Emptys and one axis rotation.


(croxis) #1

I’ll try and explain this the best I can. I have a spot light like the kind you see on the top of prison towers. The base swivels 360 degs. Two prongs from the base hold up the light-case from the side. It kind of looks like the little text picture.
|-O-|
| |
|___|

I want the lightcase to be able to be able to swivel on its supposts so it can point into the sky or onto the ground. It looks fine while the base is aligned with the views, but as soon as I rotate the base to point at an odd angle I can’t tilt the light because it will ‘unhook’ from its supports. Right now the light fixture is a child to an empty and the empty is a child to a base. (one of the empty’s axis goes through the light where I want it to pivot) What I want to know is how I can restrict the empty so it can only rotate on one axis, the axit that goes through the side, supports.

Or am I going about this the wrong way?

Thank you for your help, and if what I said made no sense at all I’ll find a place to post the blend file!


(tordat) #2

Hi, don’t know if I completally understood your problem (my english,you know)

Summary: rotating base 360 ° around z-axis, simultaniously a rotating spot e. g. 270° around x-axis.

The procedure you described makes sense to me. (Tried it and it worked)
Your problem may result wether from not precisely placed objects (empties, base, light, etc), they should be centred at the same xy-values if z-axis is up, and the spot and its parent empty should share all three coordinates, or (less likely) from problems with the IPOs that haven’t been properly set up.

For the coordinate problem you should first press Center New (Edit Buttons) for every object and place them with the help of the N button pop up, and or with the snap function (Shift+S).

Hope that’s what your question is about.


(hweihe) #3

I’m also not sure if this is what you wanted to know…

It seems not to be possible to restrict the rotation when using the mouse. But when you press N and change the RotX, RotY and RotZ values, the empty rotates its axes.

For animation purposes you can edit the RotX-, RotY- and RotZ-IPO by manually adding points. (pressing I, Rot would generate IPOS for all three Rot-IPOS).

Hope that helps…

Holger