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Scienthsine

Formula in Advanced Character Physics Paper

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I've never quite _fully_ finished a verlet particle physics system based on this paper. I always get stuck on the Rigid Bodies section on page 3. Specifically when he's going through and deriving a formula for separating a constraint that has collided with a wall, it doesn't make sense to me. He eventually defines a symbol 'lambda' as:
[img]http://www.gamasutra.com/resource_guide/20030121/jacobsen_files/image022.gif[/img]
However, delta is defined earlier in _this_ section as (q-p)

So wouldn't that be delta*delta... and wouldn't that cancel out with the bottom delta^2 to just: lambda = 1/(0.75^2+0./25^2) ? (Ofcourse with actual variables instead of constants for 0.75 and 0.25)

Do note that q and p are vectors, so the dot is a dot product... but the same rules still apply right?

This is the paper:
[url="http://www.gamasutra.com/resource_guide/20030121/jacobson_03.shtml"]http://www.gamasutra.com/resource_guide/20030121/jacobson_03.shtml[/url]
Though note that some of the symbols are messed when not in an image.
This copy of it has all the symbols even in the text:
[url="http://www.gotoandplay.it/_articles/2005/08/advCharPhysics_p02.php?PHPSESSID=566f57fb1cf5f20c333dab15b6436005"]http://www.gotoandplay.it/_articles/2005/08/advCharPhysics_p02.php?PHPSESSID=566f57fb1cf5f20c333dab15b6436005[/url]

I'd very much appreciate any clarification or explanation anyone could provide. This has been a stumbling block for me for several years.

Thanks,
James Newman

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