What is post-processing in Three.js?

Post-processing refers to the technique of applying effects to a rendered scene after it has been drawn to the screen. This can include effects like bloom, depth of field, and color correction, which enhance the visual quality of the scene.

How do I set up the EffectComposer?

To set up the EffectComposer, you first create an instance of it with your renderer, then add passes for rendering the scene and any additional effects you want to apply. The final pass should render to the screen.

Can I adjust effect parameters at runtime?

Yes, many effect parameters can be adjusted at runtime, allowing for dynamic changes based on user input or other conditions in your application.

What types of effects can I use with this skill?

This skill supports a variety of effects including bloom, depth of field, anti-aliasing (FXAA and SMAA), and ambient occlusion, among others.

Is this skill suitable for beginners?

While the skill is accessible, it is recommended for users with an intermediate understanding of Three.js, as it requires familiarity with rendering concepts and the Three.js library.

Three.js Post-Processing

Name: Three.js Post-Processing
Availability: InStock
Author: calesthio

Free

Enhance your 3D scenes with advanced visual effects.

by calesthio46.8k stars on calesthio/openmontage

2 views

Updated Aug 3, 2026

Get this skill

Free · Opens the source repo

What Three.js Post-Processing does

The Three.js Post-Processing skill provides a comprehensive framework for adding visual effects to your WebGL scenes using Three.js. By utilizing the EffectComposer, developers can layer various post-processing effects such as bloom, depth of field, and anti-aliasing to create stunning visuals. This skill is particularly useful for developers looking to enhance the aesthetic quality of their 3D applications, whether for games, simulations, or interactive visualizations.

At its core, the skill leverages the EffectComposer to manage multiple rendering passes. Each pass can apply different effects, allowing for complex visual compositions. For example, you can add a bloom effect to create a glowing look for bright areas, or implement depth of field to simulate camera focus effects. The skill also includes support for anti-aliasing techniques like FXAA and SMAA, which help to smooth out jagged edges in rendered images, improving overall visual fidelity.

The implementation is straightforward, with clear examples provided for common effects. Developers can easily integrate these effects into their existing Three.js projects. The skill also allows for runtime adjustments to effect parameters, enabling dynamic visual changes based on user interactions or scene conditions. This flexibility makes it suitable for a wide range of applications, from static visualizations to interactive experiences.

This skill is ideal for developers and designers who are already familiar with Three.js and want to enhance their projects with professional-grade visual effects. It streamlines the process of adding complex visual features without requiring deep knowledge of shader programming or graphics techniques.

When to use it

Use this skill when you need to apply post-processing effects to your Three.js projects to improve visual quality and user experience.

When not to use it

This skill may not be suitable for projects that do not require visual enhancements or for developers unfamiliar with Three.js.

What you can build with it

Adding Bloom Effects

Use the UnrealBloomPass to create a glowing effect for bright areas in your scene, enhancing the overall visual impact.

Implementing Depth of Field

Utilize the BokehPass to simulate camera focus effects, allowing for a more realistic representation of depth in your 3D scenes.

Enhancing Image Quality with Anti-Aliasing

Incorporate FXAA or SMAA passes to smooth out jagged edges in your rendered images, improving the quality of your visuals.

How to install Three.js Post-Processing

View source

1. Install with the skills CLI

npx skills add calesthio/openmontage/threejs-postprocessing --agent claude-code

2. Or install it manually

Download the skill folder and drop it into ~/.claude/skills/ for all projects, or .claude/skills/ to scope it to one repo. Restart Claude Code so it picks up the new skill.

