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mandelbrot.js
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mandelbrot.js
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var canvas;
var gl;
var squareVerticesBuffer;
var shaderProgram;
var vertexPositionAttribute;
var iterations = 1000;
var zoomTarget = 1;
var zoom = 1;
var offset = [0, 0];
// Running this is suprisingly intensive for web browsers
var invalidated = true;
var color = 0;
var isDown = false; // whether mouse is pressed
var last = [0, 0]; // lastmouse
function start() {
canvas = document.getElementById("glcanvas");
if (canvas.addEventListener) {
// IE9, Chrome, Safari, Opera
canvas.addEventListener("mousewheel", MouseWheelHandler, false);
// Firefox
canvas.addEventListener("DOMMouseScroll", MouseWheelHandler, false);
canvas.addEventListener('mousedown', mouseDown, false);
canvas.addEventListener('mouseup', mouseUp, false);
canvas.addEventListener('mousemove', mouseMove, false);
document.getElementById('iterations').addEventListener("input", updateIterations, false);
var rb = document.getElementsByName("color");
for(var i = 0; i < rb.length; i++) {
rb[i].onclick = (function(i) { return function() { updateColor(i); }}(i));
}
}
initWebGL(canvas);
if (gl) {
gl.clearColor(0.0, 0.0, 0.0, 1.0);
initShaders();
initBuffers();
drawScene();
}
}
function initWebGL() {
gl = null;
try {
gl = canvas.getContext('webgl') || canvas.getContext('experimental-webgl');
}
catch(e) {
}
if (!gl)
alert("Unable to initialize WebGL. Your browser may not support it.");
}
function initBuffers() {
squareVerticesBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVerticesBuffer);
var vertices = [
1.0, 1.0, 0.0,
-1.0, 1.0, 0.0,
1.0, -1.0, 0.0,
-1.0, -1.0, 0.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
}
function drawScene(lastTime) {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
updatePosition();
if (invalidated) {
gl.viewport(0, 0, canvas.width, canvas.height);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
gl.bindBuffer(gl.ARRAY_BUFFER, squareVerticesBuffer);
gl.vertexAttribPointer(vertexPositionAttribute, 3, gl.FLOAT, false, 0, 0);
setWindowUniforms(canvas.width, canvas.height);
setPositionUniforms();
setRenderingUniforms();
gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
invalidated = false;
}
setTimeout(()=>drawScene(), 30);
}
function initShaders() {
var fragmentShader = getShader(gl, "shader-fs");
var vertexShader = getShader(gl, "shader-vs");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS))
alert("Unable to initialize the shader program: " + gl.getProgramInfoLog(shader));
gl.useProgram(shaderProgram);
vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
gl.enableVertexAttribArray(vertexPositionAttribute);
}
function getShader(gl, id) {
var shaderScript = document.getElementById(id);
if (!shaderScript)
return null;
var theSource = "";
var currentChild = shaderScript.firstChild;
while(currentChild) {
if (currentChild.nodeType == 3)
theSource += currentChild.textContent;
currentChild = currentChild.nextSibling;
}
var shader;
if (shaderScript.type == "x-shader/x-fragment")
shader = gl.createShader(gl.FRAGMENT_SHADER);
else if (shaderScript.type == "x-shader/x-vertex")
shader = gl.createShader(gl.VERTEX_SHADER);
else
return null;
gl.shaderSource(shader, theSource);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
alert("An error occurred compiling the shaders: " + gl.getShaderInfoLog(shader));
return null;
}
return shader;
}
function setPositionUniforms() {
var xUniform = gl.getUniformLocation(shaderProgram, 'offsetX');
var yUniform = gl.getUniformLocation(shaderProgram, 'offsetY');
var zUniform = gl.getUniformLocation(shaderProgram, 'zoom');
gl.uniform1f(xUniform, offset[0]);
gl.uniform1f(yUniform, offset[1]);
gl.uniform1f(zUniform, Math.pow(2, zoom));
}
function setWindowUniforms(wWidth, wHeight) {
var ww = gl.getUniformLocation(shaderProgram, 'ww');
var wh = gl.getUniformLocation(shaderProgram, 'wh');
gl.uniform1f(ww, wWidth);
gl.uniform1f(wh, wHeight);
}
function setRenderingUniforms() {
var i = gl.getUniformLocation(shaderProgram, 'maxIterations');
var j = gl.getUniformLocation(shaderProgram, 'colorScheme');
gl.uniform1i(i, iterations);
gl.uniform1i(j, color);
}
function updatePosition() {
var speed = 0.25;
var delta = (zoomTarget - zoom) * speed;
if (delta != 0)
invalidated = true;
zoom += delta;
}
/* Controls */
function mouseDown(e) {
isDown = true;
last = [
e.offsetX,
e.offsetY
];
};
function mouseUp(e) {
isDown = false;
};
function mouseMove(e)
{
if(!isDown) return;
var x = e.offsetX;
var y = e.offsetY;
offset[0] -= ((x - last[0]) / canvas.width) / (0.4*Math.pow(2, zoom));
offset[1] += ((y - last[1]) / canvas.height) / (0.4*Math.pow(2, zoom));
last = [
x,
y
];
invalidated = true;
}
function MouseWheelHandler() {
var e = window.event;
zoomTarget += Math.max(-1, Math.min(1, (e.wheelDelta || -e.detail)));
if (zoomTarget == 0)
zoomTarget = 0.01;
invalidated = true;
}
function updateIterations() {
iterations = document.getElementById('iterations').value;
document.getElementById('num-iterations').innerHTML = iterations + " iterations";
invalidated = true;
}
function updateColor(i) {
color = i;
invalidated = true;
}