Position contraint issue (or not?)


Hi Folks,

I am trying to achieve a rig for a dragon, and i attach an image of what it is looking like.
I will explain how i made it, for you to understand, and after i will tell you what are the issues.

So i made a normal ik/fk system for the arm, which blend between the ik and the fk chain. I put an attribute on the fk chain for following or not the chest movement. I ve done this by making 3 points at the fk upper arm Pivot:

  • one parented to the chest but with inherit rotations unchecked
  • one parented to the chest normally
  • one position constrained and orientation constrained on the 2 others for blending between

for the wings i made 2 sections:

  • one between the pinky and the shoulder
  • one between the index finger and the pinky

I made a line skined on the 2 extremes fingers of the section and on the green sphere shape in the middle of the line which is parented on the yellow point at the middle of the line.
this point has a position constraint between the last bone of the pinky finger and the index finger.

My problem is when i start to animate the wings i have 2 issues:

  • one is visual, the fk chain seems to move at the center of the scene, but the pivot keeps good.
  • The other is more problematic because sometimes when i put a key on the index finger control, the yellow point in the middle of the yellow line at the outline of the wing ( see image), move out suddenly, and even if i cancel the key, with no key at all, for that frame the points keeps moving out…
    it s very strange as i dont put any key at all on it. sometimes just by clicking the green sphere shape control, everything back on its spot…

I discover that the problem is coming from the parent of the sphere shape on the yellow point position constrained, because when i unparent the sphere control, everything works fine (except it no longer follow the fingers position)

So if one of you could tell me if I am making a mistake or if it is a strange bug from max, I will appreciate, because i truly dont understand why its happening…