Objects and Materials Part 1 (Wavefront 3D Model Specification)
Published:
1.1. wavefront .obj
the OBJ format, the MTL format was used and documented by Wavefront Technologies in the 1990s in association with its Advanced Visualizer software. Object files can be in ASCII format (.obj) or binary format (.mod). Vertices are stored in a counter-clockwise, and in object space (un-normalized).