I have 10 bones in a line and 4 points in a spline. How can I correctly position the points in the bones? I’ve found that relative values are useless because every point in the location has the value “0,0,0” and was automatically placed along the 10 bones by the system. I also can’t use WorldLocation. What’s the best way to ensure that, for example, ControlPoints2 is exactly on the relative value “50,0,0”? WorldLocation would be even better.
You would probably have better luck with using control rig. You get get the bones transform (relative or world space) and use a lerp node to get the position between to bones if needed.
Edit:
Am I understanding correctly that you want to use 4 control points to control a 10 chain bone length via spline IK?
Perhaps this video might help as it tackles a similar setup
Yes, this function is the only one available. The video is for ControlRig. I don’t want to animate anything; I want to bend the bones using a blueprint. But mathematically, I don’t know how to implement this so that the points can be moved using the blueprint. I can’t even read the points, can I?
Why not just override the bone rotation via the transform (Modify) Bone node? You would keep the length of the bone intact (prevent stretching),and you also set the mode to “Add to existing” to just offset the rotation by a value?
What use case are you trying to implement?
Is it a bending sim or do you need to actually move the bones (for instance an impact deformation)?
It’s going to be a fishing rod. I want mostly just the tip to bend. Moving all the bones using PhysicsAnimation is too much for the engine, and the bones start to jitter. So I thought I’d try bending the bones with less computation. I would have used SplineIK with a method I wanted to try. I’ve placed two physics constraints in series, and the spheres are the connecting nodes that will transfer the values to SplineIK.
My problem is that I don’t know how to calculate the values if the location of the nodes in the spline IK is unknown. I can’t work with relative values or world locations in that case. I need to transfer something like an offset.
Together with Gemini, I found a solution. It’s static and can’t simply be used for other situations with different fishing rods if they have more or fewer bones. I noticed that with the correct number of bones and control points, the control points are placed precisely on the bones and not in between. I took advantage of this and distributed regular sphere components onto the fishing rod, onto the bones where the control points were located. See the yellow circles. The yellow circles are exactly where the control points were distributed in the spline. The three thicker spheres are connected by two physical constraints.
Then I used this formula. It’s supposed to subtract the thicker spheres with the control points (spheres).
