## Study week day 3: Vectors Matrices and Vertices

In this post, I blindly set out on a mission, a mission that may or may not change, and has changed.

I was going through these tutorials and as helpful as they are, it’s just syntax at this point. I am able to modify, through trial and error, and create and move things, the problem is I don’t fully understand what’s going down. In these three things: Vectors Matrices and Vertices, are giant question marks.

So I’ve decided to back it up, and get an understanding of how to represent, modify, and move 3D objects.

What I know and understand.

A vertices is a set of three x, y and z axis that create one point (or corner) of a 3D object. x and y axis is left right, top and down, 2D stuff, the z axis is the third dimension.

These are stored in a matrix, which is just a grid of numbers, rows and columns, that hold these vertices, kinda like an array of vertices. example:

1, 0, 0, 0

0, 1, 0, 0

0, 0, 1, 0

0, 0, 0, 1

This is called the identity matrix (correct me if I’m wrong). It’s like a null matrix as anything you try to translate it into would end up being the same thing as it was before the translation. I cannot explain it much more as the technical concepts of translation still escapes me, but I know it’s used to move the objects axis in a uniform manner, keeping the integrity of the shape, I get the concepts, I just don’t know how it all works (yet).

Not sure what the fourth axis is for; I know it should always be a one, and “is needed to transform points this way” I read that it was also not always needed, but helpful. It’s a one, so it’s not going to be a problem, as one times anything is always the later.

I’m spending time just doing matrix math, and it’s fun, and is giving me a better understanding of what’s going on, then, I will go back to the code. Really, this matrix math concept is the only thing that’s new in what I’m doing, so I’m pretty confident that I’m on the right track with this.

March 4, 2010 at 4:09 pm

the fourth axis is for scaling and transparency as I remember.this page of gam666 may help you a little bit.