[Opensim-dev] Questions about Vehicle scripting calls

[James Stallings II]

I've been working with vehicle scripting on opensims now for over 4 years.
There are lots of historical scripts I have written or adapted from the
work of others, or collaborated on with others in the OSgrid scripting
forums. These include sailing scripts, automobile scripts, and yes, even a
helicopter script. Dave Coyle said over three years ago that my helicopter
was "the most satisfying vehicle he'd ever seen on an opensim'.

In fact, Owen Oyen and I produced the first vehicles on OSgrid *without any
vehicle functions at all*. These were sailboats that entirely simulated
'sailboat physics' using llSetRot, llGetRot, llApplyImpulse and friends.
The boat was clunky, did not heel, moved in anything but a smooth fashion,
and was hell on the simulation. My more 'modern' boats can be found on
Littlefield region on OSgrid, as well as a historical display documenting
the work on the aquavita. The working copies of the boats are in a vendor;
those sitting at the dock have had the scripts ripped out to reduce lag on
the sim, don't take copies of those.

Later (much later than that boat, the 'Aquavita"), I worked extensively
with Kitto Flora to get ODE implemetations of such vehicle scripting
functions working as  work now. The work is imperfect, but not all of the
problems are with ODE proper; some have to do with various math functions'
implementation in opensim, and how they differ from the same math functions
as implemented in SL under havoc. The short story is, LL's functions are
broken in terms of how physics actually dictates real-world objects behave;
and the same functions are incomplete here, as the developers who worked on
them refused to implement the broken math, and no resolution could be
reached among the devs as to how to proceed, so the functions on opensims
are incomplete and/or unfinished.

All of this is more or less ancient history. I've got many very simple test
objects needed to reproduce these errors as test cases in inventory on the
grid, and related mantis entries filed, but quite frankly they've been
ignored for so long I lost interest a couple years back and haven't really
bothered with vehicles since. Who wants to sail a boat that doesn't heel?
Who want's to fly an airplane that has no inertia if a vector component is
on the z-axis? Not to mention, incoming physics 'fixes' often break the
workarounds, with no explanation of how to take advantage of the
improvements.

It's really discouraging to be told about your now non-functional
helicopter you've been using for most of a year that 'those vehicle
functions never really worked anyway'.

One of the problems is that to make something work you have to be able to
define 'working' in a manner that lends itself to implementation by nuts
and bolts coders, and (so far) no one has presented themselves that has
that sort of exhaustive knowledge of LL's vehicle physics.

I'm not a nay-sayer; I really hope this stuff can be made to work someday;
but I long ago lost hope as I'll likely be dead and buried before it
happens at current rates of development, especially if everyone forgets or
ignores all the prior work that has been done or that the issues raised are
not so new as the users encountering them.

I'm available to help with this, as much or as little as is needed, but
you'll have to be patient with me as, at this point, I've largely forgotten
a lot of what I knew about this, having given up on going blue in the face
trying to get anyone to take notice of the issues I was raising.


Cheers
James aka Hiro Protagonist


On Thu, Jun 7, 2012 at 4:38 AM, Bengt Falke <bengt at falke.nu> wrote:

> This is getting more and more interesting for each post on the
> subject......
>
> I think it would be a good thing to collect all the relevant information
> about physics and scripting in the forum so it is available to all
> struggling with this. Are there still active work going on with ODE or are
> our only option to find ways around the problems or hope for the Bullet
> engine?
>
> I saw in another post a reference to a OSGrid scripting forum and I assume
> it is this section you are referring to (please correct me if I am wrong):
> http://forums.osgrid.org/viewforum.php?f=5&sid=d584d594240e0917e41480491af385ec
>
> That might anyhow be a good place to post in.
> Void Pipe
>
>
>
>
> _______________________________________________
> Opensim-dev mailing list
> Opensim-dev at lists.berlios.de
> https://lists.berlios.de/mailman/listinfo/opensim-dev
>



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