threejs-textures

# Three.js Textures

## Quick Start

```javascript
import * as THREE from "three";

// Load texture
const loader = new THREE.TextureLoader();
const texture = loader.load("texture.jpg");

// Apply to material
const material = new THREE.MeshStandardMaterial({
  map: texture,
});
```

## Texture Loading

### Basic Loading

```javascript
const loader = new THREE.TextureLoader();

// Async with callbacks
loader.load(
  "texture.jpg",
  (texture) => console.log("Loaded"),
  (progress) => console.log("Progress"),
  (error) => console.error("Error"),
);

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

### Promise Wrapper

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

// Usage
const [colorMap, normalMap, roughnessMap] = await Promise.all([
  loadTexture("color.jpg"),
  loadTexture("normal.jpg"),
  loadTexture("roughness.jpg"),
]);
```

## Texture Configuration

### Color Space

Critical for accurate color reproduction.

```javascript
// Color/albedo textures - use sRGB
colorTexture.colorSpace = THREE.SRGBColorSpace;

// Data textures (normal, roughness, metalness, AO) - leave as default
// Do NOT set colorSpace for data textures (NoColorSpace is default)
```

### Wrapping Modes

```javascript
texture.wrapS = THREE.RepeatWrapping; // Horizontal
texture.wrapT = THREE.RepeatWrapping; // Vertical

// Options:
// THREE.ClampToEdgeWrapping - Stretches edge pixels (default)
// THREE.RepeatWrapping - Tiles the texture
// THREE.MirroredRepeatWrapping - Tiles with mirror flip
```

### Repeat, Offset, Rotation

```javascript
// Tile texture 4x4
texture.repeat.set(4, 4);
texture.wrapS = THREE.RepeatWrapping;
texture.wrapT = THREE.RepeatWrapping;

// Offset (0-1 range)
texture.offset.set(0.5, 0.5);

// Rotation (radians, around center)
texture.rotation = Math.PI / 4;
texture.center.set(0.5, 0.5); // Rotation pivot
```

### Filtering

```javascript
// Minification (texture larger than screen pixels)
texture.minFilter = THREE.LinearMipmapLinearFilter; // Default, smooth
texture.minFilter = THREE.NearestFilter; // Pixelated
texture.minFilter = THREE.LinearFilter; // Smooth, no mipmaps

// Magnification (texture smaller than screen pixels)
texture.magFilter = THREE.LinearFilter; // Smooth (default)
texture.magFilter = THREE.NearestFilter; // Pixelated (retro games)

// Anisotropic filtering (sharper at angles)
texture.anisotropy = renderer.capabilities.getMaxAnisotropy();
```

### Generate Mipmaps

```javascript
// Usually true by default
texture.generateMipmaps = true;

// Disable for non-power-of-2 textures or data textures
texture.generateMipmaps = false;
texture.minFilter = THREE.LinearFilter;
```

## Texture Types

### Regular Texture

```javascript
const texture = new THREE.Texture(image);
texture.needsUpdate = true;
```

### Data Texture

Create texture from raw data.

```javascript
// Create gradient texture
const size = 256;
const data = new Uint8Array(size * size * 4);

for (let i = 0; i < size; i++) {
  for (let j = 0; j < size; j++) {
    const index = (i * size + j) * 4;
    data[index] = i; // R
    data[index + 1] = j; // G
    data[index + 2] = 128; // B
    data[index + 3] = 255; // A
  }
}

const texture = new THREE.DataTexture(data, size, size);
texture.needsUpdate = true;
```

### Canvas Texture

```javascript
const canvas = document.createElement("canvas");
canvas.width = 256;
canvas.height = 256;
const ctx = canvas.getContext("2d");

// Draw on canvas
ctx.fillStyle = "red";
ctx.fillRect(0, 0, 256, 256);
ctx.fillStyle = "white";
ctx.font = "48px Arial";
ctx.fillText("Hello", 50, 150);

const texture = new THREE.CanvasTexture(canvas);

// Update when canvas changes
texture.needsUpdate = true;
```

### Video Texture

```javascript
const video = document.createElement("video");
video.src = "video.mp4";
video.loop = true;
video.muted = true;
video.play();

const texture = new THREE.VideoTexture(video);
texture.colorSpace = THREE.SRGBColorSpace;

// No need to set needsUpdate - auto-updates
```

### Compressed Textures

```javascript
import { KTX2Loader } from "three/examples/jsm/loaders/KTX2Loader.js";

const ktx2Loader = new KTX2Loader();
ktx2Loader.setTranscoderPath("path/to/basis/");
ktx2Loader.detectSupport(renderer);

ktx2Loader.load("texture.ktx2", (texture) => {
  material.map = texture;
});
```

## Cube Textures

For environment maps and skyboxes.

