I just don't get why there is a glMatrixMode in OpenGL
- by René Nyffenegger
I just don't understand what OpenGL's glMatrixMode is for.
As far as I can see, when glMatrixMode(GL_MODELVIEW) is called, it
is followed by glVertex, glTranslate, glRotate and the like,
that is, OpenGL commands that place some objects somewhere in
the space. On the other hand, if glOrtho or glFrustum or gluProjection
is called (ie how the placed objects are rendered), it has a preceeding call of glMatrixMode(GL_PROJECTION).
I guess what I have written so far is an assumption on which someone will prove
me wrong, but is not the point of using different *Matrix Mode*s exactly
because there are different kinds of gl-functions: those concerned with
placing objects and those with how the objects are rendered?
So, if someone could shed some light on this issue, I'd certainly appreciate
it.