1 // Compress gamma curve.
4 // uniform float PREFIX(linear_scale);
5 // uniform float PREFIX(c)[5];
6 // uniform float PREFIX(beta);
8 vec4 FUNCNAME(vec2 tc) {
11 // We could reasonably get values outside (0.0, 1.0), but the formulas below
12 // are not valid outside that range, so clamp before we do anything else.
13 x.rgb = clamp(x.rgb, 0.0, 1.0);
15 vec3 a = x.rgb * PREFIX(linear_scale);
17 // Fourth-order polynomial approximation to pow(). See the .cpp file for details.
19 vec3 b = PREFIX(c)[0] + (PREFIX(c)[1] + (PREFIX(c)[2] + (PREFIX(c)[3] + PREFIX(c)[4] * s) * s) * s) * s;
21 vec3 f = vec3(greaterThan(x.rgb, vec3(PREFIX(beta))));
22 x = vec4(mix(a, b, f), x.a);