Method extractGeometry

packages/asset-system/src/loaders/FBXLoader.ts:690–731

* Extract geometry from FBX Geometry node * 从 FBX Geometry 节点提取几何数据

(node: FBXNode)

     * 从 FBX Geometry 节点提取几何数据
     */
    private extractGeometry(node: FBXNode): FBXGeometry | null {
        // Get geometry ID and name
        // 获取几何 ID 和名称
        const id = node.properties[0] as bigint;
        const nameProp = node.properties[1];
        let name = 'Geometry';
        if (typeof nameProp === 'string') {
            // FBX name format: "Name\x00\x01Geometry"
            name = nameProp.split('\x00')[0] || name;
        }

        // Find Vertices, PolygonVertexIndex, etc.
        // 查找 Vertices、PolygonVertexIndex 等
        let vertices: number[] = [];
        let indices: number[] = [];
        let normals: number[] | undefined;
        let uvs: number[] | undefined;

        for (const child of node.children) {
            if (child.name === 'Vertices') {
                const prop = child.properties[0];
                vertices = this.toNumberArray(prop);
            } else if (child.name === 'PolygonVertexIndex') {
                // FBX uses negative indices for polygon end markers
                // FBX 使用负索引作为多边形结束标记
                const prop = child.properties[0];
                const polyIndices = this.toNumberArray(prop);

                // Convert polygon indices to triangles
                // 将多边形索引转换为三角形
                indices = this.triangulatePolygons(polyIndices);
            } else if (child.name === 'LayerElementNormal') {
                normals = this.extractLayerElement(child, 'Normals');
            } else if (child.name === 'LayerElementUV') {
                uvs = this.extractLayerElement(child, 'UV');
            }
        }

        if (vertices.length === 0) return null;

        return { id, name, vertices, indices, normals, uvs };
    }

    /**
     * Convert FBX property to number array