### CubeTextureLoader

```javascript
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
]);

// As background
scene.background = cubeTexture;

// As environment map
scene.environment = cubeTexture;
material.envMap = cubeTexture;
```

### Equirectangular to Cubemap

```javascript
import { RGBELoader } from "three/examples/jsm/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();
});
```

## HDR Textures

### RGBELoader

```javascript
import { RGBELoader } from "three/examples/jsm/loaders/RGBELoader.js";

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

### EXRLoader

```javascript
import { EXRLoader } from "three/examples/jsm/loaders/EXRLoader.js";

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

### Background Options

```javascript
scene.background = texture;
scene.backgroundBlurriness = 0.5; // 0-1, blur background
scene.backgroundIntensity = 1.0; // Brightness
scene.backgroundRotation.y = Math.PI; // Rotate background
```

## Render Targets

Render to texture for effects.

```javascript
// Create render target
const renderTarget = new THREE.WebGLRenderTarget(512, 512, {
  minFilter: THREE.LinearFilter,
  magFilter: THREE.LinearFilter,
  format: THREE.RGBAFormat,
});

// Render scene to target
renderer.setRenderTarget(renderTarget);
renderer.render(scene, camera);
renderer.setRenderTarget(null); // Back to screen

// Use as texture
material.map = renderTarget.texture;
```

### Depth Texture

```javascript
const renderTarget = new THREE.WebGLRenderTarget(512, 512);
renderTarget.depthTexture = new THREE.DepthTexture(
  512,
  512,
  THREE.UnsignedShortType,
);

// Access depth
const depthTexture = renderTarget.depthTexture;
```

### Multi-Sample Render Target

```javascript
const renderTarget = new THREE.WebGLRenderTarget(512, 512, {
  samples: 4, // MSAA
});
```

## CubeCamera

Dynamic environment maps for reflections.

```javascript
const cubeRenderTarget = new THREE.WebGLCubeRenderTarget(256, {
  generateMipmaps: true,
  minFilter: THREE.LinearMipmapLinearFilter,
});

const cubeCamera = new THREE.CubeCamera(0.1, 1000, cubeRenderTarget);
scene.add(cubeCamera);

// Apply to reflective material
reflectiveMaterial.envMap = cubeRenderTarget.texture;

// Update in animation loop (expensive!)
function animate() {
  // Hide reflective object, update env map, show again
  reflectiveObject.visible = false;
  cubeCamera.position.copy(reflectiveObject.position);
  cubeCamera.update(renderer, scene);
  reflectiveObject.visible = true;
}
```

## UV Mapping

### Accessing UVs

```javascript
const uvs = geometry.attributes.uv;

// Read UV
const u = uvs.getX(vertexIndex);
const v = uvs.getY(vertexIndex);

// Modify UV
uvs.setXY(vertexIndex, newU, newV);
uvs.needsUpdate = true;
```

### Second UV Channel (for AO maps)

```javascript
// Required for aoMap
geometry.setAttribute("uv2", geometry.attributes.uv);

// Or create custom second UV
const uv2 = new Float32Array(vertexCount * 2);
// ... fill uv2 data
geometry.setAttribute("uv2", new THREE.BufferAttribute(uv2, 2));
```

### UV Transform in Shader

```javascript
const material = new THREE.ShaderMaterial({
  uniforms: {
    map: { value: texture },
    uvOffset: { value: new THREE.Vector2(0, 0) },
    uvScale: { value: new THREE.Vector2(1, 1) },
  },
  vertexShader: `
    varying vec2 vUv;
    uniform vec2 uvOffset;
    uniform vec2 uvScale;

    void main() {
      vUv = uv * uvScale + uvOffset;
      gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
    }
  `,
  fragmentShader: `
    varying vec2 vUv;
    uniform sampler2D map;

    void main() {
      gl_FragColor = texture2D(map, vUv);
    }
  `,
});
```

## Texture Atlas

Multiple images in one texture.

```javascript
// Atlas with 4 sprites (2x2 grid)
const atlas = loader.load("atlas.png");
atlas.wrapS = THREE.ClampToEdgeWrapping;
atlas.wrapT = THREE.ClampToEdgeWrapping;

// Select sprite by UV offset/scale
function selectSprite(row, col, gridSize = 2) {
  atlas.offset.set(col / gridSize, 1 - (row + 1) / gridSize);
  atlas.repeat.set(1 / gridSize, 1 / gridSize);
}

// Select top-left sprite
selectSprite(0, 0);
```

