// Compress gamma curve. uniform float PREFIX(linear_scale); uniform float PREFIX(c0), PREFIX(c1), PREFIX(c2), PREFIX(c3), PREFIX(c4); uniform float PREFIX(beta); vec4 FUNCNAME(vec2 tc) { vec4 x = INPUT(tc); // We could reasonably get values outside (0.0, 1.0), but the formulas below // are not valid outside that range, so clamp before we do anything else. x.rgb = clamp(x.rgb, 0.0, 1.0); vec3 a = x.rgb * PREFIX(linear_scale); // Fourth-order polynomial approximation to pow(). See the .cpp file for details. vec3 s = sqrt(x.rgb); vec3 b = PREFIX(c0) + (PREFIX(c1) + (PREFIX(c2) + (PREFIX(c3) + PREFIX(c4) * s) * s) * s) * s; vec3 f = vec3(greaterThan(x.rgb, vec3(PREFIX(beta)))); x = vec4(mix(a, b, f), x.a); return x; }