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CSS

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HTML 

              
                <!--

An attempt to try out a technique mentioned by @minionsart and @ciaccodavide on Twitter:
https://twitter.com/minionsart/status/964257071423283200
https://twitter.com/ciaccodavide/status/964407412634472448

-->

<script type="x-shader/x-fragment" id="shader-flame-fragment">
uniform vec3 colorStart;
uniform vec3 colorEnd;
uniform sampler2D textureGradient;
uniform sampler2D textureNoise;
uniform float threshold;

varying vec2 vUv;
	
void main() {
	float gradient = texture2D(textureGradient, vUv).r;
	float noise = texture2D(textureNoise, vUv).r;
	float alpha = gradient * noise;
	
	if (alpha < threshold) discard;
	
	float alphaRender = (1.0 - threshold) * alpha;
	
	vec3 color = mix(colorStart, colorEnd, alphaRender);
	gl_FragColor = vec4(color, 1.0);
}
</script>

<script type="x-shader/x-fragment" id="shader-gradient-fragment">
uniform float power;
varying vec2 vUv;
	
void main() {
	float darkness = pow(1.0 - vUv.y, power);
	
	gl_FragColor = vec4(darkness, darkness, darkness, 1.0);
}
</script>

<script type="x-shader/x-fragment" id="shader-noise-fragment">
uniform int octaves;
uniform float persistence;
uniform float scale;
uniform float speed;
uniform float time;

varying vec2 vUv;

const int OCTAVES_MAX = 16;

float noiseOctaves(int octaves, vec2 position, float persistence, vec2 frequency) {
	if (octaves == 0) return 0.0;
	
	float amplitude = 1.0;
	float amplitudeSum = 0.0;
	float noise = 0.0;
	
	for (int i = 0; i < OCTAVES_MAX; i++) {
		if (i >= octaves) break;
		
		float octave = float(i);
		float t = octave / float(octaves);
		
		noise = noise + pnoise(position * frequency, frequency) * amplitude;
		
		amplitudeSum = amplitudeSum + amplitude;
		amplitude = amplitude * persistence;
		frequency = 2.0 * frequency;
	}
	
	return (1.0 + noise / amplitudeSum) * 0.5;
}
	
	
void main() {
	vec2 position = vec2(0.0, -time) * speed + vUv;
	float noise = noiseOctaves(octaves, position, persistence, vec2(scale, scale));
	
	gl_FragColor = vec4(noise, noise, noise, 1.0);
}
</script>

<script type="x-shader/x-vertex" id="shader-passthrough-vertex">
varying vec2 vUv;

void main() {
	vUv = uv.xy;
	
	gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
}
</script>

<script type="x-shader/x-fragment" id="shader-texture-fragment">
uniform sampler2D texture;
varying vec2 vUv;
	
void main() {
	gl_FragColor = texture2D(texture, vUv);
}
</script>

<script type="x-shader/x-generic" id="shader-noise-2d">
//
// GLSL textureless classic 2D noise "cnoise",
// with an RSL-style periodic variant "pnoise".
// Author:  Stefan Gustavson ([email protected])
// Version: 2011-08-22
//
// Many thanks to Ian McEwan of Ashima Arts for the
// ideas for permutation and gradient selection.
//
// Copyright (c) 2011 Stefan Gustavson. All rights reserved.
// Distributed under the MIT license. See LICENSE file.
// https://github.com/stegu/webgl-noise
//

vec4 mod289(vec4 x)
{
  return x - floor(x * (1.0 / 289.0)) * 289.0;
}

vec4 permute(vec4 x)
{
  return mod289(((x*34.0)+1.0)*x);
}

vec4 taylorInvSqrt(vec4 r)
{
  return 1.79284291400159 - 0.85373472095314 * r;
}

vec2 fade(vec2 t) {
  return t*t*t*(t*(t*6.0-15.0)+10.0);
}

// Classic Perlin noise
float cnoise(vec2 P)
{
  vec4 Pi = floor(P.xyxy) + vec4(0.0, 0.0, 1.0, 1.0);
  vec4 Pf = fract(P.xyxy) - vec4(0.0, 0.0, 1.0, 1.0);
  Pi = mod289(Pi); // To avoid truncation effects in permutation
  vec4 ix = Pi.xzxz;
  vec4 iy = Pi.yyww;
  vec4 fx = Pf.xzxz;
  vec4 fy = Pf.yyww;

