According to MSDN, we are multiplying the current matrix with the perspective matrix. What matrix are we talking about here? Also from MSDN:
"The glFrustum function multiplies the current matrix by this matrix, with the result replacing the current matrix. That is, if M is the current matrix and F is the frustum perspective matrix, then glFrustum replaces M with M • F."
Now, from my current knowledge of grade 12 calculus (in which I am currently), M is a vector and M dot product F returns a scalar, so how can one replace a vector with a scalar?
I'm also not sure what "clipping" planes are and how they can be referenced via one float value.
Please phrase your answer in terms of the parameters, and also conceptually. I'd really appreciate that.
I'm trying to learn openGL via this tutorial: http://www.youtube.com/watch?v=WdGF7Bw6SUg. It is actually not really good because it explains nothing or else it assumes one knows openGL. I'd really appreciate a link to a tutorial otherwise, I really appreciate your time and responses! I'm sure I can struggle through and figure things out.
You misunderstand what it's saying. M is a matrix. M•F therefore is also a matrix. It constructs a perspective matrix. See this article for an explanation of how it is constructed and when you want to use glFrustum() vs. gluPerspective():
glFrustum() and gluPerspective() both produce perspective projection matrices that you can use to transform from eye coordinate space to clip coordinate space. The primary difference between the two is that glFrustum() is more general and allows off-axis projections, while gluPerspective() only produces symmetrical (on-axis) projections. Indeed, you can use glFrustum() to implement gluPerspective().
Clipping planes are planes that cut out sections of the world so they don't have to be rendered. The frustum describes where the planes are in space. Its sides define the view volume.