#version 430
layout(local_size_x = 8, local_size_y = 8) in;

#include <sdf>
#include <utils>
#include <noise>

const float MAX_DISTANCE = 1000.; // 1000.
const int MAX_ITERATIONS = 800; // 600+
const float MIN_GAP = 0.001;

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

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

uniform vec3 camera_position = vec3(0, 0, -3);

const int O_SANDWICH_FILL = 1;
const int O_SANDWICH_WAFER = 2;

float time = seconds * 2;
int break_sym = int(int(time) % 40 == 14 || int(time) % 40 == 18 || int(time) % 40 == 36);
int break_sym_2 = int(int(time) % 40 == 20 || int(time) % 40 == 3);

float sdf_icecream_sandwich(in vec3 p, in bool show_bite, inout int obj_id) {
  float fill = sdf_box(p, vec3(0.18, 0.04, 0.1), 0.02);
  float wafernoise = 0.00062 * noise(p * 900);
  vec3 wafersize = vec3(0.20, 0.016, 0.12) + wafernoise;
  float wafer = sdf_box(p - vec3(0, 0.056, 0), wafersize, 0.014);
  wafer = min(wafer, sdf_box(p - vec3(0, -0.056, 0), wafersize, 0.014));

  {
    vec3 dotp = p - vec3(0, -0.07, 0);
    float gap = 0.07;
    dotp.xz -= round(dotp.xz / gap) * gap;
    float dots = sdf_circle(dotp, 0.006);
    wafer = max(wafer, -dots);
  }
  {
    vec3 dotp = p - vec3(0, 0.07, 0);
    float gap = 0.07;
    dotp.xz -= round(dotp.xz / gap) * gap;
    float dots = sdf_circle(dotp, 0.006);
    wafer = max(wafer, -dots);
  }

  if (show_bite) {
    vec3 teethp = p - vec3(-0.19, -0.07, -0.11);
    float theta = atan(teethp.z, teethp.x);
    float biteradius = 0.08 + 0.003 * sin(theta * 18);
    fill = max(fill, -sdf_capsule(teethp, 0.12, biteradius));
    wafer = max(wafer, -sdf_capsule(teethp, 0.12, biteradius + 8.0 * wafernoise));
  }

  float dist = min(fill, wafer);
  if (dist == wafer) obj_id = O_SANDWICH_WAFER;
  else obj_id = O_SANDWICH_FILL;
  return dist;
}

void rotate_all_axes(inout vec3 p, float theta) {
  mat2x2 rot = mat2x2(cos(theta), -sin(theta), sin(theta), cos(theta));
  p.xy *= rot;
  p.yz *= rot;
  p.xz *= rot;
}

float scene(in vec3 p, out int obj_id) {
  float sw;
  int sw_id;
  float rotation_time = seconds;
  {
    vec3 swp = p;
    {
      float theta = rotation_time / 26 + 0.3 * break_sym + 0.17 * break_sym_2;
      swp.xy *= mat2x2(cos(theta), -sin(theta), sin(theta), cos(theta));
    }
    vec2 p1rot, p2rot;
    float id = rotational_repetition(swp.xy, 20, p1rot, p2rot);
    int odd = int(id) % 2;
    vec3 offset = vec3(3.5 - 0.06 * odd * break_sym, 0, 4.5);
    float theta = -rotation_time / 6 + 0.1 + 0.5 * break_sym;
    int sw1_id, sw2_id;
    vec3 p1 = vec3(p1rot, swp.z) - offset;
    vec3 p2 = vec3(p2rot, swp.z) - offset;
    rotate_all_axes(p1, theta);
    rotate_all_axes(p2, theta);
    float b1 = sdf_icecream_sandwich(p1, bool(break_sym), sw1_id);
    float b2 = sdf_icecream_sandwich(p2, bool(break_sym), sw2_id);
    sw = min(b1, b2);
    if (sw == b1) sw_id = sw1_id;
    else if (sw == b2) sw_id = sw2_id;
  }
  {
    vec3 swp = p;
    {
      float theta = rotation_time / 20 + 0.3 * break_sym;
      swp.xy *= mat2x2(cos(theta), -sin(theta), sin(theta), cos(theta));
    }
    vec2 p1rot, p2rot;
    float id = rotational_repetition(swp.xy, 20, p1rot, p2rot);
    int odd = int(id) % 2;
    vec3 offset = vec3(1 - 0.06 * odd * break_sym, 0, 0);
    float theta = rotation_time / 4 + 0.3 * break_sym;
    int sw1_id, sw2_id;
    vec3 p1 = vec3(p1rot, swp.z) - offset;
    vec3 p2 = vec3(p2rot, swp.z) - offset;
    rotate_all_axes(p1, theta);
    rotate_all_axes(p2, theta);
    float b1 = sdf_icecream_sandwich(p1, bool(break_sym), sw1_id);
    float b2 = sdf_icecream_sandwich(p2, bool(break_sym), sw2_id);
    sw = min(sw, min(b1, b2));
    if (sw == b1) sw_id = sw1_id;
    else if (sw == b2) sw_id = sw2_id;
  }
  {
    vec3 swp = p - vec3(0, 0, 0.5);
    {
      float theta = rotation_time / 12 + 0.3 * break_sym;
      swp.xy *= mat2x2(cos(theta), -sin(theta), sin(theta), cos(theta));
    }
    vec2 p1rot, p2rot;
    float id = rotational_repetition(swp.xy, 36, p1rot, p2rot);
    int odd = int(id) % 2;
    vec3 offset = vec3(0.8 - 0.06 * odd * break_sym, 0, 0);
    float theta = -rotation_time / 5 + 0.3 + 0.3 * break_sym;
    int sw1_id, sw2_id;
    vec3 p1 = vec3(p1rot, swp.z) - offset;
    vec3 p2 = vec3(p2rot, swp.z) - offset;
    rotate_all_axes(p1, theta);
    rotate_all_axes(p2, theta);
    float b1 = sdf_icecream_sandwich(p1, bool(break_sym), sw1_id);
    float b2 = sdf_icecream_sandwich(p2, bool(break_sym), sw2_id);
    sw = min(sw, min(b1, b2));
    if (sw == b1) sw_id = sw1_id;
    else if (sw == b2) sw_id = sw2_id;
  }

