I'm fairly n00b-ish to MEL and expressions, so maybe someone here can shed a bit of light on this strange behavior within Maya.
All I want to do is automate the rolling of a wheel. I'm using an expression:
pCylinder1.translateX / polyCylinder1.radius;
I've set "Convert Units" to "None," so the expression is working solely in radians. I did create a different expression that used degrees, but the result was the same. I also tried parenting the wheel to a car body, but again, the same result.
When I move the object interactively in the viewport, the wheel spins in the wrong direction. When I create keyframes and play back the animation, the wheel spins in the correct direction. What gives? I've done this exact same thing in 3ds Max with no problems.