@rbernon had also noticed that under the SDL backend, effects with a direction of mostly right with a bit of up played mostly up/down and not right/left as would be expected.
Traced this down using a `INT16` for the rotation angle in the SDL backend, which isn't large enough to represent 36000. Overflowing would effectively subtract 66536, amounting to a 65536 % 36000 = 29536 centi-degree rotation. End effect was effects mostly right with a bit of up (those over 327 degrees) where changed to mostly up with a bit of right (rotated counter-clockwise 65 degrees).
This patch changes the local computation variable to INT32, which also matches what is used by the SDL library.