Threejs Geometry

Three.js 几何体

适用场景

• 需要在 Three.js 中创建或优化几何体。
• 任务涉及内置形状、自定义 BufferGeometry、顶点或实例化渲染。
• 关注的是网格结构本身，而非场景设置或材质。

快速开始

import * as THREE from "three";

// Built-in geometry
const box = new THREE.BoxGeometry(1, 1, 1);
const sphere = new THREE.SphereGeometry(0.5, 32, 32);
const plane = new THREE.PlaneGeometry(10, 10);

// Create mesh
const material = new THREE.MeshStandardMaterial({ color: 0x00ff00 });
const mesh = new THREE.Mesh(box, material);
scene.add(mesh);

内置几何体

基本形状

// Box - width, height, depth, widthSegments, heightSegments, depthSegments
new THREE.BoxGeometry(1, 1, 1, 1, 1, 1);

// Sphere - radius, widthSegments, heightSegments, phiStart, phiLength, thetaStart, thetaLength
new THREE.SphereGeometry(1, 32, 32);
new THREE.SphereGeometry(1, 32, 32, 0, Math.PI * 2, 0, Math.PI); // Full sphere
new THREE.SphereGeometry(1, 32, 32, 0, Math.PI); // Hemisphere

// Plane - width, height, widthSegments, heightSegments
new THREE.PlaneGeometry(10, 10, 1, 1);

// Circle - radius, segments, thetaStart, thetaLength
new THREE.CircleGeometry(1, 32);
new THREE.CircleGeometry(1, 32, 0, Math.PI); // Semicircle

// Cylinder - radiusTop, radiusBottom, height, radialSegments, heightSegments, openEnded
new THREE.CylinderGeometry(1, 1, 2, 32, 1, false);
new THREE.CylinderGeometry(0, 1, 2, 32); // Cone
new THREE.CylinderGeometry(1, 1, 2, 6); // Hexagonal prism

// Cone - radius, height, radialSegments, heightSegments, openEnded
new THREE.ConeGeometry(1, 2, 32, 1, false);

// Torus - radius, tube, radialSegments, tubularSegments, arc
new THREE.TorusGeometry(1, 0.4, 16, 100);

// TorusKnot - radius, tube, tubularSegments, radialSegments, p, q
new THREE.TorusKnotGeometry(1, 0.4, 100, 16, 2, 3);

// Ring - innerRadius, outerRadius, thetaSegments, phiSegments
new THREE.RingGeometry(0.5, 1, 32, 1);

高级形状

// Capsule - radius, length, capSegments, radialSegments
new THREE.CapsuleGeometry(0.5, 1, 4, 8);

// Dodecahedron - radius, detail
new THREE.DodecahedronGeometry(1, 0);

// Icosahedron - radius, detail (0 = 20 faces, higher = smoother)
new THREE.IcosahedronGeometry(1, 0);

// Octahedron - radius, detail
new THREE.OctahedronGeometry(1, 0);

// Tetrahedron - radius, detail
new THREE.TetrahedronGeometry(1, 0);

// Polyhedron - vertices, indices, radius, detail
const vertices = [1, 1, 1, -1, -1, 1, -1, 1, -1, 1, -1, -1];
const indices = [2, 1, 0, 0, 3, 2, 1, 3, 0, 2, 3, 1];
new THREE.PolyhedronGeometry(vertices, indices, 1, 0);

基于路径的形状

// Lathe - points[], segments, phiStart, phiLength
const points = [
  new THREE.Vector2(0, 0),
  new THREE.Vector2(0.5, 0),
  new THREE.Vector2(0.5, 1),
  new THREE.Vector2(0, 1),
];
new THREE.LatheGeometry(points, 32);

// Extrude - shape, options
const shape = new THREE.Shape();
shape.moveTo(0, 0);
shape.lineTo(1, 0);
shape.lineTo(1, 1);
shape.lineTo(0, 1);
shape.lineTo(0, 0);

const extrudeSettings = {
  steps: 2,
  depth: 1,
  bevelEnabled: true,
  bevelThickness: 0.1,
  bevelSize: 0.1,
  bevelSegments: 3,
};
new THREE.ExtrudeGeometry(shape, extrudeSettings);

