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8bitworkshop/presets/script/mandel.js

48 lines
976 B
JavaScript

// slider UI objects
mx = ui.slider(0,2000).initial(1028)
my = ui.slider(0,2000).initial(1409)
ms = ui.slider(0,2000).initial(615)
// compute slider-derived values
xofs = (mx.value-1000)/500
yofs = (my.value-1000)/500
zoom = Math.pow(0.99, ms.value)
// create bitmap
fract = bitmap.indexed(512,256,8)
// compute fractal using assign()
fract.assign(mandel)
// mandelbrot pixel function
function mandel(x,y) {
return iterateEquation(
(x-fract.width/2)*zoom-xofs,
(y-fract.height/2)*zoom-yofs, 10, 256)[0];
}
// mandelbrot compute function
function iterateEquation(Cr, Ci, escapeRadius, iterations)
{
var Zr = 0;
var Zi = 0;
var Tr = 0;
var Ti = 0;
var n = 0;
for ( ; n<iterations && (Tr+Ti)<=escapeRadius; ++n ) {
Zi = 2 * Zr * Zi + Ci;
Zr = Tr - Ti + Cr;
Tr = Zr * Zr;
Ti = Zi * Zi;
}
for ( var e=0; e<4; ++e ) {
Zi = 2 * Zr * Zi + Ci;
Zr = Tr - Ti + Cr;
Tr = Zr * Zr;
Ti = Zi * Zi;
}
return [n, Tr, Ti];
}