Script: Wave

function start() {
    var start = Playground.AddVector2('start', new Vector2(Playground.PLAYFIELD_WIDTH / 2 - 100, Playground.PLAYFIELD_HEIGHT / 2));
    var end = Playground.AddVector2('end', new Vector2(Playground.PLAYFIELD_WIDTH / 2 + 100, Playground.PLAYFIELD_HEIGHT / 2));
    var frequency = Playground.AddInt('frequency', 1);
    var amplitude = Playground.AddFloat('amplitude', 90);

    Playground.AddOptionVector2(start, 'Start');
    Playground.AddOptionVector2(end, 'End');
    Playground.AddOptionInt(frequency, 'Frequency', 1, 8);
    Playground.AddOptionFloat(amplitude, 'Amplitude', 2, -200, 200);
}

function update() {
    var start = Playground.GetValueVector2('start');
    var end = Playground.GetValueVector2('end');
    var frequency = Playground.GetValueInt('frequency');
    var amplitude = Playground.GetValueFloat('amplitude');

    var points = [];

    var angle = Math.atan2(end.y - start.y, end.x - start.x) + Math.PI / 2;
    
    for (var i = 0; i < frequency; i++) {
        var vStart = lerp(start, end, i / frequency);
        var vEnd = lerp(start, end, (i + 1) / frequency);
        var crest = lerp(vStart, vEnd, 0.25);
        var center = lerp(vStart, vEnd, 0.5);
        var trough = lerp(vStart, vEnd, 0.75);

        points.push(vStart);
        points.push(rotate(add(crest, new Vector2(0, amplitude)), crest, angle + Math.PI / 2));
        points.push(center);
        points.push(center);
        points.push(rotate(add(trough, new Vector2(0, amplitude)), trough, angle - Math.PI / 2));
        points.push(vEnd);
    }

    Playground.AddSlider(CurveType.Bezier, points);
}