Spline Builder

class Example extends Phaser.Scene
{
    graphics;
    ball;
    handles;
    curve;
    path;
    parts = 8;

    preload ()
    {
        this.load.setBaseURL('https://cdn.phaserfiles.com/v410');
        this.load.image('ball', 'assets/sprites/shinyball.png');
        this.load.spritesheet('dragcircle', 'assets/sprites/dragcircle.png', { frameWidth: 16 });
    }

    create ()
    {
        this.handles = this.add.group();

        this.ball = this.add.image(0, 0, 'ball').setDepth(1000);

        this.path = { t: 0, vec: new Phaser.Math.Vector2() };

        this.curve = new Phaser.Curves.Spline([ new Phaser.Math.Vector2(50, 300) ]);

        let tween = this.tweens.add({
            targets: this.path,
            t: 1,
            ease: 'Sine.easeInOut',
            duration: 500,
            repeat: -1
        });

        const _this = this;

        const createPointHandle = point =>
        {
            const handle = this.handles.create(point.x, point.y, 'dragcircle', 0).setInteractive();

            handle.setData('vector', point);

            _this.input.setDraggable(handle);
        };

        createPointHandle(this.curve.points[0]);

        this.input.on('pointerdown', (pointer, gameObjects) =>
        {

            //  Check we didn't click an existing handle
            if (gameObjects.length > 0)
            {
                return;
            }

            const vec = this.curve.addPoint(pointer.x, pointer.y);

            createPointHandle(vec);

            this.parts += 8;

            tween.stop();

            this.path.t = 0;

            tween = _this.tweens.add({
                targets: this.path,
                t: 1,
                ease: 'Sine.easeInOut',
                duration: 500 * (this.curve.points.length + 1),
                repeat: -1
            });

        });

        this.input.on('dragstart', (pointer, gameObject) =>
        {

            gameObject.setFrame(1);

        });

        this.input.on('drag', (pointer, gameObject, dragX, dragY) =>
        {

            gameObject.x = dragX;
            gameObject.y = dragY;

            gameObject.getData('vector').set(dragX, dragY);

        });

        this.input.on('dragend', (pointer, gameObject) =>
        {

            gameObject.setFrame(0);

        });

        this.graphics = this.add.graphics();

    }

    update ()
    {
        this.graphics.clear();

        this.graphics.lineStyle(2, 0xffffff, 1);

        this.curve.draw(this.graphics, this.parts);

        this.curve.getPoint(this.path.t, this.path.vec);

        this.ball.setPosition(this.path.vec.x, this.path.vec.y);
    }
}

const config = {
    scale: { mode: Phaser.Scale.FIT },
    type: Phaser.AUTO,
    width: 800,
    height: 600,
    backgroundColor: '#2d2d2d',
    parent: 'game-container',
    scene: Example
};

const game = new Phaser.Game(config);