---
title: "Perlin Noise Custom Shader Displacement"
description: "Demonstrates how to inject custom GLSL code into a shader using shader additions to generate Perlin noise. The resulting shader is rendered to a texture and applied as a real-time displacement filter to an image."
phaser: "4.1.0"
size: "1280x720"
files: 1
url: https://phaser.io/oss/examples/v4.1.0/game%20objects/shader/view/custom-shader-perlin-noise
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.

# Perlin Noise Custom Shader Displacement

Demonstrates how to inject custom GLSL code into a shader using shader additions to generate Perlin noise. The resulting shader is rendered to a texture and applied as a real-time displacement filter to an image.

A Phaser 4.1.0 example in [Game Objects / Shader](https://phaser.io/oss/examples/v4.1.0/game%20objects/shader.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/game%20objects/shader/view/custom-shader-perlin-noise.

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 shader perlin noise.js

```js
const perlinNoiseFunction = `
// Assign this snippet to \`fragmentHeader\` in the shader config.
// This places it above the \`main\` function in the fragment shader.

// We declare this here so it can be used in the fragment process.
uniform float time;

vec2 rand2 (vec2 co) {
    co = vec2(dot(co, vec2(127.1, 311.7)), dot(co, vec2(269.5, 183.3)));
    return fract(sin(co) * 43758.5453);
}

float perlinNoise (vec2 uv)
{
    vec2 i = floor(uv);
    vec2 f = fract(uv);
    return mix(mix(dot(rand2(i + vec2(0.0, 0.0)), f - vec2(0.0, 0.0)),
                dot(rand2(i + vec2(1.0, 0.0)), f - vec2(1.0, 0.0)), f.x),
            mix(dot(rand2(i + vec2(0.0, 1.0)), f - vec2(0.0, 1.0)),
                dot(rand2(i + vec2(1.0, 1.0)), f - vec2(1.0, 1.0)), f.x), f.y) * 0.5 + 0.5;
}
`;

const waveProcess = `
// Assign this snippet to \`fragmentProcess\` in the shader config.
// This places it within the \`main\` function in the fragment shader.
// The \`fragColor\` variable is defined above this, and output below this.

// Direct the noise down the screen.
vec2 timeOffset = vec2(0.0, time);

// Base frequency, to match screen aspect ratio of this example.
// Change this or set it as a uniform to match your game.
vec2 frequency = vec2(16, 9);

// Accumulate noise from three different frequencies.
float noise0 = perlinNoise(outTexCoord * frequency * 3.0 + timeOffset * 2.0);
float noise1 = perlinNoise(outTexCoord * frequency * 5.0 + timeOffset / 1.345);
float noise2 = perlinNoise(outTexCoord * frequency * 7.0 + timeOffset / 2.1);
float sum = noise0 * 0.5 + noise1 * 0.3 + noise2 * 0.2;

// Round the sum up to 0.5 if below, to create flat areas.
sum = max(sum, 0.5);

fragColor = vec4(vec3(sum), 1.0);
`;

class Example extends Phaser.Scene
{
    constructor()
    {
        super();
    }

    preload()
    {
        this.load.setBaseURL('https://cdn.phaserfiles.com/v410');
        this.load.image('bg', 'assets/pics/purple-bars.jpg');
    }

    create()
    {
        const shaderConfig = {
            name: 'Noise',
            // By omitting `fragmentSource`, the default fragment shader is used.
            // It has template points for accepting additions.
            shaderAdditions: [
                {
                    name: 'PerlinNoise',
                    additions: {
                        fragmentHeader: perlinNoiseFunction,
                        fragmentProcess: waveProcess
                    }
                }
            ],
            setupUniforms: (setUniform, drawingContext) => {
                // Don't let time grow too large, or it will lose precision.
                setUniform('time', (this.game.loop.time % 1000000) / 500);
            }
        };

        const shader = this.add.shader(shaderConfig, 640, 360, 1280, 720);
        shader.setRenderToTexture('ooze');

        const bg = this.add.image(640, 360, 'bg')
            .enableFilters()
            .setDisplaySize(1280, 720);

        bg.filters.internal.addDisplacement('ooze', 0, 0.5);
    }
}

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

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

## More in Shader

- [Custom Shader Texture Coordinates](https://phaser.io/oss/examples/v4.1.0/game%20objects/shader/view/custom-shader-texture-coordinates.md): Demonstrates how to apply a custom shader to a specific frame from a texture atlas using setTextureCoordinatesFromFrame and building shaders using modular additions.
- [Gradient Circle Wipe Mask](https://phaser.io/oss/examples/v4.1.0/game%20objects/shader/view/gradient-circle-wipe.md): Demonstrates creating a radial transition between two images by using a dynamic shader as a mask, with the circle's radius controlled by the distance of the pointer from the center.
- [Gradient Linear Wipe Mask](https://phaser.io/oss/examples/v4.1.0/game%20objects/shader/view/gradient-linear-wipe.md): Demonstrates how to use a shader-generated linear gradient as a dynamic mask to create a smooth transition between two images controlled by the pointer.
- [Gradient Ripple Reflection](https://phaser.io/oss/examples/v4.1.0/game%20objects/shader/view/gradient-ripples.md): Demonstrates how to use a procedurally generated gradient shader as a displacement map to create a dynamic water ripple effect on a reflected scene.
- [Gradient Shine](https://phaser.io/oss/examples/v4.1.0/game%20objects/shader/view/gradient-shine.md): Create an animated gradient shine effect by combining modular shader additions with normal map displacement and additive blending.
- [Linear Gradient Shader](https://phaser.io/oss/examples/v4.1.0/game%20objects/shader/view/gradient-linear.md): Demonstrates creating a linear gradient using the Shader Game Object by composing multiple GLSL fragments and configuring uniforms for positions, colors, and step counts.
- [Random Noise Shader Additions](https://phaser.io/oss/examples/v4.1.0/game%20objects/shader/view/custom-shader-random-noise.md): Demonstrates how to use the shaderAdditions property to inject custom GLSL code into the default fragment shader, creating dynamic noise effects with time-based uniforms.
- [Shader Bilinear Gradient Displacement](https://phaser.io/oss/examples/v4.1.0/game%20objects/shader/view/gradient-bilinear.md): Create complex background effects by combining modular shader additions, render-to-texture, and displacement filters using bilinear and linear gradients.

---

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