mapcol(3G)

NAME
     mapcol - changes a color map entry

FORTRAN 77 SPECIFICATION
     subroutine mapcol(i, red, green, blue)
     integer*4 i, red, green, blue

PARAMETERS
     i       expects the index into the color map.

     red     expects an intensity value in the range 0 to 255 for red to be
             associated with the index.

     green   expects an intensity value in the range 0 to 255 for green to be
             associated with the index.

     blue    expects an intensity value in the range 0 to 255 for blue to be
             associated with the index.

DESCRIPTION
     mapcol loads entry i of the color map for the current drawing mode with
     (red, green, blue).  Pixels written with color index i are displayed with
     the specified RGB intensities.  The valid range for i depends on the
     number of bitplanes available in the current drawing and buffer modes,
     i.e. the value returned by getpla.  Using Ni to represent 2 raised to the
     return value of getpla in drawing mode i, the valid ranges are:

          NORMDR       0 to Nn-1.
          OVRDRW       1 to No-1.
          UNDRDR       0 to Nu-1.
          PUPDRW       1 to Np-1.
          CURSDR       1 to getgde(GDBCUR).

     If Ni is 1, then no indices are valid.  Invalid indices are ignored by
     mapcol.

     In multimap mode, mapcol updates only the small color map currently
     selected by setmap.

     The color map entry that controls the color of the cross-hair cursor
     (cursor type CCROSS) is returned by the getgde inquiry GDXHCI.

SEE ALSO
     color, cursty, drawmo, gammar, getgde, getmco, getpla, glcompa, setmap

NOTES
     This subroutine is available only in immediate mode.

     On the IRIS-4D G, you should not alter the top 256 colors (color indices
     3840 to 4095).  The system uses these colors for the cursor, overlay bit-
     planes, and RGB mode. If you alter the colors to which these features are
     mapped, some screen features will appear in strange colors.
     In IRIX 4.0, mapcolor is implemented as an emulation layer on top of the
     request XStoreColors.  In order to avoid a serious degradation in perfor-
     mance, mapcolor requests are buffered and only sent to the window server
     when an input routine (e.g. qtest) or gflush is called.

     In situations where the immediate results of mapcolor are more important
     than speed, there is a glcompat call to disable this behavior.