Global variables

Two global variables are required for easy window cleanup: a pointer to the currently running application and a handle to the global OpenGL Vertex Array Object (VAO). Instead of each draw call having its own VAO, one will be bound for the entire duration of the sample.

To do this, create the following global variables:

Application* gApplication = 0;

GLuint gVertexArrayObject = 0;

Throughout the rest of this book, there will be no other global variables. Global variables can make the program state harder to track. The reason these two exist is to easily reference them when the application is shutting down later. Next, you will start implementing the WinMain function to open a new window.