I am taking a course in computergraphics and we talk a lot about OpenGL and the math you need to do everything OpenGL does "by hand". A Question which was asked in an old exam (I am preparing at the moment) was:
Why is the following Cameraposition considered problematic? eye = (0,0,0), at=(0,-2,0) and up = (0,1,0)
Is it because the eye-at = (0,2,0) and therefore the cross product of up x (eye-at) = (0,0,0) and that means, that no real transformation matrix can be constructed?
I found a post where someone asked a similiar question ( https://gamedev.stackexchange.com/a/45328/50476 ), but the explanation is somehow strange for me, because he says that he wants to calculate the cross product of the eye vector and the up vector. But there is no need for that, if you want to be able to calculate the transformation matrix?