Ok Here it goes. (assumed that all is done in Front view)
!. You need to have a model so lets build a simple model and then subsurface it.
2. Add a armature, a Bicep Bone, Forearm bone, and a hand bone.
3. Within your armature make two more bones. These will mark the pivot points for the tracking. Name them M1 and M2 ,put M1 at the base of the bicep and M2 on the first third of the forearm like shown in fig C, slightly above the forearmbone. Size and direction doesnt matter I just put them facing up so i can see them.
4. Select the armature, then go into editmode (tab) , select all (a). Goto edit buttons (f9) . Now from the drop down menus parent the M1 to the Bicep, and M2 to the Forearm. Tab again to get out of bone edit mode.
5. Tab again to get out of bone edit mode. Add a empty and call it E1, Add another empty and call it E2. Selete E1 and goto the constraints buttons.(its right next to the edit buttons) Add a constraint for E1 -> copy location. obj = Armature, then bone will pop up underneath obj. In bone type M1. Then do the same for E2 add constrain for E2 -> copy location. obj= Armature, Bone = M2.
6.Add two more Emptys and call them ET1 and ET2. Place them close to the Marker bones of same number ET1 by M1 and ET2 by M2. Parent ET1 to E1, (grab ET1 then shift select E1 and ctrl p, make parent) Parent ET2 to E2.
7. Add a plane Call the mesh T1 (track 1). Make another plane (T2) (I made my planes a bit elogated and moved the pivot point to one side so i could see the tracking better). Now Take your plane T1 and Parent it to ET1 and same with T2. Parent it to ET2
8. Select your armature and add two more bones about 1/4 the size of the bicep named UB and LB (upper bicep and lower bicep). have them face each other. Make sure Your in Edit bone mode otherwize you will have two armatures. (if you have to join the two make sure you grab the original first, otherwize you might have to reasign your emptys.)Place them within the plane. UB to T1 and Lb to T2. Select your armature , go into pose mode ctrl + tab , then select UB and add a constraint to copy location of T1 also add one to copy rotation of T1. do the same for Lb and copy location and rotation of T2.
9. Ok now we can start tracking each other. out of pose mode, out of edit mode. select the Plane T1 and then shift select Plane T2 and
Press ctrl + T, (Make track), Selecet T2 shift select T1 and ctrl + t (make track. then goto animation buttons (f7). Play with Track xyz and up xyz for both T1 and T2. I ended up useing Track z up z for both. When you make your planes make sure you dont rotate them. if you have troubles. delete both planes and remake them. set up tracking before you rig them up. then when you add the bones the bones might not follow how you had the planes tracking each other. Do not rotate the planes. play with the track x y z untill the bones following each other. If you get it all set up and move the emptys ET1 or ET2 and both bones do not follow each other ( like only one moves) then you need ot reset it up (just the planes).
10. Now you can go into edit mode and delete the vertexs from the planes. Do not delete the object. Go into pose mode and move the forearm. The bones should track each other nicely. you can move the marker bones and the two emptys et1 and et2 to adjust how the tracking happens.
11. I think you have to use groups for the mesh to bend right. I will go over that in the next installment of this tutorial. Try making a group for each bone and assign the vertexs to the right groups. then parent your mesh to the armature. You can also add a empty and have a ik solver on the hand bone. this will allow you to just move the empty for animations and the muscle deform will work by it self. Any questions welcome. [email protected] I am going to write more on the subject soon. just getting to late now.