threejs-helpers

When to use this skill

ALWAYS use this skill when the user mentions:

• Visualizing axes, grids, camera frusta, shadow cameras, light directions
• Showing skeleton bones, bounding boxes, normals/tangents for mesh inspection
• Light probe or rect area visualization via helper classes

IMPORTANT: helpers vs production meshes

• Helpers are debug objects; do not use as final scene geometry.

Trigger phrases include:

• "AxesHelper", "GridHelper", "CameraHelper", "SkeletonHelper", "VertexNormalsHelper"
• "辅助线", "法线显示", "包围盒调试"

How to use this skill

1. Attach helper to the object it describes (e.g., CameraHelper(light.shadow.camera)).
2. Update when targets move — some helpers need per-frame refresh.
3. Gate behind debug flags — remove helpers in production builds to save draw calls.
4. Performance — helpers add draw calls; disable when profiling performance issues.
5. Addons — import from three/addons/helpers/... paths per threejs-dev-setup.

Example: Debug flag pattern for conditional helpers

import * as THREE from 'three';

const DEBUG = import.meta.env.DEV; // Vite-style; adapt for your bundler
const debugGroup = new THREE.Group();
debugGroup.visible = DEBUG;
scene.add(debugGroup);

// Add helpers only in development
if (DEBUG) {
  debugGroup.add(new THREE.AxesHelper(5));
  debugGroup.add(new THREE.GridHelper(10, 10));

  // Shadow camera helper for directional light
  const shadowHelper = new THREE.CameraHelper(directionalLight.shadow.camera);
  debugGroup.add(shadowHelper);
}

// Toggle helpers at runtime via console or GUI
// debugGroup.visible = !debugGroup.visible;

See examples/workflow-light-camera-helpers.md.

Doc map (official)

Scope

• In scope: Core + Addons helpers for visualization.
• Out of scope: Production meshes or shipping art (threejs-geometries, threejs-lights); orbit/transform gizmo behavior (threejs-controls); editor UX parity with DCC tools; physics debug beyond helper stubs.

Common pitfalls and best practices

• Too many helpers obscures view—toggle per subsystem.
• Wrong attachment parent misaligns helper transforms.
• Helpers inherit scene graph transforms—parent under a debug group to batch hide/show.
• Some helpers duplicate geometry cost; strip in production or use #ifdef DEBUG style flags.
• CameraHelper for shadow cameras must reference light.shadow.camera, not the main view camera.

Documentation and version

Helpers are listed under Helpers (core) and Addons → Helpers in three.js docs. They are for debug only; production meshes and lighting should use real geometry/lights (threejs-geometries, threejs-lights).

Agent response checklist

When answering under this skill, prefer responses that:

1. Link the helper class (AxesHelper, CameraHelper, …) being used.
2. State that helpers are not shipping art—strip or gate behind debug flags.
3. Pair shadow/light helpers with threejs-lights tuning workflows.
4. Mention performance cost when many helpers are enabled.
5. Import paths follow threejs-dev-setup addon conventions.

References

• Manual (debug workflow context): https://threejs.org/manual/
• Docs index (Helpers group): https://threejs.org/docs/#Helpers
• Examples: https://threejs.org/docs/DirectionalLightHelper.html

Keywords

English: helper, debug, axes, grid, skeleton, normals, light helper, three.js

中文： 辅助、调试、坐标轴、网格、骨架、法线、Helper、three.js