Plotting Generalized Curves  

We have seen how geodesic curves and grid lines can be drawn. The Plot class includes another method, AST_GENCURVE, which allows curves of any form to be drawn. The caller supplies a Mapping which maps offset along the curve into the corresponding position in the current Frame of the Plot. AST_GENCURVE, then takes care of Mapping these positions into graphics coordinates. The choice of exactly which positions along the curve are to be used to define the curve is also made by AST_GENCURVE, using an adaptive algorithm which concentrates points around areas where the curve is bending sharply or is discontinuous in graphics coordinates.

The IntraMap class may be of particular use in this context since it allows you to code your own Mappings to do any transformation you choose.