---
title: "Creating a Custom Shader Filter"
description: "Demonstrates how to create and apply a custom WebGL filter by defining a fragment shader, a Filter Controller, and a RenderNode to convert a bump map into a normal map in real-time."
phaser: "4.1.0"
size: "1280x720"
files: 1
url: https://phaser.io/oss/examples/v4.1.0/filters/view/custom-filter
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.

# Creating a Custom Shader Filter

Demonstrates how to create and apply a custom WebGL filter by defining a fragment shader, a Filter Controller, and a RenderNode to convert a bump map into a normal map in real-time.

A Phaser 4.1.0 example in [Filters](https://phaser.io/oss/examples/v4.1.0/filters.md). It runs at 1280 × 720, 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/filters/view/custom-filter.

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

### custom filter.js

```js
// Define custom filter.

// This custom filter is a simple example of a filter that converts a bump map to a normal map.
// The filter is defined in two parts: a Controller and a RenderNode.

// The Controller is the main interface for the filter.
class BumpToNormal extends Phaser.Filters.Controller
{
    constructor (camera)
    {
        // The name 'FilterBumpToNormal' is defined in FilterBumpToNormal.
        super(camera, 'FilterBumpToNormal');

        // Properties on the controller are used to pass data to the shader.
        this.radius = 1;
    }
}

// The fragment shader for the filter.
const fragmentShaderBumpToNormal =
`
// BUMP_TO_NORMAL_FS
#pragma phaserTemplate(shaderName)

precision mediump float;

uniform sampler2D uMainSampler;

uniform vec2 resolution;
uniform float radius;

varying vec2 outTexCoord;

void main ()
{
    // Sample neighboring texels.
    vec2 texelSize = radius / resolution;
    vec4 center = texture2D(uMainSampler, outTexCoord);
    vec4 right = texture2D(uMainSampler, outTexCoord + vec2(texelSize.x, 0.0));
    vec4 left = texture2D(uMainSampler, outTexCoord - vec2(texelSize.x, 0.0));
    vec4 top = texture2D(uMainSampler, outTexCoord + vec2(0.0, texelSize.y));
    vec4 bottom = texture2D(uMainSampler, outTexCoord - vec2(0.0, texelSize.y));

    // Calculate the normal.
    float dx = (left.r + left.g + left.b) - (right.r + right.g + right.b);
    float dy = (top.r + top.g + top.b) - (bottom.r + bottom.g + bottom.b);
    vec3 normal = normalize(vec3(dx, dy, 1.0));

    // Convert the normal to color.
    vec4 color = vec4(normal * 0.5 + 0.5, center.a);

    gl_FragColor = color;
}
`;

// This RenderNode is required for rendering the custom filter.
class FilterBumpToNormal extends Phaser.Renderer.WebGL.RenderNodes.BaseFilterShader
{
    constructor (manager)
    {
        // The name 'FilterBumpToNormal' is used by the Controller.
        super('FilterBumpToNormal', manager, null, fragmentShaderBumpToNormal);
    }

    // This method sets up the uniforms for the shader.
    setupUniforms (controller, drawingContext)
    {
        const programManager = this.programManager;

        programManager.setUniform('resolution', [ drawingContext.width, drawingContext.height ]);
        programManager.setUniform('radius', controller.radius);
    }
}

// End custom filter definition.


class Example extends Phaser.Scene
{
    preload ()
    {
        this.load.setBaseURL('https://cdn.phaserfiles.com/v410');
        this.load.image('distortion8', 'assets/textures/distortion8.png');
    }

    create ()
    {
        if (!this.renderer.renderNodes.hasNode('FilterBumpToNormal'))
        {
            // Load the custom filter.
            // We load during scene creation because the renderer has booted by this point.
            this.renderer.renderNodes.addNodeConstructor('FilterBumpToNormal', FilterBumpToNormal);
        }

        // Add an unfiltered image.
        this.add.image(0, 360, 'distortion8')
        .setOrigin(0, 0.5);

        // Add an image for filtering.
        const image = this.add.image(1280, 360, 'distortion8')
        .setOrigin(1, 0.5)
        .enableFilters();
        const blur = image.filters.internal.addBlur();
        blur.strength = 2;

        // Add custom filter to the image.
