| <!DOCTYPE html>
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| <html>
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| <head>
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| <title>Neon Light</title>
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| </head>
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| <body>
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| <canvas id="canvas" width="1400" height="600"></canvas>
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| </body>
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| </html>
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| <style type="text/css">
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| body{
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| background: black;
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| margin: 0px;
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| overflow: hidden;
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| background-repeat: no-repeat;
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| }
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| </style>
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| <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
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| <script type="text/javascript">
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| var canvas = document.getElementById("canvas");
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|
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| canvas.width = window.innerWidth;
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| canvas.height = window.innerHeight;
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|
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| // Initialize the GL context
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| var gl = canvas.getContext('webgl');
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| if(!gl){
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| console.error("Unable to initialize WebGL.");
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| }
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|
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| //Time step
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| var dt = 0.015;
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| //Time
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| var time = 0.0;
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|
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| //************** Shader sources **************
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| var vertexSource = `
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| attribute vec2 position;
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| void main() {
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| gl_Position = vec4(position, 0.0, 1.0);
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| }
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| `;
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|
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| var fragmentSource = `
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| precision highp float;
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| uniform float width;
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| uniform float height;
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| vec2 resolution = vec2(width, height);
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| uniform float time;
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| #define POINT_COUNT 8
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| vec2 points[POINT_COUNT];
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| const float speed = -0.5;
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| const float len = 0.25;
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| float intensity = 0.9;
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| float radius = 0.015;
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|
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| //https://www.shadertoy.com/view/MlKcDD
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| //Signed distance to a quadratic bezier
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| float sdBezier(vec2 pos, vec2 A, vec2 B, vec2 C){
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| vec2 a = B - A;
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| vec2 b = A - 2.0*B + C;
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| vec2 c = a * 2.0;
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| vec2 d = A - pos;
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| float kk = 1.0 / dot(b,b);
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| float kx = kk * dot(a,b);
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| float ky = kk * (2.0*dot(a,a)+dot(d,b)) / 3.0;
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| float kz = kk * dot(d,a);
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| float res = 0.0;
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| float p = ky - kx*kx;
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| float p3 = p*p*p;
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| float q = kx*(2.0*kx*kx - 3.0*ky) + kz;
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| float h = q*q + 4.0*p3;
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| if(h >= 0.0){
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| h = sqrt(h);
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| vec2 x = (vec2(h, -h) - q) / 2.0;
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| vec2 uv = sign(x)*pow(abs(x), vec2(1.0/3.0));
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| float t = uv.x + uv.y - kx;
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| t = clamp( t, 0.0, 1.0 );
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|
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| // 1 root
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| vec2 qos = d + (c + b*t)*t;
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| res = length(qos);
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| }else{
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| float z = sqrt(-p);
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| float v = acos( q/(p*z*2.0) ) / 3.0;
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| float m = cos(v);
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| float n = sin(v)*1.732050808;
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| vec3 t = vec3(m + m, -n - m, n - m) * z - kx;
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| t = clamp( t, 0.0, 1.0 );
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|
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| // 3 roots
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| vec2 qos = d + (c + b*t.x)*t.x;
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| float dis = dot(qos,qos);
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| res = dis;
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| qos = d + (c + b*t.y)*t.y;
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| dis = dot(qos,qos);
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| res = min(res,dis);
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| qos = d + (c + b*t.z)*t.z;
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| dis = dot(qos,qos);
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| res = min(res,dis);
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| res = sqrt( res );
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| }
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| return res;
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| }
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| //http://mathworld.wolfram.com/HeartCurve.html
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| vec2 getHeartPosition(float t){
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| return vec2(16.0 * sin(t) * sin(t) * sin(t),
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| -(13.0 * cos(t) - 5.0 * cos(2.0*t)
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| - 2.0 * cos(3.0*t) - cos(4.0*t)));
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| }
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|
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| //https://www.shadertoy.com/view/3s3GDn
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| float getGlow(float dist, float radius, float intensity){
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| return pow(radius/dist, intensity);
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| }
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| float getSegment(float t, vec2 pos, float offset, float scale){
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| for(int i = 0; i < POINT_COUNT; i++){
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| points[i] = getHeartPosition(offset + float(i)*len + fract(speed * t) * 6.28);
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| }
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| vec2 c = (points[0] + points[1]) / 2.0;
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| vec2 c_prev;
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| float dist = 10000.0;
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| for(int i = 0; i < POINT_COUNT-1; i++){
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| //https://tinyurl.com/y2htbwkm
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| c_prev = c;
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| c = (points[i] + points[i+1]) / 2.0;
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| dist = min(dist, sdBezier(pos, scale * c_prev, scale * points[i], scale * c));
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| }
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| return max(0.0, dist);
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| }
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| void main(){
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| vec2 uv = gl_FragCoord.xy/resolution.xy;
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| float widthHeightRatio = resolution.x/resolution.y;
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| vec2 centre = vec2(0.5, 0.5);
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| vec2 pos = centre - uv;
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| pos.y /= widthHeightRatio;
