Viewport Routines.

viewport(left, right, bottom, top)

Specify which part of the screen to draw in. Left, right, bottom, and top are real values in screen coordinates (-1.0 to 1.0).

    Fortran:
         subroutine viewport(left, right, bottom, top)
         real left, right, bottom, top

    C:
         vogle_viewport(left, right, bottom, top)
              float      left, right, bottom, top;

    Pascal:
         procedure ViewPort(left, right, bottom, top: real);

pushviewport()

Save current viewport.

    Fortran:
         subroutine pushviewport

    C:
         vogle_pushviewport()

    Pascal:
         procedure PushViewPort;

popviewport()

Retrieve last viewport.

    Fortran:
         subroutine popviewport

    C:
         vogle_popviewport()

    Pascal:
         procedure PopViewPort;

getviewport(left, right, bottom, top)

Returns the left, right, bottom and top limits of the current viewport in screen coordinates (-1.0 to 1.0).

    Fortran:
         subroutine getviewport(left, right, bottom, top)
         real left, right, bottom, top

    C:
         vogle_getviewport(left, right, bottom, top)
              float      *left, *right, *bottom, *top;

    Pascal:
         procedure GetViewPort(var left, right, bottom, top: real)

expandviewport()

When Vogle does viewport calculations, it will normally begin by using the largest square it can fit onto the actual display device. This call says to use the whole device... however you must then take into account any distortion that will occur due to the non square mapping. Thus, a viewport of (-1.0, 1.0, -1.0, 1.0) will map into the whole display device.

    Fortran:
        subroutine expandviewport

    C:
        vogle_expandviewport()

    Pascal:
        procedure ExpandViewport

unexpandviewport()

Does the reverse of expandviewport. Basically, it returns vogle to using the largest square of the device for it's viewport calculations.

    Fortran:
        subroutine unexpandviewport

    C:
        vogle_unexpandviewport()

    Pascal:
        procedure UnExpandViewport