No world-reference Z-axis rotation?

Try this...

Rez a box. In the edit wondow make sure you've selected world reference. In the Object tab, under Rotation, give the box some Z-axis rotation, say 33 degrees. Now click and hold the X-axis rotation up arrow to spin the box about the X-axis. It tumbles, as you'd expect. Pay close attention to where the X-axis intersects the box. As the box spins the axis stays locked on the same location on the box.

Now try the reverse. First reset the rotation to 0, 0, 0. Then give the box some X-axis rotation, say 33 degrees. Now click and hold the Z-axis rotation up arrow to spin the box about the Z-axis. Note that the box doesn't tumble. Pay close attention to where the Z-axis intersects the box. It's not staying locked in one place; it's tracing a circle path. The box is rotating about its *local* Z-axis, not the world Z-axis.

Why is this?

I can't recreate this. For me, when I've rotated the box onto it's corner via the x axis and then slowly change the z with the up and down arrows in the rotation fields, the line where the world axis intersects the box traces a circle on the 'top' face of the cube, which is what i would expect if the box had been tilted.

edit -- er, rather, what you are describing is exactly what i would expect to happen, as by using the world Ruler mode, you're causing the cube to rotate at that point on the world grid. Change your Ruler mode to Local, and then try the same experiment -- _that's_ when the cube is actually rotating along it's local z-axis.

an even more long-winded edit -- the size of the cube is what's making the line that intersects with the top of the cube trace a circle -- the larger the cube, the larger the circle that line would trace. But at the point in space where the center of the cube is, it's still rotating via the world grid, and not its local axis.

YOU know.. I've been building since July. I build every single day.
I never noticed a ruler mode. Just been using "World" all this time.

That said, I've never found anything counter-rational or counter-intuitive about the rotation axes.

It shouldn't do that. If it's rotating about the world Z-axis and not its own, the Z-axis should stay locked in one place and the cube should rotate about that point.

It should look like this...

http://pics.livejournal.com/anyaristow/pic/0000htge/g1

But instead it looks as you describe...

http://pics.livejournal.com/anyaristow/pic/0000fa77/g1

That is not a world-reference rotation; it is a local-reference rotation. The axis it's actually rotating about looks like this...

http://pics.livejournal.com/anyaristow/pic/0000g8ez/g1

That's local-reference, not world-reference.



Changing the ruler mode has no effect on how it behaves when you push the object using the rotation up/down arrows in the edit window. For X- and Y-axis rotations it is always making a world-reference rotation, and for Z-axis rotations it is always making a local-reference rotation, regardless the state of the ruler mode.



It shouldn't be tracing a circle at all.

Repeat the experiment with a Z-axis rotation and spin about the X-axis and you'll see it works as I describe.

The result of this is that it's impossible to make a precise rotation on two axis without a script or some serious math. You have to calculate the end rotation. You can't just rotate on one axis and then the other, as you can using the globe rotation controls and the ruler mode. But the globe rotation controls don't give you precise control unless you want a rotation that is on the grid.