VIEWPORTS IN OPEN GL

• To specify the viewport parameters, do
glViewport( xvmin, yvmin, vpWidth, vpHeight)
with parameters given in integer screen coordinates. The first two give the
position of the lower left corner relative to the lower left corner of the display
window.

• By default, the viewport is the entire window. window.

• You can create multiple viewports within a window.

• To get the parameters for the active viewport, use
glGetIntegerv( GL_VIEWPORT, vpArray);
where vpArray is a 4 element integer array. The contents of vpArray after
the function returns will be the same as the arguments given to glViewport
in the same order