文件格式：

catpart catproduct model exp session prt asm xpr xas ipt iam sldprt sldasm x_t x_b igs iges stp step vda sat sab ply obj qobj off ptx vmi bre dae ctm pts apts xyz gts pdb tri asc x3d x3dv wrl 3d 3ds ac ac3d acc ase ask b3d blend bvh cob csm dxf enff hmp ifc irr irrmesh lwo lws lxo m3 md2 md3 md5anim md5camera md5mesh mdc mdl mesh.xml mot ms3d ndo nff obj off pk3 ply prj q3o q3s raw scn smd stl ter uc vta x xgl xml zgl