PLSCMAP1L(3plplot)						    PLplot API							PLSCMAP1L(3plplot)

NAME

       plscmap1l - Set color map1 colors using a piece-wise linear relationship

SYNOPSIS

       plscmap1l(itype, npts, pos, coord1, coord2, coord3, rev)

DESCRIPTION

       Set  color  map1  colors  using a piece-wise linear relationship between position in the color map (from 0 to 1) and position in HLS or RGB
       color space (see the PLplot documentation).  May be called at any time.

       The idea here is to specify a number of control points that define the mapping between palette 1 input positions (intensities) and HLS  (or
       RGB).   Between these points, linear interpolation is used which gives a smooth variation of color with input position.	Any number of con-
       trol points may be specified, located at arbitrary positions, although typically 2 - 4 are enough. Another way of stating this is  that	we
       are traversing a given number of lines through HLS (or RGB) space as we move through color map1 entries.  The control points at the minimum
       and maximum position (0 and 1) must always be specified.  By adding more control points you can get more variation.  One good technique for
       plotting  functions that vary about some expected average is to use an additional 2 control points in the center (position ~= 0.5) that are
       the same lightness as the background (typically white for paper output, black for crt), and same hue as the boundary control points.   This
       allows the highs and lows to be very easily distinguished.

       Each  control  point must specify the position in color map1 as well as three coordinates in HLS or RGB space.  The first point must corre-
       spond to position = 0, and the last to position = 1.

       The hue is interpolated around the "front" of the color wheel (red<->green<->blue<->red) unless the "rev" flag is set  to  true,  in  which
       case  interpolation  (between  the  i  and i + 1 control point for rev[i]) proceeds around the back (reverse) side.  Specifying rev=NULL is
       equivalent to setting rev[]= false for every control point.

       Bounds on coordinatesRGBR[0, 1]magnitudeRGBG[0, 1]magnitudeRGBB[0,  1]magnitudeHLShue[0,  360]degreesHLSlightness[0,  1]magnitudeHLSsatura-
       tion[0, 1]magnitude

       Redacted form: plscmap1l(itype, pos, coord1, coord2, coord3, rev)

       This function is used in examples 8,11,12,15,20,21.

ARGUMENTS

       itype (PLBOOL, input)
	      true: RGB, false: HLS.

       npts (PLINT, input)
	      number of control points

       pos (PLFLT *, input)
	      position for each control point (between 0.0 and 1.0, in ascending order)

       coord1 (PLFLT *, input)
	      first coordinate (H or R) for each control point

       coord2 (PLFLT *, input)
	      second coordinate (L or G) for each control point

       coord3 (PLFLT *, input)
	      third coordinate (S or B) for each control point

       rev (PLBOOL: *, input)
	      reverse flag for each control point. (rev[i] refers to the interpolation interval between the i and i + 1 control points).

AUTHORS

       Geoffrey  Furnish  and  Maurice LeBrun wrote and maintain PLplot.  This man page was automatically generated from the DocBook source of the
       PLplot documentation, maintained by Alan W. Irwin and Rafael Laboissiere.

SEE ALSO

       PLplot documentation at http://plplot.sourceforge.net/resources.

								   August, 2012 						PLSCMAP1L(3plplot)