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The Swiss Army Knife of Vector Graphics Scripting
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<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Tadpoles</title>
<link rel="stylesheet" href="../css/style.css">
<script type="text/javascript" src="../../dist/paper-full.js"></script>
<script type="text/paperscript" canvas="canvas">
// Adapted from Flocking Processing example by Daniel Schiffman:
// http://processing.org/learning/topics/flocking.html
var Boid = Base.extend({
initialize: function(position, maxSpeed, maxForce) {
var strength = Math.random() * 0.5;
this.acceleration = new Point();
this.vector = Point.random() * 2 - 1;
this.position = position.clone();
this.radius = 30;
this.maxSpeed = maxSpeed + strength;
this.maxForce = maxForce + strength;
this.amount = strength * 10 + 10;
this.count = 0;
this.createItems();
},
run: function(boids) {
this.lastLoc = this.position.clone();
if (!groupTogether) {
this.flock(boids);
} else {
this.align(boids);
}
this.borders();
this.update();
this.calculateTail();
this.moveHead();
},
calculateTail: function() {
var segments = this.path.segments,
shortSegments = this.shortPath.segments;
var speed = this.vector.length;
var pieceLength = 5 + speed / 3;
var point = this.position;
segments[0].point = shortSegments[0].point = point;
// Chain goes the other way than the movement
var lastVector = -this.vector;
for (var i = 1; i < this.amount; i++) {
var vector = segments[i].point - point;
this.count += speed * 10;
var wave = Math.sin((this.count + i * 3) / 300);
var sway = lastVector.rotate(90).normalize(wave);
point += lastVector.normalize(pieceLength) + sway;
segments[i].point = point;
if (i < 3)
shortSegments[i].point = point;
lastVector = vector;
}
this.path.smooth();
},
createItems: function() {
this.head = new Shape.Ellipse({
center: [0, 0],
size: [13, 8],
fillColor: 'white'
});
this.path = new Path({
strokeColor: 'white',
strokeWidth: 2,
strokeCap: 'round'
});
for (var i = 0; i < this.amount; i++)
this.path.add(new Point());
this.shortPath = new Path({
strokeColor: 'white',
strokeWidth: 4,
strokeCap: 'round'
});
for (var i = 0; i < Math.min(3, this.amount); i++)
this.shortPath.add(new Point());
},
moveHead: function() {
this.head.position = this.position;
this.head.rotation = this.vector.angle;
},
// We accumulate a new acceleration each time based on three rules
flock: function(boids) {
var separation = this.separate(boids) * 3;
var alignment = this.align(boids);
var cohesion = this.cohesion(boids);
this.acceleration += separation + alignment + cohesion;
},
update: function() {
// Update velocity
this.vector += this.acceleration;
// Limit speed (vector#limit?)
this.vector.length = Math.min(this.maxSpeed, this.vector.length);
this.position += this.vector;
// Reset acceleration to 0 each cycle
this.acceleration = new Point();
},
seek: function(target) {
this.acceleration += this.steer(target, false);
},
arrive: function(target) {
this.acceleration += this.steer(target, true);
},
borders: function() {
var vector = new Point();
var position = this.position;
var radius = this.radius;
var size = view.size;
if (position.x < -radius) vector.x = size.width + radius;
if (position.y < -radius) vector.y = size.height + radius;
if (position.x > size.width + radius) vector.x = -size.width -radius;
if (position.y > size.height + radius) vector.y = -size.height -radius;
if (!vector.isZero()) {
this.position += vector;
var segments = this.path.segments;
for (var i = 0; i < this.amount; i++) {
segments[i].point += vector;
}
}
},
// A method that calculates a steering vector towards a target
// Takes a second argument, if true, it slows down as it approaches
// the target
steer: function(target, slowdown) {
var steer,
desired = target - this.position;
var distance = desired.length;
// Two options for desired vector magnitude
// (1 -- based on distance, 2 -- maxSpeed)
if (slowdown && distance < 100) {
// This damping is somewhat arbitrary:
