Hallo Michael,
schön, dass du die Definition des Richtungscosinus geklärt hast. Zu deiner Sourcecodefrage ist mir eingefallen, dass Ivan Krastev, der Designer des Raytrace-Programms MODAS, in der ReadMe-Datei erwähnte, dass er vor der Modas-Entwicklung mal einen Sourcecode veröffentlicht hat. Hier die entsprechende Passage:
> "After I advertised my "Telescope Design and Analysis Tools" in "Sky & Telescope" magazine (Software Showcase, October issue, 1997, p.65) over 100 amateur astronomers from all over the world contacted me. Many amateurs were using RAYTRACE.EXE from Harrie Rutten and Martin Venrooij, but that program was already compiled (executable file) and could not be changed.
Amateur astronomers and telescope makers were particularly glad that my tools were in BASIC and that the source code was provided. Hence, they could extend, change and customize the software for their own particular needs. Furthermore, a working skew ray tracing numerical method for amateurs (without bugs) had not previously been published. Some telescope makers also asked for tools for advanced amateur astronomers and programmers. "
Ist zwar 'nur' in Basic, aber vielleicht hilft es dir trotzdem weiter. Wenn du an die S+T Ausgabe nicht herankommst, kann ich mir vorstellen, dass Ivan Krastev dir gern weiterhilft. Seine Adresse findest du in der Modas-ReadMe (kostenlose Demo), wahrscheinlich auch wenn du unter modas googlest.
Gruß
Hans-Jürgen