// Tube - path, tubularSegments, radius, radialSegments, closed
const curve = new THREE.CatmullRomCurve3([
  new THREE.Vector3(-1, 0, 0),
  new THREE.Vector3(0, 1, 0),
  new THREE.Vector3(1, 0, 0),
]);
new THREE.TubeGeometry(curve, 64, 0.2, 8, false);

文字几何体

import { FontLoader } from "three/examples/jsm/loaders/FontLoader.js";
import { TextGeometry } from "three/examples/jsm/geometries/TextGeometry.js";

const loader = new FontLoader();
loader.load("fonts/helvetiker_regular.typeface.json", (font) => {
  const geometry = new TextGeometry("Hello", {
    font: font,
    size: 1,
    depth: 0.2, // Was 'height' in older versions
    curveSegments: 12,
    bevelEnabled: true,
    bevelThickness: 0.03,
    bevelSize: 0.02,
    bevelSegments: 5,
  });

  // Center text
  geometry.computeBoundingBox();
  geometry.center();

  const mesh = new THREE.Mesh(geometry, material);
  scene.add(mesh);
});

BufferGeometry

所有几何体的基类。以类型化数组存储数据，便于 GPU 高效处理。

自定义 BufferGeometry

const geometry = new THREE.BufferGeometry();

// Vertices (3 floats per vertex: x, y, z)
const vertices = new Float32Array([
  -1,
  -1,
  0, // vertex 0
  1,
  -1,
  0, // vertex 1
  1,
  1,
  0, // vertex 2
  -1,
  1,
  0, // vertex 3
]);
geometry.setAttribute("position", new THREE.BufferAttribute(vertices, 3));

// Indices (for indexed geometry - reuse vertices)
const indices = new Uint16Array([
  0,
  1,
  2, // triangle 1
  0,
  2,
  3, // triangle 2
]);
geometry.setIndex(new THREE.BufferAttribute(indices, 1));

// Normals (required for lighting)
const normals = new Float32Array([0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1]);
geometry.setAttribute("normal", new THREE.BufferAttribute(normals, 3));

// UVs (for texturing)
const uvs = new Float32Array([0, 0, 1, 0, 1, 1, 0, 1]);
geometry.setAttribute("uv", new THREE.BufferAttribute(uvs, 2));

// Colors (per-vertex colors)
const colors = new Float32Array([
  1,
  0,
  0, // red
  0,
  1,
  0, // green
  0,
  0,
  1, // blue
  1,
  1,
  0, // yellow
]);
geometry.setAttribute("color", new THREE.BufferAttribute(colors, 3));
// Use with: material.vertexColors = true

BufferAttribute 类型

// Common attribute types
new THREE.BufferAttribute(array, itemSize);

// Typed array options
new Float32Array(count * itemSize); // Positions, normals, UVs
new Uint16Array(count); // Indices (up to 65535 vertices)
new Uint32Array(count); // Indices (larger meshes)
new Uint8Array(count * itemSize); // Colors (0-255 range)

// Item sizes
// Position: 3 (x, y, z)
// Normal: 3 (x, y, z)
// UV: 2 (u, v)
// Color: 3 (r, g, b) or 4 (r, g, b, a)
// Index: 1

修改 BufferGeometry

const positions = geometry.attributes.position;

// Modify vertex
positions.setXYZ(index, x, y, z);

// Access vertex
const x = positions.getX(index);
const y = positions.getY(index);
const z = positions.getZ(index);

// Flag for GPU update
positions.needsUpdate = true;

// Recompute normals after position changes
geometry.computeVertexNormals();

// Recompute bounding box/sphere after changes
geometry.computeBoundingBox();
geometry.computeBoundingSphere();

交错缓冲区（高级）

// More efficient memory layout for large meshes
const interleavedBuffer = new THREE.InterleavedBuffer(
  new Float32Array([
    // pos.x, pos.y, pos.z, uv.u, uv.v (repeated per vertex)
    -1, -1, 0, 0, 0, 1, -1, 0, 1, 0, 1, 1, 0, 1, 1, -1, 1, 0, 0, 1,
  ]),
  5, // stride (floats per vertex)
);

geometry.setAttribute(
  "position",
  new THREE.InterleavedBufferAttribute(interleavedBuffer, 3, 0),
); // size 3, offset 0
geometry.setAttribute(
  "uv",
  new THREE.InterleavedBufferAttribute(interleavedBuffer, 2, 3),
); // size 2, offset 3

