Circular Drop Zone

class Example extends Phaser.Scene
{
    preload ()
    {
        this.load.setBaseURL('https://cdn.phaserfiles.com/v410');
        this.load.atlas('cards', 'assets/atlas/cards.png', 'assets/atlas/cards.json');
    }

    create ()
    {
        //  Create a stack of random cards

        const frames = this.textures.get('cards').getFrameNames();

        const x = 100;
        let y = 100;

        for (let i = 0; i < 64; i++)
        {
            const image = this.add.image(x, y, 'cards', Phaser.Math.RND.pick(frames)).setInteractive();

            this.input.setDraggable(image);

            y += 6;
        }

        //  A drop zone positioned at 600x300 with a circular drop zone 128px in radius
        const zone = this.add.zone(600, 300).setCircleDropZone(128);

        //  Just a visual display of the drop zone
        const graphics = this.add.graphics();

        graphics.lineStyle(2, 0xffff00);

        graphics.strokeCircle(zone.x, zone.y, zone.input.hitArea.radius);

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

            this.children.bringToTop(gameObject);

        }, this);

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

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

        });

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

            graphics.clear();
            graphics.lineStyle(2, 0x00ffff);
            graphics.strokeCircle(zone.x, zone.y, zone.input.hitArea.radius);

        });

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

            graphics.clear();
            graphics.lineStyle(2, 0xffff00);
            graphics.strokeCircle(zone.x, zone.y, zone.input.hitArea.radius);

        });

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

            gameObject.x = dropZone.x;
            gameObject.y = dropZone.y;

            gameObject.input.enabled = false;

        });

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

            if (!dropped)
            {
                gameObject.x = gameObject.input.dragStartX;
                gameObject.y = gameObject.input.dragStartY;
            }

        });
    }
}

const config = {
    scale: { mode: Phaser.Scale.FIT },
    type: Phaser.WEBGL,
    parent: 'game-container',
    width: 1024,
    height: 600,
    scene: Example
};

const game = new Phaser.Game(config);