Doom Fire

#version 300 es
// ╔═════════════╦════════════════╗
// ║ Marco Gomez ║ https://mgz.me ║
// ╚═════════════╩════════════════╝
precision highp float;

uniform sampler2D prgm4Texture;
uniform vec2 resolution;
uniform float time;

out vec4 fragColor;

void main(void) {
  vec2 uv = gl_FragCoord.xy / resolution.xy;
  vec4 prgm4 = texture(prgm4Texture, uv);
  fragColor = prgm4;
}

#version 300 es
// ╔═════════════╦════════════════╗
// ║ Marco Gomez ║ https://mgz.me ║
// ╚═════════════╩════════════════╝
precision highp float;

uniform sampler2D prgm1Texture;
uniform vec2 resolution;
uniform float time;
uniform bool mousedown;
uniform int frame;

out vec4 fragColor;

const float PI = acos(-1.0);

const vec2 rv2 = vec2(12.9898, 78.233);
const float rf = 43758.5453;

void main(void) {
  bool source = (gl_FragCoord.y < 4.0 && mousedown == false);
  vec2 uv = gl_FragCoord.xy / resolution.xy;
  float rand = fract(sin(mod(dot(uv + time, rv2), PI)) * rf);
  ivec2 offset = ivec2(rand * (-2.0) + 0.5, -int(rand > 0.5));
  float heat = texelFetch(prgm1Texture, ivec2(gl_FragCoord.xy) + offset, 0).r - 0.002;
  float c = max(heat, 0.0) * float(!source) + float(source);
  fragColor = vec4(vec3(c, c * c, pow(c, 12.0)), 1.0);
}

#version 300 es
// ╔═════════════╦════════════════╗
// ║ Marco Gomez ║ https://mgz.me ║
// ╚═════════════╩════════════════╝
precision highp float;

uniform sampler2D prgm1Texture;
uniform vec2 resolution;

out vec4 fragColor;

void main(void) {
  fragColor = texelFetch(
    prgm1Texture,
    ivec2(gl_FragCoord.xy) / 3 + ivec2(int(floor(resolution.x / 3.0)),0),
    0
  );
}

#version 300 es
// ╔═════════════╦════════════════╗
// ║ Marco Gomez ║ https://mgz.me ║
// ╚═════════════╩════════════════╝
precision highp float;

uniform sampler2D prgm2Texture;
uniform sampler2D noiseTexture;
uniform vec2 resolution;
uniform float time;
uniform float fft;

out vec4 fragColor;

const float PI = acos(-1.0);
const float TAU = PI * 2.0;
const mat2 m2 = mat2(0.80, -0.60, 0.60, 0.80);

float gaussian(float z, float u, float o) {
  return (
    1.0 / (o * sqrt(TAU))
  ) * exp(-(((z - u) * (z - u)) / (2.0 * (o * o))));
}

vec3 gaussGrain(float t) {
  vec2 ps = vec2(1.0) / resolution.xy;
  vec2 uv = gl_FragCoord.xy * ps;
  float seed = dot(uv, vec2(12.9898, 78.233));
  float noise = fract(sin(seed) * 43758.5453 + t);
  noise = gaussian(noise, 0.0, 0.5);
  return vec3(noise);
}

float noise(vec2 x) {
  vec2 p = floor(x);
  vec2 f = fract(x);
  f = f * f * (3.0 - 2.0 * f);
  float a = texture(noiseTexture, (p + vec2(0.5, 0.5 + fft * 0.25)) / 256.0, 0.0).x;
  float b = texture(noiseTexture, (p + vec2(1.5, 0.5 + fft * 0.25)) / 256.0, 0.0).x;
  float c = texture(noiseTexture, (p + vec2(0.5, 1.5 + fft * 0.25)) / 256.0, 0.0).x;
  float d = texture(noiseTexture, (p + vec2(1.5, 1.5 + fft * 0.25)) / 256.0, 0.0).x;
  return mix(mix(a, b, f.x), mix(c, d, f.x), f.y);
}

