Running a standalone grid on your home computer is not big thing to do. Finding all the information you need to get it working as you want is a bit of a pain. All the people that are working on OSGrid know where everything is. So, they don’t write it down.
When I reinstalled my OpenSim server (I broke mine upgrading) it did not let me walk on prims. Everything was phantom. Setting things to physical did not help, they were still behaving as if phantom. So, I started looking for how to fix that.
There is a page on configuration details: OpenSim configuration file This has interesting bits of information and links and is a mix of accurate and out dated information.
A more detailed set of instructions for installing OpenSim is on V-Business.
As it says: The Quick And Easy Guide to Running Opensim On Your PC
A well explained and very useful OpenSim Configuration Command Line Manual was written by Maxx Monde. There is also a more detailed install guide and one for installing MySQL. If you read through the install guide you will see Maxx says the ‘basicPhysics’ engine is limited to detecting your AV’s collisions with the ground but not objects. Everything else will be phantom. So, now we know the problem. We need a different physics engine.
There are several physics engines that can be used with OpenSim. ODE is the best but is said to only works with versions 6.7 and later. It works on the current 6.6 r9993. My downloaded file is labeled 6.6 r9993, which is supposed to have several engines bundled with it – I find it does. When running it says it is 6.5 r9993. I assume this is just another missed detail in the building process.
Onward… There is an OpenSim page on selecting the physics engine: OpenSim Physics Engines After reading it, I decided the page is a bit dated and often as confusing as it is helpful. I need that email I saw I saw somewhere for geekiness enhancement…
It seems one can either change the engine by using a command line when starting the server or add a command to the configuration file.
For the command line add: -physics=OpenDynamicsEngine.
To add the RealPhysX engine (Windows or Linux) one adds the command line instruction: -physics=RealPhysX – Warning: One must add several DLL’s that are not included with OpenSim for legal reasons.
Then there is this command: -physics=modified_BulletX, which lets you run BulletX as the physics engine. Warning: It did not work for me, sim software crashed.
To add it to the configuration file add it in the OpenSim.ini file. Now if I can just find those instructions. It seems the instructions to change the configuration files that are in OpenSim/bin/config-include don’t apply to my version (6.6 or 6.5). There is no bin folder in my install.
After a lot of looking I find most of the documentation to be out of date or at least different than what my December build for Windows installed. Not much help.
The more I searched the more frustrated I got. There is just nothing out there telling me what they did with the recent build of OpenSim and how to install a different physics engine. If I can’t find something via Google that usually means there is such an obvious answer no one puts it in their tutorials and blogs. So, I started looking for the OpenSim.ini file and found it. Most of the instructions you need are within that file.
How to Change OpenSim’s Physics Engine
Once you find it, it is, of course, easy. There is an OpenSim.ini file in the OpenSim folder (C:\Program Files\OpenSim – by default on Windows).
Open the INI file with Notepad or any plan text editor. Look through the files for the section on physics.[sourcecode language=”text”] ; ##
; ## PHYSICS
; if you would like to allow prims to be physical and move by physics with the physical checkbox in the client set this to true.
physical_prim = true
; Select a mesher here. ZeroMesher is save and fast.
; ZeroMesher also means that the physics engine models the physics of prims
; sticking to the basic shapes the engine does support. Usually this is only a box.
; Meshmerizer gives a better handling of complex prims by using triangle meshes.
; Note, that only ODE physics currently deals with meshed prims in a satisfactoring way
meshing = ZeroMesher
;meshing = Meshmerizer
; Choose one of the physics engines below
;physics = basicphysics
;physics = POS
physics = OpenDynamicsEngine
;physics = modified_BulletX
Changing the physics engine in OpenSim is as easy as adding and removing a semi-colon. If you have read the old pages at OpenSim.org you may have the idea that ODE won’t work. It does.
If you have any prims set to physical, expect your sim to be slow. At least mine was but I had set a bunch of tightly fit prims to physical when I was trying to figure out why I was falling through the floor. I was getting about 5 FPS on the server. Once I cleaned those up it jumped up to 45.
I started with ODE and once I got my physical prims cleared out it sort of works. I don’t fall through floors. However collisions are not what one expects. You can’t open a hole in a prim and go through it. At least on my sim you can’t. Also walking down steep stairs is out, one fly’s down.
I tried changing the meshing to Meshmerizer. That helped. With the meshing changed I can walk through the holes in prims. I still fly down stairs. The server was up to 45 FPS.
I tried modified_BulletX. That crashed.
I tried POS. It works well. I don’t fly down stairs. I flail at the bottom of the stairs. Even with meshing changed to Meshmerizer I can’t walk through a prim hole.
Now I can walk on prims…
When I tried to make my first upgrade I managed to break my sim. It would have been nice if I had a backup of my region to have restored to my new install. It’s tough being new.
WhiteStar Magic wrote a post on OSGRID.org’s forum on how to make a command line script to make a backup of your regions. OpenSim Region Backup He provides instructions for backing up your MySQL and for restoring.
There is good information out there. The OSGrid server software changes quickly so documentation seems to lag. The OpenSim.org web site also seems to be behind and a mix of new and years old information. OSGRID.org has a good forum that is active. There is lots of good information there.
In your exploring you will see CentOS (Community ENTerprise Operating System) several times. For Windows people like me that is the name of a Linux like operating system. It seems people running OSGrids like it.
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