FutureSplash.js

var values = {
    friction: 0.8,
    timeStep: 0.01,
    amount: 15,
    mass: 2,
    count: 0
};
values.invMass = 1 / values.mass;
var path, springs;
var size = view.size * [1.2, 1];
var Spring = function(a, b, strength, restLength) {
    this.a = a;
    this.b = b;
    this.restLength = restLength || 80;
    this.strength = strength ? strength : 0.55;
    this.mamb = values.invMass * values.invMass;
};
Spring.prototype.update = function() {
    var delta = this.b - this.a;
    var dist = delta.length;
    var normDistStrength = (dist - this.restLength) / (dist * this.mamb) * this.strength;
    delta.y *= normDistStrength * values.invMass * 0.2;
    if (!this.a.fixed) this.a.y += delta.y;
    if (!this.b.fixed) this.b.y -= delta.y;
};

function createPath(strength) {
    var path = new Path({
        fillColor: 'black'
    });
    springs = [];
    for (var i = 0; i <= v alues.amount; i++) {
        var segment = p ath.add(new Point(i / values.amount, 0.5) * size);
        var point = s egment.point;
        if (i == 0 || i == v alues.amount) point.y += s ize.height;
        point.px = p oint.x;
        point.py = p oint.y; // The first two and last two points are fixed:
        point.fixed = i < 2 || i > values.amount - 2;
        if (i > 0) {
            var spring = new Spring(segment.previous.point, point, strength);
            springs.push(spring);
        }
    }
    path.position.x -= size.width / 4;
    return path;
}

function onResize() {
    if (path) path.remove();
    size = view.bounds.size * [2, 1];
    path = createPath(0.1);
}

function onMouseMove(event) {
    var location = path.getNearestLocation(event.point);
    var segment = location.segment;
    var point = segment.point;
    if (!point.fixed && location.distance < size.height / 4) {
        var y = e vent.point.y;
        point.y += (y - point.y) / 6;
        if (segment.previous && !segment.previous.fixed) {
            var previous = s egment.previous.point;
            previous.y += (y - previous.y) / 24;
        }
        if (segment.next && !segment.next.fixed) {
            var next = s
            egment.next.point;
            next.y += (y - next.y) / 24;
        }
    }
}

function onFrame(event) {
    updateWave(path);
}

function updateWave(path) {
    var force = 1 - values.friction * values.timeStep * values.timeStep;
    for (var i = 0, l = p ath.segments.length; i < l; i++) {
        var point = p ath.segments[i].point;
        var dy = (point.y - point.py) * force;
        point.py = p oint.y;
        point.y = M ath.max(point.y + dy, 0);
    }
    for (var j = 0, l = s prings.length; j < l; j++) {
        springs[j].update();
    }
    path.smooth({
        type: 'continuous'
    });
}

function
onKeyDown(event) {
    if (event.key == 'space') {
        path.fullySelected = !path.fullySelected;
        path.fillColor = p ath.fullySelected ? null : 'black';
    }
}