threejs-lights

## When to use this skill **ALWAYS use this skill when the user mentions:** - Enabling `castShadow` / `receiveShadow`, shadow map size, bias, normal bias, camera frusta for shadow casters - Physical lights: intensity, distance/decay, angle/penumbra for spots, rect area setup - `LightProbe` for irradiance-style probes; `IESSpotLight` with IES data **IMPORTANT: lights vs loaders vs node-tsl** | Topic | Skill | |-------|--------| | Light classes and shadows | **threejs-lights** | | Loading IES/HDR files | **threejs-loaders** | | LightNode / TSL lighting | **threejs-node-tsl** | **Trigger phrases include:** - "DirectionalLight", "SpotLight", "RectAreaLight", "castShadow", "shadow map" - "阴影", "点光源", "面光源", "LightProbe" ## How to use this skill 1. **Base recipe**: ambient/hemisphere fill + directional sun + local points/spots. 2. **Shadows**: enable on renderer, mark casters/receivers, tune map size vs performance, adjust bias to remove acne/peter-panning. 3. **RectArea**: initialize addon libs per docs page before using light type. 4. **Probes**: place probes; generate data via addon generator when applicable; relate to materials env reflections (**threejs-materials**, **threejs-textures**). 5. **IES**: load profile via loader skill, attach to `IESSpotLight` per docs. 6. **Performance**: limit shadow-casting lights; use layers (**threejs-objects**) to exclude objects. See [examples/workflow-directional-shadow.md](examples/workflow-directional-shadow.md). ## Doc map (official) | Docs section | Representative links | |--------------|----------------------| | Lights | https://threejs.org/docs/Light.html | | Directional | https://threejs.org/docs/DirectionalLight.html | | Spot | https://threejs.org/docs/SpotLight.html | | Rect area | https://threejs.org/docs/RectAreaLight.html | ## Scope - **In scope:** Core lights, shadow maps, probes, listed addons for rect area and probe generation. - **Out of scope:** CSM deep theory (see addon Csm docs if user names it); baked lightmaps in DCC. ## Common pitfalls and best practices - Shadow map resolution must match scene scale—tiny shadows on huge worlds look blocky. - Point light shadows are six-face expensive—use wisely. - `RectAreaLight` without required libs yields black or wrong shading—verify init. - Mismatched physical units (intensity vs exposure) with **threejs-renderers** tone mapping causes blown or dim scenes. - Shadow **bias** / **normalBias** trade-offs: acne vs peter-paning—tune with helper frusta (**threejs-helpers**). ## Documentation and version Light and shadow classes live under [Lights](https://threejs.org/docs/#Lights) in [three.js docs](https://threejs.org/docs/). `RectAreaLight` and probe addons depend on extra init from **Addons → Lights**; IES profiles require **threejs-loaders** for file fetch before the light API is usable. ## Agent response checklist When answering under this skill, prefer responses that: 1. Link the concrete light type (`DirectionalLight`, `SpotLight`, …) and shadow pages when shadows are on. 2. Separate **IES loading** to **threejs-loaders** and **LightNode** topics to **threejs-node-tsl**. 3. Give practical shadow map size / bias guidance with **threejs-helpers** for frustum visualization. 4. Mention `renderer.shadowMap.enabled` alongside light `castShadow` (see **threejs-renderers**). 5. Note performance cost of multiple shadow-casting lights. ## References - https://threejs.org/docs/#Lights - https://threejs.org/docs/DirectionalLight.html - https://threejs.org/docs/SpotLight.html - https://threejs.org/docs/LightShadow.html ## Keywords **English:** lights, shadows, directional, spotlight, rectarea, lightprobe, three.js **中文：** 灯光、阴影、平行光、聚光灯、面光源、LightProbe、three.js