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This commit is contained in:
Brooke Vibber 2023-01-07 21:19:40 -08:00
parent c3c5968749
commit c5a62cfa1d
3 changed files with 95 additions and 5 deletions
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13
fixed.js
View file

@ -17,11 +17,11 @@ let bytes = Math.ceil(bits / 8) * entries;
let epsilonBits = 1 ;
let epsilon = 2 ** epsilonBits;
function toFixed(float) {
export function toFixed(float) {
return Math.round(float * base);
}
function toFloat(fixed) {
export function toFloat(fixed) {
return fixed / base;
}
@ -48,12 +48,12 @@ for (let i = 0; i < entries * 2; i++) {
// returns fixed point
function log2(fixed) {
export function log2(fixed) {
return enloggen[toIndex(fixed)];
}
// returns rounded integer
function pow2(fixed) {
export function pow2(fixed) {
let n = toIndex(fixed);
if (n > empower.length) {
n = empower.length - 1;
@ -61,7 +61,7 @@ function pow2(fixed) {
return empower[entries + n];
}
function mul(a, b) {
export function mul(a, b) {
if (a == 0) return 0;
if (b == 0) return 0;
let la = log2(a)|0;
@ -93,6 +93,7 @@ for (let i = 0; i < powEntries; i++) {
}
*/
/*
// now just try multipling numbers
let deltas = 0;
let deltaAvg = 0;
@ -153,3 +154,5 @@ for (let i = 0; i < enloggen.length; i++) {
m = Math.max(m, enloggen[i]);
}
console.log(`max enloggen entry is ${m}`);
*/

22
sim.html Normal file
View file

@ -0,0 +1,22 @@
<!DOCTYPE html>
<html>
<meta charset="utf-8">
<title>Mandelbrot fixed-point test</title>
<style type="text/css">
/* */
</style>
<body>
<h1>Mandelbrot fixed-point test</h1>
<h2>Float</h2>
<canvas id="float" width="256" height="256"></canvas>
<h2>Fixed-point imul</h2>
<canvas id="imul" width="256" height="256"></canvas>
<h2>Fixed-point log</h2>
<canvas id="log" width="256" height="256"></canvas>
<script async type="module" src="sim.js"></script>
</body>
</html>

65
sim.js Normal file
View file

@ -0,0 +1,65 @@
import {toFixed, toFloat, mul} from './fixed.js';
let max = 256;
let width = 256;
let height = 256;
let zoom = 1;
let black = 0xff000000;
let tricolor = [
0xffff0000,
0xff00ff00,
0xff0000ff,
];
let palette = new Uint32Array(256);
palette[0] = black;
for (let i = 0; i < 255; i++) {
palette[i + 1] = tricolor[i % 3];
}
function nap() {
return new Promise((resolve) => setTimeout(() => resolve()));
}
async function setup(id, iterfunc) {
let canvas = document.getElementById(id);
let ctx = canvas.getContext('2d');
let imageData = ctx.createImageData(width, height);
let rgba = new Uint32Array(imageData.data.buffer);
for (let y = 0; y < height; y++) {
let cy = (y * 2 - height) / (height / 2);
for (let x = 0; x < width; x++) {
let cx = (x * 2 - width) / (width / 2);
let i = iterfunc(cx, cy);
let color = palette[i];
rgba[y * width + x] = color;
rgba[(256 - y) * width + x] = color;
if (x % 16 == 15) {
ctx.putImageData(imageData, 0, 0);
await nap();
}
}
}
}
setup('float', (cx, cy) => {
let zx = 0;
let zy = 0;
let zx_2 = 0;
let zy_2 = 0;
let zx_zy = 0;
for (let i = 1; i < max; i++) {
zx = zx_2 - zy_2 + cx;
zy = zx_zy + zx_zy + cy;
zx_2 = zx * zx;
zy_2 = zy * zy;
zx_zy = zx * zy;
if (zx_2 >= 4 || zy_2 >= 4 || zx_2 + zy_2 >= 4) {
return i;
}
}
return 0;
}).then(() => {
console.log('done');
})