Anthropic's agentic coding CLI, and the reference implementation of Agent Skills. Drop a skill folder into ~/.claude/skills and Claude Code loads it automatically whenever a task matches the skill's description. Claude Code docs

Inside SKILL.md

Written by calesthio

Three.js Post-Processing

Quick Start

import * as THREE from "three";
import { EffectComposer } from "three/addons/postprocessing/EffectComposer.js";
import { RenderPass } from "three/addons/postprocessing/RenderPass.js";
import { UnrealBloomPass } from "three/addons/postprocessing/UnrealBloomPass.js";

// Setup composer
const composer = new EffectComposer(renderer);

// Render scene
const renderPass = new RenderPass(scene, camera);
composer.addPass(renderPass);

// Add bloom
const bloomPass = new UnrealBloomPass(
  new THREE.Vector2(window.innerWidth, window.innerHeight),
  1.5, // strength
  0.4, // radius
  0.85, // threshold
);
composer.addPass(bloomPass);

// Animation loop - use composer instead of renderer
function animate() {
  requestAnimationFrame(animate);
  composer.render(); // NOT renderer.render()
}

EffectComposer Setup

import { EffectComposer } from "three/addons/postprocessing/EffectComposer.js";
import { RenderPass } from "three/addons/postprocessing/RenderPass.js";

const composer = new EffectComposer(renderer);

// First pass: render scene
const renderPass = new RenderPass(scene, camera);
composer.addPass(renderPass);

// Add more passes...
composer.addPass(effectPass);

// Last pass should render to screen
effectPass.renderToScreen = true; // Default for last pass

// Handle resize
function onResize() {
  const width = window.innerWidth;
  const height = window.innerHeight;

  camera.aspect = width / height;
  camera.updateProjectionMatrix();

  renderer.setSize(width, height);
  composer.setSize(width, height);
}

Common Effects

Bloom (Glow)

import { UnrealBloomPass } from "three/addons/postprocessing/UnrealBloomPass.js";

const bloomPass = new UnrealBloomPass(
  new THREE.Vector2(window.innerWidth, window.innerHeight),
  1.5, // strength - intensity of glow
  0.4, // radius - spread of glow
  0.85, // threshold - brightness threshold
);

composer.addPass(bloomPass);

// Adjust at runtime
bloomPass.strength = 2.0;
bloomPass.threshold = 0.5;
bloomPass.radius = 0.8;

Selective Bloom

Apply bloom only to specific objects.

import { UnrealBloomPass } from "three/addons/postprocessing/UnrealBloomPass.js";
import { ShaderPass } from "three/addons/postprocessing/ShaderPass.js";

// Layer setup
const BLOOM_LAYER = 1;
const bloomLayer = new THREE.Layers();
bloomLayer.set(BLOOM_LAYER);

// Mark objects to bloom
glowingMesh.layers.enable(BLOOM_LAYER);

// Dark material for non-blooming objects
const darkMaterial = new THREE.MeshBasicMaterial({ color: 0x000000 });
const materials = {};

function darkenNonBloomed(obj) {
  if (obj.isMesh && !bloomLayer.test(obj.layers)) {
    materials[obj.uuid] = obj.material;
    obj.material = darkMaterial;
  }
}

function restoreMaterial(obj) {
  if (materials[obj.uuid]) {
    obj.material = materials[obj.uuid];
    delete materials[obj.uuid];
  }
}

// Custom render loop
function render() {
  // Render bloom pass
  scene.traverse(darkenNonBloomed);
  composer.render();
  scene.traverse(restoreMaterial);

  // Render final scene over bloom
  renderer.render(scene, camera);
}

FXAA (Anti-Aliasing)

import { ShaderPass } from "three/addons/postprocessing/ShaderPass.js";
import { FXAAShader } from "three/addons/shaders/FXAAShader.js";

const fxaaPass = new ShaderPass(FXAAShader);
fxaaPass.material.uniforms["resolution"].value.set(
  1 / window.innerWidth,
  1 / window.innerHeight,
);

composer.addPass(fxaaPass);

// Update on resize
function onResize() {
  fxaaPass.material.uniforms["resolution"].value.set(
    1 / window.innerWidth,
    1 / window.innerHeight,
  );
}

SMAA (Better Anti-Aliasing)

import { SMAAPass } from "three/addons/postprocessing/SMAAPass.js";

const smaaPass = new SMAAPass(
  window.innerWidth * renderer.getPixelRatio(),
  window.innerHeight * renderer.getPixelRatio(),
);

composer.addPass(smaaPass);

