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From: Paul Wellner Bou <paul@pu...>  20080314 10:19:56

Hello again, I thought about other possibilities... well, the nicest way would be a triangulation working like the matlab griddata function. As the griddata in matlab is a compiled mex file and the source not published I can't have a look inside it. There are a few workarounds... 1) Using polar coordinates as Alan Irwin suggested. Using this method I have to trust the triangulation alogrithm of plplot to work right with more or less rectangular data. 2) As this is a ray (wave front) tracing result it would be possible to calculate the rays in a way to produce a rectangular grid. As side effect I would save calculation time: As the intersections of rays and spline surfaces is done by iterations (newton) I would save this step if I define the intersections before and just calculate then the resulting direction. Concerning this fact, an interesting idea. 3) Converting the circular eye glass blanks to rectangles. Calculating the rays through them and using plgriddata to calculate the regular grid. As in 1) I have to assume that the plgriddata function works everytime as expected. I could cut the points outside the circle off, later, before drawing them and before defining the contour levels. Perhaps the best way would be a mixture between 2) and 3). Using a rectangular spot with rays going through a rectangular eye glass. I'll try... Thanks very much and regards Paul. 