#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 readonly image2D subtexture;
layout(rgba8) uniform writeonly image2D output_image;

uniform float flow_field[400];
uniform vec2 particles[100];
uniform int particles_count;

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

float gen_pattern(in vec2 p, out vec3 coloring_factor, out vec3 coloring_factor2) {
  float s1 = sample_noise(p + sample_noise(p) * vec2(0.5, 0.1));
  float s2 = sample_noise(p + sample_noise(p) * vec2(0.8, 0.4));
  float s3 = sample_noise(p + sample_noise(p));
  coloring_factor = vec3(0.204, 0.11, 0.01) * vec3(s1 * s2, 0.3 * s3, 0.3 * s3);
  coloring_factor2 = vec3(0.4, 0.3 * s3, 0.3 * s3);
  return sample_noise(p + s2 * s1 * s3);
}

vec3 srgb(in float r, in float g, in float b) {
  return vec3(pow(r, 2.2), pow(g, 2.2), pow(b, 2.2));
}

void main() {
  vec2 uv = vec2(gl_GlobalInvocationID.xy) / imageSize(output_image).xy;

  // vec3 coloring_factor;
  // vec3 coloring_factor2;
  // float v = gen_pattern(uv, coloring_factor, coloring_factor2);
  // coloring_factor = srgb(0.941, 0.827, 0.706);
  // coloring_factor2 = srgb(0.204, 0.11, 0.01);
  // coloring_factor2 = srgb(0.204, 0.11, 0.01);
  // coloring_factor2 = srgb(0.104, 0.06, 0.00);
  // vec3 color = mix(coloring_factor, coloring_factor2, clamp(v, 0., 1.));

  ivec2 grid = ivec2(20, 20);
  vec2 p = uv * grid;
  int ffidx = int(p.x) + int(p.y) * grid.y;
  float cell = flow_field[ffidx];
  // vec3 color = vec3(ffidx/400.);
  vec3 color = vec3(cell);
  // subtexture

  for (int i = 0; i < particles_count; i++) {
    vec2 p = particles[i];
    if (length(uv - p) - 0.01 <= 0) {
      color = vec3(1, 0, 0);
    }
  }

  // color = imageLoad(noise_texture, ivec2(uv * imageSize(output_image).xy)).xyz;
  imageStore(output_image, ivec2(gl_GlobalInvocationID.xy), vec4(color, 1));
}