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HTML

              
                <canvas id="view"></canvas>

<script id="flame-frag" type="x-shader/x-vertex">
    
  /**
   * Original shader by @kuvkar (https://www.shadertoy.com/view/4tXXRn) 
   */
  
  varying vec2 vTextureCoord;  
  
  uniform sampler2D uSampler;
  uniform sampler2D mapSampler;  
  uniform vec4 filterArea;  
  uniform vec2 dimensions;
  uniform float time;
  
  float rand(vec2 co) {
    return fract(sin(dot(co.xy ,vec2(12.9898, 78.233))) * 43758.5453);
  }
  
  mat2 rotz(float angle) {
    mat2 m;
    m[0][0] = cos(angle); m[0][1] = -sin(angle);
    m[1][0] = sin(angle); m[1][1] = cos(angle);
    return m;
  }  
  
  // Fractal Brownian Motion
  float fbm(vec2 uv) {        
    
    float n = (texture2D(mapSampler, uv).r - 0.5) * 0.5;
    n += (texture2D(mapSampler, uv * 2.0).r - 0.5) * 0.5 * 0.5;
    n += (texture2D(mapSampler, uv * 3.0).r - 0.5) * 0.5 * 0.5 * 0.5;    
    return n + 0.5;    
  }
  
  void main() {
    
    vec2 uv = (vTextureCoord * filterArea.xy) / dimensions;
    uv.y = 1.0 - uv.y;
    
    vec2 _uv = uv;
    uv -= vec2(0.5);
    uv.y /= dimensions.x / dimensions.y;      
    
    vec2 centerUV = uv;
    
    // height variation from fbm
    float variationH = fbm(vec2(time * 0.3)) * 1.1;
    
    // flame "speed"
    vec2 offset = vec2(0.0, -time * 0.05);
        
    // flame turbulence
    float f = fbm(uv * 0.1 + offset); // rotation from fbm        
    float l = max(0.1, length(uv)); // rotation amount normalized over distance
	  uv += rotz(((f - 0.5) / l) * smoothstep(-0.2, 0.4, _uv.y) * 0.45) * uv;    
    
    // flame thickness
    float flame = 1.3 - length(uv.x) * 5.0;
    
    // bottom of flame 
    float blueflame = pow(flame * 0.9, 15.0);
    blueflame *= smoothstep(0.2, -1.0, _uv.y);
    blueflame /= abs(uv.x * 2.0);
    blueflame = clamp(blueflame, 0.0, 1.0);
    
    // flame
    flame *= smoothstep(1.0, variationH * 0.5, _uv.y);
	  flame = clamp(flame, 0.0, 1.0);
    flame = pow(flame, 3.0);
    flame /= smoothstep(1.1, -0.1, _uv.y);    
	
    // colors
    vec4 col = mix(vec4(1.0, 1.0, 0.0, 0.0), vec4(1.0, 1.0, 0.6, 0.0), flame);
    col = mix(vec4(1.0, 0.0, 0.0, 0.0), col, smoothstep(0.0, 1.6, flame));
    gl_FragColor = col;
    
	  // a bit blueness on the bottom
    vec4 bluecolor = mix(vec4(0.0, 0.0, 1.0, 0.0), gl_FragColor, 0.95);
    gl_FragColor = mix(gl_FragColor, bluecolor, blueflame);
    
    // clear bg outside of the flame
    gl_FragColor *= flame;
    gl_FragColor.a = flame;
    
    // bg halo
    float haloSize = 0.5;
    float centerL = 1.0 - (length(centerUV + vec2(0.0, 0.1)) / haloSize);
    vec4 halo = vec4(0.8, 0.3, 0.3, 0.0) * 1.0 * fbm(vec2(time * 0.035)) * centerL + 0.02;
    vec4 finalCol = mix(halo, gl_FragColor, gl_FragColor.a);
    gl_FragColor = finalCol;

    // just a hint of noise
    gl_FragColor *= mix(rand(uv) + rand(uv * 0.45), 1.0, 0.9);
    gl_FragColor = clamp(gl_FragColor, 0.0, 1.0);
  }
</script>
              
            
!

CSS

              
                body {
  background: #000;
}

#view {
  position: fixed;
  top: 0;
  left: 0;
}
              
            
!

JS

              
                console.clear();

const flameFrag = document.querySelector("#flame-frag").textContent;
const baseUrl = "https://s3-us-west-2.amazonaws.com/s.cdpn.io/106114/";

const manifest = [
  { name: "noise", url: "noise-texture-11.png?v=9" }
];


//
// FLAME FILTER
// ===========================================================================
class FlameFilter extends PIXI.Filter {
  
  constructor(texture, time = 0.0) {    
    super(null, flameFrag);
       
    this.uniforms.dimensions = new Float32Array(2);   
    this.texture = texture;
    this.time = time;
  }
  
  get texture() {
    return this.uniforms.mapSampler;
  }
  
  set texture(texture) {
    texture.baseTexture.wrapMode = PIXI.WRAP_MODES.REPEAT;
    this.uniforms.mapSampler = texture;
  }
  
  apply(filterManager, input, output, clear) {
          
    this.uniforms.dimensions[0] = input.sourceFrame.width;
    this.uniforms.dimensions[1] = input.sourceFrame.height;    
    this.uniforms.time = this.time;

    filterManager.applyFilter(this, input, output, clear);
  }
}


//
// APPLICATION
// ===========================================================================
class Application extends PIXI.Application {
    
  constructor() {
    
    if (window.devicePixelRatio > 1) {
      PIXI.settings.RESOLUTION = 2;
    }
    
    PIXI.settings.PRECISION_FRAGMENT = "highp";
    
    super({
      view: document.querySelector("#view"),
      width: window.innerWidth,
      height: window.innerHeight,
      backgroundColor: 0x000000,
      autoResize: true
    });   
    
    this.isResized = true;    
    this.loader.baseUrl = baseUrl;   
  }
    
  load(manifest) {
    
    this.loader
      .add(manifest)
      .load((l, r) => this.init(r));   
  }
    
  init(resources) {     
        
    this.flame = new FlameFilter(resources.noise.texture);
       
    this.stage.filterArea = this.screen;
    this.stage.filters = [this.flame];
       
    this.ticker.add(this.update, this);                     
    window.addEventListener("resize", () => this.isResized = true);
  }
   
  update(delta) {
    
    if (this.isResized) {
      this.renderer.resize(window.innerWidth, window.innerHeight);
      this.isResized = false;
    }
    
    this.flame.time += 0.1 * delta;
  }
}

const app = new Application();
app.load(manifest);

              
            
!
999px

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