SSAO (Ambient Occlusion)

import { SSAOPass } from "three/addons/postprocessing/SSAOPass.js";

const ssaoPass = new SSAOPass(
  scene,
  camera,
  window.innerWidth,
  window.innerHeight,
);
ssaoPass.kernelRadius = 16;
ssaoPass.minDistance = 0.005;
ssaoPass.maxDistance = 0.1;

composer.addPass(ssaoPass);

// Output modes
ssaoPass.output = SSAOPass.OUTPUT.Default;
// SSAOPass.OUTPUT.Default - Final composited output
// SSAOPass.OUTPUT.SSAO - Just the AO
// SSAOPass.OUTPUT.Blur - Blurred AO
// SSAOPass.OUTPUT.Depth - Depth buffer
// SSAOPass.OUTPUT.Normal - Normal buffer

Depth of Field (DOF)

import { BokehPass } from "three/addons/postprocessing/BokehPass.js";

const bokehPass = new BokehPass(scene, camera, {
  focus: 10.0, // Focus distance
  aperture: 0.025, // Aperture (smaller = more DOF)
  maxblur: 0.01, // Max blur amount
});

composer.addPass(bokehPass);

// Update focus dynamically
bokehPass.uniforms["focus"].value = distanceToTarget;

Film Grain

import { FilmPass } from "three/addons/postprocessing/FilmPass.js";

const filmPass = new FilmPass(
  0.35, // noise intensity
  0.5, // scanline intensity
  648, // scanline count
  false, // grayscale
);

composer.addPass(filmPass);

Vignette

import { ShaderPass } from "three/addons/postprocessing/ShaderPass.js";
import { VignetteShader } from "three/addons/shaders/VignetteShader.js";

const vignettePass = new ShaderPass(VignetteShader);
vignettePass.uniforms["offset"].value = 1.0; // Vignette size
vignettePass.uniforms["darkness"].value = 1.0; // Vignette intensity

composer.addPass(vignettePass);

Color Correction

import { ShaderPass } from "three/addons/postprocessing/ShaderPass.js";
import { ColorCorrectionShader } from "three/addons/shaders/ColorCorrectionShader.js";

const colorPass = new ShaderPass(ColorCorrectionShader);
colorPass.uniforms["powRGB"].value = new THREE.Vector3(1.2, 1.2, 1.2); // Power
colorPass.uniforms["mulRGB"].value = new THREE.Vector3(1.0, 1.0, 1.0); // Multiply

composer.addPass(colorPass);

Gamma Correction

import { GammaCorrectionShader } from "three/addons/shaders/GammaCorrectionShader.js";

const gammaPass = new ShaderPass(GammaCorrectionShader);
composer.addPass(gammaPass);

Pixelation

import { RenderPixelatedPass } from "three/addons/postprocessing/RenderPixelatedPass.js";

const pixelPass = new RenderPixelatedPass(6, scene, camera); // 6 = pixel size

composer.addPass(pixelPass);

Glitch Effect

import { GlitchPass } from "three/addons/postprocessing/GlitchPass.js";

const glitchPass = new GlitchPass();
glitchPass.goWild = false; // Continuous glitching

composer.addPass(glitchPass);

Halftone

import { HalftonePass } from "three/addons/postprocessing/HalftonePass.js";

const halftonePass = new HalftonePass(window.innerWidth, window.innerHeight, {
  shape: 1, // 1 = dot, 2 = ellipse, 3 = line, 4 = square
  radius: 4, // Dot size
  rotateR: Math.PI / 12,
  rotateB: (Math.PI / 12) * 2,
  rotateG: (Math.PI / 12) * 3,
  scatter: 0,
  blending: 1,
  blendingMode: 1,
  greyscale: false,
});

composer.addPass(halftonePass);

Outline

import { OutlinePass } from "three/addons/postprocessing/OutlinePass.js";

const outlinePass = new OutlinePass(
  new THREE.Vector2(window.innerWidth, window.innerHeight),
  scene,
  camera,
);

outlinePass.edgeStrength = 3;
outlinePass.edgeGlow = 0;
outlinePass.edgeThickness = 1;
outlinePass.pulsePeriod = 0;
outlinePass.visibleEdgeColor.set(0xffffff);
outlinePass.hiddenEdgeColor.set(0x190a05);

