Peter Cracknell wrote:
> 
> Well I don't know if you can call it IK, as it only takes 2 points and finds
> a third, but after about 2 hours I managed to produce a macro that takes the
> two lengths (upper leg and lower leg in my case) and the co-ordinates off
> the waist and foot and produces the knee point.

Well, I hope you learned a lot from the resolution of the system,
but the exact mechanical simulation of the knee is not that simple...
If I remember correctly, the axis of rotation moves along the upper leg
when the angle changes. (which mean that the length of the upper leg will
be function of the angle) (And if IRRC, the deplacement of the axis is not
along a straight line.)
But may be you do not need such a precise modelisation.

> 
> With that in place I went about animating the foot as if it were running so
> that the knee would follow.  All I did was move the foot in a circle
> (xpos=sin(clockstuff) ,ypos=cos(clockstuff)) and it produced the following.
> 
> There are probably some amazing IK style-running macros/files out there, but
> my aim is to produce my own (then I know how to work it!) - has anyone got
> any tips on improving this system (does the ankle go in an exact circle or
> more of an ellipse?) as I'd like to produce a running man in the end, thanks
> 

I do not know, but you may gain knowledge by looking at some cartoons tutorial.


P.S.: The animation is running smooth.

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