float fbm (vec2 uv) {
  float f = 0.0;
  f += 0.5000 * noise(uv); uv = m2 * uv * 2.02;
  f += 0.2500 * noise(uv); uv = m2 * uv * 2.03;
  f += 0.1250 * noise(uv); uv = m2 * uv * 2.01;
  f += 0.0625 * noise(uv);
  return f / 0.9375;
}

vec3 clouds(vec2 uv) {
  vec3 color;
  float t = time * 0.75;
  vec2 q = vec2( 0.0 ), r = vec2( 0.0 );
  q.x = fbm(uv + t * 0.25);
  q.y = fbm(uv + vec2(1.0));
  r.x = fbm(uv + q + vec2(1.7, 9.2) + 0.31 * t * 0.25);
  r.y = fbm(uv + q + vec2(8.3, 2.8) + 0.21 * t * 0.25);
  float f = fbm(uv + r);
  color = mix(vec3(1.0, 1.0, 1.0), vec3(0.3, 1.6, 1.6), clamp((f * f) * 2.0, 0.0, 1.0) + fft * 0.5);
  color = mix(color, vec3(0.4, 0.2, 0.16), clamp(length(q) + fft * 0.33, 0.0, 1.0));
  color = mix(color, vec3(0.4, 0.7, 3.00), clamp(length(r.x) + fft * 0.33, 0.0, 1.0));
  return color * color * color;
}

vec2 curve(vec2 uv) {
  uv *= 1.1;
  uv.x *= 1.0 + pow((abs(uv.y) / 5.0), 2.0);
  uv.y *= 1.0 + pow((abs(uv.x) / 5.0), 2.0);
  uv = (uv / 2.0) + 0.5;
  uv = uv * 0.92 + 0.08;
  return uv;
}

void main(void) {
  vec2 uv = gl_FragCoord.xy / resolution.y;
  vec2 suv = gl_FragCoord.xy / resolution.xy;
  vec4 prgm2 = texture(prgm2Texture, suv);
  uv.y *= (resolution.x / resolution.y) * -.0625 - 1.0;
  vec2 p = -1.0 + 2.0 * uv;
  float frameScale = 29.97;
  float frameTime = floor(time * frameScale) / frameScale;
  p.x -= frameTime * 0.25;
  p.y += frameTime * 0.5;
  vec3 g = gaussGrain(frameTime) * 0.04;
  vec2 pRes = resolution.xy / 24.0;
  p = floor(p * pRes) / pRes;
  vec3 col = clouds(p * 3.0) - g;
  vec3 lum = vec3(0.299, 0.587, 0.114) * 0.75;
  col = vec3(dot(col, lum));
  col = clamp(col * col, 0.0, 1.0);
  col = mix(prgm2.xyz, prgm2.xyz * col, 0.35);
  fragColor = vec4(col, 1.0);
}

#version 300 es
// ╔═════════════╦════════════════╗
// ║ Marco Gomez ║ https://mgz.me ║
// ╚═════════════╩════════════════╝
precision highp float;

uniform sampler2D prgm3Texture;
uniform vec2 resolution;
uniform float time;

out vec4 fragColor;

const float PI = acos(-1.0);
const float TAU = PI * 2.0;
const float hardscan = -16.0; // -8.0 = soft | -16.0 = medium
const float hardPix = -4.0; // -2.0 = soft | -4.0 = hard
const float maskDark = 0.5;
const float maskLight = 2.5;

float toLinear(float c) {
  return (c <= 0.04045) ? c / 12.92 : pow(abs((c + 0.055) / 1.055), 2.4);
}

vec3 toLinear(vec3 c) {
  return vec3(toLinear(c.r), toLinear(c.g), toLinear(c.b));
}

float toSRGB(float c) {
  return(c < 0.0031308 ? c * 12.92 : 1.055 * pow(abs(c), 0.41666) - 0.055);
}

vec3 toSRGB(vec3 c) {
  return vec3(toSRGB(c.r), toSRGB(c.g), toSRGB(c.b));
}

vec3 fetch(vec2 pos, vec2 off, vec2 res) {
  pos = floor(pos * res + off) / res;
  if (max(abs(pos.x - 0.5), abs(pos.y - 0.5)) > 0.5) {
    return vec3(0.0);
  }
  return toLinear(texture(prgm3Texture, pos.xy, -16.0).xyz);
}

