Loader.parse()

Loader.parse() 是Three.js加载器中的一个工具方法，用于处理特定格式的数据并返回可供Three.js使用的几何信息对象。

参数

• data： Object / ArrayBuffer / AudioBuffer / string / Blob。需要处理的数据，可以是对象、二进制数据、字符串、音频缓冲区或Blob。

• path： String。 可选参数，表示数据文件的路径。

• onLoad： Function。可选参数，当数据加载完成后调用的回调函数。

• onError： Function。可选参数，当数据加载错误时调用的回调函数。

返回值

解析后的几何信息，类型为 THREE.BufferGeometry 或 THREE.Geometry。

示例

以下示例演示了如何使用 Loader.parse() 方法从 OBJ 文件的字符串数据中提取几何信息：

// ObjLoader.js 文件解析函数
function parse ( text ) {
  const vertexPattern = /^\s*v\s/;
  const normalPattern = /^\s*vn\s/;
  const uvPattern = /^\s*vt\s/;
  const facePattern1 = /^\s*f\s/;
  const facePattern2 = /^\s*(-?\d+)\s*(-?\d+)\s*(-?\d+)\s*(-?\d+)\s*/;

  const geometry = new THREE.Geometry();

  const vertices = [];
  const normals = [];
  const uvs = [];

  function addVertex ( x, y, z ) {
    vertices.push( float( x ), float( y ), float( z ) );
  }

  function addNormal ( x, y, z ) {
    normals.push( float( x ), float( y ), float( z ) );
  }

  function addUV ( x, y ) {
    uvs.push( float( x ), float( y ) );
  }

  function addFace ( a, b, c, d, ua, ub, uc, ud, na, nb, nc, nd ) {
    const vertexIndices = [ a, b, c ];
    const uvIndices = [ ua, ub, uc ];
    const normalIndices = [ na, nb, nc ];
    if ( d !== undefined ) {
      vertexIndices.push( d );
      uvIndices.push( ud );
      normalIndices.push( nd );
    }

    const faceNormal = new THREE.Vector3();

    const vertexA = scope.vertices[ vertexIndices[ 0 ] - 1 ];
    const vertexB = scope.vertices[ vertexIndices[ 1 ] - 1 ];
    const vertexC = scope.vertices[ vertexIndices[ 2 ] - 1 ];

    faceNormal.fromArray( vertexNormals, normalIndices[ 0 ] * 3 );
    this.checkFaceNormal( faceNormal, vertexA, vertexB, vertexC );

    const face = new THREE.Face3( vertexIndices[ 0 ] - 1, vertexIndices[ 1 ] - 1, vertexIndices[ 2 ] - 1, faceNormal.toArray() );

    geometry.faces.push( face );
  }

  const lines = text.split( '\n' );

  for ( let i = 0; i < lines.length; i ++ ) {
    const line = lines[ i ];
    const lineFirstChar = line.charAt( 0 );

    if ( lineFirstChar === 'v' ) {

      const data = line.split( ' ' );

      switch ( data[ 0 ] ) {
        case 'v':
          addVertex( data[ 1 ], data[ 2 ], data[ 3 ] );
          break;
        case 'vn':
          addNormal( data[ 1 ], data[ 2 ], data[ 3 ] );
          break;
        case 'vt':
          addUV( data[ 1 ], data[ 2 ] );
          break;
      }

    } else if ( lineFirstChar === 'f' ) {

      const lineData = line.substr( 1 ).trim();
      const vertexData = lineData.split( ' ' );
      const faceVertices = [];

      for (let j = 0; j < vertexData.length; j ++ ) {
        const vertex = vertexData[ j ];

        if ( vertex.length > 0 ) {

          const vertexParts = vertex.split( '/' );
          faceVertices.push( parseInt( vertexParts[ 0 ] ) );

        }

      }

      const vertexCount = faceVertices.length;

      if ( vertexCount === 3 ) {

        addFace( faceVertices[ 0 ], faceVertices[ 1 ], faceVertices[ 2 ] );

      } else if ( vertexCount === 4 ) {

        addFace( faceVertices[ 0 ], faceVertices[ 1 ], faceVertices[ 2 ], faceVertices[ 3 ] );

      }

    }

  }

  geometry.vertices = new Float32Array( vertices );
  geometry.uvs = new Float32Array( uvs );
  geometry.normals = new Float32Array( normals );

  geometry.computeBoundingBox();
  geometry.computeBoundingSphere();

  return geometry;
}

// main.js 文件
const loader = new THREE.OBJLoader();

// 从字符串数据中提取几何信息
const geometry = loader.parse(obj_string_data);

// 创建网格并渲染到场景中
const material = new THREE.MeshBasicMaterial({ color: 0x00ff00 });
const mesh = new THREE.Mesh(geometry, material);
scene.add(mesh);

注意事项

在使用 Loader.parse() 方法时，需要根据加载的数据类型编写对应的解析函数，将数据格式化为可供 Three.js 使用的几何信息对象。