---
title: "Ball Mesh Depth Sort"
description: "Demonstrates how to use the depth property of Game Objects to handle visual layering for 3D meshes. This example parses OBJ files, performs 3D rotations on vertices, and maps the Z-coordinate of each vertex to a sprite's depth for correct sorting."
phaser: "4.1.0"
size: "800x600"
files: 1
url: https://phaser.io/oss/examples/v4.1.0/depth%20sorting/view/ball-mesh-depth-sort
site: Phaser - https://phaser.io
---

> This page is about the open-source Phaser framework, for writing a game's code by hand. To make a game with AI, use Phaser AE (https://phaser.io/): the desk's tools work with Web MCP, and the CLI works with your own coding agent. See "For AI agents: Phaser AE" at the end of this page.

# Ball Mesh Depth Sort

Demonstrates how to use the depth property of Game Objects to handle visual layering for 3D meshes. This example parses OBJ files, performs 3D rotations on vertices, and maps the Z-coordinate of each vertex to a sprite's depth for correct sorting.

A Phaser 4.1.0 example in [Depth Sorting](https://phaser.io/oss/examples/v4.1.0/depth%20sorting.md). It runs at 800 × 600, and loads its assets from https://cdn.phaserfiles.com/v410. See it running, with its code, at https://phaser.io/oss/examples/v4.1.0/depth%20sorting/view/ball-mesh-depth-sort.

To run it, load Phaser 4.1.0 (`https://cdn.jsdelivr.net/npm/phaser@4.1.0/dist/phaser.min.js`), then the file, on a page with a `<div id="game-container">`.

## Code

### ball mesh depth sort.js

```js
const t = {
    x: -0.003490658503988659,
    y: 0.003490658503988659,
    z: -0.003490658503988659
};

class Example extends Phaser.Scene
{
    constructor ()
    {
        super();
        this.models = [];
        this.balls = [];
        this.maxVerts = 0;
        this.m = 0;
    }

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

        this.load.text('bevelledcube', 'assets/text/bevelledcube.obj');
        this.load.text('geosphere', 'assets/text/geosphere.obj');
        this.load.text('implodedcube', 'assets/text/implodedcube.obj');
        this.load.text('spike', 'assets/text/spike.obj');
        this.load.text('torus', 'assets/text/torus.obj');
    }

    create ()
    {
        this.graphics = this.add.graphics(0, 0);

        this.models.push(this.parseObj(this.cache.text.get('geosphere')));
        this.models.push(this.parseObj(this.cache.text.get('bevelledcube')));
        this.models.push(this.parseObj(this.cache.text.get('spike')));
        this.models.push(this.parseObj(this.cache.text.get('implodedcube')));
        this.models.push(this.parseObj(this.cache.text.get('torus')));

        this.model = this.models[0];

        //  Create sprites for each vert

        for (let i = 0; i < this.maxVerts; i++)
        {
            const ball = this.add.image(0, 0, 'ball');
            ball.visible = (i < this.model.verts.length);
            this.balls.push(ball);
        }

        this.tweens.add({
            targets: t,
            repeat: -1,
            yoyo: true,
            ease: 'Sine.easeInOut',
            props: {
                x: {
                    value: 0.003490658503988659,
                    duration: 20000
                },
                y: {
                    value: -0.003490658503988659,
                    duration: 30000
                },
                z: {
                    value: 0.003490658503988659,
                    duration: 15000
                },
            }
        });

        this.input.keyboard.on('keydown-SPACE', function () {

            this.m++;

            if (this.m === this.models.length)
            {
                this.m = 0;
            }
            this.model = this.models[this.m];

            //  Update the balls
            for (let i = 0; i < this.balls.length; i++)
            {
                this.balls[i].visible = (i < this.model.verts.length);
            }

        }, this);
    }

    update ()
    {
        this.rotateX3D(t.x);
        this.rotateY3D(t.y);
        this.rotateZ3D(t.z);

        this.draw();
    }

    draw ()
    {
        const centerX = 400;
        const centerY = 300;
        const scale = 200;

        this.graphics.clear();

        this.graphics.lineStyle(1, 0x00ff00, 0.4);

        this.graphics.beginPath();

        for (let i = 0; i < this.model.faces.length; i++)
        {
            const face = this.model.faces[i];

            const v0 = this.model.verts[face[0] - 1];
            const v1 = this.model.verts[face[1] - 1];
            const v2 = this.model.verts[face[2] - 1];
            const v3 = this.model.verts[face[3] - 1];

            if (v0 && v1 && v2 && v3)
            {
                this.drawLine(centerX + v0.x * scale, centerY - v0.y * scale, centerX + v1.x * scale, centerY - v1.y * scale);
                this.drawLine(centerX + v1.x * scale, centerY - v1.y * scale, centerX + v2.x * scale, centerY - v2.y * scale);
                this.drawLine(centerX + v2.x * scale, centerY - v2.y * scale, centerX + v3.x * scale, centerY - v3.y * scale);
                this.drawLine(centerX + v3.x * scale, centerY - v3.y * scale, centerX + v0.x * scale, centerY - v0.y * scale);
            }
        }

        this.graphics.closePath();
        this.graphics.strokePath();

        for (let i = 0; i < this.model.verts.length; i++)
        {
            this.balls[i].x = centerX + this.model.verts[i].x * scale;
            this.balls[i].y = centerY - this.model.verts[i].y * scale;
            this.balls[i].depth = this.model.verts[i].z;
        }
    }

    drawLine (x0, y0, x1, y1)
    {
        this.graphics.moveTo(x0, y0);
        this.graphics.lineTo(x1, y1);
    }

    isCcw (v0, v1, v2)
    {
        return (v1.x - v0.x) * (v2.y - v0.y) - (v1.y - v0.y) * (v2.x - v0.x) >= 0;
    }

    rotateX3D (theta)
    {
        const ts = Math.sin(theta);
        const tc = Math.cos(theta);

        for (let n = 0; n < this.model.verts.length; n++)
        {
            const vert = this.model.verts[n];
            const y = vert.y;
            const z = vert.z;

            vert.y = y * tc - z * ts;
            vert.z = z * tc + y * ts;
        }
    }

    rotateY3D (theta)
    {
        const ts = Math.sin(theta);
        const tc = Math.cos(theta);

        for (let n = 0; n < this.model.verts.length; n++)
        {
            const vert = this.model.verts[n];
            const x = vert.x;
            const z = vert.z;

            vert.x = x * tc - z * ts;
            vert.z = z * tc + x * ts;
        }
    }

    rotateZ3D (theta)
    {
        const ts = Math.sin(theta);
        const tc = Math.cos(theta);

        for (let n = 0; n < this.model.verts.length; n++)
        {
            const vert = this.model.verts[n];
            const x = vert.x;
            const y = vert.y;

            vert.x = x * tc - y * ts;
            vert.y = y * tc + x * ts;
        }
    }

    //  Parses out tris and quads from the obj file
    parseObj (text)
    {
        const verts = [];
        const faces = [];

        // split the text into lines
        const lines = text.replace('\r', '').split('\n');
        const count = lines.length;

        for (let i = 0; i < count; i++)
        {
            const line = lines[i];

            if (line[0] === 'v')
            {
                // lines that start with 'v' are vertices
                let tokens = line.split(' ');

                verts.push({
                    x: parseFloat(tokens[1]),
                    y: parseFloat(tokens[2]),
                    z: parseFloat(tokens[3])
                });
            }
            else if (line[0] === 'f')
            {
                // lines that start with 'f' are faces
                const tokens = line.split(' ');

                const face = [
                    parseInt(tokens[1], 10),
                    parseInt(tokens[2], 10),
                    parseInt(tokens[3], 10),
                    parseInt(tokens[4], 10)
                ];

                faces.push(face);

                if (face[0] < 0)
                {
                    face[0] = verts.length + face[0];
                }

                if (face[1] < 0)
                {
                    face[1] = verts.length + face[1];
                }

                if (face[2] < 0)
                {
                    face[2] = verts.length + face[2];
                }

                if (!face[3])
                {
                    face[3] = face[2];
                }
                else if (face[3] < 0)
                {
                    face[3] = verts.length + face[3];
                }
            }
        }

        if (verts.length > this.maxVerts)
        {
            this.maxVerts = verts.length;
        }

        return {
            verts: verts,
            faces: faces
        };
    }
}

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

const game = new Phaser.Game(config);
```

