building 2-d stick figure model in Java w/inverse kin. and physics

Hi,
The subject says it all :), but I'll try to be more specific. I'm trying to build a 2-d model of a simple (human) stick figure for a 2-d
rock-climbing game I'm writing for fun in Java. I would like to do it in a nice object-oriented way, but more importantly, I want to be able to do the following: keeping 2 feet and 1 hand fixed in position, I want to be able to grab the other hand and move it to an exact location, and have the body follow. The main constraints are: the limbs are not elastic, and the joints each have a range of motion that cannot be exceeded.
I can see that when I move the right hand, often there will be an infinite number of possible "solutions" or positions of the rest of the body, so I will need additional constraints. Ideally, the other hand and feet will support the weight of the figure, and I will calculate the body position support the body and maximize efficiency (ie. so the 'climber' doesn't get tired quickly)
I am not a mech. engineer, so I'm partly doing this as an exercise to learn how to model a 2-d figure and add "realistic" features, such as the inverse kinematics and also balance and various forces.
I'd like to start with something simple that I can understand, so if anyone has simple examples that are similar, that would be helpful. Also, online tutorials or even just suggestions for how to "model" this figure would be useful. I'm pretty much a beginner, but interested in learning. I realize there is already a 3-d climbing game, and I also realize there is complex software to handle this stuff, but I'm interested in this ground-up approach, since I really want to learn as much as possible.
Here is the basic configuration of the stick figure (open to slight modification):
O _/|\_ ^ / \ | |
I.e. the "fixed points" are the hands and feet (except the one being moved by the user/player), and the points to be automatically positioned are the elbows, knees, "neck" (point where arms, head and torso join) and "hips" (point where legs and torso join) I would like to be able to pick any hand/foot and move it and have the rest of the body follow based on 'balance' and 'strength'.
I think I am starting to understand that the position of each joint is subject to "limb" length, and then I have to impose these other constraints so that I end up minimizing/maximizing a function. I just don't quite know how to set that up.
Pseudocode/general algorithm data-structure hints are very welcome too.
Please email response.
Thanks for your patience and any help or guidance! G
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I don't know if this will be much help to you, but it seems related and is fun anyway: http://www.sodaplay.com /
Mitch Berkson
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On Sat, 27 Dec 2003 02:15:43 -0500, "Mitch Berkson"

That's really cool.
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