> But I can't understand how transformations other than rotation on the vertical axis can be performed. Roll is visible in the game clip. I think it's not a tr

> But I can't understand how transformations other than rotation on the vertical axis can be performed. Roll is visible in the game clip. I think it's not a true roll but just each column of pixels raised up or down so that the horizon is tilted appropriately. Given the fast movement and the nature of the scene, the user doesn't notice that vertical features in the scene are not rotated. It's neat.