-
Notifications
You must be signed in to change notification settings - Fork 0
/
script.js
114 lines (87 loc) · 2.6 KB
/
script.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
// width and height of window
const WIDTH = window.innerWidth,
HEIGHT = window.innerHeight;
// maximum number of points visible per frame
var numOfPoints = 200;
// arrays for storing point radius and position data
var pointsX, pointsY, pointsRadius;
// current angle to draw points from
var angle = 0;
// colors to cycle through
var colors = [
"white"
];
// currently assigned color
var currentColorIndex;
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) {
// initialize point data arrays
pointsX = new Array(numOfPoints);
pointsY = new Array(numOfPoints);
pointsRadius = new Array(numOfPoints);
// initialize color
currentColorIndex = 0;
}
function update() {
// update angle
angle += Math.PI * 4 / numOfPoints;
if (angle > Math.PI * 2) {
angle -= Math.PI * 2;
}
// update color
if (currentColorIndex < colors.length - 1) {
currentColorIndex++;
} else {
currentColorIndex = 0;
}
// update positions of points
for (var i = 0; i < numOfPoints; i++) {
// calculate distance from center of screen
var distance = Math.pow(Math.sqrt(WIDTH * WIDTH + HEIGHT * HEIGHT), i / numOfPoints);
// calculate and assign calculated values
pointsX[i] = WIDTH / 2 + Math.cos(angle - (i + 1) / numOfPoints * Math.PI * 2) * distance;
pointsY[i] = HEIGHT / 2 + Math.sin(angle - (i + 1) / numOfPoints * Math.PI * 2) * distance;
pointsRadius[i] = distance / numOfPoints * 2;
}
}
function render(c) {
// screen fade out effect
c.fillStyle = "black";
c.globalAlpha = 0.05;
c.fillRect(0, 0, WIDTH, HEIGHT);
c.globalAlpha = 1;
// draw points at their current positions
for (var i = 0; i < numOfPoints; i++) {
// only draw points that are visible in the window
if (
(pointsX[i] >= -pointsRadius[i] && pointsX[i] <= WIDTH + pointsRadius[i]) &&
(pointsY[i] >= -pointsRadius[i] && pointsY[i] <= HEIGHT + pointsRadius[i])
) {
// draw single point
c.fillStyle = colors[currentColorIndex];
c.beginPath();
c.arc(pointsX[i], pointsY[i], pointsRadius[i], 0, 2 * Math.PI);
c.fill();
c.closePath();
}
}
}
// function for generating rgba() string
function rgb(r, g, b) {
return "rgba(" + [r, g, b].join(",") + ",1)";
}