# Simple spring bone simulation for attached leaves in VFX Graph

Hello all,

I am currently working on a project where users can control an avatar using a Kinect camera. The avatar is created in realtime in the VFX graph, where ivys grow on the invisible skinned mesh of a character and leaves grow out of the ivys. See the picture below for a first impression.

Now, our goal is that the leaves move semi-realistically with the movement of the user, e.g., if people jump up, the tip of the leaves should rotate downwards. I’m not really sure that we need to deform the mesh, probably rotating the leave with the stem as its pivot would be enough.

However, I don’t really know where to start, as all the simulations I’m finding (like hair simulation etc. are way too complex) for what we want to achieve. Can anyone point me in the direction of what I’m looking for?

I guess what I’m looking for is a very, very simplified version of a spring bone simulation?

if it’s done entirely with VFX graph then those leaves don’t have any bones

but maybe you can set it up in a way that only the branches are vfx and where a branch ends, you just add a (predefined or another vfx graph) leave to it, then you can just rotate that based on the motion vector from the kinect

but I don’t know enough about vfx graph, it would work if you can direct the growth of branches to go to a certain location and if that’s possible, you can make branches and non-interacting leaves grow and end near any of these locations and from there the other vfx graph that grows motion-affected leaves takes over, and then you would simply rotate that leave-graph vfx based on kinect motion

i hope you get what i mean

Hey, this is definitely something that I can do. Right now, the VFX for leaves and the VFX for ivys are separate and I can control both where leaves grow as well as where the ivy grows.

My problem is more with the rotation of the leaves, since in reality they would not rotate with the Kinect motion (e.g., if a person jumps, then the leaves would rotate downwards, not upwards). This is of course, because the leaf stem is attached to the body and the tip follows the movement with a delay. And that is what I want to simulate

EDIT: Ah, what I could do is definite each leaf as a combination of stem position and tip position and the rotation as the LookAt rotation between those two points! Then move the stem position with the avatar and let the tip position dragged by gravity. That should do the trick.