# Three.js Materials

## Quick Start

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

// PBR material (recommended for realistic rendering)
const material = new THREE.MeshStandardMaterial({
  color: 0x00ff00,
  roughness: 0.5,
  metalness: 0.5,
});

const mesh = new THREE.Mesh(geometry, material);
```

## Material Types Overview

| Material             | Use Case                              | Lighting           |
| -------------------- | ------------------------------------- | ------------------ |
| MeshBasicMaterial    | Unlit, flat colors, wireframes        | No                 |
| MeshLambertMaterial  | Matte surfaces, performance           | Yes (diffuse only) |
| MeshPhongMaterial    | Shiny surfaces, specular highlights   | Yes                |
| MeshStandardMaterial | PBR, realistic materials              | Yes (PBR)          |
| MeshPhysicalMaterial | Advanced PBR, clearcoat, transmission | Yes (PBR+)         |
| MeshToonMaterial     | Cel-shaded, cartoon look              | Yes (toon)         |
| MeshNormalMaterial   | Debug normals                         | No                 |
| MeshDepthMaterial    | Depth visualization                   | No                 |
| ShaderMaterial       | Custom GLSL shaders                   | Custom             |
| RawShaderMaterial    | Full shader control                   | Custom             |

## MeshBasicMaterial

No lighting calculations. Fast, always visible.

```javascript
const material = new THREE.MeshBasicMaterial({
  color: 0xff0000,
  transparent: true,
  opacity: 0.5,
  side: THREE.DoubleSide, // FrontSide, BackSide, DoubleSide
  wireframe: false,
  map: texture, // Color/diffuse texture
  alphaMap: alphaTexture, // Transparency texture
  envMap: envTexture, // Reflection texture
  reflectivity: 1, // Env map intensity
  fog: true, // Affected by scene fog
});
```

## MeshLambertMaterial

Diffuse-only lighting. Fast, no specular highlights.

```javascript
const material = new THREE.MeshLambertMaterial({
  color: 0x00ff00,
  emissive: 0x111111, // Self-illumination color
  emissiveIntensity: 1,
  map: texture,
  emissiveMap: emissiveTexture,
  envMap: envTexture,
  reflectivity: 0.5,
});
```

## MeshPhongMaterial

Specular highlights. Good for shiny, plastic-like surfaces.

```javascript
const material = new THREE.MeshPhongMaterial({
  color: 0x0000ff,
  specular: 0xffffff, // Highlight color
  shininess: 100, // Highlight sharpness (0-1000)
  emissive: 0x000000,
  flatShading: false, // Flat vs smooth shading
  map: texture,
  specularMap: specTexture, // Per-pixel shininess
  normalMap: normalTexture,
  normalScale: new THREE.Vector2(1, 1),
  bumpMap: bumpTexture,
  bumpScale: 1,
  displacementMap: dispTexture,
  displacementScale: 1,
});
```

## MeshStandardMaterial (PBR)

Physically-based rendering. Recommended for realistic results.

```javascript
const material = new THREE.MeshStandardMaterial({
  color: 0xffffff,
  roughness: 0.5, // 0 = mirror, 1 = diffuse
  metalness: 0.0, // 0 = dielectric, 1 = metal

  // Textures
  map: colorTexture, // Albedo/base color
  roughnessMap: roughTexture, // Per-pixel roughness
  metalnessMap: metalTexture, // Per-pixel metalness
  normalMap: normalTexture, // Surface detail
  normalScale: new THREE.Vector2(1, 1),
  aoMap: aoTexture, // Ambient occlusion (uses uv2!)
  aoMapIntensity: 1,
  displacementMap: dispTexture, // Vertex displacement
  displacementScale: 0.1,
  displacementBias: 0,

  // Emissive
  emissive: 0x000000,
  emissiveIntensity: 1,
  emissiveMap: emissiveTexture,

  // Environment
  envMap: envTexture,
  envMapIntensity: 1,

  // Other
  flatShading: false,
  wireframe: false,
  fog: true,
});

// Note: aoMap requires second UV channel
geometry.setAttribute("uv2", geometry.attributes.uv);
```

## MeshPhysicalMaterial (Advanced PBR)

Extends MeshStandardMaterial with advanced features.

