[Jarod Gibson]

so the three leg pieces I have are now joined together and move together when the effector is moved but the movement is focused around the knee joint rather than the foot (ankle) joint. Example. When I move the upper leg down (like a squat), the foot leaves the ground moving up as the knee bends. I want the foot to stay still on the ground.

Can this be done?

Thanks again!

[Jarod Gibson]

I see.

It works now. I was cutting out that part of the code thinking that your layman’s terms explainations of the expression were directions.

err.

Thanks a lot Dan.

[Jarod Gibson]

cw = false;
upper = false;
upperLimb = "L upper leg";
lowerLimb = "L lower leg";
extremity = "L foot";
effector = "L foot control";

function getWorldPos(theLayerName){
  L = thisComp.layer(theLayerName);
  return L.toWorld(L.anchorPoint);
}

A = getWorldPos(upperLimb);
B = getWorldPos(lowerLimb);
C = getWorldPos(extremity);
E = getWorldPos(effector);

a = length(B,C);
b = length(E,A);
c = length(A,B);

x = (b*b + c*c - a*a )/(2*b);
alpha = Math.acos(clamp(x/c,-1,1));
if{
  y = b - x;
  gamma = Math.acos(clamp(y/a,-1,1));
  result = (cw ? 1 : -1)*radiansToDegrees(gamma + alpha);
  V1 = B - A;
  adj1 = radiansToDegrees(Math.atan2(V1[1],V1[0]));
  V2 = C - B;
  adj2 = radiansToDegrees(Math.atan2(V2[1],V2[0]));
  result +  adj1 - adj2 + value;
}

Okay. I understand now about the effectors.

That’s the expression I am trying to use on a lower limb.
I do get an error that is referring to line 24 and layer 18.

Thanks!

[Jarod Gibson]

Hi Dan,

This doesn’t seem to work in cs4.
Also, on your website when outlining your technique, you don’t say what to do about parenting the effectors…

Any suggestions?
Thanks a lot!

[Jarod Gibson]

I think it had something to do with the codec i was trying to playback. I was using animation (the same as most of my clips). I then used DVCPRO50 and there was no problem.

Still seems odd to me.

Thanks guys.

[Jarod Gibson]

Thanks guys. I will try starting the arm at 0 degrees. Can’t wait for those other expressions you mentioned. Thank you both!

Jarod

[Jarod Gibson]

I am seeing something else.
For example, if I were to replicate the arm you animated on your website, the hand would not stay attached even that much. It’s like it’s held together with loose threads….
Thanks!

Jarod