Method parseHeader

src/ply.ts:81–189

()

  // this.elements will contain all the elements in the file, typically
  // "vertex" contains the Gsplat data.
  async parseHeader() {
    const bufferStream = new ReadableStream({
      start: (
        controller: ReadableStreamController<Uint8Array<ArrayBuffer>>,
      ) => {
        // Assume the header is less than 64KB
        controller.enqueue(this.fileBytes.slice(0, 65536));
        controller.close();
      },
    });
    const decoder = bufferStream
      .pipeThrough(new TextDecoderStream())
      .getReader();

    // Find the end of the text section of the PLY file
    this.header = "";
    const headerTerminator = "end_header\n";
    while (true) {
      const { value, done } = await decoder.read();
      if (done) {
        throw new Error("Failed to read header");
      }

      this.header += value as string;
      const endHeader = this.header.indexOf(headerTerminator);
      if (endHeader >= 0) {
        this.header = this.header.slice(0, endHeader + headerTerminator.length);
        break;
      }
    }
    // Partition the file into header and binary data
    const headerLen = new TextEncoder().encode(this.header).length;
    this.data = new DataView(this.fileBytes.buffer, headerLen);

    this.elements = {};
    let curElement: PlyElement | null = null;
    this.comments = [];

    this.header
      .trim()
      .split("\n")
      .forEach((line: string, lineIndex: number) => {
        const trimmedLine = line.trim();
        if (lineIndex === 0) {
          if (trimmedLine !== "ply") {
            throw new Error("Invalid PLY header");
          }
          return;
        }
        if (trimmedLine.length === 0) {
          return; // Skip empty lines
        }

        const fields = trimmedLine.split(" ");
        switch (fields[0]) {
          case "format":
            if (fields[1] === "binary_little_endian") {
              this.littleEndian = true;