clear(3G)

NAME
     clear - clears the viewport

FORTRAN 77 SPECIFICATION
     subroutine clear

PARAMETERS
     none

DESCRIPTION
     clear sets the bitplane area of the viewport to the current color.
     Multiple bitplane buffers can be cleared simultaneously using the backbu,
     frontb, and zdraw commands.  Current polygon fill pattern and writemask
     affect the operation of clear.  The screen mask, when it is set to a
     subregion of the viewport, bounds the cleared region.  Alpha function,
     blend function, logical operation, stenciling, texture mapping, and z
     buffering, however, are ignored by clear.  Stencil and z buffer contents
     are not affected by clear (except in the special case of zdraw).

     Like other drawing commands, clear operates on the currently active
     framebuffer, one of normal, popup, overlay, or underlay, based on the
     current draw mode (see drawmo).

     After clear executes, the graphics position is undefined.

SEE ALSO
     afunct, backbu, blendf, czclea, drawmo, frontb, logico, scrmas, setpat,
     stenci, texbin, zbuffe, zdraw

NOTE
     On the IRIS-4D B, G, GT, GTX, and VGX models, clear runs faster when the
     window is completely unobscured.

     On the Personal Iris, XS, XS24, XZ, Elan and Extreme systems, clear runs
     faster when the visible window area consists of four or fewer rectangular
     regions.