[Opensim-dev] Questions about Vehicle scripting calls

[Mike Higgins]

     llKeyframedMotion is key (pun intended). I'd be willing to bet that 
after discounting cars and airplanes and such, 99% of the remaining 
physical objects in SL are only physical to try and get smooth liner 
motion. I assume that llKeyframedMotion is easier on the SIM than 
physical objects and vehicles. And a lot of the vehicles that use the 
physical vehicle API could probably be done as non-physical objects with 
llKeyframedMotion. I encourage you to donate this to OpenSim soon 
Melanie, so people will get used to using it and save us from using physics.

On 6/7/12 5:52 AM, Melanie wrote:
> Hi,
>
> we use a module that is been developed for us as custom work. It
> allows running unmodified SL vehicle scripts - well, mostly. We also
> have llSetKeyframedMotion() for things that don't really need to be
> physical. The latter will be donated to OpenSim at some point.
>
> Melanie
>
> On 06/06/2012 19:41, Bengt Falke wrote:
>> Does anybody know what kind of physics Avination use? Physics works better there if I remember correctly?
>> Void Pipe
>>
>> 6 jun 2012 kl. 19:10 skrev James Hughes:
>>
>>> I have been experimenting with trains in SL and would like to make a physical one that works in OpenSim. Hopefully these cases aren't some limitation of the physics engines and can have a proper fix.
>>>
>>> -BlueWall
>>>
>>> On 06/05/2012 07:46 PM, Mike Higgins wrote:
>>>> I was talking to Justin Clark-Casey at the OpenSim developers meeting
>>>> this morning, and he suggested that the mailing lists would be the
>>>> easiest way to have a conversation about vehicle physics on OpenSim.
>>>> Justin you there? Is this where you meant? Anyone else want to talk
>>>> about vehicle scripting in OpenSim?
>>>>
>>>> I am in the process of testing the OpenSim vehicle scripting calls and
>>>> trying to find out what works and what can be worked around. I am
>>>> submitting mantis reports when I think I see a true bug, issue numbers
>>>> 0006039 <http://opensimulator.org/mantis/view.php?id=6039> and 0006040
>>>> <http://opensimulator.org/mantis/view.php?id=6040> for starters. Instead
>>>> of submitting 1000 line vehicle scripts that do not work, I am writing
>>>> small 10-line scripts that demonstrate a particular problem.
>>>>
>>>> Issue 0006040 <http://opensimulator.org/mantis/view.php?id=6040> is
>>>> particularly interesting because if my hypothesis is correct, the linear
>>>> motor direction is being actively projected onto the global XY plane. I
>>>> cannot get an airplane to glide up, or a balloon to rise using the
>>>> linear motor. (Hover height works with balloons, but not the linear
>>>> motor even with hover height disabled). The interesting thing about this
>>>> is that my hypothesis suggests that there is extra code doing this
>>>> projection onto the XY plane. I checked the vehicle flags and there
>>>> isn't one that should force this extra projection into the calculations.
>>>> Vehicle type balloon is supposed to have all the flags removed, but just
>>>> to be sure I used the remove call to clear them all. The linear motor
>>>> still cannot go up. Can someone familiar with the code look at the
>>>> linear motor and tell me why this is happening and if there is a way to
>>>> disable it? (I tried turning flags like VEHICLE_FLAG_NO_DEFLECTION_UP on
>>>> to see if this flag was inverted, and if it applied to the motor instead
>>>> of deflection, but no luck).
>>>>
>>>> The fun thing is that I can write one kind of vehicle that works well --
>>>> assuming this bug is there. I built a vehicle that has the linear motor
>>>> set to <0,0,20>, pointing straight up. When the vehicle is perfectly
>>>> horizontal, the projection of this motor onto XY is <0,0,0> and the
>>>> vehicle does nothing. But then when you tilt the vehicle in any
>>>> direction, the projection of the linear motor on XY becomes non-zero and
>>>> causes it to start moving in the direction of tilt. This feels a lot
>>>> like an RL helicopter, so I used the control keys to pitch down/up to
>>>> move forward/backwards, added yaw left and right, and used page-up/down
>>>> to increase/decrease the hover height. I put it in a hacked together
>>>> helicopter build and it is a lot of fun!
>>>>
>>>> I'm looking for work-arounds for the current vehicle routine behaviors.
>>>> One work-around for an airplane is to turn on hover height, check the
>>>> airplane speed and pitch once a second in timer(), calculate what
>>>> altitude the plane should get to in the next second, and set hover
>>>> height to that altitude. The things we do to get stuff working!
>>>>
>>>>
>>>>
>>>>
>>>>
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