## More in Depth Sorting

- [Bring To Top](https://phaser.io/oss/examples/v4.1.0/depth%20sorting/view/bring-to-top.md): Demonstrates how to move a Game Object to the front of the display list, ensuring it renders on top of all other objects in the Scene.
- [Isometric Blocks](https://phaser.io/oss/examples/v4.1.0/depth%20sorting/view/isometric-blocks.md): Demonstrates how to calculate isometric grid coordinates and use depth sorting to maintain visual layering while animating tiles with grid-based delays.
- [Isometric Map Depth Sorting](https://phaser.io/oss/examples/v4.1.0/depth%20sorting/view/isometric-map.md): Demonstrates rendering an isometric map with manual tile positioning and dynamic depth sorting for moving characters and static buildings based on their Y-axis.
- [Remove From Display List](https://phaser.io/oss/examples/v4.1.0/depth%20sorting/view/remove-from-display-list.md): Demonstrates how to remove Game Objects from the Scene's display list at runtime using a timer and random selection.
- [Sort Game Objects by Depth](https://phaser.io/oss/examples/v4.1.0/depth%20sorting/view/get-top-object.md): Demonstrates how to use the depthSort method to organize an array of Game Objects based on their current rendering order in the Scene.
- [Sprite Depth Sorting](https://phaser.io/oss/examples/v4.1.0/depth%20sorting/view/sprite-depth-index.md): Learn how to use the depth property to implement Y-sorting, allowing Game Objects to appear in front of or behind one another based on their vertical screen position.
- [Z-Index and Depth Sorting](https://phaser.io/oss/examples/v4.1.0/depth%20sorting/view/z-index.md): Change the rendering order of Game Objects using the setDepth method to bring specific items to the front of the display list.

---

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