EdgesGeometry 与 WireframeGeometry

// Edge lines (only hard edges)
const edges = new THREE.EdgesGeometry(boxGeometry, 15); // 15 = threshold angle
const edgeMesh = new THREE.LineSegments(
  edges,
  new THREE.LineBasicMaterial({ color: 0xffffff }),
);

// Wireframe (all triangles)
const wireframe = new THREE.WireframeGeometry(boxGeometry);
const wireMesh = new THREE.LineSegments(
  wireframe,
  new THREE.LineBasicMaterial({ color: 0xffffff }),
);

点

// Create point cloud
const geometry = new THREE.BufferGeometry();
const positions = new Float32Array(1000 * 3);

for (let i = 0; i < 1000; i++) {
  positions[i * 3] = (Math.random() - 0.5) * 10;
  positions[i * 3 + 1] = (Math.random() - 0.5) * 10;
  positions[i * 3 + 2] = (Math.random() - 0.5) * 10;
}

geometry.setAttribute("position", new THREE.BufferAttribute(positions, 3));

const material = new THREE.PointsMaterial({
  size: 0.1,
  sizeAttenuation: true, // Size decreases with distance
  color: 0xffffff,
});

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

线

// Line (connected points)
const points = [
  new THREE.Vector3(-1, 0, 0),
  new THREE.Vector3(0, 1, 0),
  new THREE.Vector3(1, 0, 0),
];
const geometry = new THREE.BufferGeometry().setFromPoints(points);
const line = new THREE.Line(
  geometry,
  new THREE.LineBasicMaterial({ color: 0xff0000 }),
);

// LineLoop (closed loop)
const loop = new THREE.LineLoop(geometry, material);

// LineSegments (pairs of points)
const segmentsGeometry = new THREE.BufferGeometry();
segmentsGeometry.setAttribute(
  "position",
  new THREE.BufferAttribute(
    new Float32Array([
      -1,
      0,
      0,
      0,
      1,
      0, // segment 1
      0,
      1,
      0,
      1,
      0,
      0, // segment 2
    ]),
    3,
  ),
);
const segments = new THREE.LineSegments(segmentsGeometry, material);

InstancedMesh

高效渲染同一几何体的多个副本。

const geometry = new THREE.BoxGeometry(1, 1, 1);
const material = new THREE.MeshStandardMaterial({ color: 0x00ff00 });
const count = 1000;

const instancedMesh = new THREE.InstancedMesh(geometry, material, count);

// Set transforms for each instance
const dummy = new THREE.Object3D();
const matrix = new THREE.Matrix4();

for (let i = 0; i < count; i++) {
  dummy.position.set(
    (Math.random() - 0.5) * 20,
    (Math.random() - 0.5) * 20,
    (Math.random() - 0.5) * 20,
  );
  dummy.rotation.set(Math.random() * Math.PI, Math.random() * Math.PI, 0);
  dummy.scale.setScalar(0.5 + Math.random());
  dummy.updateMatrix();

  instancedMesh.setMatrixAt(i, dummy.matrix);
}

// Flag for GPU update
instancedMesh.instanceMatrix.needsUpdate = true;

// Optional: per-instance colors
instancedMesh.instanceColor = new THREE.InstancedBufferAttribute(
  new Float32Array(count * 3),
  3,
);
for (let i = 0; i < count; i++) {
  instancedMesh.setColorAt(
    i,
    new THREE.Color(Math.random(), Math.random(), Math.random()),
  );
}
instancedMesh.instanceColor.needsUpdate = true;

scene.add(instancedMesh);

运行时更新实例

// Update single instance
const matrix = new THREE.Matrix4();
instancedMesh.getMatrixAt(index, matrix);
// Modify matrix...
instancedMesh.setMatrixAt(index, matrix);
instancedMesh.instanceMatrix.needsUpdate = true;

// Raycasting with instanced mesh
const intersects = raycaster.intersectObject(instancedMesh);
if (intersects.length > 0) {
  const instanceId = intersects[0].instanceId;
}

InstancedBufferGeometry（高级）

用于超出变换/颜色之外的自定义逐实例属性。

const geometry = new THREE.InstancedBufferGeometry();
geometry.copy(new THREE.BoxGeometry(1, 1, 1));

