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mexican hat with delay
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<html> | |
<body> | |
<canvas width="800" height="500" style="background-color:black"> </canvas> | |
<script> | |
"use strict" | |
const delay = 10 | |
const canvas = document.querySelector("canvas") | |
const ctx = canvas.getContext("2d") | |
const {width, height} = canvas | |
ctx.fillStyle = "black" | |
ctx.fillRect(0, 0, width, height) | |
const d = new Float32Array(160) | |
for (let l = 0; l <= 159; l++) { | |
d[l] = 100 | |
} | |
const dr = 3.14/180 | |
const s = 2 // view scale | |
function pset(x, y, color) { | |
ctx.globalCompositeOperation = "lighter" | |
ctx.fillStyle = color | |
ctx.fillRect(s*x, s*y, s, s) | |
} | |
function sleep(msec) { | |
return new Promise(resolve => setTimeout(resolve, msec)); | |
} | |
main() | |
async function main() { | |
for (let y = -180; y <= 180; y += 6) { | |
for (let x = -180; x <= 180; x += 4) { | |
await sleep(delay); | |
const r = dr * Math.sqrt(x*x + y*y) | |
const z = 100 * Math.cos(r) - 30 * Math.cos(3*r) | |
const sx = Math.floor(80 + x/3 - y/6) | |
const sy = Math.floor(40 - y/6 - z/4) | |
if ((sx < 0) || (sx >= 160)) { continue } | |
if (d[sx] <= sy) { continue } | |
const zz = Math.floor((z+100) * 0.035) + 1 | |
if ((zz==1) || (zz==3) || (zz==5) || (zz==7)) { | |
pset(sx*2, sy*2, "#26F") // blue | |
} | |
if ((zz==2) || (zz==3) || (zz>=6)) { | |
pset(sx*2, sy*2, "#F26") // red | |
} | |
if (zz>=4) { | |
pset(sx*2, sy*2, "#0F0") // green | |
} | |
d[sx] = sy | |
} | |
} | |
} | |
</script> | |
</body> | |
</html> |
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test.mp4