[ODE] Why is it that most commercial entities roll their owncollision system?

[Megan Fox]

Alright, that makes perfect sense.  Thanks for the explanation... I was afraid they were doing more than that sort of optimization (though thinking about, there isn't much more they could do, without also altering ODE's other sections).

-Megan Fox

> You can usually know things about the objects in the game that'll 
> drastically
> simplify the cost of collision detection.
> 
> For example, in a car racing game, you could store a height map 
> of the track and
> do collision detection by a simple 2D array lookup with 
> interpolation.   That's
> going to be orders of magnitude faster than a general triangle 
> mesh lookup.
> 
> In a flight simulator, you can know that if you are higher than 
> the highest
> hilltop in your world, you can skip over all collision testing 
> with the ground.
> 
> There are lots of dramatic short-cuts you can do when you know 
> about the nature
> of the world you are in.  All ODE knows about is a big pile of 
> shapes with no
> particular organisation.