scrmas(3G)scrmas(3G)NAMEscrmas - defines a rectangular screen clipping mask
FORTRAN 77 SPECIFICATION
subroutine scrmas(left, right, bottom, top)
integer*4 left, right, bottom, top
PARAMETERS
left expects the window coordinate of the left-most pixel column
within the mask region.
right expects the window coordinate of the right-most pixel column
within the mask region.
bottom expects the window coordinate of the lowest pixel row within the
mask region.
top expects the window coordinate of the highest pixel row within
the mask region.
DESCRIPTIONscrmas defines a subregion of the current viewport that can be updated by
drawing commands. Pixels outside this region cannot be modified by any
drawing commands, including point, line, polygon, character, pixel write,
and pixel copy commands. All pixel bitplane buffers, including color,
depth, accumulation, and stencil buffers, are write protected. scrmas
operates in all draw modes.
The enabled subregion is specified as a screen-aligned rectangle in
window coordinates. Like viewpo, the boundary specification is
inclusive, so the call scrmas(0,0,0,0) specifies a 1-pixel rectangle in
the lower-left corner of the window.
When viewpo is called, the screen mask is set to match the newly
specified viewport. Any previous scrmas specification is lost.
scrmas must be specified entirely within the current viewport.
SEE ALSO
drawmo, getscr, viewpo
NOTE
If you set left to be greater than right or bottom to be greater than
top, all pixels in the viewport are write protected.
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