        // Note that the filter requires a camera to be passed to it.
        const bumpToNormal = image.filters.internal.add(
            new BumpToNormal(image.filterCamera)
        );
        bumpToNormal.radius = 8;

        // Tween the blur strength.
        this.tweens.add({
            targets: blur,
            strength: 0,
            duration: 2000,
            yoyo: true,
            repeat: -1
        });
    }
}

const config = {
    scale: { mode: Phaser.Scale.FIT },
    type: Phaser.AUTO,
    width: 1280,
    height: 720,
    backgroundColor: '#000000',
    parent: 'game-container',
    scene: Example
};

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

## More in Filters

- [Additive Blend Highlighting](https://phaser.io/oss/examples/v4.1.0/filters/blend/view/blend-add-highlight-object.md): Demonstrates creating glow and highlight effects by applying additive blend filters to Render Textures, including color channel manipulation and tweening filter intensity.
- [Blocky Pixel Filter](https://phaser.io/oss/examples/v4.1.0/filters/blocky/view/blocky-pixels.md): Demonstrates applying a pixelation effect to the camera using the Blocky filter, including how to toggle the effect active state via user input.
- [Bloom Filter Impact Effect](https://phaser.io/oss/examples/v4.1.0/filters/bloom/view/destroy-planet-bloom-filter.md): Demonstrates how to apply and animate a bloom filter on game objects. When a bullet hits the planet, a tween increases the bloom's blur strength to create a glowing impact visual.
- [Bloom with Parallel Filters](https://phaser.io/oss/examples/v4.1.0/filters/parallel%20filters/view/bloom-with-parallel-filters.md): Demonstrates how to create a custom bloom effect by processing a camera through parallel filter tracks, applying threshold and blur filters to one track, and blending it back using additive blending.
- [Combine Color Matrix Alpha Transfer](https://phaser.io/oss/examples/v4.1.0/filters/combine%20color%20matrix/view/combine-color-matrix.md): Demonstrates how to use the Combine Color Matrix filter to map the brightness data of one texture onto the alpha channel of another, including how to invert the resulting alpha.
- [Container Composite Alpha](https://phaser.io/oss/examples/v4.1.0/filters/view/composite-alpha-demo.md): Demonstrates the difference between standard alpha and composite alpha in containers. Setting 'filtersForceComposite' ensures a container renders as a flattened layer, preventing overlapping child elements from showing through each other.
- [Custom Filter with Secondary Texture Input](https://phaser.io/oss/examples/v4.1.0/filters/view/custom-filter-with-image-input.md): This example demonstrates how to create a multi-pass custom filter that uses a secondary image as a strength map to selectively control blur intensity across a Game Object.
- [Custom Shine Filter](https://phaser.io/oss/examples/v4.1.0/filters/view/custom-shine-filter.md): Learn how to apply a custom external shine filter effect to a Game Object using a specialized render node controller.
- [Custom Shine Filter with Progress Control](https://phaser.io/oss/examples/v4.1.0/filters/view/custom-shine-filter-with-progress-control.md): Demonstrates applying a custom shine filter to an image and manually controlling its animation progress using a tween.
- [Filter Sampler](https://phaser.io/oss/examples/v4.1.0/filters/sampler/view/sampler.md): Demonstrates how to use the Sampler filter to retrieve color data from a specific pixel coordinate on an image, using the result to update the game background color.
- [Panorama Blur Filter](https://phaser.io/oss/examples/v4.1.0/filters/panorama%20blur/view/panorama-blur.md): Use the Panorama Blur filter to pre-render blurred environment maps and apply them to normal-mapped sprites via the Image Light filter.
- [Sprite Filter Auto-Focus](https://phaser.io/oss/examples/v4.1.0/filters/view/auto-focus-filter-demo.md): Demonstrates how filters automatically adapt to transformed Game Objects. This example applies color shifts and dynamic motion blur to multiple rotating and moving sprites.
- [All 14 examples in Filters](https://phaser.io/oss/examples/v4.1.0/filters.md)

---

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