Method parse

packages/asset-system/src/loaders/FBXLoader.ts:160–322

* Parse FBX content * 解析 FBX 内容

(content: IAssetContent, context: IAssetParseContext)

     * 解析 FBX 内容
     */
    async parse(content: IAssetContent, context: IAssetParseContext): Promise<IGLTFAsset> {
        const buffer = content.binary;
        if (!buffer) {
            throw new Error('FBX loader requires binary content');
        }

        // Detect format (binary or ASCII)
        // 检测格式（二进制或 ASCII）
        // FBX binary header is "Kaydara FBX Binary  \0" (21 bytes + null)
        // FBX 二进制头是 "Kaydara FBX Binary  \0"（21字节 + 空字节）
        const headerBytes = new Uint8Array(buffer, 0, Math.min(21, buffer.byteLength));
        const headerString = String.fromCharCode(...headerBytes);
        const isBinary = headerString.startsWith('Kaydara FBX Binary');

        let geometries: FBXGeometry[];
        let models: FBXModel[];
        let materials: FBXMaterial[];
        let animStacks: FBXAnimationStack[] = [];
        let deformers: FBXDeformer[] = [];
        let connections: FBXConnection[] = [];

        if (isBinary) {
            const result = this.parseBinary(buffer);
            geometries = result.geometries;
            models = result.models;
            materials = result.materials;
            animStacks = result.animStacks;
            deformers = result.deformers;
            connections = result.connections;
        } else {
            // Try ASCII parsing (no animation support for ASCII yet)
            // 尝试 ASCII 解析（ASCII 格式暂不支持动画）
            const text = new TextDecoder().decode(buffer);
            const result = this.parseASCII(text);
            geometries = result.geometries;
            models = result.models;
            materials = result.materials;
        }

        // Build skeleton data FIRST to get cluster -> joint index mapping
        // 先构建骨骼数据以获取簇->关节索引映射
        const clusterToJointIndex = new Map<bigint, number>();
        const skeleton = this.buildSkeletonData(deformers, models, connections, clusterToJointIndex) ?? undefined;

        // Convert to mesh data with skinning (using the cluster mapping)
        // 转换为带蒙皮的网格数据（使用簇映射）
        const meshes = this.buildMeshes(geometries, deformers, connections, clusterToJointIndex);

        // Build material list
        // 构建材质列表
        const gltfMaterials = this.buildMaterials(materials);

        // Build geometry ID to mesh index map | 构建几何体ID到网格索引的映射
        const geometryToMeshIndex = new Map<bigint, number>();
        geometries.forEach((geom, index) => {
            if (index < meshes.length) {
                geometryToMeshIndex.set(geom.id, index);
            }