23.1.2 Orthographic Projection

The call glOrtho, r, b, t, u, f(l, r, b, t, u, f) generates R, where:

$$R = \pmatrix{{2 \over {r-l}}&0&0&-{{r+l} \over {r-l}}\cr 0&{... ...over 2}\cr 0&0&{{f-n} \over 2}&{{n+f} \over 2}\cr 0&0&0&1\cr}$$

R is defined as long as $l \neq r$, $t \neq b$, and $n \neq f$.