Had to learn Pythagoras and Trigonometry as I didn't realise that a large amount of game development relies on them.

Plus SDL can't draw circles so I came up with a function that takes steps and draws them with lines, this way you can drop the steps right down to basic triangles -or just a line or a dot- and then go from there. Plus it makes it easy to build filled circles or thick outlined ones, depending on how they are drawn.

Plus they help with collision detection which I have just managed to get up and running smoothly. Working on elastic collisions now so I can have a play with them and see how they work and where it can/can't be used.

Time to start looking into quad trees next, one step closer to the start of a game world.