As you may understand with the name of project, there is two triangle and they are rotating. We have used the simple code for developing this project. Let start doing it. First we have defined a global variable for angle.

The whole program is divided into three parts - Display, Timer and Main. We will code each of them one by one. First We will define the Display Function, where we are going to use simple primitive opengl function for drawing triangle GL_TRIANGLE. We use the global GAngle variable to rotate the drawn triangle. You can experiment with the angle and try how it turn out to be. You can also experiments with the vertices coordinate which draw triangles.