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script.js
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script.js
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// window dimensions
const WIDTH = window.innerWidth,
HEIGHT = window.innerHeight;
// matrices of tile opacity and opacity change rate
var tiles, tileRate;
// dimensions of each tile
var tileSize = 12;
window.onload = function(e) {
// canvas setup
var canvas = document.getElementById("canvas");
var c = canvas.getContext("2d");
canvas.width = WIDTH;
canvas.height = HEIGHT;
// initial setup
init(c);
// main logic loop
var loop = function() {
update();
render(c);
window.requestAnimationFrame(loop, canvas);
}
window.requestAnimationFrame(loop, canvas);
}
function init(c) {
// calculate tiles across and vertically
var tilesX = Math.round(WIDTH / tileSize) + 1;
var tilesY = Math.round(HEIGHT / tileSize) + 1;
// initialize tile data arrays
tiles = new Array(tilesX);
tileRate = new Array(tilesX);
for (var x = 0; x < tiles.length; x++) {
tiles[x] = new Array(tilesY);
tileRate[x] = new Array(tilesY);
}
// set initial tile data values
for (var x = 0; x < tiles.length; x++) {
for (var y = 0; y < tiles[x].length; y++) {
tiles[x][y] = Math.random();
tileRate[x][y] = Math.random() * .01;
}
}
}
function update() {
// update tile opacity based on opacity change rates
for (var x = 0; x < tiles.length; x++) {
for (var y = 0; y < tiles[x].length; y++) {
tiles[x][y] = (tiles[x][y] + tileRate[x][y]) % 1;
}
}
}
function render(c) {
// fill tiles black
c.fillStyle = "black";
for (var x = 0; x < tiles.length; x++) {
for (var y = 0; y < tiles[x].length; y++) {
c.globalAlpha = tiles[x][y];
c.fillRect(x * tileSize, y * tileSize, tileSize, tileSize);
}
}
// screen fade out effect
c.fillStyle = "crimson";
c.globalAlpha = .06;
c.fillRect(0, 0, WIDTH, HEIGHT)
c.globalAlpha = 1;
}