Re: [Algorithms] Kinematic Collision

[<Pau...@sc...>]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

> How can you be sure that interpenetration never occurs then? Floating 
> point errors seems to produce small but very relevant
> problems for me. As an example, when simply dropping a capsule to the 
> floor using the 'inner skin' method without bias the
> solved position right before penetration should be 0.0 but the 
> calculations will very often produce a number such as -2e-06,
> so in my world creating 'a perfectly stable' solver doesn't exist.

The idea with the inner hull is that even if (more like when, actually) 
you get a slight error like you mention, it doesn't matter because you can 
move the object back by the distance between outer hull and the inner hull 
which means that next frame you don't start penetrated.

> Why is using a bias considered a 'hack', isn't it just to avoid this 
> kind of problems?

Its a hack because it introduces other problems - just using the outer 
hull and then moving that back means you are moving the object to a point 
just before where it was the last time; this can push it through other 
objects (imagine being on the inside of a triangle (in 2d) in a corner).

> I also run with a bounce of 0, meaning I never apply a position vector 
> away from the contact, maybe its not legal to have it
> zero?

No, thats perfectly legal :) Otherwise all your characters would bounce 
around the world like they were on pogo sticks! :)

Cheers, Paul.
**********************************************************************
This email and any files transmitted with it are confidential and intended 
solely for the use of the individual or entity to whom they are addressed. 
If you have received this email in error please notify pos...@sc...
This footnote also confirms that this email message has been checked for 
all known viruses.
Sony Computer Entertainment Europe Limited
Registered Office: 10 Great Marlborough Street, London W1F 7LP, United 
Kingdom
Registered in England: 3277793
**********************************************************************
P Please consider the environment before printing this e-mail

-----BEGIN PGP SIGNATURE-----
Version: PGP Universal 2.9.1 (Build 287)
Charset: US-ASCII

wsBVAwUBSp951XajGqjtoMHxAQjGkwf/V0yO90qpM1KlHGgAZsWELt4EqF1lQiBQ
faApgU0iPGtmGHx8p8HSTAIMoSvtyBCN8klXzynNxeCgeQnqrdQJ27QMcYCSVGTA
vN/PwRD/FPERoPis6yGSNwP510OAPh/kQZOdZ6YxBeHfqVYlUWAak7/zszLUziPh
s4tafQRk877eIjzKu+Wc7mi2ElSOU+DnSoEB3WMtoHcxuQPpY2ZwTqSYKaisC96f
/XMBnEqb/sqNKuhgPVIe2VMRr+yqzgQjYUlbBiKlAqidos6Jch0EZA5hwV9yDF+o
SjOiHqxNpOyL1vO1kuODddnPITLgb0Ao1NOkXrqHk85E4WfkiFZZyA==
=tDp5
-----END PGP SIGNATURE-----