vec2 dist(vec2 pos, vec2 res) {
  pos = pos * res;
  return -((pos - floor(pos)) - vec2(0.5));
}

float gauss(float pos, float scale) {
  return exp2(scale * pos * pos);
}

vec3 horz3(vec2 pos, float off, vec2 res) {
  vec3 b = fetch(pos, vec2(-1.0, off), res);
  vec3 c = fetch(pos, vec2(+0.0, off), res);
  vec3 d = fetch(pos, vec2(+1.0, off), res);
  float dst = dist(pos, res).x;
  float scale = hardPix;
  float wb = gauss(dst - 1.0, scale);
  float wc = gauss(dst + 0.0, scale);
  float wd = gauss(dst + 1.0, scale);
  return (b * wb + c * wc + d * wd) / (wb + wc + wd);
}

vec3 horz5(vec2 pos, float off, vec2 res) {
  vec3 a = fetch(pos, vec2(-2.0, off), res);
  vec3 b = fetch(pos, vec2(-1.0, off), res);
  vec3 c = fetch(pos, vec2(+0.0, off), res);
  vec3 d = fetch(pos, vec2(+1.0, off), res);
  vec3 e = fetch(pos, vec2(+2.0, off), res);
  float dst = dist(pos, res).x;
  float scale = hardPix;
  float wa = gauss(dst - 2.0, scale);
  float wb = gauss(dst - 1.0, scale);
  float wc = gauss(dst + 0.0, scale);
  float wd = gauss(dst + 1.0, scale);
  float we = gauss(dst + 2.0, scale);
  return (a * wa + b * wb + c * wc + d * wd + e * we) / (wa + wb + wc + wd + we);
}

float scan(vec2 pos, float off, vec2 res) {
  float dst = dist(pos, res).y;
  return gauss(dst + off, hardscan);
}

vec3 tri(vec2 pos, vec2 res) {
  vec3 a = horz3(pos, -1.0, res);
  vec3 b = horz5(pos, +0.0, res);
  vec3 c = horz3(pos, +1.0, res);
  float wa = scan(pos, -1.0, res);
  float wb = scan(pos, +0.0, res);
  float wc = scan(pos, +1.0, res);
  return a * wa + b * wb + c * wc;
}

vec3 mask(vec2 pos) {
  pos.x += pos.y * 3.0;
  vec3 m = vec3(maskDark, maskDark, maskDark);
  pos.x = fract(pos.x / 6.0);
  if (pos.x < 0.333) {
    m.r = maskLight;
  } else if (pos.x < 0.666) {
    m.g = maskLight;
  } else {
    m.b = maskLight;
  }
  return m;
}

float bar(float pos, float bar) {
  pos -= bar;
  return pos * pos < 4.0 ? 0.0 : 1.0;
}

float rand(vec2 uv, float t) {
  float seed = dot(uv, vec2(12.9898, 78.233));
  return fract(sin(seed) * 43758.5453123 + t);
}

float gaussian(float z, float u, float o) {
  return (
    (1.0 / (o * sqrt(TAU))) *
    (exp(-(((z - u) * (z - u)) / (2.0 * (o * o)))))
  );
}

vec3 gaussgrain(float t) {
  vec2 ps = vec2(1.0) / resolution.xy;
  vec2 uv = gl_FragCoord.xy * ps;
  float noise = rand(uv, t);
  noise = gaussian(noise, 0.0, 0.5);
  return vec3(noise);
}

void main(void) {
  vec2 res = vec2(resolution.x / 5.0, resolution.y / 4.0);
  vec2 uv = gl_FragCoord.xy / resolution.xy;
  float frameScale = 29.97;
  float frameTime = floor(time * frameScale) / frameScale;
  vec3 g = gaussgrain(frameTime) * 0.07;
  vec4 color = vec4(tri(uv, res) * mask(gl_FragCoord.xy), 1.0);
  color.xyz = toSRGB(color.xyz * 2.0) - g;
  fragColor = color;
}