support smooth viewport based move

[ericoporto]

Use fractional residue to move the viewport and give illusion of smooth camera if the game native resolution is bigger than the camera size by a power of 2 (2, 4, ...).

Commit: bcf8710

smooth_rellax.mp4

residue.mp4

[ericoporto]

ezgif-1-296ae4d82a.mp4