70 lines
1.6 KiB
JavaScript
70 lines
1.6 KiB
JavaScript
function mandelIter(cx, cy, maxIter) {
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var x = 0.0;
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var y = 0.0;
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var xx = 0;
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var yy = 0;
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var xy = 0;
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var i = maxIter;
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while (i-- && xx + yy <= 4) {
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xy = x * y;
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xx = x * x;
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yy = y * y;
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x = xx - yy + cx;
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y = xy + xy + cy;
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}
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return maxIter - i;
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}
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function mandelbrot(canvas, xmin, xmax, ymin, ymax, iterations) {
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var width = canvas.width;
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var height = canvas.height;
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var ctx = canvas.getContext('2d');
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var img = ctx.getImageData(0, 0, width, height);
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var pix = img.data;
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for (var ix = 0; ix < width; ++ix) {
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for (var iy = 0; iy < height; ++iy) {
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var x = xmin + (xmax - xmin) * ix / (width - 1);
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var y = ymin + (ymax - ymin) * iy / (height - 1);
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var i = mandelIter(x, y, iterations);
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var ppos = 4 * (width * iy + ix);
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if (i > iterations) {
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pix[ppos] = 0;
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pix[ppos + 1] = 0;
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pix[ppos + 2] = 0;
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} else {
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var c = 3 * Math.log(i) / Math.log(iterations - 1.0);
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if (c < 1) {
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pix[ppos] = 255 * c;
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pix[ppos + 1] = 0;
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pix[ppos + 2] = 0;
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}
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else if ( c < 2 ) {
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pix[ppos] = 255;
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pix[ppos + 1] = 255 * (c - 1);
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pix[ppos + 2] = 0;
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} else {
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pix[ppos] = 255;
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pix[ppos + 1] = 255;
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pix[ppos + 2] = 255 * (c - 2);
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}
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}
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pix[ppos + 3] = 255;
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}
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}
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ctx.putImageData(img, 0, 0);
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}
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var canvas = document.createElement('canvas');
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canvas.width = 900;
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canvas.height = 600;
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document.body.insertBefore(canvas, document.body.childNodes[0]);
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mandelbrot(canvas, -2, 1, -1, 1, 1000);
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