BoxGeometry constructor

BoxGeometry([ double size = 1.0 ])

Implementation

BoxGeometry([double size = 1.0]) {
  double k = size / 2;

  List<List<double>> cornerVertices = [
    [-k, -k, -k],
    [k, -k, -k],
    [-k, k, -k],
    [k, k, -k],
    [-k, -k, k],
    [k, -k, k],
    [-k, k, k],
    [k, k, k],
  ];

  List<List<double>> faceNormals = [
    [1, 0, 0],
    [-1, 0, 0],
    [0, 1, 0],
    [0, -1, 0],
    [0, 0, 1],
    [0, 0, -1],
  ];

  List<List<double>> uvCoords = [
    [1, 0],
    [0, 0],
    [0, 1],
    [1, 1],
  ];

  List<List<int>> cubeFaceIndices = [
    [3, 7, 5, 1], // right
    [6, 2, 0, 4], // left
    [6, 7, 3, 2], // ??
    [0, 1, 5, 4], // ??
    [7, 6, 4, 5], // front
    [2, 3, 1, 0],
  ];

  for (int f = 0; f < 6; ++f) {
    List<int> faceIndices = cubeFaceIndices[f];
    for (int v = 0; v < 4; ++v) {
      List<double> position = cornerVertices[faceIndices[v]];
      List<double> normal = faceNormals[f];
      List<double> uv = uvCoords[v];

      // Each face needs all four vertices because the normals and texture
      // coordinates are not all the same.
      vertices.addAll(position);
      normals.addAll(normal);
      uvs.addAll(uv);
    }
    // Two triangles make a square face.
    int offset = 4 * f;
    indices.addAll([offset + 0, offset + 1, offset + 2]);
    indices.addAll([offset + 0, offset + 2, offset + 3]);
  }

  // Set index buffers and attributes.
  setIndex(indices);
  setAttribute('position', Float32BufferAttribute(vertices, 3));
  setAttribute('normal', Float32BufferAttribute(normals, 3));
  setAttribute('uv', Float32BufferAttribute(uvs, 2));
}