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body
background: #000
margin: 0
overflow: hidden
var canvas,
c;
var dots = [];
var dot_count = 40;
var dot_radius = 2;
var dot_stroke_color = hsla(0,50,100,0.8);
var dot_stroke_weight = 5;
var dot_speed = 3;
var dot_speed_max = 4;
var dot_speed_min = 1;
var dot_turn = 2;
var dot_gravity = 0.000;
var dot_avoidance_distance = 70;
var dot_avoidance_strength = 0.6;
var screenWidth = window.innerWidth;
var screenHeight = window.innerHeight;
var screenMin = (screenWidth < screenHeight) ? screenWidth : screenHeight;
img = new Image();
img.src = 'https://s3-us-west-2.amazonaws.com/s.cdpn.io/2361/dot.png';
function setup() {
frameRate = 30;
setupCanvas();
makeDots(dot_count);
}
function makeDots(count) {
for(var i = 0; i < count; i++) {
var r = randomInteger(0,screenMin*0.4);
var d = randomInteger(0,360);
dots.push(new Dot(r, d, i));
}
}
function draw() {
c.clearRect(-screenWidth/2, -screenHeight/2, screenWidth, screenHeight);
c.strokeStyle = dot_stroke_color;
c.lineWidth = dot_stroke_weight;
for(var i = 0; i < dots.length; i++) {
var dot = dots[i];
dot.update(canvas);
dot.draw(c);
}
}
function setupCanvas() {
canvas = document.createElement('canvas');
c = canvas.getContext('2d');
canvas.width = screenWidth;
canvas.height = screenHeight;
document.body.appendChild(canvas);
c.globalCompositeOperation = "lighter";
c.translate(screenWidth/2, screenHeight/2);
}
Dot = function(r, d, index) {
var pos = this.pos = new Vector2(r,0).rotate(d);
var vel = this.vel = new Vector2(dot_speed,0);
var ang = this.ang = 180-pos.angle();
var dir = this.dir = randomInteger(0,1);
var index = this.index;
vel.rotate(ang);
this.update = function(canvas) {
// randomly change clockwiseness
if (randomInteger(0,100) == 0) {
dir = (dir == 1) ? 0 : 1;
}
// rotate
if (dir) {
vel.rotate(dot_turn);
} else {
vel.rotate(-dot_turn);
}
// gravity
var change_gravity = new Vector2(pos.x*dot_gravity,pos.y*dot_gravity);
vel.minusEq(change_gravity);
// dot avoidance
for (var i = 0; i < dots.length; i++) {
var adot = dots[i];
if (i != this.index) {
var delta = adot.pos.minusNew(this.pos);
var delta_mag = Math.sqrt((delta.x*delta.x)+(delta.y*delta.y));
if (delta_mag < dot_avoidance_distance) {
delta.multiplyEq((dot_avoidance_distance-delta_mag)/dot_avoidance_distance*dot_avoidance_strength);
pos.minusEq(delta);
}
}
}
// edge avoidance
if (pos.x > screenWidth*0.4) {
vel.x += -0.3;
} else if (pos.x < -screenWidth*0.4) {
vel.x += 0.3;
}
if (pos.y > screenHeight*0.4) {
vel.y += -0.3;
} else if (pos.y < -screenHeight*0.4) {
vel.y += 0.3;
}
// min and max speeds
var mag = Math.sqrt((vel.x*vel.x)+(vel.y*vel.y));
if (mag < dot_speed_min) {
vel.multiplyEq(dot_speed_min/mag);
} else if (mag > dot_speed_max) {
vel.multiplyEq(dot_speed_max/mag);
}
// add velocity to position
pos.plusEq(vel);
};
this.draw = function(c) {
// save the current canvas state
c.save();
// move to where the particle should be
c.translate(pos.x, pos.y);
// scale it dependent on the size of the particle
var s = 0.8;
c.scale(s,s);
//c.rotate(ang);
// move the draw position to the center of the image
c.translate(img.width*-0.5, img.width*-0.5);
// set the composition mode
c.globalCompositeOperation = this.compositeOperation;
// and draw it!
c.drawImage(img,0,0);
// and restore the canvas state
c.restore();
};
};
Also see: Tab Triggers