Lines, who doesn't love lines. They start at one point and end at another. In fact, lines are essential. What makes up a triangle? 3 lines. How do we draw a circle? A lot of lines. Knowing about them would be a good idea :)
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Pythagoras theorem is essential if you are doing anything that involves triangles. One of the building blocks of mathematics.
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The distance formula is one of the first things you learn once you get into maths. It is fundamental, especially when it comes to collision in computer games.
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Level of Detail is a means of decreasing the polygon count of an object to gain a speed boost in your application. This is an extremely simple take on this, which simply draws every fourth vertex. The best part is, that on such a large terrain, you don't even notice this.
Vertex Buffer Objects are used to store vertices, their indices and other information on the graphics card, for OpenGL to access directly. They are extremely fast and effecient, and are meant to supersede Display Lists. So lets use them for our terrain!
Textures are going to be what make and break this terrain. A nice looking tutorial, and you will be seeing grass, mud, rocks and sand, but a bad texture and you will see just a bunch of colors. Lets add a nice texture to our terrain shall we?
We have a basic class setup to hold our terrain, so now lets load in some data for us to display. 
The moment we have been waiting for. Lets finally get something drawing out to our window. Even if it doesn't look like we would expect :) 
We have a basic class setup to hold our terrain, so now lets load in some data for us to display. 
Terrain is one of those things that so far, hasn't been perfectly recreated in computer graphics. But it is almost there! Looking over a beautiful landscape can be one of the most amazing feelings in the world. And is probably my inspiration for these tutorials.