[Opensim-dev] New MOSES Physics Video

Tue Apr 14 20:49:52 UTC 2015

I believe there is a means in the LLUDP protocol to stuff many updates for
many objects into a single packet, though I'm not sure OpenSimulator is
smart enough to do it in your simulation. It may be a way to improve
networking performance quite a bit when may physical objects change
velocity during the same simulation frame.

On Tue, Apr 14, 2015 at 1:44 PM, steve l <salbiedermann at gmail.com> wrote:

> Hi!
>
> Robert- Thanks for the answer and the thought you put into it!
>
> So I am going to play dummy (Not far from the truth!) here. This means
> that we need to do re-writing on several parts of OS to speed things up and
> eliminate bottlenecks. a couple of questions then.
>
> 1. Is the explosion of blocks or prims something that the viewer can
> handle? Or is this too tricky to make happen with the wide variations of
> machine running viewers and even more so that soon the viewer will run in a
> web browser?
>
> 2. Is there a way to make the explosion an overlay streaming event that
> runs over the current screen? - Just a crazy idea.... I am thinking of this
> more on a browser-viewer as that needs to run on devices that would have
> issues processing all that...
>
> 3. Is it possible to make OS Physics run faster than 11FPS?
>
> 4. It seems that the number of avatars exponentially changes the workload
> here. Maybe a graphics server could be designed as a sub service to handle
> that type of load, maybe running on a GPU instead of a CPU? It just seems
> to me that with all the other things that the region server has to do,
> offloading some of the heavy lifting would be a good thing. Maybe it is
> time to think of an OS "Pro" level of setup that separates the workload a
> bit more would be a good idea.
>
> These things always get me thinking...!
>
> Steve LaVigne
> A Dimension Beyond, Inc.
> www.adimensionbeyond.com
>
> On Tue, Apr 14, 2015 at 10:45 AM, Adams, Robert <robert.adams at intel.com>
> wrote:
>
>>  I don’t think the only problem is finding a physics engine that can
>> handle 240 moving objects. Another is optimizing the updates from the
>> physics engine.
>>
>>
>>
>> Think of the whole pipeline: the physics engine computes interactions and
>> new locations/rotations for each object. That position update is sent to
>> the simulator. The simulator updates the object data structures and sets an
>> update flag. The location/position update is noticed and an update
>> packet[1] is created and placed in output queues for each viewer. At some
>> time, the packet is transmitted to each viewer.
>>
>>
>>
>> The update processing time can easily be more than the physics engine
>> time.
>>
>>
>>
>> The OpenSimulator physics engines are run 11 times a second so they
>> generate 11 position updates a second for each moving object. So, even an
>> efficient physics engine will generate (240 * 11) updates per second which
>> then turn into (240 * 11 * numberOfAvatars) packets sent per second.
>>
>>
>>
>> There are many optimizations possible in this chain.
>>
>>
>>
>> -- mb
>>
>>
>>
>> [1] This is technically wrong for the current version of OpenSimulator.
>> For the technically inclined, an ‘update needed’ packet is put in the
>> output queue and the actual packet to transmit is created when it is time
>> to send the update. This is done because the update output packet queue can
>> get long and the position/location information can be stale if multiple
>> updates are in the queue. Only one ‘update needed’ packet is put in the
>> queue and the current object location/rotation is put in the transmitted
>> packet at the time of transmission.
>>
>>
>>
>> *From:* owner-moses-list at lists.mitre.org [mailto:
>> owner-moses-list at lists.mitre.org] *On Behalf Of *steve l
>> *Sent:* Tuesday, April 14, 2015 8:09 AM
>> *To:* Michael Emory Cerquoni
>> *Cc:* opensim-dev at opensimulator.org; moses-list at lists.mitre.org
>> *Subject:* Re: [Opensim-dev] New MOSES Physics Video
>>
>>
>>
>> Hi!
>>
>> An excellent video on the physics of exploding grenades and the wall.  On
>> the OS Dev list Mister Blue has an excellent observation that the server
>> crashes are due to the extreme amount of changes that have to be sent to
>> every avatar. His idea of a client side solution might just be a good one.
>> In the end is there any way that OpenSim can handle more events than that
>> in it's present form? Is there any physics engine that can handle 240
>> moving scripted objects moving at once without lag?
>>
>> If we could get OS to the point that it would handle this load easily, we
>> would have all our load issues solved!
>>
>> Steve LaVigne
>>
>>
>>
>> On Tue, Apr 14, 2015 at 6:33 AM, Michael Emory Cerquoni <
>> nebadon2025 at gmail.com> wrote:
>>
>> Could these test scripts be shared so testing against other engines can
>> occur as well, I would be interested to see how this same test goes against
>> ODE and BulletSim as well.
>>
>>
>>
>> On Tue, Apr 14, 2015 at 8:18 AM, Maxwell, Douglas CIV USARMY ARL (US) <
>> douglas.maxwell3.civ at mail.mil> wrote:
>>
>>    Good Morning, as you all know the MOSES developers are working on
>> PhysX integration into the Open Simulator to support functionality
>> currently not possible in the platform.  We are a methodical group and a
>> couple months ago I asked one of our interns to work with the developers to
>> create a series of baseline physics behavior case studies.  The first case
>> study is a destructible wall caused by an explosive charge.  This wall is
>> composed of blocks that are tested at a high density and a low density to
>> simulate different destruction effects.
>>
>>
>>
>> The goal here is to eventually have all of the prims in the sim loaded
>> with the scripts needed to react to any type of random explosive charge set
>> by the participants in the training scenario.
>>
>>
>>
>> The video can be found below:
>>
>>
>>
>> https://youtu.be/jSofWcwWi7g
>>
>>
>>
>> Your feedback is welcome.
>>
>>
>>
>> Observations:
>>
>> 1)  Current limitations of the open simulator prevent us from expanding
>> the tests beyond a simple wall.
>>
>> 2)  The scripts exercise the engine well and expose limitations between
>> the sim frame rate and the physics frame rate.
>>
>> 3)  It is easy to crash the sim with this demonstration, especially if
>> more than a handful of people are present (more than 3-4 client
>> connections).
>>
>>
>>
>> Douglas Maxwell, MSME
>> Science and Technology Manager
>> Virtual World Strategic Applications
>> U.S. Army Research Lab
>>
>> Human Research & Engineering Directorate
>> Simulation & Training Technology Center
>> (c) (407) 242-0209 <%28407%29%20242-0209>
>>
>>
>>
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>> Opensim-dev at opensimulator.org
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>>
>>
>>
>>
>> --
>>
>> Michael Emory Cerquoni
>>
>>
>>
>
>
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