Getting mouse coordinates with a fixed render script

Hi! I recently set my game to use a fixed rendering script, but this seems to have made getting mouse coordinates much more difficult. Originally, the origin (0,0) was placed at the bottom left of the game (red below), which makes sense.

However, now with the new render script the origin will be at the bottom left of the window (red below), as opposed to the game (green below). Is there a way to get/change the mouse coordinates to be from the bottom corner of the game screen?

If you change the projection in your render script you also need to convert the mouse/screen coordinates to the coordinate space your game is rendered in.