// Add per-instance attribute
const offsets = new Float32Array(count * 3);
for (let i = 0; i < count; i++) {
  offsets[i * 3] = Math.random() * 10;
  offsets[i * 3 + 1] = Math.random() * 10;
  offsets[i * 3 + 2] = Math.random() * 10;
}
geometry.setAttribute("offset", new THREE.InstancedBufferAttribute(offsets, 3));

// Use in shader
// attribute vec3 offset;
// vec3 transformed = position + offset;

几何体工具函数

import * as BufferGeometryUtils from "three/examples/jsm/utils/BufferGeometryUtils.js";

// Merge geometries (must have same attributes)
const merged = BufferGeometryUtils.mergeGeometries([geo1, geo2, geo3]);

// Merge with groups (for multi-material)
const merged = BufferGeometryUtils.mergeGeometries([geo1, geo2], true);

// Compute tangents (required for normal maps)
BufferGeometryUtils.computeTangents(geometry);

// Interleave attributes for better performance
const interleaved = BufferGeometryUtils.interleaveAttributes([
  geometry.attributes.position,
  geometry.attributes.normal,
  geometry.attributes.uv,
]);

常用模式

居中几何体

geometry.computeBoundingBox();
geometry.center(); // Move vertices so center is at origin

缩放适配

geometry.computeBoundingBox();
const size = new THREE.Vector3();
geometry.boundingBox.getSize(size);
const maxDim = Math.max(size.x, size.y, size.z);
geometry.scale(1 / maxDim, 1 / maxDim, 1 / maxDim);

克隆与变换

const clone = geometry.clone();
clone.rotateX(Math.PI / 2);
clone.translate(0, 1, 0);
clone.scale(2, 2, 2);

变形目标

// Base geometry
const geometry = new THREE.BoxGeometry(1, 1, 1, 4, 4, 4);

// Create morph target
const morphPositions = geometry.attributes.position.array.slice();
for (let i = 0; i < morphPositions.length; i += 3) {
  morphPositions[i] *= 2; // Scale X
  morphPositions[i + 1] *= 0.5; // Squash Y
}

geometry.morphAttributes.position = [
  new THREE.BufferAttribute(new Float32Array(morphPositions), 3),
];

const mesh = new THREE.Mesh(geometry, material);
mesh.morphTargetInfluences[0] = 0.5; // 50% blend

性能建议

1. 使用索引几何体：通过索引复用顶点
2. 合并静态网格：用 mergeGeometries 减少绘制调用
3. 使用 InstancedMesh：适用于大量相同对象
4. 选择合适的分段数：分段越多越平滑，但性能开销越大
5. 释放不再使用的几何体：geometry.dispose()

// Good segment counts for common uses
new THREE.SphereGeometry(1, 32, 32); // Good quality
new THREE.SphereGeometry(1, 64, 64); // High quality
new THREE.SphereGeometry(1, 16, 16); // Performance mode

// Dispose when done
geometry.dispose();

BatchedMesh（r183）

BatchedMesh 是 InstancedMesh 的高级替代方案，支持在单次绘制调用中渲染多种几何体。自 r183 起，支持逐实例透明度和逐实例线框。

const batchedMesh = new THREE.BatchedMesh(maxGeometryCount, maxVertexCount, maxIndexCount);
batchedMesh.sortObjects = true; // Enable depth sorting for transparency

// Add different geometries
const boxId = batchedMesh.addGeometry(new THREE.BoxGeometry(1, 1, 1));
const sphereId = batchedMesh.addGeometry(new THREE.SphereGeometry(0.5, 16, 16));

// Add instances of those geometries
const instance1 = batchedMesh.addInstance(boxId);
const instance2 = batchedMesh.addInstance(sphereId);

// Set transforms
const matrix = new THREE.Matrix4();
matrix.setPosition(2, 0, 0);
batchedMesh.setMatrixAt(instance1, matrix);

// Per-instance opacity (r183)
batchedMesh.setOpacityAt(instance1, 0.5);

// Per-instance visibility
batchedMesh.setVisibleAt(instance2, false);

scene.add(batchedMesh);

另请参阅

• threejs-fundamentals — 场景设置与 Object3D
• threejs-materials — 网格材质类型
• threejs-shaders — 自定义顶点操作

使用限制

• 仅当任务明确匹配上述范围时才使用本技能。
• 不要将输出视为特定环境验证、测试或专家审查的替代品。
• 如果缺少所需输入、权限、安全边界或成功标准，应停止并请求澄清。