Contents /
Previous /
Next
Homogeneous Coordinates
OpenGL works in the homogeneous coordinates of
three-dimensional projective geometry, so for internal
calculations, all vertices are represented with four
floating-point coordinates
(x, y, z, w)
If w is different from zero, these coordinates correspond to
the euclidean three-dimensional point:
(x/w, y/w,z/w).
You can specify the w coordinate in OpenGL
commands, but that is rarely done.
If the w coordinate
is not specified, it is understood to be 1.0.