[Closed] Twist Bones

Apr 10, 2018 10:03 am

This is an old question, but I didn’t find a solution yet, any trick to create twist bones that don’t flip at angle greater than ±180? I know the logic is true, quaternion will flip at -+180 and we need to use rotation stored in the rotation controller, but controller wouldn’t be updated if we rotate the parent or other effected objects, any idea?

1 Reply

MZ1

Apr 10, 2018 10:03 am

I have an idea, what about storing rotation(X) in attribute , then wiring to that attribute instead of current rotation. this is my first try:


clearlistener()
with redraw off
(
   delete objects 
   Obj = teapot()
   TargetA = teapot pos:[100,0,0]
   CA = attributes "RigTracks" 
   (
      parameters parameterBlock rollout:parameterBlockUI
      (
         LastX type:#float ui:LastXUI
         NewX type:#float ui:NewXUI
      )
      rollout parameterBlockUI "Bend"
      (
         spinner LastXUI "OldX:" range:[-1e9,1e9,0]
         spinner NewXUI "NewX:" range:[-1e9,1e9,0]
      )
   )
   Md = EmptyModifier name:"CutAttributes"
   addmodifier TargetA Md
   custattributes.add Md CA
   Md.RigTracks[#LastX].controller = bezier_float()
   Md.RigTracks[#NewX].controller = bezier_float()
   RS = rotation_Script()
   RS.addnode "TargetA" TargetA
   RS.addobject "LastX" Md.RigTracks[#LastX]
   RS.addobject "NewX" Md.RigTracks[#NewX]
   RS.script =
"
   fn GetX Rot =
   (
      r = quattoeuler Rot order:7
      r.x+r.z
   )
   x1 = GetX TargetA.rotation
   if x1 < 0 do x1+=360
   deltaX = abs(x1 - LastX.value)
   if x1 < LastX.value do deltaX = -deltaX
   NewX.value += deltaX
   LastX.value = x1
   quat (NewX.value/2) [1,0,0]
"
   Obj.rotation.controller = RS
   select TargetA
)

above code is not completed and has some bugs, but kinda shows my idea.