Reprinted: https: //www.cnblogs.com/Taiwantomzhang/p/3993703.html
.obj file, each line indicates that the significance of the line identifier.
"V" - coordinates of the point, the order of x, y, z;
"Vt" - texture coordinates, the order of x, y;
"Vn" - Vector coordinate method, the order of x, y, z;
"F" - as used in surface texture coordinate index point coordinates / / vector coordinate method;
"Mtllib" - material library file obj file used.;
"G" - a group name of the group;
"Usemtl" - once the use of the flag, the flag behind the "f" of all affected until the next "usemtl"; "usemtl" logo symbol material used are from the material library file withdrawn; Group inside "f" 0-N can use a "usemtl" opposite rendered display control, when using more than 1 "usemtl" flag, the processing program that has been read to "f" are refractory; obj read while viewing the source code, some uses this identifier, and some do not use this flag, used some "usemtl" flag to "f" dividing the read surface, the process described herein using "usemtl" flag to "f" surface is divided into a mesh, but taking into account different group can use the same "usemtl" flag (i.e., a different group are used usemtl AAA), therefore the "g" and "usemtl "combine the two names as the name of the mesh