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rozek/Bangle_MandelbrotSet_120x120.js

Last active December 6, 2019 08:48
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Bangle.js: displays a Mandelbrot set with 120x120 px resolution
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Bangle_MandelbrotSet_120x120.js
Bangle.setLCDMode('120x120');
g.clear();
const Width = g.getWidth();
const Height = g.getHeight();
/**** color mapping (especially for Bangle.js) ****/
function PaletteEntry (r,g,b) { // 8-bit modes use the "web color palette"
return r*36 + g*6 + b;
}
let ColorMap = [0]; // not part of Mandelbrot set? then leave pixel black
for (let i = 0; i < 3; i++) {
ColorMap.push(PaletteEntry(i,i,5));
}
for (let i = 3; i < 6; i++) {
ColorMap.push(PaletteEntry(i,i,5));
ColorMap.push(PaletteEntry(i,i,5));
ColorMap.push(PaletteEntry(i,i,5));
ColorMap.push(PaletteEntry(i,i,5));
}
const ColorCount = ColorMap.length;
/**** EscapeTimeOf ****/
const maxIterations = ColorCount;
function EscapeTimeOf (x,y) { // slightly optimized
let re = x, imag = y;
let r2 = x*x, i2 = y*y, z2 = (x+y)*(x+y);
for (let i = 0; i < maxIterations; i++) {
let newRe = r2 - i2 + x;
let newImag = z2 - r2 - i2 + y;
r2 = newRe*newRe;
i2 = newImag*newImag;
z2 = (newRe+newImag)*(newRe+newImag);
if (r2 + i2 > 4) { return i }
}
return 0;
}
/**** draw Mandelbrot set ****/
const xOffset = -1.9; const Zoom = 50;
const yOffset = -1.2;
for (let y = 0; y < Height; y++) {
for (let x = 0; x < Width; x++) {
let EscapeTime = EscapeTimeOf(
xOffset + x/Zoom, yOffset + y/Zoom
);
if (EscapeTime > 0) {
g.setPixel(x,y,ColorMap[EscapeTime]);
}
}
}
g.flip();
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