defpat(3G)

NAME
     defpat - defines patterns

FORTRAN 77 SPECIFICATION
     subroutine defpat(n, size, mask)
     integer*4 n, size
     integer*2 mask((size*size)/16)

PARAMETERS
     n      expects the constant that you want to use as an identifier for the
            pattern described by mask.  This constant is used as an index into
            a table of patterns. By default, pattern 0 is a 16X16 solid
            pattern that cannot be changed.

     size   expects the size of the pattern: 16, 32, or 64 for a 16x16-,
            32x32-, or 64x64-bit pattern, respectively.

     mask   expects an array of 16-bit integers that form the actual bit
            pattern.  The system stores the pattern in a pattern table at
            index n.  The pattern is described from left to right and bottom
            to top, just as characters are described in a raster font.

DESCRIPTION
     defpat allows you to define an arbitrary pattern and assign it an
     identifier. You can later reference this pattern in other routines via
     its identifier.  Patterns are available to all windows when using
     multiple windows.

     Patterns affect the filling of polygons, including rectangles, arcs, and
     circles, as well as polygons specified with individual vertices.  They
     also affect the filling of the window when clear(3g) is called.  Patterns
     have no effect on the scan conversion of points, lines, or characters, or
     on pixel write or copy operations.

     When a pattern is active (see setpat) it is effectively replicated across
     the entire screen, with the edges of pattern tiles aligned to the left
     and bottom edges of the screen.  Bit 15 of each 16-bit description word
     is leftmost, and words are assembled left to right, then bottom to top,
     to form each pattern square.  Pixels on the screen that correspond to
     zeros in the pattern remain unmodified during scan conversion of
     polygons.  No changes are made to any bitplane bank of a protected pixel.

SEE ALSO
     deflin, defras, getpat, setpat

NOTES
     This routine is available only in immediate mode.

     Some machines do not support 64x64 patterns.  Call getgde(GDPATS) to
     determine the availability of 64x64 patterns.
     There is a performance penalty on the Personal Iris for non-solid
     patterns.

     When defpat is used to modify the current pattern, the new pattern
     becomes current only when setpat is called again.