desired.length = this.maxSpeed * (distance / 100);
} else {
desired.length = this.maxSpeed;
}
steer = desired - this.vector;
steer.length = Math.min(this.maxForce, steer.length);
return steer;
},
separate: function(boids) {
var desiredSeperation = 60;
var steer = new Point();
var count = 0;
// For every boid in the system, check if it's too close
for (var i = 0, l = boids.length; i < l; i++) {
var other = boids[i];
var vector = this.position - other.position;
var distance = vector.length;
if (distance > 0 && distance < desiredSeperation) {
// Calculate vector pointing away from neighbor
steer += vector.normalize(1 / distance);
count++;
}
}
// Average -- divide by how many
if (count > 0)
steer /= count;
if (!steer.isZero()) {
// Implement Reynolds: Steering = Desired - Velocity
steer.length = this.maxSpeed;
steer -= this.vector;
steer.length = Math.min(steer.length, this.maxForce);
}
return steer;
},
// Alignment
// For every nearby boid in the system, calculate the average velocity
align: function(boids) {
var neighborDist = 25;
var steer = new Point();
var count = 0;
for (var i = 0, l = boids.length; i < l; i++) {
var other = boids[i];
var distance = this.position.getDistance(other.position);
if (distance > 0 && distance < neighborDist) {
steer += other.vector;
count++;
}
}
if (count > 0)
steer /= count;
if (!steer.isZero()) {
// Implement Reynolds: Steering = Desired - Velocity
steer.length = this.maxSpeed;
steer -= this.vector;
steer.length = Math.min(steer.length, this.maxForce);
}
return steer;
},
// Cohesion
// For the average location (i.e. center) of all nearby boids,
// calculate steering vector towards that location
cohesion: function(boids) {
var neighborDist = 100;
var sum = new Point();
var count = 0;
for (var i = 0, l = boids.length; i < l; i++) {
var other = boids[i];
var distance = this.position.getDistance(other.position);
if (distance > 0 && distance < neighborDist) {
sum += other.position; // Add location
count++;
}
}
if (count > 0) {
sum /= count;
// Steer towards the location
return this.steer(sum, false);
}
return sum;
}
});
var heartPath = new Path('M514.69629,624.70313c-7.10205,-27.02441 -17.2373,-52.39453 -30.40576,-76.10059c-13.17383,-23.70703 -38.65137,-60.52246 -76.44434,-110.45801c-27.71631,-36.64355 -44.78174,-59.89355 -51.19189,-69.74414c-10.5376,-16.02979 -18.15527,-30.74951 -22.84717,-44.14893c-4.69727,-13.39893 -7.04297,-26.97021 -7.04297,-40.71289c0,-25.42432 8.47119,-46.72559 25.42383,-63.90381c16.94775,-17.17871 37.90527,-25.76758 62.87354,-25.76758c25.19287,0 47.06885,8.93262 65.62158,26.79834c13.96826,13.28662 25.30615,33.10059 34.01318,59.4375c7.55859,-25.88037 18.20898,-45.57666 31.95215,-59.09424c19.00879,-18.32178 40.99707,-27.48535 65.96484,-27.48535c24.7373,0 45.69531,8.53564 62.87305,25.5957c17.17871,17.06592 25.76855,37.39551 25.76855,60.98389c0,20.61377 -5.04102,42.08691 -15.11719,64.41895c-10.08203,22.33203 -29.54687,51.59521 -58.40723,87.78271c-37.56738,47.41211 -64.93457,86.35352 -82.11328,116.8125c-13.51758,24.0498 -23.82422,49.24902 -30.9209,75.58594z');
var boids = [];
var groupTogether = false;
// Add the boids:
for (var i = 0; i < 30; i++) {
var position = Point.random() * view.size;
boids.push(new Boid(position, 10, 0.05));
}
function onFrame(event) {
for (var i = 0, l = boids.length; i < l; i++) {
if (groupTogether) {
var length = ((i + event.count / 30) % l) / l * heartPath.length;
var point = heartPath.getPointAt(length);
if (point)
boids[i].arrive(point);
}
boids[i].run(boids);
}
}
// Reposition the heart path whenever the window is resized:
function onResize(event) {
heartPath.fitBounds(view.bounds);
heartPath.scale(0.8);
}
function onMouseDown(event) {
groupTogether = !groupTogether;
}
function onKeyDown(event) {
if (event.key == 'space') {
var layer = project.activeLayer;
layer.selected = !layer.selected;
return false;
}
}
</script>
<style>
body {
background: black;
}
</style>
</head>
<body>
<canvas id="canvas" resize></canvas>
</body>
</html>