Before we get too far into our new code, I want to make some quick changes to the game.hpp file to add some functionality we will be using later in this chapter. The first thing I want to add near the top of the game.hpp file is a few macros that will let us quickly convert from an angle in degrees to radians, and also from radians to degrees. I find myself doing this a lot when using SDL because SDL, for some reason, wants rotations in degrees, and every other library out there uses radians. So, let's go ahead and add the following two lines of code somewhere near the top of the game.hpp file:
#define DEG_TO_RAD(deg) ((float)deg/180.0)*3.14159
#define RAD_TO_DEG(rad) ((float)rad*180.0)/3.14159
We will be changing the size of our canvas from 320 x 200 to 800 x 600. To make this easy to switch later, let's go ahead and define a few macros we will use...