#version 430
layout(local_size_x = 1, local_size_y = 1) in;

uniform float seconds = 0;
layout(rgba8) uniform readonly image2D noise_texture;
layout(rgba8) uniform writeonly image2D output_image;

uniform float antialiasing = 0.28;
uniform bool enable_antialiasing = false;

float sample_noise(in vec2 p) {
  vec4 noise = imageLoad(noise_texture, ivec2(p * imageSize(noise_texture)));
  return noise.x;
}

vec3 image(vec2 uv) {
  float v = sample_noise(uv);
  vec3 color = mix(vec3(0), vec3(1), v);
  return color;
}

vec3 antialiased_image(vec2 uv) {
  vec2 resolution = vec2(imageSize(output_image).xy);
  float s = antialiasing / max(resolution.x, resolution.y);
  vec3 sum = vec3(0);
  int count = 0;
  for (int i = -2; i < 2; i++)
    for (int j = -2; j < 2; j++, count++)
      sum += image(uv + vec2(i, j) * s);
  return sum / count;
}

void main() {
  vec2 resolution = vec2(imageSize(output_image).xy);
  float aspect_ratio = resolution.y / resolution.x;
  vec2 uv = (gl_GlobalInvocationID.xy - resolution / 2) * vec2(1.0, aspect_ratio) / resolution;

  vec3 color = enable_antialiasing ? antialiased_image(uv) : image(uv);

  imageStore(output_image, ivec2(gl_GlobalInvocationID.xy), vec4(color, 1));
}