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var increment = 0.01;
var iterations = 30;
var startI = -2.5;
var startJ = -2.5;
var power = 2;
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var width = canvas.width;
var height = canvas.height;
function reciprocal(re, im)
{
return [re/(re*re+im*im), -im/(im*im+re*re)];
}
function add(re1, im1, re2, im2)
{
return [re1+re2, im1+im2];
}
function multiply(re1, im1, re2, im2)
{
return [re1*re2-im1*im2, re1*im2+re2*im1];
}
function cpower(re, im, power)
{
if (power < 0)
{
var r = reciprocal(re, im);
return cpower(r[0], r[1], -power);
}
var x = [re, im];
var i = 1;
while (i < power)
{
x = multiply(x[0], x[1], re, im);
i++;
}
return x;
}
function iterate(z, power, c)
{
var x = cpower(z[0], z[1], power);
return add(x[0], x[1], c[0], c[1]);
}
function cabs(z)
{
return Math.sqrt(z[0]*z[0]+z[1]*z[1]);
}
function num_iterations(power, c, max_iterations)
{
var iterations = 0;
var z = [0, 0];
while (iterations < max_iterations && cabs(z) < 2)
{
z = iterate(z, power, c);
iterations++;
}
return iterations;
}
function draw_mandelbrot()
{
var size = width*increment;
var endI = startI+size;
var endJ = startJ+size;
var imgData = ctx.createImageData(width, height);
for (var i = startI; i < endI; i+=increment)
{
for (var j = startJ; j < endJ; j+=increment)
{
var ipos = i*(1.0/increment)-startI*(1.0/increment);
var jpos = j*(1.0/increment)-startJ*(1.0/increment);
jpos = Math.floor(Math.round(jpos));
ipos = Math.floor(Math.round(ipos));
var x = num_iterations(power, [i, j], iterations)/iterations * 255
imgData.data[4*(jpos*width+ipos)] = x;
imgData.data[1+4*(jpos*width+ipos)] = x;
imgData.data[2+4*(jpos*width+ipos)] = x;
imgData.data[3+4*(jpos*width+ipos)] = 255;
}
}
ctx.putImageData(imgData, 0, 0);
}
function draw()
{
}
function map(val, startA, endA, startB, endB)
{
return (endB-startB)*((val-startA)/(endA-startA))+startB;
}
function mousePressed(e)
{
var x;
var y;
if (e.pageX || e.pageY) {
x = e.pageX;
y = e.pageY;
}
else {
x = e.clientX;
y = e.clientY;
}
x -= canvas.offsetLeft;
y -= canvas.offsetTop;
if (x < 0 || x > width || y < 0 || y > height)
return;
if (e.button == 0)
{
increment /= 2;
startI = map(x, 0, width, startI, startI+width*increment);
startJ = map(y, 0, height, startJ, startJ+width*increment);
draw_mandelbrot();
}
}
function keyPressed(e)
{
var key = String.fromCharCode(e.keyCode);
if (key == "A")
{
increment /= 2;
startI = startI+width*increment/2;
startJ = startJ+height*increment/2;
draw_mandelbrot();
}
if (key == "Q")
{
increment *= 2;
startI = startI-width*increment/2;
startJ = startJ-height*increment/2;
draw_mandelbrot();
}
if (key == "P")
{
power++;
draw_mandelbrot();
}
if (key == "L")
{
power--;
draw_mandelbrot();
}
if (key == "I")
{
iterations = Math.floor(iterations*1.5);
draw_mandelbrot();
}
if (key == "K")
{
iterations = Math.floor(iterations/1.5);
draw_mandelbrot();
}
}
canvas.addEventListener("mousedown", mousePressed);
document.body.addEventListener("keydown", keyPressed);
draw_mandelbrot();
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