Threejs Loaders

Three.js Loaders

When to Use

• You need to load models, textures, HDR/EXR assets, or other external resources in Three.js.
• The task involves GLTFLoader, TextureLoader, RGBELoader, EXRLoader, DRACOLoader, KTX2Loader, MeshoptDecoder, LoadingManager, or async asset orchestration.
• You are managing scene assets (loading, caching, disposing) rather than authoring geometry or shaders directly.
• You need loading progress bars, retry/fallback logic, or batched asset loading with Promise.all.

Prerequisites

• A Three.js project with three installed (import paths assume three/addons/... or three/examples/jsm/...).
• A renderer instance is required before using PMREMGenerator, KTX2Loader.detectSupport(renderer), or renderer.capabilities.getMaxAnisotropy().
• For Draco-compressed GLB: a decoder path must be configured (CDN or local copy).
• For KTX2 textures: a transcoder path must be configured and renderer support detected.
• For Meshopt (r183+): import MeshoptDecoder and pass it to the GLTF loader.

Procedure

1. Basic GLTF/GLB Loading

import * as THREE from "three";
import { GLTFLoader } from "three/addons/loaders/GLTFLoader.js";

const loader = new GLTFLoader();

loader.load("model.glb", (gltf) => {
  const model = gltf.scene;
  scene.add(model);

  // Animations
  const animations = gltf.animations;
  if (animations.length > 0) {
    const mixer = new THREE.AnimationMixer(model);
    animations.forEach((clip) => {
      mixer.clipAction(clip).play();
    });
  }

  // Cameras and asset info from the file
  const cameras = gltf.cameras;
  console.log(gltf.asset);   // Version, generator, etc.
  console.log(gltf.userData); // Custom data from Blender/etc.
});

2. Coordinate Multiple Loaders with LoadingManager

Use a LoadingManager to track aggregate progress across multiple loaders and fire a single onLoad when all assets are done.

const manager = new THREE.LoadingManager();

manager.onStart = (url, loaded, total) => {
  console.log(`Started loading: ${url}`);
};

manager.onLoad = () => {
  console.log("All assets loaded!");
  startGame();
};

manager.onProgress = (url, loaded, total) => {
  const progress = (loaded / total) * 100;
  console.log(`Loading: ${progress.toFixed(1)}%`);
  updateProgressBar(progress);
};

manager.onError = (url) => {
  console.error(`Error loading: ${url}`);
};

const textureLoader = new THREE.TextureLoader(manager);
const gltfLoader = new GLTFLoader(manager);

textureLoader.load("texture1.jpg");
textureLoader.load("texture2.jpg");
gltfLoader.load("model.glb");
// onLoad fires when ALL are complete

3. Texture Loading and Configuration

const loader = new THREE.TextureLoader();

// Callback style
loader.load(
  "texture.jpg",
  (texture) => {
    material.map = texture;
    material.needsUpdate = true;
  },
  undefined, // onProgress is NOT supported for image loading
  (error) => {
    console.error("Error loading texture", error);
  },
);

// Synchronous return (loads async internally)
const texture = loader.load("texture.jpg");
material.map = texture;

Configure color space, wrapping, filtering, and anisotropy:

const texture = loader.load("texture.jpg", (tex) => {
  // Color space — critical for accuracy
  tex.colorSpace = THREE.SRGBColorSpace;          // For color/albedo maps
  // tex.colorSpace = THREE.LinearSRGBColorSpace; // For data maps (normal, roughness)

  // Wrapping
  tex.wrapS = THREE.RepeatWrapping;
  tex.wrapT = THREE.RepeatWrapping;
  // Alternatives: ClampToEdgeWrapping, MirroredRepeatWrapping

  // Repeat / offset / rotation
  tex.repeat.set(2, 2);
  tex.offset.set(0.5, 0.5);
  tex.rotation = Math.PI / 4;
  tex.center.set(0.5, 0.5);

  // Filtering
  tex.minFilter = THREE.LinearMipmapLinearFilter; // Default
  tex.magFilter = THREE.LinearFilter;             // Default
  // NearestFilter — pixelated; LinearFilter — smooth; LinearMipmapLinearFilter — smooth + mipmaps

  // Anisotropic filtering (sharper at grazing angles)
  tex.anisotropy = renderer.capabilities.getMaxAnisotropy();

  tex.flipY = true; // Usually true for standard textures
  tex.needsUpdate = true;
});

4. CubeTextureLoader (Skybox / Environment)

const loader = new THREE.CubeTextureLoader();

const cubeTexture = loader.load([
  "px.jpg", "nx.jpg", // +X / -X
  "py.jpg", "ny.jpg", // +Y / -Y
  "pz.jpg", "nz.jpg", // +Z / -Z
]);

scene.background = cubeTexture;
scene.environment = cubeTexture;
material.envMap = cubeTexture;

