Elements are the shapes in the model. The polygonal elements are points, lines and faces. Free-form elements are on the Free-form curves and surfaces page.
p – Point
One or more points, each given by a geometric vertex number.
p 1 2 3l – Line
A polyline through at least two vertices, in order. Each point may also name a
texture vertex, as v/vt. Lines have no normals.
l 1 2 3 4
l 5/1 6/2f – Face
A polygon of at least three corners. Its corners run counterclockwise when the face is seen from the outside. A corner is a geometric vertex number, optionally followed by a texture vertex number and a normal number, separated by slashes.
| Form | Names | Example |
|---|---|---|
v | The vertex only | f 1 2 3 |
v/vt | Vertex and texture vertex | f 1/1 2/2 3/3 |
v//vn | Vertex and normal | f 1//1 2//1 3//1 |
v/vt/vn | All three | f 1/1/1 2/2/1 3/3/1 |
Every corner of a face has the same form: the specification says mixing them is not legal. If a face names no texture vertices it ignores any texture map, and if it names normals they take the place of smoothing groups.
fo is an old name for f and is no longer used since version
2.11 of the format. It is read the same way, and written back as f.
v 0 0 0
v 1 0 0
v 1 1 0
v 0 1 0
vn 0 0 1
f 1//1 2//1 3//1 4//1
f -4//-1 -3//-1 -2//-1What the explorer checks
When a file is opened here, every element is checked as it is read. These are this site’s reports; a program opening the file may treat them differently.
- A reference out of range: 0, a negative number that reaches back past the first vertex of its kind, or a positive number with no such vertex in the file.
- A reference to a vertex defined later in the file, which is unusual.
- A face with fewer than three corners, or one that uses the same vertex twice.
- A face with no area, because its corners lie on one point or line.
- A polygon that is not flat: one of its corners is more than 1% of the polygon’s size away from the plane through the others.
- A face that mixes corner forms.