sculpt_face_sets_randomize_colors_invoke(bContext *C,
   int totnode;
   Mesh *mesh = ob->data;
 
-  int new_seed = BLI_hash_int(PIL_check_seconds_timer_i() & UINT_MAX);
-  mesh->face_sets_color_seed = new_seed;
+  mesh->face_sets_color_seed += 1;
   if (ss->face_sets) {
     const int random_index = clamp_i(
-        ss->totpoly * BLI_hash_int_01(new_seed), 0, max_ii(0, ss->totpoly - 1));
+        ss->totpoly * BLI_hash_int_01(mesh->face_sets_color_seed), 0, max_ii(0, ss->totpoly - 1));
     mesh->face_sets_color_default = ss->face_sets[random_index];
   }
-  BKE_pbvh_face_sets_color_set(pbvh, new_seed, mesh->face_sets_color_default);
+  BKE_pbvh_face_sets_color_set(pbvh, mesh->face_sets_color_seed, mesh->face_sets_color_default);
 
   BKE_pbvh_search_gather(pbvh, NULL, NULL, &nodes, &totnode);
   for (int i = 0; i < totnode; i++) {
diff --git a/source/blender/gpu/intern/gpu_buffers.c b/source/blender/gpu/intern/gpu_buffers.c
index 5eae86e50f0..33f61b5f5f4 100644
--- a/source/blender/gpu/intern/gpu_buffers.c
+++ b/source/blender/gpu/intern/gpu_buffers.c
@@ -189,15 +189,17 @@ static void gpu_pbvh_batch_init(GPU_PBVH_Buffers *buffers, GPUPrimType prim)
  * \{ */
 
 /* Returns the Face Set random color for rendering in the overlay given its ID and a color seed. */
+#define GOLDEN_RATIO_CONJUGATE 0.618033988749895f
 static void face_set_overlay_color_get(const int face_set, const int seed, uchar *r_color)
 {
   float rgba[4];
-  const float random_mod_hue = BLI_hash_int_01(abs(face_set) + seed);
+  float random_mod_hue = GOLDEN_RATIO_CONJUGATE * (abs(face_set) + (seed % 10));
+  random_mod_hue = random_mod_hue - floorf(random_mod_hue);
   const float random_mod_sat = BLI_hash_int_01(abs(face_set) + seed + 1);
   const float random_mod_val = BLI_hash_int_01(abs(face_set) + seed + 2);
   hsv_to_rgb(random_mod_hue,
-             0.45f + (random_mod_sat * 0.35f),
-             1.0f - (random_mod_val * 0.45f),
+             0.6f + (random_mod_sat * 0.25f),
+             1.0f - (random_mod_val * 0.35f),
              &rgba[0],
              &rgba[1],
              &rgba[2]);