Yusof Bandar a Computer Science Student
Published
Edited
Mar 2, 2019
2 stars
rain = {
function renderRain(amount = 500, options = {}) {
options = defaultRainOptions(options);
let w = 960,
h = 500;
const canvas = DOM.canvas(w,h);
let context = d3.select(canvas).node().getContext('2d');
let rainDrops = d3.range(amount).map(function () {
let zIndex = getRandomArbitrary(0, 10);
return {
x: getRandomArbitrary(-10, w),
y: getRandomArbitrary(-100, -600),
z: zIndex,
d: map(zIndex, 0, 10, 3, 10),
length: map(zIndex, 0, 10, options.minLength, options.maxLength),
}
})
let timer = d3.timer(function () {
context.clearRect(0, 0,w,h);
for (let i = 0, length = rainDrops.length; i < length; i++) {
let x = rainDrops[i].x
let oldx = rainDrops[i].x;
let y = rainDrops[i].y
let dropLength = rainDrops[i].length;
x += wind
y += rainDrops[i].d;
if (y > h) {
y = getRandomArbitrary(-100, -600);
x = getRandomArbitrary(-100, w+100);
}
rainDrops[i].y = y;
context.beginPath();
context.moveTo(rainDrops[i].x,y);
context.lineTo(x,y+dropLength);
context.stroke();
context.closePath();
if (x > w) {
x = getRandomArbitrary(-100, w+100);
} else if (x < 0) {
x = getRandomArbitrary(-100, w+100);
}
rainDrops[i].x = x;
}
})
invalidation.then(() => timer.stop());
return canvas;
}
function defaultRainOptions(options) {
const MINLENGTH = 5,
MAXLENGTH = 20;
if (!("minLength" in options)) {
options.minLength = MINLENGTH;
}
if (!("maxLength" in options)) {
options.maxLength = MAXLENGTH;
}
return options;
}
function getRandomArbitrary(min, max) {
return Math.random() * (max - min) + min;
}
function map (num, in_min, in_max, out_min, out_max){
return (num - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}
function defaultRainOptions(options) {
const MINLENGTH = 5,
MAXLENGTH = 20;
if (!("minLength" in options)) {
options.minLength = MINLENGTH;
}
if (!("maxLength" in options)) {
options.maxLength = MAXLENGTH;
}
return options;
}
return renderRain(numberDrops);
}
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