5. HDR / EXR Environment Loading

import { RGBELoader } from "three/addons/loaders/RGBELoader.js";
import { EXRLoader } from "three/addons/loaders/EXRLoader.js";

// HDR
new RGBELoader().load("environment.hdr", (texture) => {
  texture.mapping = THREE.EquirectangularReflectionMapping;
  scene.environment = texture;
  scene.background = texture;
});

// EXR
new EXRLoader().load("environment.exr", (texture) => {
  texture.mapping = THREE.EquirectangularReflectionMapping;
  scene.environment = texture;
});

6. PMREMGenerator (Prefiltered PBR Environment)

import { RGBELoader } from "three/addons/loaders/RGBELoader.js";

const pmremGenerator = new THREE.PMREMGenerator(renderer);
pmremGenerator.compileEquirectangularShader();

new RGBELoader().load("environment.hdr", (texture) => {
  const envMap = pmremGenerator.fromEquirectangular(texture).texture;

  scene.environment = envMap;
  scene.background = envMap;

  texture.dispose();
  pmremGenerator.dispose();
});

7. GLTF with Draco Compression

import { GLTFLoader } from "three/addons/loaders/GLTFLoader.js";
import { DRACOLoader } from "three/addons/loaders/DRACOLoader.js";

const dracoLoader = new DRACOLoader();
dracoLoader.setDecoderPath("https://www.gstatic.com/draco/versioned/decoders/1.5.6/");
dracoLoader.preload();

const gltfLoader = new GLTFLoader();
gltfLoader.setDRACOLoader(dracoLoader);

gltfLoader.load("compressed-model.glb", (gltf) => {
  scene.add(gltf.scene);
});

8. GLTF with KTX2 Textures

import { GLTFLoader } from "three/addons/loaders/GLTFLoader.js";
import { KTX2Loader } from "three/addons/loaders/KTX2Loader.js";

const ktx2Loader = new KTX2Loader();
ktx2Loader.setTranscoderPath(
  "https://cdn.jsdelivr.net/npm/three@0.183.0/examples/jsm/libs/basis/",
);
ktx2Loader.detectSupport(renderer);

const gltfLoader = new GLTFLoader();
gltfLoader.setKTX2Loader(ktx2Loader);

gltfLoader.load("model-with-ktx2.glb", (gltf) => {
  scene.add(gltf.scene);
});

9. GLTF with Meshopt Compression (r183+)

KHR_meshopt_compression is an alternative to Draco that often provides better compression for animated meshes and preserves mesh topology.

import { GLTFLoader } from "three/addons/loaders/GLTFLoader.js";
import { MeshoptDecoder } from "three/addons/libs/meshopt_decoder.module.js";

const gltfLoader = new GLTFLoader();
gltfLoader.setMeshoptDecoder(MeshoptDecoder);

gltfLoader.load("compressed-model.glb", (gltf) => {
  scene.add(gltf.scene);
});

10. Process GLTF Content (Shadows, Centering, Scaling)

loader.load("model.glb", (gltf) => {
  const model = gltf.scene;

  // Enable shadows on all meshes
  model.traverse((child) => {
    if (child.isMesh) {
      child.castShadow = true;
      child.receiveShadow = true;
    }
  });

  // Find a specific named object
  const head = model.getObjectByName("Head");

  // Adjust material envMap intensity
  model.traverse((child) => {
    if (child.isMesh && child.material) {
      child.material.envMapIntensity = 0.5;
    }
  });

  // Center and normalize scale
  const box = new THREE.Box3().setFromObject(model);
  const center = box.getCenter(new THREE.Vector3());
  const size = box.getSize(new THREE.Vector3());

  model.position.sub(center);
  const maxDim = Math.max(size.x, size.y, size.z);
  model.scale.setScalar(1 / maxDim);

  scene.add(model);
});

11. Other Model Formats

OBJ + MTL:

import { OBJLoader } from "three/addons/loaders/OBJLoader.js";
import { MTLLoader } from "three/addons/loaders/MTLLoader.js";

const mtlLoader = new MTLLoader();
mtlLoader.load("model.mtl", (materials) => {
  materials.preload();

  const objLoader = new OBJLoader();
  objLoader.setMaterials(materials);
  objLoader.load("model.obj", (object) => {
    scene.add(object);
  });
});

