# Threejs Postprocessing

> Addon screen-space post-processing for three.js using EffectComposer, Pass base class, RenderPass, and stock passes such as UnrealBloomPass, SSAOPass, SSRPass, BokehPass, OutlinePass, FXAAPass/SMAAPass, TAARenderPass, and ShaderPass; references the Shaders addon group for underlying shader modules; contrasts with core PostProcessing class used in node/WebGPU stacks (see threejs-node-tsl and threejs-renderers). Use when building composer chains—not for basic renderer tone mapping alone (threejs-renderers).

- Skill: `full-stack-skills/threejs-postprocessing` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add full-stack-skills/threejs-postprocessing`
- Raw SKILL.md: https://api.skillmd.com/api/skills/full-stack-skills/threejs-postprocessing/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: full-stack-skills (https://skillmd.com/u/full-stack-skills)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/full-stack-skills/threejs-postprocessing

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## When to use this skill

**ALWAYS use this skill when the user mentions:**

- `EffectComposer`, `RenderPass`, stacking passes, resize of composer
- Bloom, SSAO, SSR, DOF, outline, glitch, film grain, TAA—**addon** pass names
- `ShaderPass` with shader modules from Addons **Shaders** group

**IMPORTANT: postprocessing vs renderers vs node-tsl**

| Pipeline | Skill |
|----------|--------|
| Classic composer + passes | **threejs-postprocessing** |
| Renderer output color/tone only | **threejs-renderers** |
| Node/TSL post nodes | **threejs-node-tsl** |

**Trigger phrases include:**

- "EffectComposer", "RenderPass", "UnrealBloomPass", "SSAOPass", "后期"
- "泛光", "环境光遮蔽", "描边"

## How to use this skill

1. **Chain**: `RenderPass` → effect passes → output; ensure size matches renderer and DPR changes.
2. **Resize**: call `composer.setSize` alongside renderer resize workflows.
3. **Half-float**: many passes expect appropriate render target types—cite docs for your version.
4. **Performance**: each pass has cost—profile with `renderer.info` sparingly.
5. **Shader modules**: link Addons **Shaders** list instead of inlining huge GLSL in SKILL.
6. **Output**: final pass should align color management with renderer (**threejs-renderers**).
7. **Contrast**: mention core `PostProcessing` class separately to avoid name collision confusion.

See [examples/workflow-composer-bloom.md](examples/workflow-composer-bloom.md).

## Doc map (official)

| Docs section | Representative links |
|--------------|----------------------|
| Postprocessing | https://threejs.org/docs/EffectComposer.html |
| Postprocessing | https://threejs.org/docs/RenderPass.html |
| Postprocessing | https://threejs.org/docs/UnrealBloomPass.html |
| Shaders (addon modules) | https://threejs.org/docs/module-CopyShader.html |

## Scope

- **In scope:** Addon postprocessing passes and composer wiring; pointers to shader modules.
- **Out of scope:** Custom full-screen pipeline design outside three docs; engine-level frame graphs.

## Common pitfalls and best practices

- Forgetting composer resize produces smeared or low-res effects.
- Pass order matters—bloom often after main scene pass, outline may need masks.
- Some passes need depth—ensure depth buffer availability per pass docs.

## Documentation and version

Addon passes live under [Postprocessing](https://threejs.org/docs/#Postprocessing) and **Shaders** modules in [three.js docs](https://threejs.org/docs/). Pass constructors and required buffers change across versions—link the specific pass page (e.g. `UnrealBloomPass`) rather than guessing uniform names.

## Agent response checklist

When answering under this skill, prefer responses that:

1. Link `EffectComposer`, `RenderPass`, or the named pass (`SSAOPass`, …).
2. Contrast **addon** composer stack with core `PostProcessing` + **threejs-node-tsl** when users mix terms.
3. Require `setSize` on composer when **threejs-renderers** resizes.
4. Point to **Shaders** group for raw shader modules used by `ShaderPass`.
5. Warn about VR frame-time when stacking heavy passes (**threejs-webxr**).

## References

- https://threejs.org/docs/#Postprocessing
- https://threejs.org/docs/EffectComposer.html
- https://threejs.org/docs/RenderPass.html

## Keywords

**English:** effectcomposer, renderpass, bloom, ssao, ssr, outline, postprocessing, three.js

**中文：** 后期、EffectComposer、泛光、SSAO、SSR、屏幕空间、three.js

## 能力边界

### ✅ 适用场景
- 当你需要使用此技能对应的技术栈时
- 当项目需要遵循最佳实践时
- 当需要快速上手或深入理解核心概念时

### ⚠️ 需要注意
- 复杂业务逻辑需要结合具体场景调整
- 性能优化需要根据实际数据量评估

### ❌ 不适用场景
- 不相关的技术栈或框架
- 需要完全自定义的特殊场景

## 常见陷阱 (Gotchas)

1. **版本兼容性**：注意框架版本与依赖库的兼容性，不同版本 API 可能有差异
2. **配置文件格式**：配置文件格式错误是最常见的问题，建议使用编辑器的语法检查
3. **环境变量**：确保所有必要的环境变量已正确设置，敏感信息不要硬编码
4. **依赖冲突**：多版本共存时注意依赖冲突，使用 lock 文件锁定版本
5. **性能陷阱**：大数据量场景下注意性能优化，避免 N+1 查询等常见问题

## 使用流程

### Step 1: 环境准备
确保开发环境已安装必要的依赖和工具。

### Step 2: 配置初始化
根据项目需求进行基础配置。

### Step 3: 核心功能使用
按照示例代码实现核心功能。

### Step 4: 测试验证
运行测试确保功能正常。

### Step 5: 部署上线
完成开发后进行部署和监控。