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Sierpinski Triangle on HTML5 canvas using chaos game rules
<canvas id="canvas" width="640" height="480">
<p>Your browser doesn't support canvas.</p>
</canvas>
if(typeof console=='undefined')console={log:function(){}};
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var iter = 50000;
var clear = function() { canvas.width = canvas.width; };
var setPixel = function(imageData, point, r, g, b, a) {
a = typeof a == 'undefined' ? 255 : a;
i = (point.x + point.y * imageData.width) * 4;
imageData.data[i ] = r;
imageData.data[i+1] = g;
imageData.data[i+2] = b;
imageData.data[i+3] = a;
};
var rnd = function(maxRange) {
return Math.floor(Math.random()*maxRange);
};
var midpoint = function(p1, p2) {
return {x:Math.round((p1.x+p2.x)/2), y:Math.round((p1.y+p2.y)/2)};
};
$(document).ready( function() {
var imgd = ctx.createImageData(canvas.width, canvas.height);
var a,b,c,x;
var randomStart = false;
if(randomStart) {
//Start at a random location
a = {x: rnd(canvas.width), y:rnd(canvas.width)};
b = {x: rnd(canvas.width), y:rnd(canvas.width)};
c = {x: rnd(canvas.width), y:rnd(canvas.width)};
x = {x: rnd(canvas.width), y:rnd(canvas.width)};
}else {
//Or start at a fixed location
a = {x:135, y:57};
b = {x:370, y:203};
c = {x:220, y:388};
x = {x:639, y:350};
}
console.log('a: ' + a.x + ',' + a.y);
console.log('b: ' + b.x + ',' + b.y);
console.log('c: ' + c.x + ',' + c.y);
console.log('x: ' + x.x + ',' + x.y);
setPixel(imgd, a, 255, 0, 0);
setPixel(imgd, b, 255, 0, 0);
setPixel(imgd, c, 255, 0, 0);
setPixel(imgd, x, 255, 0, 0);
for(var i=0; i<iter; i++) {
var choice = rnd(3);
if(choice == 0 ) {
//a
x = midpoint(a, x);
}else if(choice == 1) {
//b
x = midpoint(b, x);
}else if(choice == 2) {
//c
x = midpoint(c, x);
}
//console.log('Plotting ' + x.x + ',' + x.y);
setPixel(imgd, x, rnd(255), rnd(255), rnd(255));
}
ctx.putImageData(imgd, 0, 0);
console.log('Finished plotting');
});
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