Attaching a light source to a swinging cable

[couch]

I would like to attach a light source to a swinging suspension lamp. Unfortunately I can't figure out a way to transfer the animation of a point representing the end of the cable up to the light on scene level. 

Light instancing is not possible in this case and I don't want to use light geometry. Please help.

[anim]

you can use Rivet Object to get point's position and rotation (if you have correct N and up vectors) as object level transform

then just parent your light to the rivet object

[couch]

Thanks a lot, but how can I get the correct N vector? I used orient along curve to give the point the correct orientation during the animation.  However, I fail to apply it to the Normals. No matter what I do, N always aligns itself parallel to one of the scene axes. And so does the light.

 

I’ve attached my scene if you or anybody else want to have a look. The point Lamp_Example.hiplcwhere I would want to attach the lamp can be found in the green colored network box.

[anim]

here is a bit simplified setup Lamp_Example_fix.hiplc

it should be possible to fully instance your lamps with lights at the end points using instance node, but I don't know the requirements of Arnold for light instancing so for now just rivetting each individually

[couch]

Thanks for the example anim. It works like a charm and is much cleaner than mine of course. The vex code wasa bit hard to follow, but I could still transfer your techniques into my scene. Arnold does not support light instancing at all, as far as I know.