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https://github.com/scratchfoundation/paper.js.git
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Add Flock example.
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Jonathan Puckey
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1 changed files with 246 additions and 0 deletions
246
examples/Animated/Flock.html
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246
examples/Animated/Flock.html
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<!DOCTYPE html>
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<title>Example</title>
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<script type="text/javascript">var root = '../../'</script>
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<script type="text/javascript" src="../../src/load.js"></script>
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<script type="text/paperscript" canvas="canvas">
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document.currentStyle = {
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strokeColor: 'white',
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strokeWidth: 2,
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strokeCap: 'round'
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};
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var bounds = document.bounds,
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width = bounds.width,
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height = bounds.height;
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var Boid = Base.extend({
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initialize: function(position, maxSpeed, maxForce) {
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var strength = Math.random() * 0.5;
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this.acc = new Point(0, 0);
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this.vel = new Point(Math.random() * 2 - 1, Math.random() * 2 - 1);
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this.loc = position.clone();
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this.r = 30;
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this.maxSpeed = maxSpeed + strength;
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this.maxForce = maxForce + strength;
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this.path = new Path();
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this.head = new Path.Circle(this.loc, 3);
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this.head.style = {
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fillColor: 'white',
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strokeColor: null,
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};
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for(var i = 0, l = strength * 10 + 10; i < l; i++) {
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this.path.add(this.loc);
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}
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this.firstSegment = this.path.segments[0];
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this.lastRot = 0;
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this.count = 0;
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},
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run: function(boids) {
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this.lastLoc = this.loc.clone();
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if(!groupTogether)
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this.flock(boids);
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this.borders();
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this.update();
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this.firstSegment.point = this.loc;
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var lastPoint = this.firstSegment.point;
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var lastVector = this.loc - this.lastLoc;
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var segments = this.path.segments;
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for (var i = 1, l = segments.length; i < l; i++) {
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var segment = segments[i];
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var vector = lastPoint - segment.point;
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this.count += this.vel.length * 10;
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var rotated = lastVector.rotate(90).normalize(Math.sin((this.count + i * 3) / 300));
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lastPoint = segment.point = lastPoint + lastVector.normalize(-5 - this.vel.length / 3);
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segment.point += rotated;
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lastVector = vector;
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}
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this.path.smooth();
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this.head.position = this.loc;
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},
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// We accumulate a new acceleration each time based on three rules
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flock: function(boids) {
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var sep = this.separate(boids) * 3;
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var ali = this.align(boids);
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var coh = this.cohesion(boids);
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this.acc += sep + ali + coh;
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},
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update: function() {
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// Update velocity
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this.vel += this.acc;
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// Limit speed (vector#limit?)
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this.vel.length = Math.min(this.maxSpeed, this.vel.length);
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this.loc += this.vel;
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// Reset acceleration to 0 each cycle
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this.acc.length = 0;
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},
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seek: function(target) {
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this.acc += this.steer(target, false);
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},
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arrive: function(target) {
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this.acc += this.steer(target, true);
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},
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// A method that calculates a steering vector towards a target
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// Takes a second argument, if true, it slows down as it approaches the target
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steer: function(target, slowdown) {
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var steer,
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desired = target - this.loc,
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d = desired.length;
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if (d > 0) {
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// Two options for desired vector magnitude (1 -- based on distance, 2 -- maxSpeed)
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if (slowdown && d < 100) {
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desired.length = this.maxSpeed * (d / 100); // This damping is somewhat arbitrary
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} else {
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desired.length = this.maxSpeed;
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}
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steer = desired - this.vel;
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steer.length = Math.min(this.maxForce, steer.length);
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} else {
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steer = new Point(0, 0);
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}
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return steer;
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},
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borders: function() {
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var loc = this.loc,
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r = this.r,
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oldLoc = this.loc.clone();
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if (loc.x < -r) loc.x = width + r;
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if (loc.y < -r) loc.y = height + r;
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if (loc.x > width + r) loc.x = -r;
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if (loc.y > height + r) loc.y = -r;
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var vector = this.loc - oldLoc;
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if(!vector.isZero())
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this.path.position += vector;
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},
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separate: function(boids) {
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var desiredSeperation = 60,
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steer = new Point(0, 0),
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count = 0;
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// For every boid in the system, check if it's too close
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for (var i = 0, l = boids.length; i < l; i++) {
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var other = boids[i];
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var d = other.loc.getDistance(this.loc);
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if (d > 0 && d < desiredSeperation) {
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// Calculate vector pointing away from neighbor
