DEMO version ! After registering you will receive a complete version.

Description

This functions sets the rectangular clipping region. All graphics outside
this rectangle will not be drawn. The rectangle is defined by the points
('Xleft','Ytop') and ('Xright','Ybottom').
If all 4 parameters have the value 0, the current screen width and height
become the new 'Xright' and 'Ybottom'. 'Xleft' and 'Ytop' are 0.
The function returns the coordinates of the old viewport.

This function can be used only if you have set the screen to a graphic mode
using FGLSetMode().


Syntax

  FGLSetViewport(< Xleft >,< Ytop >,< Xright >,< Ybottom >) -> OldView.