Im using OpenGL to make a tic tac toe game and my screen is set up where the screen is -12.0 to 12.0 on the x-axis and -10.0 to 10.0 on the y axis. I used WM_MOUSEMOVE to get the mouse coords but the mouse is 0,0 in the upper left. How would i get it so the mouse is with my screen?

Thanks
Chris