diff options
Diffstat (limited to 'source/blender/blenlib/intern/math_color_inline.c')
-rw-r--r-- | source/blender/blenlib/intern/math_color_inline.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/source/blender/blenlib/intern/math_color_inline.c b/source/blender/blenlib/intern/math_color_inline.c index f5aaddc0ea3..52ca229fe27 100644 --- a/source/blender/blenlib/intern/math_color_inline.c +++ b/source/blender/blenlib/intern/math_color_inline.c @@ -317,19 +317,27 @@ MINLINE int compare_rgb_uchar(const unsigned char col_a[3], return 0; } +/* Using a triangle distribution which gives a more final uniform noise. + * See Banding in Games:A Noisy Rant(revision 5) Mikkel Gjøl, Playdead (slide 27) */ +/* Return triangle noise in [-0.5..1.5[ range */ MINLINE float dither_random_value(float s, float t) { - static float vec[2] = {12.9898f, 78.233f}; - float value; - - value = sinf(s * vec[0] + t * vec[1]) * 43758.5453f; - return value - floorf(value); + /* Original code from https://www.shadertoy.com/view/4t2SDh */ + /* The nois 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); + /* Convert uniform distribution into triangle-shaped distribution. */ + return nrnd0 + nrnd1 - 0.5f; } MINLINE void float_to_byte_dither_v3( unsigned char b[3], const float f[3], float dither, float s, float t) { - float dither_value = dither_random_value(s, t) * 0.005f * dither; + float dither_value = dither_random_value(s, t) * 0.0033f * dither; b[0] = unit_float_to_uchar_clamp(dither_value + f[0]); b[1] = unit_float_to_uchar_clamp(dither_value + f[1]); |