[Algorithms] RE: Fast Collision Queries

[Sam M. <sam...@ho...>]

>From: "Mark Wayland" <mwa...@to...>
>Think of it as "layered" collision information with the
>nav mesh being the coarse representation and the actual real collision data
>being the fine detail representation.

It's an interesting approach, but I can't see any reason why the nav mesh
can't be *exactly* the same as the unobstructed space? (Although it would
get exceptionally complex if it had curved edges). If you have an exact
representation for your unobstructed space you have no need to do collision
at all. In fact, even if your representation for your unobstructed space is
more of an approximation, providing it doesn't contain any areas where you
would actually still collide (ie. it is a subset of the true unobstructed
space and doesn't contain any regions that are actually obstructed) you can
still just restrict your npc to that. Providing it's a good enough
approximation I doubt the player will notice that an npc can't get right
upclose to a particular wall, or can't stand really close to a barrel, etc.


>From: "Brett Bibby" <res...@ga...>
>I still need to handle really uneven ground for hand-modeled meshes. I can 
>generate a height-map, but I'm wondering what the other options are. In the

>hand-modeled terrains we want caves that span multiple elevations, which is

>why we want to add a non-height-map mesh handling. We'll continue to use 
>height-mapped terrains for levels that are flat with no overhangs.

Not quite sure what your saying tbh? At a guess, I would treat the problem
of 'matching the npc's feet to the floor' and 'making sure they don't walk
through any obstructions' as different problems. There's usually a really
easy (if marginally hacky) solution to matching npcs feet to the floor,
where as the later constitutes 'real' collision. You don't want to be doing
any 'real' collision where you can - literally - avoid it (like all npcs
wandering on the ground). You will always have to at least snap them to the
floor though.

Hope I'm making sense :)
Sam

P.s. It was pointed out that I used the term 'lc' in my last post - office
speak for 'lead caveman' (our player character). Must.. Think... Out of..
The box...