  vec4 i = permute(permute(ix) + iy);

  vec4 gx = fract(i * (1.0 / 41.0)) * 2.0 - 1.0 ;
  vec4 gy = abs(gx) - 0.5 ;
  vec4 tx = floor(gx + 0.5);
  gx = gx - tx;

  vec2 g00 = vec2(gx.x,gy.x);
  vec2 g10 = vec2(gx.y,gy.y);
  vec2 g01 = vec2(gx.z,gy.z);
  vec2 g11 = vec2(gx.w,gy.w);

  vec4 norm = taylorInvSqrt(vec4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));
  g00 *= norm.x;  
  g01 *= norm.y;  
  g10 *= norm.z;  
  g11 *= norm.w;  

  float n00 = dot(g00, vec2(fx.x, fy.x));
  float n10 = dot(g10, vec2(fx.y, fy.y));
  float n01 = dot(g01, vec2(fx.z, fy.z));
  float n11 = dot(g11, vec2(fx.w, fy.w));

  vec2 fade_xy = fade(Pf.xy);
  vec2 n_x = mix(vec2(n00, n01), vec2(n10, n11), fade_xy.x);
  float n_xy = mix(n_x.x, n_x.y, fade_xy.y);
  return 2.3 * n_xy;
}

// Classic Perlin noise, periodic variant
float pnoise(vec2 P, vec2 rep)
{
  vec4 Pi = floor(P.xyxy) + vec4(0.0, 0.0, 1.0, 1.0);
  vec4 Pf = fract(P.xyxy) - vec4(0.0, 0.0, 1.0, 1.0);
  Pi = mod(Pi, rep.xyxy); // To create noise with explicit period
  Pi = mod289(Pi);        // To avoid truncation effects in permutation
  vec4 ix = Pi.xzxz;
  vec4 iy = Pi.yyww;
  vec4 fx = Pf.xzxz;
  vec4 fy = Pf.yyww;

  vec4 i = permute(permute(ix) + iy);

  vec4 gx = fract(i * (1.0 / 41.0)) * 2.0 - 1.0 ;
  vec4 gy = abs(gx) - 0.5 ;
  vec4 tx = floor(gx + 0.5);
  gx = gx - tx;

  vec2 g00 = vec2(gx.x,gy.x);
  vec2 g10 = vec2(gx.y,gy.y);
  vec2 g01 = vec2(gx.z,gy.z);
  vec2 g11 = vec2(gx.w,gy.w);

  vec4 norm = taylorInvSqrt(vec4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));
  g00 *= norm.x;  
  g01 *= norm.y;  
  g10 *= norm.z;  
  g11 *= norm.w;  

  float n00 = dot(g00, vec2(fx.x, fy.x));
  float n10 = dot(g10, vec2(fx.y, fy.y));
  float n01 = dot(g01, vec2(fx.z, fy.z));
  float n11 = dot(g11, vec2(fx.w, fy.w));

  vec2 fade_xy = fade(Pf.xy);
  vec2 n_x = mix(vec2(n00, n01), vec2(n10, n11), fade_xy.x);
  float n_xy = mix(n_x.x, n_x.y, fade_xy.y);
  return 2.3 * n_xy;
}
</script>
!

CSS 

              
                canvas {
	display: block;
}
!