  {
    vec3 sp = p * 0.8 - vec3(0, 0, -1);
    sp.yz *= mat2x2(cos(0.42), -sin(0.42), sin(0.42), cos(0.42));
    sp.xz *= mat2x2(cos(-0.42), -sin(-0.42), sin(-0.42), cos(-0.42));
    int sw1_id;
    float sando = sdf_icecream_sandwich(sp, true, sw1_id);
    sw = min(sw, sando);
    if (sw == sando) sw_id = sw1_id;
  }

  float dist = sw;
  if (dist == sw) obj_id = sw_id;
  return dist;
}

void apply_material(
  in int obj_id,
  in float dist,
  inout vec3 color,
  inout float ambient,
  inout float shine
) {
  if (obj_id == O_SANDWICH_FILL) {
    color = srgb(1);
    shine = 2.0;
  } else if (obj_id == O_SANDWICH_WAFER) {
    color = srgb(0.44, 0.27, 0.17);
    shine = 0.06;
  }
}

float raymarch_scene(vec3 ray_origin, vec3 ray_direction, out int obj_id) {
  float dist = 0.;
  for (int i = 0; i < MAX_ITERATIONS && dist <= MAX_DISTANCE; i++) {
    vec3 p = ray_origin + ray_direction * dist;
    float gap = scene(p, obj_id);
    dist += gap;
    if (gap <= MIN_GAP)
      return dist;
  }
  obj_id = -1;
  return dist;
}

vec3 surface_normal_scene(in vec3 p) {
  vec2 e = vec2(MIN_GAP, 0);
  int obj_id;
  return normalize(vec3(
      scene(p + e.xyy, obj_id) - scene(p - e.xyy, obj_id),
      scene(p + e.yxy, obj_id) - scene(p - e.yxy, obj_id),
      scene(p + e.yyx, obj_id) - scene(p - e.yyx, obj_id)));
}

vec3 image(vec2 uv) {
  vec3 campos = camera_position;
  vec3 uv_direction = normalize(vec3(uv, 1));

  int obj_id = 0;
  float dist = raymarch_scene(campos, uv_direction, obj_id);

  vec3 p = campos + uv_direction * dist;
  vec3 norm = surface_normal_scene(p);

  vec3 light = vec3(6, 8, -20);
  vec3 light_dir = normalize(light - p);

  vec3 c1 = srgb(0.74, 0.93, 0.80);
  vec3 c2 = srgb(0.98, 0.75, 0.83);
  vec3 c3 = srgb(0.59, 0.88, 0.94);
  vec3 c4 = srgb(0.98, 0.78, 0.51);

  vec2 patp = uv * 30;
  float pat = sin(patp.x) * cos(patp.y - time) - sin(3 * patp.x) - cos(3 * patp.y);
  vec3 bg_color = c1;
  bg_color = mix(bg_color, c2, step(pat, 1.0));
  bg_color = mix(bg_color, c3, step(pat, 0));
  bg_color = mix(bg_color, c4, step(pat, -1.0));
  bg_color = mix(bg_color, srgb(0.8, 0, 0), 0.25 * break_sym);

  vec3 color = bg_color;
  float ambient = 0.05;
  float shine = 1.;
  apply_material(obj_id, dist, color, ambient, shine);

  if (obj_id > 0) {
    float contrast = clamp(dot(norm, light_dir), 0, 1);
    color *= clamp((1 - ambient) * contrast + ambient, 0, 1);

    vec3 hal = normalize(light_dir - uv_direction);
    float spec =
      pow(clamp(dot(norm, hal), 0.0, 1.0), 16.0) * contrast *
        (0.04 +
          0.96 * pow(clamp(1.0 + dot(hal, uv_direction), 0.0, 1.0), 5.0));
    color += shine * 10. * spec * vec3(1.00, 0.70, 0.5);
  }

  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);

  float t = time;
  vec2 offset = vec2(mod(t * sin(t * 8 + fbm(vec2(t)) * 0.5), 0.02), 0);
  if (break_sym == 1) {
    color.r = (color.r + image(uv + offset).r + image(uv - offset).r) / 3.;
    color.g = (color.g + image(uv + vec2(offset.y, offset.x)).g + image(uv + offset).g) / 3.;
    color.b = (color.b + image(uv + vec2(offset.y, offset.x)).b + image(uv - offset).b) / 3.;
  }

  color = clamp(color, 0, 1);
  imageStore(output_image, ivec2(gl_GlobalInvocationID.xy), vec4(color, 1));
}