# Animating a winch

I wish to animate the rotation of the panels in this structure. I think I can go two ways. One is IK while the other is to keyframe the scaling and rotation of the red cable based on the rotation of the panel. Which way would be best? I cannot quite understand how to do it with IK, as I have not seen video examples of people being able to scale the geometry based on the constraint, as the cable will have to get longer. Is that possible with constraints?

What would you do? This is my first time attempting to animate with Bongo, any help and advice is highly appreciated! The cable geometry does not need to be very detailed.

I would use IK, it is easier to make the correct scale for the cables.

By using the Rubberband -joint you can easily scale the cable to fit the door movement.
You animate the door and then hook up the cables to follow the movement of the door.
Please see attached example model. DoorWithWinches.3dm (292.0 KB)

Thanks so much! by carefully studying your example I got it to work – one question for understanding though, why doesn’t it work unless I put the pivot of the curve (winch cable) at the top vertex? If I don’t do that, then it scales inappropriately.

Also using curves is great for this because you can run the command “applycrvpiping” to get pipes from the curves without having to create extra geometry manually.

If the pivot is in the middle, it will scale both sides the same, meaning if the distance to the goal is shortened the other side of the line will be shortened as well creating an unwanted gap.
When the pivot is in one end of the object it will scale it form the pivot to the goal.

You can try it with just a normal object:

• have the pivot in the middle and scale it -> scale the object in the X -axis direction. the scale will go in 2 directions according to the x-axis.
• have the pivot in the end (corner) of the object -> scale the object in X-axis direction - the scale will apply in one direction

ah it makes sense now, rubberband joint means scaling.