## Material Texture Maps

### PBR Texture Set

```javascript
const material = new THREE.MeshStandardMaterial({
  // Base color (sRGB)
  map: colorTexture,

  // Surface detail (Linear)
  normalMap: normalTexture,
  normalScale: new THREE.Vector2(1, 1),

  // Roughness (Linear, grayscale)
  roughnessMap: roughnessTexture,
  roughness: 1, // Multiplier

  // Metalness (Linear, grayscale)
  metalnessMap: metalnessTexture,
  metalness: 1, // Multiplier

  // Ambient occlusion (Linear, uses uv2)
  aoMap: aoTexture,
  aoMapIntensity: 1,

  // Self-illumination (sRGB)
  emissiveMap: emissiveTexture,
  emissive: 0xffffff,
  emissiveIntensity: 1,

  // Vertex displacement (Linear)
  displacementMap: displacementTexture,
  displacementScale: 0.1,
  displacementBias: 0,

  // Alpha (Linear)
  alphaMap: alphaTexture,
  transparent: true,
});

// Don't forget UV2 for AO
geometry.setAttribute("uv2", geometry.attributes.uv);
```

### Normal Map Types

```javascript
// OpenGL style normals (default)
material.normalMapType = THREE.TangentSpaceNormalMap;

// Object space normals
material.normalMapType = THREE.ObjectSpaceNormalMap;
```

## Procedural Textures

### Noise Texture

```javascript
function generateNoiseTexture(size = 256) {
  const data = new Uint8Array(size * size * 4);

  for (let i = 0; i < size * size; i++) {
    const value = Math.random() * 255;
    data[i * 4] = value;
    data[i * 4 + 1] = value;
    data[i * 4 + 2] = value;
    data[i * 4 + 3] = 255;
  }

  const texture = new THREE.DataTexture(data, size, size);
  texture.needsUpdate = true;
  return texture;
}
```

### Gradient Texture

```javascript
function generateGradientTexture(color1, color2, size = 256) {
  const canvas = document.createElement("canvas");
  canvas.width = size;
  canvas.height = 1;
  const ctx = canvas.getContext("2d");

  const gradient = ctx.createLinearGradient(0, 0, size, 0);
  gradient.addColorStop(0, color1);
  gradient.addColorStop(1, color2);

  ctx.fillStyle = gradient;
  ctx.fillRect(0, 0, size, 1);

  return new THREE.CanvasTexture(canvas);
}
```

## Texture Memory Management

### Dispose Textures

```javascript
// Single texture
texture.dispose();

// Material textures
function disposeMaterial(material) {
  const maps = [
    "map",
    "normalMap",
    "roughnessMap",
    "metalnessMap",
    "aoMap",
    "emissiveMap",
    "displacementMap",
    "alphaMap",
    "envMap",
    "lightMap",
    "bumpMap",
    "specularMap",
  ];

  maps.forEach((mapName) => {
    if (material[mapName]) {
      material[mapName].dispose();
    }
  });

  material.dispose();
}
```

### Texture Pooling

```javascript
class TexturePool {
  constructor() {
    this.textures = new Map();
    this.loader = new THREE.TextureLoader();
  }

  async get(url) {
    if (this.textures.has(url)) {
      return this.textures.get(url);
    }

    const texture = await new Promise((resolve, reject) => {
      this.loader.load(url, resolve, undefined, reject);
    });

    this.textures.set(url, texture);
    return texture;
  }

  dispose(url) {
    const texture = this.textures.get(url);
    if (texture) {
      texture.dispose();
      this.textures.delete(url);
    }
  }

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

## Performance Tips

1. **Use power-of-2 dimensions**: 256, 512, 1024, 2048
2. **Compress textures**: KTX2/Basis for web delivery
3. **Use texture atlases**: Reduce texture switches
4. **Enable mipmaps**: For distant objects
5. **Limit texture size**: 2048 usually sufficient for web
6. **Reuse textures**: Same texture = better batching

```javascript
// Check texture memory
console.log(renderer.info.memory.textures);

// Optimize for mobile
const maxSize = renderer.capabilities.maxTextureSize;
const isMobile = /iPhone|iPad|Android/i.test(navigator.userAgent);
const textureSize = isMobile ? 1024 : 2048;
```

## KTX2Loader BC3 Alpha Fix (r183)

As of r183, `KTX2Loader` correctly handles BC3 compressed textures with alpha channels, fixing previously incorrect alpha rendering.

## ISO 21496-1 Gainmap Metadata (r183)

Three.js r183 supports ISO 21496-1 gainmap metadata in HDR textures, enabling proper tone mapping of gainmap-based HDR images (such as those produced by recent smartphone cameras).

## See Also

- `threejs-materials` - Applying textures to materials
- `threejs-loaders` - Loading texture files
- `threejs-shaders` - Custom texture sampling