用ts写一个3个点求顶点法线

以下是使用 TypeScript 编写的计算三角形顶点法线的代码：

interface Vector3 {
  x: number;
  y: number;
  z: number;
}

interface Triangle {
  vertices: [Vector3, Vector3, Vector3];
}

function calculateTriangleNormal(triangle: Triangle): Vector3 {
  const p1 = triangle.vertices[0];
  const p2 = triangle.vertices[1];
  const p3 = triangle.vertices[2];

  const v1 = { x: p2.x - p1.x, y: p2.y - p1.y, z: p2.z - p1.z };
  const v2 = { x: p3.x - p1.x, y: p3.y - p1.y, z: p3.z - p1.z };

  const crossProduct = {
    x: v1.y * v2.z - v1.z * v2.y,
    y: v1.z * v2.x - v1.x * v2.z,
    z: v1.x * v2.y - v1.y * v2.x
  };

  const length = Math.sqrt(
    crossProduct.x * crossProduct.x +
    crossProduct.y * crossProduct.y +
    crossProduct.z * crossProduct.z
  );

  return {
    x: crossProduct.x / length,
    y: crossProduct.y / length,
    z: crossProduct.z / length
  };
}

function calculateVertexNormals(vertices: Vector3[], indices: number[]): Vector3[] {
  const vertexNormals: Vector3[] = [];

  for (let i = 0; i < vertices.length; i++) {
    vertexNormals.push({ x: 0, y: 0, z: 0 });
  }

  for (let i = 0; i < indices.length; i += 3) {
    const triangle: Triangle = {
      vertices: [
        vertices[indices[i]],
        vertices[indices[i + 1]],
        vertices[indices[i + 2]]
      ]
    };

    const normal = calculateTriangleNormal(triangle);

    vertexNormals[indices[i]].x += normal.x;
    vertexNormals[indices[i]].y += normal.y;
    vertexNormals[indices[i]].z += normal.z;

    vertexNormals[indices[i + 1]].x += normal.x;
    vertexNormals[indices[i + 1]].y += normal.y;
    vertexNormals[indices[i + 1]].z += normal.z;

    vertexNormals[indices[i + 2]].x += normal.x;
    vertexNormals[indices[i + 2]].y += normal.y;
    vertexNormals[indices[i + 2]].z += normal.z;
  }

  for (let i = 0; i < vertexNormals.length; i++) {
    const length = Math.sqrt(
      vertexNormals[i].x * vertexNormals[i].x +
      vertexNormals[i].y * vertexNormals[i].y +
      vertexNormals[i].z * vertexNormals[i].z
    );

    vertexNormals[i].x /= length;
    vertexNormals[i].y /= length;
    vertexNormals[i].z /= length;
  }

  return vertexNormals;
}

其中，`calculateTriangleNormal` 函数用于计算三角形的法线向量，`calculateVertexNormals` 函数用于计算顶点法线向量。