JS 

              
                class ShaderChunkLibrary {
	static get flameFragment() {
		return document.getElementById('shader-flame-fragment').textContent;
	}
	
	static get noise2DPeriodic() {
		return document.getElementById('shader-noise-2d').textContent;
	}
	
	static get gradientFragment() {
		return document.getElementById('shader-gradient-fragment').textContent;
	}
	
	static get noiseFragment() {
		return ShaderChunkLibrary.noise2DPeriodic + document.getElementById('shader-noise-fragment').textContent;
	}
	
	static get passThroughVertex() {
		return document.getElementById('shader-passthrough-vertex').textContent;
	}
	
	static get textureFragment() {
		return document.getElementById('shader-texture-fragment').textContent;
	}
}

class BufferRenderer {
	constructor(material) {
		this.camera = new THREE.OrthographicCamera(-0.5, 0.5, 0.5, -0.5, 1, 3);
		this.camera.position.z = 2;
		
		this.material = material;
		this.plane = BufferRenderer.createPlane(material);

		this.scene = new THREE.Scene();
		this.scene.add(this.plane);
	}
	
	render(renderer, renderTarget) {
		renderer.render(this.scene, this.camera, renderTarget);
	}
	
	static createPlane(material) {
		const geometry = new THREE.PlaneBufferGeometry(1, 1, 1, 1);
		return new THREE.Mesh(geometry, material);
	}
}

class Application {
	static get RENDERER_OPTIONS() {
		return {
			antialias: true,
		};
	}
	
	constructor() {
		this.bufferRenderers = Application.createBufferRenderers();
		
		this.buffers = new Array(3).fill().map(_ => new THREE.WebGLRenderTarget(1024, 1024, {
			wrapS: THREE.RepeatWrapping,
			wrapT: THREE.RepeatWrapping,
		}));
		
		this.cylinder = Application.createCylinder();
		
		this.planes = Application.createPlanes(32, 8);
		
		this.camera = new THREE.PerspectiveCamera(45, 1, 1, 512);
		this.camera.position.z = 256;
		
		this.renderer = new THREE.WebGLRenderer(Application.RENDERER_OPTIONS);
		
		this.scene = new THREE.Scene();
		this.scene.add(this.cylinder, ...Object.values(this.planes));
		
		this.controls = new THREE.OrbitControls(this.camera, this.renderer.domElement);
		this.controls.update();
	}
	
	setSize(width, height) {
		this.camera.aspect = width / height;
		this.camera.updateProjectionMatrix();
		
		this.renderer.setSize(width, height);
	}
	
	render(time) {
		this.controls.update();
		
		this.bufferRenderers.gradient.render(this.renderer, this.buffers[0]);
		
		this.bufferRenderers.noise.material.uniforms.time.value = time;
		this.bufferRenderers.noise.render(this.renderer, this.buffers[1]);
		
		this.planes.gradient.material.uniforms.texture.value = this.buffers[0].texture;
		this.planes.noise.material.uniforms.texture.value = this.buffers[1].texture;
		
		this.cylinder.material.uniforms.textureGradient.value = this.buffers[0].texture;
		this.cylinder.material.uniforms.textureNoise.value = this.buffers[1].texture;
		
		this.renderer.render(this.scene, this.camera);
	}
	
	static createBuffer(size) {
		return THREE.WebGLRenderTarget(size, size, {
			wrapS: THREE.RepeatWrapping,
			wrapT: THREE.RepeatWrapping,
		});
	}
	
	static createBufferRenderers() {
		const materialBasic = new THREE.MeshBasicMaterial();
		
		const materialGradient = new THREE.ShaderMaterial({
			fragmentShader: ShaderChunkLibrary.gradientFragment,
			vertexShader: ShaderChunkLibrary.passThroughVertex,
			uniforms: {
				power: { value: 1 },
			},
		});
		
		const materialNoise = new THREE.ShaderMaterial({
			fragmentShader: ShaderChunkLibrary.noiseFragment,
			vertexShader: ShaderChunkLibrary.passThroughVertex,
			uniforms: {
				octaves: { value: 1 },
				persistence: { value: 1 },
				scale: { value: 1 },
				speed: { value: 1 },
				time: { value: 0 },
			}
		});
		
		return {
			gradient: new BufferRenderer(materialGradient),
			noise: new BufferRenderer(materialNoise),
		};
	}
	
