Skip to content

Latest commit

 

History

History
executable file
·
127 lines (89 loc) · 4.3 KB

BUILD.md

File metadata and controls

executable file
·
127 lines (89 loc) · 4.3 KB

BUILDING THINGS

The Bullet physics engine is available for OpenSimulator using the BulletSim plugin. This functionality is provided by several pre-built binary executables for various target architectures. These executables include DLL's, SO's, and DYNLIB's.

BulletSim consists of the C# code that is included in the OpenSimulator sources, this C++ "glue" code which provides the interface between the C# code and the Bullet physics engine, and the Bullet physics engine itself.

The steps are to fetch the Bullet physics engine sources, build it, then build the BulletSim C++ glue code and staticlly link it with the built Bullet physics engine.

Since Bullet is supplied as a binary, there are separate versions built for different target operating systems and machine architectures. Thus the built binary filename includes the version of Bullet used, the build date, and the target machine architecture. Expect to see filenames like:

  • libBulletSim-3.25-20230122-x86_64.so (Intel arch, Linux)
  • libBulletSim-3.25-20230122-aarch64.so (ARM 64 bit arch, Linux)
  • libBulletSim-3.25-20230122-universal.dynlib (either x86 or ARM, IOS)
  • libBulletSim-3.25-20230122-x86.64.dll (Intel arch, Windows)

The selection of which binary to use must be configured in OpenSimulator. This either requires copying the correct file to as default name or editing a .config file.

NOTES

  • This builds with Bullet physics engine version 3+. Before 2023, BulletSim.dll was built with Bullet version 2.86. The 3.25 version of Bullet has been tested and does not seem to make any difference to OpenSimulator operation as most of the Bullet changes have to do with APIs and integration with Python (thus PyBullet). Refer to some of the .sh files for the process of building the BulletSim binary with the previous version of Bullet.

  • Only 64 bit architectures are supported.

BUILDING

This "official" build scripts are called from .github/workflows/build-dotnet6.yml which builds all the pieces using the Github action system.

For Linux, the script makeBullets.sh has the following build steps captured in one script.

To build by hand, several scripts that are used in build.yml are available. This builds the latest version of BulletSim with the latest version of the Bullet physics engine.

  1. Fetch the latest version from GitHub: https://github.com/bulletphysics/bullet3.
    cd trunk/unmanaged/BulletSim
    git clone --depth 1 --single-branch https://github.com/bulletphysics/bullet3.git
  1. Apply all the patches for bullet:
	cd bullet3 ; for file in ../*.patch ; do cat $file | patch -p1 ; done

There are some small changes that are needed for the using Bullet for distributed physics (physics simulation in both the serve and the client).

There are separate patch files for Bullet version 2.86. These all start with the string "2.86-". Refer to makeBullets.sh for an example of pulling and patching the 2.86 version of Bullet.

  1. Build the Bullet physics engine

a) Windows:

Install CMake for Windows.

`buildBulletCMake.ps1` builds the Bullet physics engine. Note that this
is a PowerShell script.

If one can not install `CMake` but has Visual Studio, `buildBulletVS.bat` will
build `bullet3/build3/vs2010/0Bullet3Solution.sln` which can be used by 
any modern Visual Studio to build the Bullet physics engine.
Note that after this step, the Bullet physics engine binaries will be in
the `lib` directory and the include files must be copied into `include/`.

b) Linux and IOS:

The script "buildBulletCMake.sh" has the appropriate cmake and compilation
commands for Linux and IOS.
The script builds bullet static libraries and copies them into local directories.

    ./buildBulletCMake.sh
  1. Build BulletSim

a) Windows:

Generate version file information:

    bash buildVersionInfo.sh

Build BulletSim:

    .\buildBulletSim.ps1

b) Linux and IOS:

Run BulletSim compile and link script:

    ./buildBulletSim.sh

This builds a file with a name like: `libBulletSim-3.25-20230111-x86_64.so`.
Copy this file in to the OpenSimulator `bin/lib64` directory and edit
`OpenSim.Region.PhysicsModule.BulletS.dll.config` to point to this file for
the machine architecture you are running on.