Positionable Camera

Cameras, like dielectrics, are a pain to debug, so I always develop mine incrementally. First, let’s allow for an adjustable field of view (fov). This is the visual angle from edge to edge of the rendered image. Since our image is not square, the fov is different horizontally and vertically. I always use vertical fov. I also usually specify it in degrees and change to radians inside a constructor — a matter of personal taste.