[Radiance-general] rotation

[Ian Tester]

> Hi all.
> 
> Im back with my spotlights again im afraid. Im havin immense trouble
> rotating them so that they face the same way. i have tried using a range
> of values for rx ry and rz in my xform command and keep gettin odd
> results. instead of rotating my spot they seem to actually move it.

As Francesco pointed out - you're rotating after translating. The rotations
are always performed around the origin (0,0,0). If the object isn't centred
on the origin (as it might not be after a translation) then you'll get
additional "movement". Imagine your lights being on the end of an
imaginary pole that you're swinging about.

Hope this helps,
bye
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