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threejs-postprocessing

Add glow, depth-based blur, color correction, and other finishing effects to Three.js scenes. Covers combining effects with EffectComposer, writing custom shaders for screen effects, handling window resizing, and adjusting rendering workload.

OriginalShow the original description

Three.js post-processing - EffectComposer, bloom, DOF, screen effects. Use when adding visual effects, color grading, blur, glow, or creating custom screen-space shaders.

calesthio/OpenMontage
See how to install

Good for

  • Adding glow to objects in a 3D scene
  • Adjusting background blur and scene colors
  • Highlighting selected objects with outlines
  • Creating custom screen distortion effects

Files included (1)

  • SKILL.md14.1 KB

SKILL.md (original)

Review the instructions the agent will receive before you install.

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

  1. Limit passes: Each pass adds a full-screen render
  2. Lower resolution: Use smaller render targets for blur passes
  3. Disable unused effects: Toggle passes on/off
  4. Use FXAA over MSAA: Less expensive anti-aliasing
  5. 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);

See Also

  • threejs-shaders - Custom shader development
  • threejs-textures - Render targets
  • threejs-fundamentals - Renderer setup

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