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Add dithering (#9014)

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HybridDog 2023-12-19 20:18:11 +01:00 • committed by GitHub
parent 5d3e830176
commit b1aec1b5c8
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4 changed files with 42 additions and 0 deletions
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26
client/shaders/second_stage/opengl_fragment.glsl
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@ -1,6 +1,13 @@
#define rendered texture0
#define bloom texture1
#ifdef GL_ES
// Dithering requires sufficient floating-point precision
#ifndef GL_FRAGMENT_PRECISION_HIGH
#undef ENABLE_DITHERING
#endif
#endif
struct ExposureParams {
float compensationFactor;
};
@ -79,6 +86,20 @@ vec3 applySaturation(vec3 color, float factor)
}
#endif
#ifdef ENABLE_DITHERING
// From http://alex.vlachos.com/graphics/Alex_Vlachos_Advanced_VR_Rendering_GDC2015.pdf
// and https://www.shadertoy.com/view/MslGR8 (5th one starting from the bottom)
// NOTE: `frag_coord` is in pixels (i.e. not normalized UV).
vec3 screen_space_dither(highp vec2 frag_coord) {
// Iestyn's RGB dither (7 asm instructions) from Portal 2 X360, slightly modified for VR.
highp vec3 dither = vec3(dot(vec2(171.0, 231.0), frag_coord));
dither.rgb = fract(dither.rgb / vec3(103.0, 71.0, 97.0));
// Subtract 0.5 to avoid slightly brightening the whole viewport.
return (dither.rgb - 0.5) / 255.0;
}
#endif
void main(void)
{
vec2 uv = varTexCoord.st;
@ -125,5 +146,10 @@ void main(void)
// return to sRGB colorspace (approximate)
color.rgb = pow(color.rgb, vec3(1.0 / 2.2));
#ifdef ENABLE_DITHERING
// Apply dithering just before quantisation
color.rgb += screen_space_dither(gl_FragCoord.xy);
#endif
gl_FragColor = vec4(color.rgb, 1.0); // force full alpha to avoid holes in the image.
}