text: var canvas = document.getElementById("canvas");
  
  canvas.width = window.innerWidth;
  canvas.height = window.innerHeight;
  
  // Initialize the GL context
  var gl = canvas.getContext("webgl");
  if (!gl) {
  	console.error("Unable to initialize WebGL.");
  }
  
  //Time
  var time = 0.0;
  
  //************** Shader sources **************
  
  var vertexSource = `
  attribute vec2 position;
  void main() {
  	gl_Position = vec4(position, 0.0, 1.0);
  }
  `;
  
  var fragmentSource = `
  precision highp float;
  
  uniform float width;
  uniform float height;
  vec2 resolution = vec2(width, height);
  
  uniform float time;
  
  #define POINT_COUNT 8
  
  vec2 points[POINT_COUNT];
  const float speed = -0.5;
  const float len = 0.25;
  float intensity = 1.3;
  float radius = 0.008;
  
  //https://www.shadertoy.com/view/MlKcDD
  //Signed distance to a quadratic bezier
  float sdBezier(vec2 pos, vec2 A, vec2 B, vec2 C){    
  	vec2 a = B - A;
  	vec2 b = A - 2.0*B + C;
  	vec2 c = a * 2.0;
  	vec2 d = A - pos;
  
  	float kk = 1.0 / dot(b,b);
  	float kx = kk * dot(a,b);
  	float ky = kk * (2.0*dot(a,a)+dot(d,b)) / 3.0;
  	float kz = kk * dot(d,a);      
  
  	float res = 0.0;
  
  	float p = ky - kx*kx;
  	float p3 = p*p*p;
  	float q = kx*(2.0*kx*kx - 3.0*ky) + kz;
  	float h = q*q + 4.0*p3;
  
  	if(h >= 0.0){ 
  		h = sqrt(h);
  		vec2 x = (vec2(h, -h) - q) / 2.0;
  		vec2 uv = sign(x)*pow(abs(x), vec2(1.0/3.0));
  		float t = uv.x + uv.y - kx;
  		t = clamp( t, 0.0, 1.0 );
  
  		// 1 root
  		vec2 qos = d + (c + b*t)*t;
  		res = length(qos);
  	}else{
  		float z = sqrt(-p);
  		float v = acos( q/(p*z*2.0) ) / 3.0;
  		float m = cos(v);
  		float n = sin(v)*1.732050808;
  		vec3 t = vec3(m + m, -n - m, n - m) * z - kx;
  		t = clamp( t, 0.0, 1.0 );
  
  		// 3 roots
  		vec2 qos = d + (c + b*t.x)*t.x;
  		float dis = dot(qos,qos);
          
  		res = dis;
  
  		qos = d + (c + b*t.y)*t.y;
  		dis = dot(qos,qos);
  		res = min(res,dis);
  		
  		qos = d + (c + b*t.z)*t.z;
  		dis = dot(qos,qos);
  		res = min(res,dis);
  
  		res = sqrt( res );
  	}
      
  	return res;
  }
  
  
  //http://mathworld.wolfram.com/HeartCurve.html
  vec2 getHeartPosition(float t){
  	return vec2(16.0 * sin(t) * sin(t) * sin(t),
  							-(13.0 * cos(t) - 5.0 * cos(2.0*t)
  							- 2.0 * cos(3.0*t) - cos(4.0*t)));
  }
  
  //https://www.shadertoy.com/view/3s3GDn
  float getGlow(float dist, float radius, float intensity){
  	return pow(radius/dist, intensity);
  }
  
  float getSegment(float t, vec2 pos, float offset, float scale){
  	for(int i = 0; i < POINT_COUNT; i++){
  		points[i] = getHeartPosition(offset + float(i)*len + fract(speed * t) * 6.28);
  	}
      
  	vec2 c = (points[0] + points[1]) / 2.0;
  	vec2 c_prev;
  	float dist = 10000.0;
      
  	for(int i = 0; i < POINT_COUNT-1; i++){
  		//https://tinyurl.com/y2htbwkm
  		c_prev = c;
  		c = (points[i] + points[i+1]) / 2.0;
  		dist = min(dist, sdBezier(pos, scale * c_prev, scale * points[i], scale * c));
  	}
  	return max(0.0, dist);
  }
  
  void main(){
  	vec2 uv = gl_FragCoord.xy/resolution.xy;
  	float widthHeightRatio = resolution.x/resolution.y;
  	vec2 centre = vec2(0.5, 0.5);
  	vec2 pos = centre - uv;
  	pos.y /= widthHeightRatio;
  	//Shift upwards to centre heart
  	pos.y += 0.02;
  	float scale = 0.000015 * height;
  	
  	float t = time;
      
