>>7581>Let's share what we are working on:I'm working on a GLSL debanding shader.
// Wide usage friendly PRNG, shamelessly stolen from a GLSL tricks forum post
float mod289(float x) { return x - floor(x / 289.0) * 289.0; }
float permute(float x) { return mod289((34.0*x + 1.0) * x); }
float rand(float x) { return fract(x / 41.0); }
// Helper: Calculate a stochastic approximation of the avg color around a pixel
vec4 average(sampler2D tex, vec2 pos, float range, inout float h)
{
// Compute a random rangle and distance
float dist = rand(h) * range; h = permute(h);
float dir = rand(h) * 6.2831853; h = permute(h);
vec2 pt = dist / image_size;
vec2 o = vec2(cos(dir), sin(dir));
// Sample at quarter-turn intervals around the source pixel
vec4 ref[4];
ref[0] = texture(tex, pos + pt * vec2( o.x, o.y));
ref[1] = texture(tex, pos + pt * vec2(-o.y, o.x));
ref[2] = texture(tex, pos + pt * vec2(-o.x, -o.y));
ref[3] = texture(tex, pos + pt * vec2( o.y, -o.x));
// Return the (normalized) average
return cmul*(ref[0] + ref[1] + ref[2] + ref[3])/4.0;
}
vec4 sample(sampler2D tex, vec2 pos, vec2 tex_size)
{
float h;
// Initialize the PRNG by hashing the position + a random uniform
vec3 m = vec3(pos, random) + vec3(1.0);
h = permute(permute(permute(m.x)+m.y)+m.z);
// Sample the source pixel
vec4 col = cmul*texture(tex, pos);
for (int i = 1; i <= ITERATIONS; i++) {
// Use the average instead if the difference is below the threshold
vec4 avg = average(tex, pos, i*RANGE, h);
vec4 diff = abs(col - avg);
col = mix(avg, col, greaterThan(diff, vec4(THRESHOLD/(i*16384.0))));
}
// Add some random noise to the output
vec3 noise;
noise.x = rand(h); h = permute(h);
noise.y = rand(h); h = permute(h);
noise.z = rand(h); h = permute(h);
col.rgb += (GRAIN/8192.0) * (noise - vec3(0.5));
return col;
}
Thoughts? I would greatly appreciate any suggestions