```javascript
const material = new THREE.MeshPhysicalMaterial({
  // All MeshStandardMaterial properties plus:

  // Clearcoat (car paint, lacquer)
  clearcoat: 1.0, // 0-1 clearcoat layer strength
  clearcoatRoughness: 0.1,
  clearcoatMap: ccTexture,
  clearcoatRoughnessMap: ccrTexture,
  clearcoatNormalMap: ccnTexture,
  clearcoatNormalScale: new THREE.Vector2(1, 1),

  // Transmission (glass, water)
  transmission: 1.0, // 0 = opaque, 1 = fully transparent
  transmissionMap: transTexture,
  thickness: 0.5, // Volume thickness for refraction
  thicknessMap: thickTexture,
  attenuationDistance: 1, // Absorption distance
  attenuationColor: new THREE.Color(0xffffff),

  // Refraction
  ior: 1.5, // Index of refraction (1-2.333)

  // Sheen (fabric, velvet)
  sheen: 1.0,
  sheenRoughness: 0.5,
  sheenColor: new THREE.Color(0xffffff),
  sheenColorMap: sheenTexture,
  sheenRoughnessMap: sheenRoughTexture,

  // Iridescence (soap bubbles, oil slicks)
  iridescence: 1.0,
  iridescenceIOR: 1.3,
  iridescenceThicknessRange: [100, 400],
  iridescenceMap: iridTexture,
  iridescenceThicknessMap: iridThickTexture,

  // Anisotropy (brushed metal)
  anisotropy: 1.0,
  anisotropyRotation: 0,
  anisotropyMap: anisoTexture,

  // Specular
  specularIntensity: 1,
  specularColor: new THREE.Color(0xffffff),
  specularIntensityMap: specIntTexture,
  specularColorMap: specColorTexture,
});
```

### Glass Material Example

```javascript
const glass = new THREE.MeshPhysicalMaterial({
  color: 0xffffff,
  metalness: 0,
  roughness: 0,
  transmission: 1,
  thickness: 0.5,
  ior: 1.5,
  envMapIntensity: 1,
});
```

### Car Paint Example

```javascript
const carPaint = new THREE.MeshPhysicalMaterial({
  color: 0xff0000,
  metalness: 0.9,
  roughness: 0.5,
  clearcoat: 1,
  clearcoatRoughness: 0.1,
});
```

## MeshToonMaterial

Cel-shaded cartoon look.

```javascript
const material = new THREE.MeshToonMaterial({
  color: 0x00ff00,
  gradientMap: gradientTexture, // Optional: custom shading gradient
});

// Create step gradient texture
const colors = new Uint8Array([0, 128, 255]);
const gradientMap = new THREE.DataTexture(colors, 3, 1, THREE.RedFormat);
gradientMap.minFilter = THREE.NearestFilter;
gradientMap.magFilter = THREE.NearestFilter;
gradientMap.needsUpdate = true;
```

## MeshNormalMaterial

Visualize surface normals. Useful for debugging.

```javascript
const material = new THREE.MeshNormalMaterial({
  flatShading: false,
  wireframe: false,
});
```

## MeshDepthMaterial

Render depth values. Used for shadow maps, DOF effects.

```javascript
const material = new THREE.MeshDepthMaterial({
  depthPacking: THREE.RGBADepthPacking,
});
```

## PointsMaterial

For point clouds.

```javascript
const material = new THREE.PointsMaterial({
  color: 0xffffff,
  size: 0.1,
  sizeAttenuation: true, // Scale with distance
  map: pointTexture,
  alphaMap: alphaTexture,
  transparent: true,
  alphaTest: 0.5, // Discard pixels below threshold
  vertexColors: true, // Use per-vertex colors
});

const points = new THREE.Points(geometry, material);
```

## LineBasicMaterial & LineDashedMaterial

```javascript
// Solid lines
const lineMaterial = new THREE.LineBasicMaterial({
  color: 0xffffff,
  linewidth: 1, // Note: >1 only works on some systems
  linecap: "round",
  linejoin: "round",
});

// Dashed lines
const dashedMaterial = new THREE.LineDashedMaterial({
  color: 0xffffff,
  dashSize: 0.5,
  gapSize: 0.25,
  scale: 1,
});

// Required for dashed lines
const line = new THREE.Line(geometry, dashedMaterial);
line.computeLineDistances();
```

## ShaderMaterial

Custom GLSL shaders with Three.js uniforms.

```javascript
const material = new THREE.ShaderMaterial({
  uniforms: {
    time: { value: 0 },
    color: { value: new THREE.Color(0xff0000) },
    texture1: { value: texture },
  },
  vertexShader: `
    varying vec2 vUv;
    uniform float time;

    void main() {
      vUv = uv;
      vec3 pos = position;
      pos.z += sin(pos.x * 10.0 + time) * 0.1;
      gl_Position = projectionMatrix * modelViewMatrix * vec4(pos, 1.0);
    }
  `,
  fragmentShader: `
    varying vec2 vUv;
    uniform vec3 color;
    uniform sampler2D texture1;

    void main() {
      // Use texture2D() for GLSL 1.0, texture() for GLSL 3.0 (glslVersion: THREE.GLSL3)
      vec4 texColor = texture2D(texture1, vUv);
      gl_FragColor = vec4(color * texColor.rgb, 1.0);
    }
  `,
  transparent: true,
  side: THREE.DoubleSide,
});

// Update uniform in animation loop
material.uniforms.time.value = clock.getElapsedTime();
```

### Built-in Uniforms (auto-provided)

```glsl
// Vertex shader
uniform mat4 modelMatrix;         // Object to world
uniform mat4 modelViewMatrix;     // Object to camera
uniform mat4 projectionMatrix;    // Camera projection
uniform mat4 viewMatrix;          // World to camera
uniform mat3 normalMatrix;        // For transforming normals
uniform vec3 cameraPosition;      // Camera world position

// Attributes
attribute vec3 position;
attribute vec3 normal;
attribute vec2 uv;
```

## RawShaderMaterial

Full control - no built-in uniforms/attributes.

