This allows you to draw arbitrary polylines over your charts, for example to add small diagrams, draw boxes around points, join points which are not normally in sequence, and so on.

chPlot 2 4 3              
chDraw chMapCoords 2 2½1 2, 3 3
View chClose

This will join the first to the last data point with a solid line using the colour of the last chart plotted. The columns of the ‘draw’ matrix give the (x,y) values in the two-column case. Note the mapping from chart co-ordinates to absolute values in points.

If three or more columns or arrays are passed:

• col-1 is the ‘0=penup; 1=pendown; 2=brushfill’ marker to split out polylines
• col-2 is the x-value (points from left edge of current frame)
• col-3 is the y-value (points from bottom of current frame)
• col-4 (if given) is the over-ride colour (index to colourmap or RGB composite)
• col-5 (if given) is the pattern fill (default half-tone) used if 2 appears in col-1
• col-6 (if given) is the line-weight (black if filled, else in given colour)

Note that if you draw your diagrams before the plot, you should call chSet 'nowipe' to prevent Rain from clearing the plotting space and probably wiping part or all of your artwork.