threejs-scenes

When to use this skill

ALWAYS use this skill when the user mentions:

• Scene as root, scene.background, environment or skyball setup at scene level
• Fog or FogExp2 parameters (near, far, color, density) and interaction with camera far plane
• Organizing render lists conceptually (children of scene)

IMPORTANT: scenes vs textures vs loaders

Concern	Skill
Scene + fog API	threejs-scenes
Texture sampling, PMREM generator usage	threejs-textures
Fetching HDR/glTF	threejs-loaders

Trigger phrases include:

• "Scene", "Fog", "FogExp2", "background", "雾"
• "场景根节点", "线性雾", "指数雾"

How to use this skill

1. Instantiate Scene and add lights/meshes/cameras as children per graph rules (threejs-objects).
2. Choose fog: linear Fog vs exponential FogExp2 for outdoor/horizon feel.
3. Tune fog near/far alongside camera far to avoid clipping artifacts.
4. Set scene.background to Color, Texture, or cube map per docs; env lighting still needs matching renderer/material settings.
5. When user wants IBL from HDR file, point to loaders → textures → materials pipeline explicitly.
6. Document that fog does not replace frustum culling for performance.

Example: Scene with fog and background

import * as THREE from 'three';

const scene = new THREE.Scene();
scene.background = new THREE.Color(0xa0a0a0);

// Linear fog — match color with background to hide horizon seam
scene.fog = new THREE.Fog(0xa0a0a0, 10, 50);

// Ensure camera far plane covers fog range
camera.far = 60; // slightly beyond fog far
camera.updateProjectionMatrix();

See examples/workflow-fog-background.md.

Doc map (official)

Docs section	Representative links
Scenes	https://threejs.org/docs/Scene.html
Fog	https://threejs.org/docs/Fog.html
FogExp2	https://threejs.org/docs/FogExp2.html

Scope

• In scope: Scene, fog types, background field semantics at API level.
• Out of scope: HDR / glTF file fetch (threejs-loaders); PMREM and texture sampling (threejs-textures); tone mapping / output color space defaults (threejs-renderers); full-screen fog-only post stack (threejs-postprocessing) unless tying to scene Fog; custom atmospheric scattering shaders beyond core fog API.

Common pitfalls and best practices

• Fog color should harmonize with background to hide the horizon seam.
• Very large far on camera with fog still needs scene scale consistency.
• background rotation/intensity features depend on renderer version—cite current docs.

Documentation and version

Scene, Fog, and background fields are documented under Scenes in three.js docs. Environment-related visuals often combine this skill with threejs-textures (PMREM) and threejs-loaders (HDR files) — link those pages when the user moves from “fog color” to “HDR sky”.

Agent response checklist

When answering under this skill, prefer responses that:

1. Link Scene, Fog, or FogExp2 official pages.
2. Relate fog distances to threejs-camera far plane and world scale.
3. Defer PMREM/HDR file steps to threejs-textures / threejs-loaders with one sentence each.
4. Avoid duplicating full color-management tutorials — point to renderer + textures skills.

Keywords

English: scene, fog, fogexp2, background, environment, three.js

中文： 场景、雾、Fog、背景、环境、three.js