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March 26, 2018 17:34
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CLICK THE CIRCLE
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<canvas id="canvas" width="600px" height="400px"></canvas> | |
<script src="./index.js"></script> |
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let x = 200; | |
let y = 200; | |
let r = 100; | |
let color = 'black'; | |
let canvas = document.getElementById('canvas'); | |
let ctx = canvas.getContext('2d'); | |
let colors = []; | |
// so the trick is to go the center, rotate, translate by r | |
let acc = 0.001; | |
let vx = 0; | |
let offset = 0; | |
let rad = Math.PI / 180; | |
let colorIndex = {}, colorsRGB = []; | |
let clicked = []; | |
let hovered; | |
function draw() { | |
ctx.clearRect(0, 0, 800, 400); | |
for (let i = 0, j = 0; j < 360; i++, j = i * 20) { | |
if (!colors[i]) { | |
let r = Math.floor(Math.random() * 255); | |
let g = Math.floor(Math.random() * 255); | |
let b = Math.floor(Math.random() * 255); | |
colors[i] = `rgba(${r}, ${g}, ${b}, 1)`; | |
colorsRGB[i] = [r, g, b]; | |
colorIndex[`${r}${g}${b}`] = i; | |
} | |
ctx.save(); | |
ctx.translate(x, y); | |
ctx.rotate(rad * j + offset); | |
ctx.translate(5, -100); | |
let stroke = false; | |
if (clicked[i]) { | |
clicked[i].scale += 1; | |
clicked[i].opacity -= 0.02; | |
ctx.translate( clicked[i].scale * 2, clicked[i].scale * 2); | |
[r, g, b] = colorsRGB[i]; | |
let opacity = clicked[i].opacity; | |
colors[i] = `rgba(${r}, ${g}, ${b}, ${opacity})`; | |
ctx.scale(clicked[i].scale, clicked[i].scale); | |
} else { | |
stroke = hovered === i; | |
} | |
drawCircle(0, 0, 10, colors[i], stroke); | |
ctx.restore(); | |
} | |
vx += acc; | |
if (vx < -0.03) { | |
acc = 0.0001; | |
} | |
if (vx > 0.03) { | |
acc = -0.0001; | |
} | |
offset += vx; | |
window.requestAnimationFrame(draw); | |
} | |
draw(); | |
document.getElementById('canvas').addEventListener('click', e => { | |
let x = e.offsetX; | |
let y = e.offsetY; | |
let p = ctx.getImageData(x, y, 1, 1).data; | |
let r = p[0], g = p[1], b = p[2]; | |
let key = `${r}${g}${b}` | |
let i = (colorIndex[key]); | |
if (i || i === 0) { | |
clicked[i] = { | |
scale: 1, | |
opacity: 1 | |
} | |
} | |
}); | |
document.getElementById('canvas').addEventListener('mousemove', e => { | |
let x = e.offsetX; | |
let y = e.offsetY; | |
let p = ctx.getImageData(x, y, 1, 1).data; | |
let r = p[0], g = p[1], b = p[2]; | |
let key = `${r}${g}${b}`; | |
hovered = (colorIndex[key]); | |
}); | |
function drawCircle(x, y, radius, color, stroke) { | |
ctx.fillStyle = color; | |
ctx.beginPath(); | |
ctx.arc(x, y, radius, 0, 2*Math.PI); | |
ctx.fill(); | |
if (stroke) { | |
ctx.lineWidth = 3; | |
ctx.stroke(); | |
} | |
} |
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