Cleanup: clarify license and origin of voronoi and dithering code

1 files changed, 7 insertions, 9 deletions

diff --git a/source/blender/blenlib/intern/math_color_inline.c b/source/blender/blenlib/intern/math_color_inline.c
index a5a687ef9fe..ad4b844175f 100644
--- a/source/blender/blenlib/intern/math_color_inline.c
+++ b/source/blender/blenlib/intern/math_color_inline.c
@@ -322,16 +322,14 @@ MINLINE int compare_rgb_uchar(const unsigned char col_a[3],
 /* Return triangle noise in [-0.5..1.5[ range */
 MINLINE float dither_random_value(float s, float t)
 {
-  /* Original code from https://www.shadertoy.com/view/4t2SDh */
-  /* The noise reshaping technique does not work on CPU.
-   * We generate and merge two distribution instead */
-  /* Uniform noise in [0..1[ range */
-  float nrnd0 = sinf(s * 12.9898f + t * 78.233f) * 43758.5453f;
-  float nrnd1 = sinf(s * 19.9898f + t * 119.233f) * 43798.5453f;
-  nrnd0 -= floorf(nrnd0);
-  nrnd1 -= floorf(nrnd1);
+  /* Uniform noise in [0..1[ range, using common GLSL hash function.
+   * https://stackoverflow.com/questions/12964279/whats-the-origin-of-this-glsl-rand-one-liner. */
+  float hash0 = sinf(s * 12.9898f + t * 78.233f) * 43758.5453f;
+  float hash1 = sinf(s * 19.9898f + t * 119.233f) * 43798.5453f;
+  hash0 -= floorf(hash0);
+  hash1 -= floorf(hash1);
   /* Convert uniform distribution into triangle-shaped distribution. */
-  return nrnd0 + nrnd1 - 0.5f;
+  return hash0 + hash0 - 0.5f;
 }
 
 MINLINE void float_to_byte_dither_v3(