// Select objects to outline
outlinePass.selectedObjects = [mesh1, mesh2];

composer.addPass(outlinePass);

Custom ShaderPass

Create your own post-processing effects.

import { ShaderPass } from "three/addons/postprocessing/ShaderPass.js";

const CustomShader = {
  uniforms: {
    tDiffuse: { value: null }, // Required: input texture
    time: { value: 0 },
    intensity: { value: 1.0 },
  },
  vertexShader: `
    varying vec2 vUv;

    void main() {
      vUv = uv;
      gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
    }
  `,
  fragmentShader: `
    uniform sampler2D tDiffuse;
    uniform float time;
    uniform float intensity;
    varying vec2 vUv;

    void main() {
      vec2 uv = vUv;

      // Wave distortion
      uv.x += sin(uv.y * 10.0 + time) * 0.01 * intensity;

      vec4 color = texture2D(tDiffuse, uv);
      gl_FragColor = color;
    }
  `,
};

const customPass = new ShaderPass(CustomShader);
composer.addPass(customPass);

// Update in animation loop
customPass.uniforms.time.value = clock.getElapsedTime();

Invert Colors Shader

const InvertShader = {
  uniforms: {
    tDiffuse: { value: null },
  },
  vertexShader: `
    varying vec2 vUv;
    void main() {
      vUv = uv;
      gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
    }
  `,
  fragmentShader: `
    uniform sampler2D tDiffuse;
    varying vec2 vUv;

    void main() {
      vec4 color = texture2D(tDiffuse, vUv);
      gl_FragColor = vec4(1.0 - color.rgb, color.a);
    }
  `,
};

Chromatic Aberration

const ChromaticAberrationShader = {
  uniforms: {
    tDiffuse: { value: null },
    amount: { value: 0.005 },
  },
  vertexShader: `
    varying vec2 vUv;
    void main() {
      vUv = uv;
      gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
    }
  `,
  fragmentShader: `
    uniform sampler2D tDiffuse;
    uniform float amount;
    varying vec2 vUv;

    void main() {
      vec2 dir = vUv - 0.5;
      float dist = length(dir);

      float r = texture2D(tDiffuse, vUv - dir * amount * dist).r;
      float g = texture2D(tDiffuse, vUv).g;
      float b = texture2D(tDiffuse, vUv + dir * amount * dist).b;

      gl_FragColor = vec4(r, g, b, 1.0);
    }
  `,
};

Combining Multiple Effects

import { EffectComposer } from "three/addons/postprocessing/EffectComposer.js";
import { RenderPass } from "three/addons/postprocessing/RenderPass.js";
import { UnrealBloomPass } from "three/addons/postprocessing/UnrealBloomPass.js";
import { ShaderPass } from "three/addons/postprocessing/ShaderPass.js";
import { FXAAShader } from "three/addons/shaders/FXAAShader.js";
import { VignetteShader } from "three/addons/shaders/VignetteShader.js";
import { GammaCorrectionShader } from "three/addons/shaders/GammaCorrectionShader.js";

const composer = new EffectComposer(renderer);

// 1. Render scene
composer.addPass(new RenderPass(scene, camera));

// 2. Bloom
const bloomPass = new UnrealBloomPass(
  new THREE.Vector2(window.innerWidth, window.innerHeight),
  0.5,
  0.4,
  0.85,
);
composer.addPass(bloomPass);

// 3. Vignette
const vignettePass = new ShaderPass(VignetteShader);
vignettePass.uniforms["offset"].value = 0.95;
vignettePass.uniforms["darkness"].value = 1.0;
composer.addPass(vignettePass);

// 4. Gamma correction
composer.addPass(new ShaderPass(GammaCorrectionShader));

// 5. Anti-aliasing (always last before output)
const fxaaPass = new ShaderPass(FXAAShader);
fxaaPass.uniforms["resolution"].value.set(
  1 / window.innerWidth,
  1 / window.innerHeight,
);
composer.addPass(fxaaPass);

