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/* 4x4 bayer matrix prepared for 8bit UNORM precision error. */
#define P(x) (((x + 0.5) * (1.0 / 16.0) - 0.5) * (1.0 / 255.0))
const vec4 dither_mat4x4[4] = vec4[4](
vec4( P(0.0), P(8.0), P(2.0), P(10.0)),
vec4(P(12.0), P(4.0), P(14.0), P(6.0)),
vec4( P(3.0), P(11.0), P(1.0), P(9.0)),
vec4(P(15.0), P(7.0), P(13.0), P(5.0))
);
float bayer_dither_noise() {
ivec2 tx1 = ivec2(gl_FragCoord.xy) % 4;
ivec2 tx2 = ivec2(gl_FragCoord.xy) % 2;
return dither_mat4x4[tx1.x][tx1.y];
}
/* From http://aras-p.info/texts/CompactNormalStorage.html
* Using Method #4: Spheremap Transform */
vec3 normal_decode(vec3 enc)
{
vec2 fenc = enc.xy * 4.0 - 2.0;
float f = dot(fenc, fenc);
float g = sqrt(1.0 - f / 4.0);
vec3 n;
n.xy = fenc*g;
n.z = 1 - f / 2;
if (enc.z > 0.5) {
n = -n;
}
return n;
}
/* From http://aras-p.info/texts/CompactNormalStorage.html
* Using Method #4: Spheremap Transform */
vec3 normal_encode(vec3 n)
{
float p = sqrt(n.z * 8.0 + 8.0);
vec3 result = vec3(n.xyz / p + 0.5);
result.z = (gl_FrontFacing)? 0.0: 1.0;
return result;
}
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