Hello there!
Ever since, I used C-Funtions for my vector/vertex manipulation-code. I now decided to wrap my vectors up in C++ classes and ran across the problem of properly handling homogenous vectors. As the packing of vectors and vertices in 4-float manner is ideal, you essentially get a 4th component for free. In your math libraries, do you handle the 4th component (commonly named w) at all? I mean, the difference of two vertices (with w=1 per definition) yields a vector (w=0), which makes perfect sense, but how often would one really need this distinction in-data? You see, I want to handle things nice and correctly, but implementing the dot-product for four dimensions for example breaks nice packing for plane representations or I cannot use the standard operations in derived types. Did you ever come across occasions, which led you to set w to anything but 0 or 1, meaning you need mathematically correct handling of homogenous vectors?
I hope I explained my concerns understandably.
Best regards,
Michael
but implementing the dot-product for four dimensions for example breaks nice packing for plane representations or I cannot use the standard operations in derived types
I don’t understand you here, can you explain explicate a bit more?
Hey.
I specifically meant Packing of Normal and distance (Hesse-Form) of the plane into a 4d vector. If that vector implements its operations in 4D, the plane class would have to reimplement all needed operations on vectors.
After all, my concerns here are all about style.
Yes you would have to overload functions like cross product, addition,… for a plane or don’t make a distinction between points vectors and planes as w is always 0 for a vector, this would not cause problems.
Yes, now that I thought about using SSE extensions eventually, i will have to implement that plane packing distinctly anyways, since those SSE operations always work on 1 or all 4 components, if I understand that correctly. So I’ll probably ignore w or will do it correctly when it comes for free and add special code for planes.