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var diff = this.loc - other.loc;
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steer += diff.normalize(1 / d);
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count++;
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}
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}
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// Average -- divide by how many
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if (count > 0)
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steer /= count;
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if(steer.length > 0) {
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// Implement Reynolds: Steering = Desired - Velocity
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steer.length = this.maxSpeed;
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steer -= this.vel;
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steer.length = Math.min(steer.length, this.maxForce);
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}
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return steer;
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},
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// Alignment
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// For every nearby boid in the system, calculate the average velocity
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align: function(boids) {
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var neighborDist = 25,
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steer = new Point(0, 0),
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count = 0,
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nearest = 999;
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for (var i = 0, l = boids.length; i < l; i++) {
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var other = boids[i];
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var d = this.loc.getDistance(other.loc);
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if(d > 0 && d < nearest)
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nearest = d;
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if(d > 0 && d < neighborDist) {
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steer += other.vel;
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count++;
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}
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}
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this.head.fillColor = this.path.strokeColor = nearest < 40 ? 'red' : 'white';
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if (count > 0)
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steer /= count;
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if (steer.length > 0) {
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// Implement Reynolds: Steering = Desired - Velocity
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steer.length = this.maxSpeed;
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steer -= this.vel;
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steer.length = Math.min(steer.length, this.maxForce);
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}
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return steer;
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},
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// Cohesion
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// For the average location (i.e. center) of all nearby boids, calculate steering vector towards that location
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cohesion: function(boids) {
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var neighborDist = 100,
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sum = new Point(0, 0),
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count = 0;
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for (var i = 0, l = boids.length; i < l; i++) {
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var other = boids[i];
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var d = this.loc.getDistance(other.loc);
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if(d > 0 && d < neighborDist) {
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sum += other.loc; // Add location
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count++;
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}
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}
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if (count > 0) {
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sum /= count;
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// Steer towards the location
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return this.steer(sum, false);
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}
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return sum;
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}
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});
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var boids = [],
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center = document.bounds.center;
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for (var i = 0; i < 40; i++) {
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var position = Point.random() * document.size;
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boids.push(new Boid(position, 10, 0.05));
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}
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var letterPath = new Path(
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new Segment(new Point(514.6962890625, 624.703125), new Point(7.0966796875, -26.3369140625), new Point(-7.10205078125, -27.0244140625)), new Segment(new Point(484.29052734375, 548.6025390625), new Point(13.16845703125, 23.7060546875), new Point(-13.173828125, -23.70703125)), new Segment(new Point(407.84619140625, 438.14453125), new Point(37.79296875, 49.935546875), new Point(-27.71630859375, -36.6435546875)), new Segment(new Point(356.654296875, 368.400390625), new Point(6.41015625, 9.8505859375), new Point(-10.53759765625, -16.02978515625)), new Segment(new Point(333.80712890625, 324.25146484375), new Point(4.69189453125, 13.3994140625), new Point(-4.697265625, -13.39892578125)), new Segment(new Point(326.76416015625, 283.53857421875), new Point(0, 13.74267578125), new Point(0, -25.42431640625)), new Segment(new Point(352.18798828125, 219.634765625), new Point(-16.95263671875, 17.17822265625), new Point(16.94775390625, -17.1787109375)), new Segment(new Point(415.0615234375, 193.8671875), new Point(-24.96826171875, 0), new Point(25.19287109375, 0)), new Segment(new Point(480.68310546875, 220.66552734375), new Point(-18.552734375, -17.86572265625), new Point(13.96826171875, 13.28662109375)), new Segment(new Point(514.6962890625, 280.10302734375), new Point(-8.70703125, -26.3369140625), new Point(7.55859375, -25.88037109375)), new Segment(new Point(546.6484375, 221.0087890625), new Point(-13.7431640625, 13.517578125), new Point(19.0087890625, -18.32177734375)), new Segment(new Point(612.61328125, 193.5234375), new Point(-24.9677734375, 0), new Point(24.7373046875, 0)), new Segment(new Point(675.486328125, 219.119140625), new Point(-17.177734375, -17.06005859375), new Point(17.1787109375, 17.06591796875)), new Segment(new Point(701.2548828125, 280.10302734375), new Point(0, -23.58837890625), new Point(0, 20.61376953125)), new Segment(new Point(686.1376953125, 344.52197265625), new Point(10.076171875, -22.33203125), new Point(-10.08203125, 22.33203125)), new Segment(new Point(627.73046875, 432.3046875), new Point(28.8603515625, -36.1875), new Point(-37.5673828125, 47.412109375)), new Segment(new Point(545.6171875, 549.1171875), new Point(17.1787109375, -30.458984375), new Point(-13.517578125, 24.0498046875))
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);
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letterPath.closed = true;
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letterPath.position = document.bounds.center;
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letterPath.strokeColor = null;
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letterPath.scale(1.5);
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var count = 0,
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groupTogether = false,
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pathLength = letterPath.length,
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mouseDown = false;
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function onFrameLoop() {
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count++;
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groupTogether = mouseDown || count % 1500 > 500;
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for(var i = 0, l = boids.length; i < l; i++) {
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if (groupTogether) {
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var point = letterPath.getLocation(((i + count / 30) % l) / l * pathLength).point;
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boids[i].arrive(point);
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}
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boids[i].run(boids);
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}
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}
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function onMouseDown(event) {
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mouseDown = true;
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}
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function onMouseUp(event) {
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mouseDown = false;
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count = 0;
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}
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</script>
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</head>
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<body style='background-color: black'>
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<canvas id='canvas' width=1024 height=768></canvas>
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</body>
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