```javascript
const material = new THREE.RawShaderMaterial({
  uniforms: {
    projectionMatrix: { value: camera.projectionMatrix },
    modelViewMatrix: { value: new THREE.Matrix4() },
  },
  vertexShader: `
    precision highp float;
    attribute vec3 position;
    uniform mat4 projectionMatrix;
    uniform mat4 modelViewMatrix;

    void main() {
      gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
    }
  `,
  fragmentShader: `
    precision highp float;

    void main() {
      gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
    }
  `,
});
```

## Common Material Properties

All materials share these base properties:

```javascript
// Visibility
material.visible = true;
material.transparent = false;
material.opacity = 1.0;
material.alphaTest = 0; // Discard pixels with alpha < value

// Rendering
material.side = THREE.FrontSide; // FrontSide, BackSide, DoubleSide
material.depthTest = true;
material.depthWrite = true;
material.colorWrite = true;

// Blending
material.blending = THREE.NormalBlending;
// NormalBlending, AdditiveBlending, SubtractiveBlending, MultiplyBlending, CustomBlending

// Stencil
material.stencilWrite = false;
material.stencilFunc = THREE.AlwaysStencilFunc;
material.stencilRef = 0;
material.stencilMask = 0xff;

// Polygon offset (z-fighting fix)
material.polygonOffset = false;
material.polygonOffsetFactor = 0;
material.polygonOffsetUnits = 0;

// Misc
material.dithering = false;
material.toneMapped = true;
```

## Multiple Materials

```javascript
// Assign different materials to geometry groups
const geometry = new THREE.BoxGeometry(1, 1, 1);
const materials = [
  new THREE.MeshBasicMaterial({ color: 0xff0000 }), // right
  new THREE.MeshBasicMaterial({ color: 0x00ff00 }), // left
  new THREE.MeshBasicMaterial({ color: 0x0000ff }), // top
  new THREE.MeshBasicMaterial({ color: 0xffff00 }), // bottom
  new THREE.MeshBasicMaterial({ color: 0xff00ff }), // front
  new THREE.MeshBasicMaterial({ color: 0x00ffff }), // back
];
const mesh = new THREE.Mesh(geometry, materials);

// Custom groups
geometry.clearGroups();
geometry.addGroup(0, 6, 0); // start, count, materialIndex
geometry.addGroup(6, 6, 1);
```

## Environment Maps

```javascript
// Load cube texture
const cubeLoader = new THREE.CubeTextureLoader();
const envMap = cubeLoader.load([
  "px.jpg",
  "nx.jpg", // positive/negative X
  "py.jpg",
  "ny.jpg", // positive/negative Y
  "pz.jpg",
  "nz.jpg", // positive/negative Z
]);

// Apply to material
material.envMap = envMap;
material.envMapIntensity = 1;

// Or set as scene environment (affects all PBR materials)
scene.environment = envMap;

// HDR environment (recommended)
import { RGBELoader } from "three/examples/jsm/loaders/RGBELoader.js";
const rgbeLoader = new RGBELoader();
rgbeLoader.load("environment.hdr", (texture) => {
  texture.mapping = THREE.EquirectangularReflectionMapping;
  scene.environment = texture;
  scene.background = texture;
});
```

## Material Cloning and Modification

```javascript
// Clone material
const clone = material.clone();
clone.color.set(0x00ff00);

// Modify at runtime
material.color.set(0xff0000);
material.needsUpdate = true; // Only needed for some changes

// When needsUpdate is required:
// - Changing flat shading
// - Changing texture
// - Changing transparent
// - Custom shader code changes
```

## Performance Tips

1. **Reuse materials**: Same material = batched draw calls
2. **Avoid transparent when possible**: Transparent materials require sorting
3. **Use alphaTest instead of transparency**: When applicable, faster
4. **Choose simpler materials**: Basic > Lambert > Phong > Standard > Physical
5. **Limit active lights**: Each light adds shader complexity

```javascript
// Material pooling
const materialCache = new Map();
function getMaterial(color) {
  const key = color.toString(16);
  if (!materialCache.has(key)) {
    materialCache.set(key, new THREE.MeshStandardMaterial({ color }));
  }
  return materialCache.get(key);
}

// Dispose when done
material.dispose();
```

## See Also

- `threejs-textures` - Texture loading and configuration
- `threejs-shaders` - Custom shader development
- `threejs-lighting` - Light interaction with materials
