OBJ (or .OBJ) is a geometry definition file format first developed by Wavefront Technologies for its Advanced Visualizer animation package. The file format is open and has been adopted by other 3D graphics application vendors. The OBJ file format is a simple data-format that represents 3D geometry alone — namely, the position of each vertex, the UV position of each texture coordinate vertex, vertex normals, and the faces that make each polygon defined as a list of vertices, and texture vertices. Vertices are stored in a counter-clockwise order by default, making explicit declaration of face normals unnecessary. OBJ coordinates have no units, but OBJ files can contain scale information in a human readable comment line. Anything following a hash character (#) is a comment.

this is a comment

An OBJ file may contain vertex data, free-form curve/surface attributes, elements, free-form curve/surface body statements, connectivity between free-form surfaces, grouping and display/render attribute information. The most common elements are geometric vertices, texture coordinates, vertex normals and polygonal faces:

List of geometric vertices, with (x, y, z, [w]) coordinates, w is optional and defaults to 1.0.

v 0.123 0.234 0.345 1.0 v ...

List of texture coordinates, in (u, [v, w]) coordinates, these will vary between 0 and 1. v, w are optional and default to 0.

vt 0.500 1 [0] vt ...

List of vertex normals in (x,y,z) form; normals might not be unit vectors.

vn 0.707 0.000 0.707 vn ...

Parameter space vertices in (u, [v, w]) form; free form geometry statement (see below)

vp 0.310000 3.210000 2.100000 vp ...

Polygonal face element (see below)

f 1 2 3 f 3/1 4/2 5/3 f 6/4/1 3/5/3 7/6/5 f 7//1 8//2 9//3 f ...

Line element (see below)

l 5 8 1 2 4 9 A vertex is specified via a line starting with the letter v. That is followed by (x,y,z[,w]) coordinates. W is optional and defaults to 1.0. A right-hand coordinate system is used to specify the coordinate locations.