  	//Get first segment
    float dist = getSegment(t, pos, 0.0, scale);
    float glow = getGlow(dist, radius, intensity);
    
    vec3 col = vec3(0.0);
  
  	//White core
    col += 10.0*vec3(smoothstep(0.003, 0.001, dist));
    //Pink glow
    col += glow * vec3(1.0,0.05,0.3);
    
    //Get second segment
    dist = getSegment(t, pos, 3.4, scale);
    glow = getGlow(dist, radius, intensity);
    
    //White core
    col += 10.0*vec3(smoothstep(0.003, 0.001, dist));
    //Blue glow
    col += glow * vec3(0.1,0.4,1.0);
          
  	//Tone mapping
  	col = 1.0 - exp(-col);
  
  	//Gamma
  	col = pow(col, vec3(0.4545));
  
  	//Output to screen
   	gl_FragColor = vec4(col,1.0);
  }
  `;
  
  //************** Utility functions **************
  
  window.addEventListener("resize", onWindowResize, false);
  
  function onWindowResize() {
  	canvas.width = window.innerWidth;
  	canvas.height = window.innerHeight;
  	gl.viewport(0, 0, canvas.width, canvas.height);
  	gl.uniform1f(widthHandle, window.innerWidth);
  	gl.uniform1f(heightHandle, window.innerHeight);
  }
  
  //Compile shader and combine with source
  function compileShader(shaderSource, shaderType) {
  	var shader = gl.createShader(shaderType);
  	gl.shaderSource(shader, shaderSource);
  	gl.compileShader(shader);
  	if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
  		throw "Shader compile failed with: " + gl.getShaderInfoLog(shader);
  	}
  	return shader;
  }
  
  //From https://codepen.io/jlfwong/pen/GqmroZ
  //Utility to complain loudly if we fail to find the attribute/uniform
  function getAttribLocation(program, name) {
  	var attributeLocation = gl.getAttribLocation(program, name);
  	if (attributeLocation === -1) {
  		throw "Cannot find attribute " + name + ".";
  	}
  	return attributeLocation;
  }
  
  function getUniformLocation(program, name) {
  	var attributeLocation = gl.getUniformLocation(program, name);
  	if (attributeLocation === -1) {
  		throw "Cannot find uniform " + name + ".";
  	}
  	return attributeLocation;
  }
  
  //************** Create shaders **************
  
  //Create vertex and fragment shaders
  var vertexShader = compileShader(vertexSource, gl.VERTEX_SHADER);
  var fragmentShader = compileShader(fragmentSource, gl.FRAGMENT_SHADER);
  
  //Create shader programs
  var program = gl.createProgram();
  gl.attachShader(program, vertexShader);
  gl.attachShader(program, fragmentShader);
  gl.linkProgram(program);
  
  gl.useProgram(program);
  
  //Set up rectangle covering entire canvas
  var vertexData = new Float32Array([
  	-1.0,
  	1.0, // top left
  	-1.0,
  	-1.0, // bottom left
  	1.0,
  	1.0, // top right
  	1.0,
  	-1.0 // bottom right
  ]);
  
  //Create vertex buffer
  var vertexDataBuffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, vertexDataBuffer);
  gl.bufferData(gl.ARRAY_BUFFER, vertexData, gl.STATIC_DRAW);
  
  // Layout of our data in the vertex buffer
  var positionHandle = getAttribLocation(program, "position");
  
  gl.enableVertexAttribArray(positionHandle);
  gl.vertexAttribPointer(
  	positionHandle,
  	2, // position is a vec2 (2 values per component)
  	gl.FLOAT, // each component is a float
  	false, // don't normalize values
  	2 * 4, // two 4 byte float components per vertex (32 bit float is 4 bytes)
  	0 // how many bytes inside the buffer to start from
  );
  
  //Set uniform handle
  var timeHandle = getUniformLocation(program, "time");
  var widthHandle = getUniformLocation(program, "width");
  var heightHandle = getUniformLocation(program, "height");
  
  gl.uniform1f(widthHandle, window.innerWidth);
  gl.uniform1f(heightHandle, window.innerHeight);
  
  var lastFrame = Date.now();
  var thisFrame;
  
  function draw() {
  	//Update time
  	thisFrame = Date.now();
  	time += (thisFrame - lastFrame) / 1000;
  	lastFrame = thisFrame;
  
  	//Send uniforms to program
  	gl.uniform1f(timeHandle, time);
  	//Draw a triangle strip connecting vertices 0-4
  	gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
  
  	requestAnimationFrame(draw);
  }
  
  draw();
  