Here i doodle away some more ideas. I'm trying to simplify things so I could actually start testing things out in Maya... what i write below still doesn't make all that much sense but these are doodles trying to eventually simplify things ... The eventual goal is a python tool to easily use motion capture data on any custom rig.
// --- 3 joint test. (transfer mocap to fk behavior)
make 3 mocap joints, and parent constrain 3 mocap markers to each joint.
a.at 0 set key at 0 for rz on top, middle and end mocap joint
b.at fr 10
rotate middle jnt 30rz
rotate top jnt 10rz
c. goal is to get this animation onto a different fk chain (goal is to do this using translational info, i think this way lra of custom rig can be anything...)
d. use the 3 markers not the mocap joints for below:
make a 3 joint chain with ok lra at position of markers
make 3 locators (hip_l,knee_l,foot_l)
--have hip_l aim constrained to knee_l
--have foot_l aim constrained to knee_l .. that is knee_l tells both hip and foot where to point
--group each locator and have the knee_l_grp follow the middle marker, hip_l_grp follow top marker, foot_l_grp follow bottom marker
--finally have hip_j orient constrained (offset on) by hip_l .. i think this should result in translation of marker giving a rotation value to the joints that could resemble fk behavior… maybe those rotations can be transfered to a separate fk chain that started with same local rotation axis… knee_j orient constrained by knee_l and foot_j orient constrained by foot_l
// --- 3 joint ty test. (transfer mocap to ik behavior)
-first 3 joint chain has top and bottom lenth equal 20 making a total length of 40.
-end of first 3 joint chain is animated from its default 20,0,0 local translates to 60,0,0
-a second 3 joint chain has top and bottom length equal 5 making a total length of 10.
-the goal is to get the second joint chains end joint animated not to 5+40 but to 5+10 something else that roughly matches the first chain.
…one solution is to use the total length to compute a 0-1 number indicating what fraction of the total length did the end joint move
In terms of total length of first 3 joint chain how much did end joint move. example a .5 would mean it moved half the length of the entire chain, a 1 would mean it move an entire length of the chain, a 0 would mean it didn't move at all.
1.need the default length of the first chain, and default length of the second chain
2.need always a measurement from the top of first chain to the end joint, same for the second chain