gd::Poly Image,x,y[color]
Use this subroutine to draw a polygon. The arguments x and y should be array of the same length and of the same index values. In other words if x is indexed from 13 to 26 then y should also be indexed from 13 to 26.
The color value is optional. If this is missing the default color is used set by the subroutine gd::SetColor.