%N grscr %F $MIR/src/grscr.f
%D Set color representation
%B
      SUBROUTINE GRSCR (CI, CR, CG, CB)
      INTEGER  CI
      REAL     CR, CG, CB

 GRPCKG: SET COLOUR REPRESENTATION -- define the colour to be
 associated with a colour index.  Ignored for devices which do not
 support variable colour or intensity.  On monochrome output
 devices (e.g. VT125 terminals with monochrome monitors), the
 monochrome intensity is computed from the specified Red, Green, Blue
 intensities as 0.30*R + 0.59*G + 0.11*B, as in US color television
 systems, NTSC encoding.  Note that most devices do not have an
 infinite range of colours or monochrome intensities available;
 the nearest available colour is used.

 Arguments:

 CI (integer, input): colour index. If the colour index is outside the
       range available on the device, the call is ignored. Colour
       index 0 applies to the background colour.
 CR, CG, CB (real, input): red, green, and blue intensities,
       in range 0.0 to 1.0.
