question: @ Override public void perspective ( float fov , float aspect , float zNear , float zFar ) { float ymax = zNear * ( float ) Math . tan ( fov / 2 ) ; float ymin = - ymax ; float xmin = ymin * aspect ; float xmax = ymax * aspect ; frustum ( xmin , xmax , ymin , ymax , zNear , zFar ) ; }
target:  Similar to gluPerspective(). Implementation based on Mesa's glu.c