One thing bugging me and that is that I need to provide a link to navigationalalgorithms.com . That is where I got the basic point generator. I modified it but started with what Andres Ruiz wrote. Here is the link to the paper. http://www.mediafire.com/file/pp89of9q9fk4rbi/rotmatricesCoP.zip/file The title is “Use of Rotation Matrices to Plot a Circle of Equal Altitude” and is inside the zip file.
I’ve read some of his other papers too and I think there could be an efficient way to calculate an intersection using some of the functions I already have.