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// See lipsum.dev | |
import React, { useEffect, useRef, useState } from "react"; | |
const L = 8; | |
function baseFunc(u, v) { | |
return (x, y) => | |
Math.cos(((2 * x + 1) * u * Math.PI) / 16) * | |
Math.cos(((2 * y + 1) * v * Math.PI) / 16); | |
} | |
function drawBaseFunc(canvas, factor, u, v) { | |
const ctx = canvas.getContext("2d"); | |
const func = baseFunc(u, v); | |
const size = factor * L; | |
const imgData = ctx.createImageData(size, size); | |
for (var i = 0; i < size; i++) { | |
for (var j = 0; j < size; j++) { | |
var pixelIndex = (i + j * size) * 4; | |
var pixelColor = | |
128 + | |
Math.round(128 * func(Math.floor(i / factor), Math.floor(j / factor))); | |
imgData.data[pixelIndex + 0] = pixelColor; | |
imgData.data[pixelIndex + 1] = pixelColor; | |
imgData.data[pixelIndex + 2] = pixelColor; | |
imgData.data[pixelIndex + 3] = 255; | |
} | |
} | |
ctx.putImageData(imgData, 0, 0); | |
} | |
function BaseImage(props) { | |
const canvasRef = useRef(null); | |
const size = L * props.factor; | |
useEffect(() => { | |
const canvas = canvasRef.current; | |
drawBaseFunc(canvas, props.factor, props.u, props.v); | |
}); | |
return ( | |
<div> | |
<canvas ref={canvasRef} width={size} height={size}></canvas> | |
</div> | |
); | |
} | |
function CosinusTransform(props) { | |
const [u, setU] = useState(2); | |
const [v, setV] = useState(5); | |
return ( | |
<div> | |
<BaseImage factor={props.factor} u={u} v={v} /> | |
<div> | |
<label for="u">u = {u} </label> | |
<input | |
id="u" | |
type="range" | |
min={0} | |
max={7} | |
value={u} | |
onChange={(e) => setU(e.target.value)} | |
/> | |
</div> | |
<div> | |
<label for="v">v = {v} </label> | |
<input | |
id="v" | |
type="range" | |
min={0} | |
max={7} | |
value={v} | |
onChange={(e) => setV(e.target.value)} | |
/> | |
</div> | |
</div> | |
); | |
} | |
export { CosinusTransform } |
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