	static createCylinder() {
		const geometry = new THREE.CylinderBufferGeometry(16, 16, 64, 16, 1, true);
		const material = new THREE.ShaderMaterial({
			blending: THREE.AdditiveBlending,
			depthTest: false,
			fragmentShader: ShaderChunkLibrary.flameFragment,
			vertexShader: ShaderChunkLibrary.passThroughVertex,
			side: THREE.DoubleSide,
			transparent: true,
			uniforms: {
				colorStart: { value: null },
				colorEnd: { value: null },
				textureGradient: { value: null },
				textureNoise: { value: null },
				threshold: { value: 0 }
			},
		});
		
		return new THREE.Mesh(geometry, material);
	}
	
	static createPlanes(size, spacing = 0) {
		const createMaterial = () => new THREE.ShaderMaterial({
			fragmentShader: ShaderChunkLibrary.textureFragment,
			vertexShader: ShaderChunkLibrary.passThroughVertex,
			side: THREE.DoubleSide,
			uniforms: {
				texture: { value: null },
			},
		});
		
		const planes = {
			noise: Application.createTexturePlane(size, createMaterial()),
			gradient: Application.createTexturePlane(size, createMaterial()),
		};
		
		Object.values(planes).forEach((p, i, arr) => p.position.set(((i + 0.5) - (arr.length * 0.5)) * (size + spacing), size, 0));
		
		return planes;
	}
	
	static createTexturePlane(size, material) {
		const geometry = new THREE.PlaneBufferGeometry(size, size, 1, 1);
		
		return new THREE.Mesh(geometry, material);
	}
}

const animate = (callback) => {
	const update = (time) => {
		requestAnimationFrame(update);
		callback(time / 1000);
	};
	
	update(performance.now());
};

const createUpdateSettingsCallback = (options) => () => {
	app.cylinder.material.uniforms.colorStart.value = new THREE.Color(options.composition.colorStart);
	app.cylinder.material.uniforms.colorEnd.value = new THREE.Color(options.composition.colorEnd);
	app.cylinder.material.uniforms.threshold.value = options.composition.threshold;
	
	app.bufferRenderers.gradient.material.uniforms.power.value = options.gradient.power;
	
	app.bufferRenderers.noise.material.uniforms.octaves.value = options.noise.octaves;
	app.bufferRenderers.noise.material.uniforms.persistence.value = options.noise.persistence;
	app.bufferRenderers.noise.material.uniforms.scale.value = options.noise.scale;
	app.bufferRenderers.noise.material.uniforms.speed.value = options.noise.speed;
};

const app = new Application();
app.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(app.renderer.domElement);

const gui = new dat.GUI();
const guiOptions = {
	composition: {
		colorStart: '#F00',
		colorEnd: '#FF0',
		threshold: 0.25,
	},
	gradient: {
		power: 1.5,
	},
	noise: {
		octaves: 8,
		persistence: 0.5,
		scale: 16,
		speed: 0.75,
	},
};

const updateSettings = createUpdateSettingsCallback(guiOptions);

const guiComposition = gui.addFolder('Composition');
guiComposition.addColor(guiOptions.composition, 'colorStart').onChange(updateSettings);
guiComposition.addColor(guiOptions.composition, 'colorEnd').onChange(updateSettings);
guiComposition.add(guiOptions.composition, 'threshold', 0, 1, 0.05).onChange(updateSettings);

const guiGradient = gui.addFolder('Gradient');
guiGradient.add(guiOptions.gradient, 'power', 0, 3, 0.25).onChange(updateSettings);

const guiNoise = gui.addFolder('Noise');
guiNoise.add(guiOptions.noise, 'octaves', 1, 16, 1).onChange(updateSettings);
guiNoise.add(guiOptions.noise, 'persistence', 0, 1, 0.05).onChange(updateSettings);
guiNoise.add(guiOptions.noise, 'scale', 1, 16, 1).onChange(updateSettings);
guiNoise.add(guiOptions.noise, 'speed', -2, 2, 0.1).onChange(updateSettings);

guiComposition.open();
guiGradient.open();
guiNoise.open();

window.addEventListener('resize', () => app.setSize(window.innerWidth, window.innerHeight));

updateSettings();
animate(time => app.render(time));
!
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