import addPipelineExtras from "./addPipelineExtras.js";
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import removeExtensionsUsed from "./removeExtensionsUsed.js";
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import defaultValue from "../../Core/defaultValue.js";
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import defined from "../../Core/defined.js";
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import getMagic from "../../Core/getMagic.js";
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import getStringFromTypedArray from "../../Core/getStringFromTypedArray.js";
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import RuntimeError from "../../Core/RuntimeError.js";
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const sizeOfUint32 = 4;
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/**
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* Convert a binary glTF to glTF.
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*
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* The returned glTF has pipeline extras included. The embedded binary data is stored in gltf.buffers[0].extras._pipeline.source.
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*
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* @param {Buffer} glb The glb data to parse.
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* @returns {Object} A javascript object containing a glTF asset with pipeline extras included.
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*
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* @private
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*/
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function parseGlb(glb) {
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// Check that the magic string is present
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const magic = getMagic(glb);
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if (magic !== "glTF") {
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throw new RuntimeError("File is not valid binary glTF");
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}
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const header = readHeader(glb, 0, 5);
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const version = header[1];
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if (version !== 1 && version !== 2) {
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throw new RuntimeError("Binary glTF version is not 1 or 2");
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}
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if (version === 1) {
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return parseGlbVersion1(glb, header);
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}
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return parseGlbVersion2(glb, header);
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}
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function readHeader(glb, byteOffset, count) {
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const dataView = new DataView(glb.buffer);
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const header = new Array(count);
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for (let i = 0; i < count; ++i) {
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header[i] = dataView.getUint32(
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glb.byteOffset + byteOffset + i * sizeOfUint32,
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true
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);
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}
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return header;
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}
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function parseGlbVersion1(glb, header) {
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const length = header[2];
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const contentLength = header[3];
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const contentFormat = header[4];
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// Check that the content format is 0, indicating that it is JSON
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if (contentFormat !== 0) {
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throw new RuntimeError("Binary glTF scene format is not JSON");
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}
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const jsonStart = 20;
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const binaryStart = jsonStart + contentLength;
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const contentString = getStringFromTypedArray(glb, jsonStart, contentLength);
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const gltf = JSON.parse(contentString);
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addPipelineExtras(gltf);
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const binaryBuffer = glb.subarray(binaryStart, length);
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const buffers = gltf.buffers;
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if (defined(buffers) && Object.keys(buffers).length > 0) {
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// In some older models, the binary glTF buffer is named KHR_binary_glTF
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const binaryGltfBuffer = defaultValue(
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buffers.binary_glTF,
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buffers.KHR_binary_glTF
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);
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if (defined(binaryGltfBuffer)) {
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binaryGltfBuffer.extras._pipeline.source = binaryBuffer;
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delete binaryGltfBuffer.uri;
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}
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}
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// Remove the KHR_binary_glTF extension
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removeExtensionsUsed(gltf, "KHR_binary_glTF");
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return gltf;
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}
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function parseGlbVersion2(glb, header) {
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const length = header[2];
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let byteOffset = 12;
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let gltf;
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let binaryBuffer;
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while (byteOffset < length) {
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const chunkHeader = readHeader(glb, byteOffset, 2);
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const chunkLength = chunkHeader[0];
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const chunkType = chunkHeader[1];
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byteOffset += 8;
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const chunkBuffer = glb.subarray(byteOffset, byteOffset + chunkLength);
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byteOffset += chunkLength;
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// Load JSON chunk
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if (chunkType === 0x4e4f534a) {
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const jsonString = getStringFromTypedArray(chunkBuffer);
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gltf = JSON.parse(jsonString);
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addPipelineExtras(gltf);
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}
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// Load Binary chunk
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else if (chunkType === 0x004e4942) {
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binaryBuffer = chunkBuffer;
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}
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}
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if (defined(gltf) && defined(binaryBuffer)) {
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const buffers = gltf.buffers;
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if (defined(buffers) && buffers.length > 0) {
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const buffer = buffers[0];
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buffer.extras._pipeline.source = binaryBuffer;
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}
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}
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return gltf;
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}
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export default parseGlb;
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