FBX (often has large scale — adjust accordingly):

import { FBXLoader } from "three/addons/loaders/FBXLoader.js";

const loader = new FBXLoader();
loader.load("model.fbx", (object) => {
  object.scale.setScalar(0.01);

  const mixer = new THREE.AnimationMixer(object);
  object.animations.forEach((clip) => {
    mixer.clipAction(clip).play();
  });

  scene.add(object);
});

STL (returns geometry, not a scene object):

import { STLLoader } from "three/addons/loaders/STLLoader.js";

const loader = new STLLoader();
loader.load("model.stl", (geometry) => {
  const material = new THREE.MeshStandardMaterial({ color: 0x888888 });
  const mesh = new THREE.Mesh(geometry, material);
  scene.add(mesh);
});

PLY (returns geometry; compute vertex normals if needed):

import { PLYLoader } from "three/addons/loaders/PLYLoader.js";

const loader = new PLYLoader();
loader.load("model.ply", (geometry) => {
  geometry.computeVertexNormals();
  const material = new THREE.MeshStandardMaterial({ vertexColors: true });
  const mesh = new THREE.Mesh(geometry, material);
  scene.add(mesh);
});

12. Async / Promise-Based Loading

Promisify a loader for async/await usage:

function loadModel(url) {
  return new Promise((resolve, reject) => {
    loader.load(url, resolve, undefined, reject);
  });
}

async function init() {
  try {
    const gltf = await loadModel("model.glb");
    scene.add(gltf.scene);
  } catch (error) {
    console.error("Failed to load model:", error);
  }
}

Load multiple assets in parallel:

async function loadAssets() {
  const [modelGltf, envTexture, colorTexture] = await Promise.all([
    loadGLTF("model.glb"),
    loadRGBE("environment.hdr"),
    loadTexture("color.jpg"),
  ]);

  scene.add(modelGltf.scene);
  scene.environment = envTexture;
  material.map = colorTexture;
}

function loadGLTF(url) {
  return new Promise((resolve, reject) => {
    new GLTFLoader().load(url, resolve, undefined, reject);
  });
}

function loadRGBE(url) {
  return new Promise((resolve, reject) => {
    new RGBELoader().load(
      url,
      (texture) => {
        texture.mapping = THREE.EquirectangularReflectionMapping;
        resolve(texture);
      },
      undefined,
      reject,
    );
  });
}

function loadTexture(url) {
  return new Promise((resolve, reject) => {
    new THREE.TextureLoader().load(url, resolve, undefined, reject);
  });
}

13. Caching

Built-in cache:

THREE.Cache.enabled = true;
THREE.Cache.clear();
THREE.Cache.add("key", data);
THREE.Cache.get("key");
THREE.Cache.remove("key");

Custom asset manager with deduplication and cloning:

class AssetManager {
  constructor() {
    this.textures = new Map();
    this.models = new Map();
    this.gltfLoader = new GLTFLoader();
    this.textureLoader = new THREE.TextureLoader();
  }

  async loadTexture(key, url) {
    if (this.textures.has(key)) return this.textures.get(key);
    const texture = await new Promise((resolve, reject) => {
      this.textureLoader.load(url, resolve, undefined, reject);
    });
    this.textures.set(key, texture);
    return texture;
  }

  async loadModel(key, url) {
    if (this.models.has(key)) return this.models.get(key).clone();
    const gltf = await new Promise((resolve, reject) => {
      this.gltfLoader.load(url, resolve, undefined, reject);
    });
    this.models.set(key, gltf.scene);
    return gltf.scene.clone();
  }

  dispose() {
    this.textures.forEach((t) => t.dispose());
    this.textures.clear();
    this.models.clear();
  }
}

const assets = new AssetManager();
const texture = await assets.loadTexture("brick", "brick.jpg");
const model = await assets.loadModel("tree", "tree.glb");

14. Loading from Different Sources

Data URL / Base64:

const texture = new THREE.TextureLoader().load("data:image/png;base64,iVBORw0KGgo...");

Blob URL (revoke after use):

async function loadFromBlob(blob) {
  const url = URL.createObjectURL(blob);
  const texture = await loadTexture(url);
  URL.revokeObjectURL(url);
  return texture;
}

ArrayBuffer (parse directly without a network request):

const response = await fetch("model.glb");
const buffer = await response.arrayBuffer();

const loader = new GLTFLoader();
loader.parse(buffer, "", (gltf) => {
  scene.add(gltf.scene);
});

Custom path / URL modifier:

loader.setPath("assets/models/");
loader.load("model.glb"); // Loads from assets/models/model.glb

loader.setResourcePath("assets/textures/"); // For textures referenced inside model

manager.setURLModifier((url) => `https://cdn.example.com/${url}`);