Render to Texture

// Create render target
const renderTarget = new THREE.WebGLRenderTarget(512, 512);

// Render scene to target
renderer.setRenderTarget(renderTarget);
renderer.render(scene, camera);
renderer.setRenderTarget(null);

// Use texture
const texture = renderTarget.texture;
otherMaterial.map = texture;

Multi-Pass Rendering

// Multiple composers for different scenes/layers
const bgComposer = new EffectComposer(renderer);
bgComposer.addPass(new RenderPass(bgScene, camera));

const fgComposer = new EffectComposer(renderer);
fgComposer.addPass(new RenderPass(fgScene, camera));
fgComposer.addPass(bloomPass);

// Combine in render loop
function animate() {
  // Render background without clearing
  renderer.autoClear = false;
  renderer.clear();

  bgComposer.render();

  // Render foreground over it
  renderer.clearDepth();
  fgComposer.render();
}

WebGPU Post-Processing (Three.js r150+)

import { postProcessing } from "three/addons/nodes/Nodes.js";
import { pass, bloom, dof } from "three/addons/nodes/Nodes.js";

// Using node-based system
const scenePass = pass(scene, camera);
const bloomNode = bloom(scenePass, 0.5, 0.4, 0.85);

const postProcessing = new THREE.PostProcessing(renderer);
postProcessing.outputNode = bloomNode;

// Render
function animate() {
  postProcessing.render();
}

Performance Tips

Limit passes: Each pass adds a full-screen render
Lower resolution: Use smaller render targets for blur passes
Disable unused effects: Toggle passes on/off
Use FXAA over MSAA: Less expensive anti-aliasing
Profile with DevTools: Check GPU usage

// Disable pass
bloomPass.enabled = false;

// Reduce bloom resolution
const bloomPass = new UnrealBloomPass(
  new THREE.Vector2(window.innerWidth / 2, window.innerHeight / 2),
  strength,
  radius,
  threshold,
);

// Only apply effects in high-performance scenarios
const isMobile = /iPhone|iPad|Android/i.test(navigator.userAgent);
if (!isMobile) {
  composer.addPass(expensivePass);
}

Handle Resize

function onWindowResize() {
  const width = window.innerWidth;
  const height = window.innerHeight;
  const pixelRatio = renderer.getPixelRatio();

  camera.aspect = width / height;
  camera.updateProjectionMatrix();

  renderer.setSize(width, height);
  composer.setSize(width, height);

  // Update pass-specific resolutions
  if (fxaaPass) {
    fxaaPass.material.uniforms["resolution"].value.set(
      1 / (width * pixelRatio),
      1 / (height * pixelRatio),
    );
  }

  if (bloomPass) {
    bloomPass.resolution.set(width, height);
  }
}

window.addEventListener("resize", onWindowResize);

Frequently asked questions about Three.js Post-Processing

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Three.js Post-Processing

What Three.js Post-Processing does

When to use it

When not to use it

What you can build with it

Adding Bloom Effects

Implementing Depth of Field

Enhancing Image Quality with Anti-Aliasing

How to install Three.js Post-Processing

Inside SKILL.md

Three.js Post-Processing

Quick Start

EffectComposer Setup

Common Effects

Bloom (Glow)

Selective Bloom

FXAA (Anti-Aliasing)

SMAA (Better Anti-Aliasing)

SSAO (Ambient Occlusion)

Depth of Field (DOF)

Film Grain

Vignette

Color Correction

Gamma Correction

Pixelation

Glitch Effect

Halftone

Outline

Custom ShaderPass

Invert Colors Shader

Chromatic Aberration

Combining Multiple Effects

Render to Texture

Multi-Pass Rendering

WebGPU Post-Processing (Three.js r150+)

Performance Tips

Handle Resize

See Also

Frequently asked questions about Three.js Post-Processing

What is post-processing in Three.js?

How do I set up the EffectComposer?

Can I adjust effect parameters at runtime?

What types of effects can I use with this skill?

Is this skill suitable for beginners?

Similar skills