I am having really two simple questions, but following two things are confusing me.
If I know plane parameter (v3) of a given plane (say AB); if a pair of rays are incident at a point on the plane (say, point - O), how can I compute their incident angles (i.e. POC and POD), using v1, v2, v3? Where v1, v2 are vectors along the incident rays.
Similarly, if I have many pairs of incident rays falling onto this plane, then, how can I really identify which pairs are making large angles and which are not (i.e. DOC angle). I noticed that to get DOC angle some time, I have to add both incident angles and some time have to subtract them.