Using `gluPerspective` makes OpenGL's grid really messy and rather hard to use especially when trying to do mouse input. The grid that perspective uses is completely messed up compared to the grid you get with the mouse. When using `glOrtho` the grid is fixed to the mouse grid, but then you can only do 2D work, how would I set up perspective to get the same results as if I were using `glOrtho`?