OFF (file format)
OFF is a geometry definition file format containing the description of the composing polygons of a geometric object. It can store 2D or 3D objects, and simple extensions allow it to represent higher-dimensional objects as well. Though originally developed for Geomview, a geometry visualization software, other software has adapted the simple standard.Composition
The composition of a standard OFF file is as follows:
- First line : the letters OFF to mark the file type.
- Second line: the number of vertices, number of faces, and number of edges, in order.
- List of vertices: X, Y and Z coordinates.
- List of faces: number of vertices, followed by the indexes of the composing vertices, in order.
- *Optionally, the RGB values for the face color can follow the elements of the faces.
The four-dimensional OFF format, most notably used by Stella4D, which allows visualization of four-dimensional objects, has a few minor differences:
- First line : the letters 4OFF to mark the file type.
- Second line: the number of vertices, number of faces, number of edges, and number of cells, in order.
- List of vertices: X, Y, Z and W coordinates.
- List of faces: number of vertices, followed by the indexes of the composing vertices, in order.
- List of cells: number of faces, followed by the indexes of the composing faces, in order.
- *Optionally, the RGB values for the cell color can follow the elements of the cells.
Comments are marked with a pound sign : these are not read by the software.Example
OFF
- cube.off
- A cube
8 6 12
1.0 0.0 1.4142
0.0 1.0 1.4142
-1.0 0.0 1.4142
0.0 -1.0 1.4142
1.0 0.0 0.0
0.0 1.0 0.0
-1.0 0.0 0.0
0.0 -1.0 0.0
4 0 1 2 3 255 0 0 #red
4 7 4 0 3 0 255 0 #green
4 4 5 1 0 0 0 255 #blue
4 5 6 2 1 0 255 0
4 3 2 6 7 0 0 255
4 6 5 4 7 255 0 0
