When calculating the face normal, can I get the value by drawing a line anywhere on the surface, and finding the perpendicular line? IN other words, the normal is just the perpendicular slope, and not actually holding values relative to the face?

Correct. But there's no reason the face normal has to be perpendicular to the face if you're wanting different lighting effects.

Thanks Steve, I really appreciate your help. Could you recommend any particular book or article on DX or perhaps a good math book?

If you just want to get the normal for a triangle, you'll need three points, since there's an infinite number of lines perpendicular to a line.

Usually, if you have three vertices A, B and C, you can get the normal as:
normalize(vAB x vAC)
Where vAB is the vector from A to B (or B-A if you have A and B as points), vAC is the vector from A to C, and x is the cross product.
Also note that the order you do the cross product in depends on the winding order of the triangle (I.e. vAB x vAC may give you the opposite of the normal if your points are in counter-clockwise order, in which case you'd do vAC x vAB instead).

wow this sheds some light on things, I actually thought vectors were directions. I thought wrong. Thanks again.

Quote:Original post by VprMatrix89
wow this sheds some light on things, I actually thought vectors were directions. I thought wrong. Thanks again.

A vector has both magnitude (length) and direction. The vector (0, 0, 1) has a length of 1, and a direction of +Z. The vector (0, 0, 2) has the same direction, but twice the length.

If you have two points, and you want to get a vector that describes point B from point A (The direction from point A to point B), you just subtract B from A. Example:

That way, vAB is the direction you need to go in from point A (or the coordinates you need to add to point A) to get to point B.

Since a 3D vector has 3 components, and a 3D point has 3 components, they're usually used interchangeably.

I'd highly recommend having a look on Google for some 3D geometry tutorials; this stuff is fairly fundamental to 3D graphics and D3D and you'll probably have difficulty with other areas of D3D if you're not completely clear on the basics first.