15. Error Handling (Fallback, Retry, Timeout)

// Graceful fallback
async function loadWithFallback(primaryUrl, fallbackUrl) {
  try {
    return await loadModel(primaryUrl);
  } catch (error) {
    console.warn(`Primary failed, trying fallback: ${error}`);
    return await loadModel(fallbackUrl);
  }
}

// Retry with backoff
async function loadWithRetry(url, maxRetries = 3) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      return await loadModel(url);
    } catch (error) {
      if (i === maxRetries - 1) throw error;
      await new Promise((r) => setTimeout(r, 1000 * (i + 1)));
    }
  }
}

// Timeout via AbortController
async function loadWithTimeout(url, timeout = 30000) {
  const controller = new AbortController();
  const timeoutId = setTimeout(() => controller.abort(), timeout);
  try {
    const response = await fetch(url, { signal: controller.signal });
    clearTimeout(timeoutId);
    return response;
  } catch (error) {
    if (error.name === "AbortError") throw new Error("Loading timed out");
    throw error;
  }
}

16. Progressive Loading with Placeholder

const placeholder = new THREE.Mesh(
  new THREE.BoxGeometry(1, 1, 1),
  new THREE.MeshBasicMaterial({ wireframe: true }),
);
scene.add(placeholder);

loadModel("model.glb").then((gltf) => {
  scene.remove(placeholder);
  scene.add(gltf.scene);
});

Pitfalls

1. TextureLoader does not support onProgress — the third argument to load() is ignored for image loading. Use LoadingManager.onProgress for aggregate progress instead.
2. Color space mismatch — color/albedo maps must use THREE.SRGBColorSpace; data maps (normal, roughness, metallic) must use THREE.LinearSRGBColorSpace. Wrong assignment causes washed-out or incorrect lighting.
3. Forgetting needsUpdate — after changing texture properties (wrap, filter, colorSpace) post-load, set texture.needsUpdate = true or changes won't apply.
4. DRACOLoader decoder path mismatch — the path must end with a / and point to the correct versioned decoder directory. A wrong path silently fails on load.
5. KTX2Loader requires renderer support detection — call ktx2Loader.detectSupport(renderer) before loading or transcoding will fail.
6. FBX scale is often huge — FBX files frequently import at 100x expected scale; set object.scale.setScalar(0.01) or similar.
7. STL/PLY return geometry, not objects — you must create a Mesh with a material yourself; there is no embedded material or scene graph.
8. PMREMGenerator and source texture must be disposed — after fromEquirectangular(), dispose both the source HDR texture and the PMREMGenerator to avoid GPU memory leaks.
9. Blob URLs must be revoked — call URL.revokeObjectURL(url) after loading or memory leaks accumulate.
10. THREE.Cache is disabled by default — set THREE.Cache.enabled = true explicitly if you rely on it.
11. Meshopt requires r183+ — MeshoptDecoder import path and setMeshoptDecoder API are only available in r183 and later.
12. VRMLLoader camera support is r183+ — cameras defined in VRML files are only loaded starting r183.

Verification

1. Confirm loader imports resolve:

# Check that the addons path exists in your node_modules
Test-Path "node_modules/three/examples/jsm/loaders/GLTFLoader.js"
Test-Path "node_modules/three/examples/jsm/loaders/DRACOLoader.js"
Test-Path "node_modules/three/examples/jsm/loaders/KTX2Loader.js"

Expected output: True for each.

2. Verify a model loads without errors — open browser DevTools Console and check for:

All assets loaded!

(from LoadingManager.onLoad) with no Error loading: messages.

3. Verify texture color space at runtime:

console.log(texture.colorSpace === THREE.SRGBColorSpace); // true for albedo

4. Verify Draco decoder loaded — in DevTools Network tab, confirm requests to the decoder path (e.g., draco_decoder.wasm) returned HTTP 200.

5. Verify no GPU memory leak — after disposing a model:

model.traverse((child) => {
  if (child.isMesh) {
    child.geometry.dispose();
    if (child.material.map) child.material.map.dispose();
    child.material.dispose();
  }
});
renderer.info.memory; // geometries and textures counts should drop

6. Verify Meshopt availability (r183+):

# Check three.js version
node -e "console.log(require('three/package.json').version)"

Expected: 0.183.0 or higher.

Performance Tips

1. Use compressed formats — DRACO for geometry, KTX2/Basis for textures.
2. Load progressively — show placeholder geometry while real assets load.
3. Lazy load — only load assets needed for the current scene/view.
4. Use a CDN — faster asset delivery and caching.
5. Enable cache — THREE.Cache.enabled = true to avoid re-fetching.

Related Skills

• threejs-textures — Texture configuration and advanced sampling
• threejs-animation — Playing and blending loaded animations
• threejs-materials — Working with materials from loaded models

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.