Tilemap Snake Distance

class Example extends Phaser.Scene
{
    showDebug = false;
    player;
    helpText;
    debugGraphics;
    cursors;
    map;

    preload ()
    {
        this.load.setBaseURL('https://cdn.phaserfiles.com/v410');
        this.load.image('tiles', 'assets/tilemaps/tiles/catastrophi_tiles_16.png');
        this.load.tilemapCSV('map', 'assets/tilemaps/csv/catastrophi_level2.csv');
        this.load.spritesheet('player', 'assets/sprites/spaceman.png', { frameWidth: 16, frameHeight: 16 });
    }

    create ()
    {
        // When loading a CSV map, make sure to specify the tileWidth and tileHeight
        this.map = this.make.tilemap({ key: 'map', tileWidth: 16, tileHeight: 16 });
        const tileset = this.map.addTilesetImage('tiles');
        const layer = this.map.createLayer(0, tileset, 0, 0);

        this.anims.create({
            key: 'left',
            frames: this.anims.generateFrameNumbers('player', { start: 8, end: 9 }),
            frameRate: 10,
            repeat: -1
        });
        this.anims.create({
            key: 'right',
            frames: this.anims.generateFrameNumbers('player', { start: 1, end: 2 }),
            frameRate: 10,
            repeat: -1
        });
        this.anims.create({
            key: 'up',
            frames: this.anims.generateFrameNumbers('player', { start: 11, end: 13 }),
            frameRate: 10,
            repeat: -1
        });
        this.anims.create({
            key: 'down',
            frames: this.anims.generateFrameNumbers('player', { start: 4, end: 6 }),
            frameRate: 10,
            repeat: -1
        });

        this.player = this.physics.add.sprite(400, 300, 'player', 1);

        this.cameras.main.setBounds(0, 0, this.map.widthInPixels, this.map.heightInPixels);
        this.cameras.main.startFollow(this.player);

        this.cursors = this.input.keyboard.createCursorKeys();
    }

    update (time, delta)
    {
        this.updatePlayer();
        this.updateMap();
    }

    updateMap ()
    {
        const origin = this.map.getTileAtWorldXY(this.player.x, this.player.y);

        this.map.forEachTile(tile =>
        {
            const dist = Phaser.Math.Distance.Snake(
                origin.x,
                origin.y,
                tile.x,
                tile.y
            );

            tile.setAlpha(1 - 0.1 * dist);
        });
    }

    updatePlayer ()
    {
        this.player.body.setVelocity(0);

        // Snake movement is 4 directions only

        if (this.cursors.left.isDown)
        {
            this.player.body.setVelocityX(-100);
        }
        else if (this.cursors.right.isDown)
        {
            this.player.body.setVelocityX(100);
        }
        else if (this.cursors.up.isDown)
        {
            this.player.body.setVelocityY(-100);
        }
        else if (this.cursors.down.isDown)
        {
            this.player.body.setVelocityY(100);
        }

        // Update the animation last and give left/right animations precedence over up/down animations
        if (this.cursors.left.isDown)
        {
            this.player.anims.play('left', true);
        }
        else if (this.cursors.right.isDown)
        {
            this.player.anims.play('right', true);
        }
        else if (this.cursors.up.isDown)
        {
            this.player.anims.play('up', true);
        }
        else if (this.cursors.down.isDown)
        {
            this.player.anims.play('down', true);
        }
        else
        {
            this.player.anims.stop();
        }
    }
}

const config = {
    scale: { mode: Phaser.Scale.FIT },
    type: Phaser.AUTO,
    width: 800,
    height: 600,
    parent: 'game-container',
    pixelArt: true,
    physics: {
        default: 'arcade'
    },
    scene: Example
};

const game = new Phaser.Game(config);