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

#include <sdf>

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

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

const vec3 sky_color = vec3(0.4, 0.65, 1);
const vec3 water_color = vec3(0.02, 0.1, 0.9);
const vec3 sand_color = vec3(0.7, 0.6, 0.4);
const vec3 sun_color = vec3(1, 0.4, 0.2);
const vec3 tree_trunk_color = vec3(0.3, 0.13, 0.06);

vec3 image(vec2 uv) {
  vec3 color = vec3(0);

  vec2 sunpos = vec2(0.2, 0.1);
  float sun = sdf_circle(uv - sunpos, 0.04);
  color = mix(clamp(sun_color * 1.6, 0., 1.), sky_color, clamp(sun * 6, 0, 1));
  color = mix(color, sun_color, step(sun, 0.04));

  float water = uv.y;
  color = mix(color, water_color, step(water, -0.04));

  float sand = uv.y + sin(uv.x * 3 + 0.) * 0.07;
  color = mix(color, sand_color, step(sand, -0.23));

  float trunk = sdf_box(uv - vec2(-0.35 + sin(uv.y * 4 - 0.2) * 0.08, -0.06), vec2(0.01 + abs(uv.y * 0.2 - 0.1) * 0.3, 0.28), 0.0);
  color = mix(color, tree_trunk_color, step(trunk, 0));

  float leafbranchcurve = sin(-uv.x * 8 + 0.2) * 0.06;
  float leafsizecurve = sin(uv.x * 8 - 6.8) * 0.06;

  vec2 leafpos = uv;
  leafpos -= vec2(-0.26 + sin(uv.y * 8 + 0.5) * 0.06, 0.18 + leafbranchcurve + leafsizecurve);
  float leafgap = 0.012;
  float leafindex = clamp(round(leafpos.x / leafgap), -7, 21);
  leafpos.x = leafpos.x - leafgap * leafindex;
  float leaf = sdf_box(leafpos, vec2(abs(leafpos.y * 0.1 + 0.014) * 0.26, 0.02 - leafsizecurve), 0.0);
  color = mix(color, vec3(0.0, 0.3, 0.0), step(leaf, 0));

  float leaf_stick = sdf_box(uv - vec2(-0.13, 0.20 + leafbranchcurve), vec2(0.19, 0.008), 0.02);
  color = mix(color, vec3(0.0, 0.06, 0.0), step(leaf_stick, 0));

  return color;
}

vec3 antialiased_image(vec2 uv) {
  float anti_aliasing = 0.0006;
  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) * anti_aliasing);
  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 * 0.5) * vec2(1.0, aspect_ratio) / resolution;

  // vec3 color = antialiased_image(uv);
  vec3 color = image(uv);
  imageStore(output_image, ivec2(gl_GlobalInvocationID.xy), vec4(color, 1));
}