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| //Shift upwards to centre heart
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| pos.y += 0.02;
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| float scale = 0.000015 * height;
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| float t = time;
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| //Get first segment
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| float dist = getSegment(t, pos, 0.0, scale);
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| float glow = getGlow(dist, radius, intensity);
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| vec3 col = vec3(0.0);
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| //White core
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| col += 10.0*vec3(smoothstep(0.003, 0.001, dist));
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| //Pink glow
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| col += glow * vec3(0.94,0.14,0.4);
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|
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| //Get second segment
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| dist = getSegment(t, pos, 3.4, scale);
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| glow = getGlow(dist, radius, intensity);
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| //White core
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| col += 10.0*vec3(smoothstep(0.003, 0.001, dist));
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| //Blue glow
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| col += glow * vec3(0.2,0.6,1.0);
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| //Tone mapping
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| col = 1.0 - exp(-col);
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|
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| //Output to screen
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| gl_FragColor = vec4(col,1.0);
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| }
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| `;
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|
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| //************** Utility functions **************
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|
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| window.addEventListener('resize', onWindowResize, false);
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|
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| function onWindowResize(){
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| canvas.width = window.innerWidth;
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| canvas.height = window.innerHeight;
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| gl.viewport(0, 0, canvas.width, canvas.height);
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| gl.uniform1f(widthHandle, window.innerWidth);
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| gl.uniform1f(heightHandle, window.innerHeight);
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| }
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|
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| //Compile shader and combine with source
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| function compileShader(shaderSource, shaderType){
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| var shader = gl.createShader(shaderType);
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| gl.shaderSource(shader, shaderSource);
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| gl.compileShader(shader);
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| if(!gl.getShaderParameter(shader, gl.COMPILE_STATUS)){
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| throw "Shader compile failed with: " + gl.getShaderInfoLog(shader);
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| }
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| return shader;
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| }
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|
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| //From https://codepen.io/jlfwong/pen/GqmroZ
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| //Utility to complain loudly if we fail to find the attribute/uniform
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| function getAttribLocation(program, name) {
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| var attributeLocation = gl.getAttribLocation(program, name);
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| if (attributeLocation === -1) {
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| throw 'Cannot find attribute ' + name + '.';
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| }
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| return attributeLocation;
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| }
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|
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| function getUniformLocation(program, name) {
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| var attributeLocation = gl.getUniformLocation(program, name);
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| if (attributeLocation === -1) {
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| throw 'Cannot find uniform ' + name + '.';
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| }
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| return attributeLocation;
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| }
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|
|
| //************** Create shaders **************
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|
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| //Create vertex and fragment shaders
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| var vertexShader = compileShader(vertexSource, gl.VERTEX_SHADER);
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| var fragmentShader = compileShader(fragmentSource, gl.FRAGMENT_SHADER);
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|
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| //Create shader programs
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| var program = gl.createProgram();
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| gl.attachShader(program, vertexShader);
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| gl.attachShader(program, fragmentShader);
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| gl.linkProgram(program);
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| gl.useProgram(program);
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|
|
| //Set up rectangle covering entire canvas
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| var vertexData = new Float32Array([
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| -1.0, 1.0, // top left
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| -1.0, -1.0, // bottom left
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| 1.0, 1.0, // top right
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| 1.0, -1.0, // bottom right
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| ]);
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|
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| //Create vertex buffer
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| var vertexDataBuffer = gl.createBuffer();
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| gl.bindBuffer(gl.ARRAY_BUFFER, vertexDataBuffer);
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| gl.bufferData(gl.ARRAY_BUFFER, vertexData, gl.STATIC_DRAW);
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|
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| // Layout of our data in the vertex buffer
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| var positionHandle = getAttribLocation(program, 'position');
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|
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| gl.enableVertexAttribArray(positionHandle);
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| gl.vertexAttribPointer(positionHandle,
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| 2, // position is a vec2 (2 values per component)
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| gl.FLOAT, // each component is a float
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| false, // don't normalize values
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| 2 * 4, // two 4 byte float components per vertex (32 bit float is 4 bytes)
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| 0 // how many bytes inside the buffer to start from
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| );
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|
|
| //Set uniform handle
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| var timeHandle = getUniformLocation(program, 'time');
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| var widthHandle = getUniformLocation(program, 'width');
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| var heightHandle = getUniformLocation(program, 'height');
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| gl.uniform1f(widthHandle, window.innerWidth);
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| gl.uniform1f(heightHandle, window.innerHeight);
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|
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| function draw(){
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| //Update time
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| time += dt;
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|
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| //Send uniforms to program
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| gl.uniform1f(timeHandle, time);
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| //Draw a triangle strip connecting vertices 0-4
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| gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
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|
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| requestAnimationFrame(draw);
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| }
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|
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| draw();
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| </script> |
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