> You have a chicken-and-egg bug here: The tire contact point is
> *defined* as the intersection of the gear compression vector with the
> ground.  You can't possibly ask for the elevation beneath it until you
> know it.  Going back to the same diagram, the point of the wheel is
> the "result" of the collision detection algorithm.  All the input
> knows is the base point and the point beneath the ground:

Your analysis is correct. This is a "limitation" of our model, because our
approach uses an "approximation" that the contact point is near enough
vertical that we can just use that. This "approximation" may not be good
enough for your desires, however, and that's fine.

> Really, I'm sorry if this seems arrogant.  I'm trying to be nice.
> But, well, despite how much you think you're right here, ... you're
> not.  This algorithm you propose is incorrect.  It's not terribly
> incorrect, since it works great for lots of situations.

You're stuck in the terminology dept., still? :-) Look in the mirror and say
"approximation". Go ahead, you can do it. You physicists ... always
splitting hairs - er, I mean atoms. I didn't say we were "right". We have an
approximation, it works for what we want it to do. We are "simulating".
There are other aspects of flight simulation that we can spend our time on
that will render much more capability, and I'd venture a guess that the same
is true for YASim. It's a matter of priorities - particularly given our
schedules. ANd if we can add the ability to rest on a tilted runway with
little effort, so be it. We'll do that when we get a chance and that filters
down the queue. Someday, perhaps we'll refine it even more. I am concerned
about the shouts of disgruntled users, however - don't get me wrong. I know
we have some work to do.

> If you want to use this interface to do vertical-only compression,
> then there is nothing stopping you.  But an interface that does *only*
> vertical-only compression does not work right for the intersection
> calculations I want to do for things like ski jumps, etc...

If one does not care about ski jumps, then will it really be noticable the
difference between our current approaches? Will the overall experience be
such that someone will exclaim how "realistic" the approach is given 99% of
the runways that exist? LIke I said, it's a matter of priorities. Our
current "approximation" is pretty good for what almost everyone will see.

> Look at it from my side: there is a cool new feature that *almost*
> does what I want it to do.  But it can't do what I want unless I get
> an interface change.  But I can't get that interface change unless the
> other FDM authors agree to use it too.

I don't think this is true.

Jon


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