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18 May 2015 : Compiling OpenVDB using MinGW on Windows #

OpenVDB seems to work best on Linuxy systems. Nick Avramoussis has posted some useful and clear instructions on how to build it using VC++10/11. Unfortunately C++ libraries aren't portable between compilers, and I needed it integrated into an existing project built using MinGW.

This post chronicles my experiences with getting it to work. If you're planning to travel the same path, you should know from the start that it's quite an odyssey. OpenVDB has several dependences which also need to be built with MinGW as well. But it is possible. Here's how.

The Dependencies

OpenVDB relies on several libraries you'll need to build before you can even start on the feature presentation. The best place to start is therefore downloading each of these dependencies and collecting them together.

I've listed the version numbers I'm using. It's likely newer versions will work too.

  1. Boost 1.58
  2. ilmbase 1.0.3 source code (part of OpenEXR)
  3. OpenVDB 3.0.0. Not a dependency, but you're certainly going to need it
  4. TBB 4.3 Update 5 Source

You also need zlib, but MinGW comes with a version you can use for free. Finally, grab yourself this skeleton archive which contains some files needed to complete the build.

The Structure

Each of these will end up generating a library you'll link in to OpenVDB. In theory it doesn't matter where you stick them as long as you can point g++ to the appropriate headers and libraries. Still, to make this process (and description) easier, it'll be a big help if your folders are structured the same way I did it. By all means mix it around and enjoy the results!

I've unpacked each archive into its own folder all at the same level with the names boost, ilmbase, openvdb, tbb and test. The last contains a couple of test files, which you can grab from the skeleton archive. You can download a nice ASCII-art version of the folder structure I ended up with (limited to a depth of 2) to avoid any uncertainty.

In the next few sections I'll explain how to build each of the prerequisites. This will all be done at the command line, so you should open a command window and negotiate to the folder you unpacked all of the archives into.

Building Boost

Boost comes with a neat process for building with all sorts of toolchains, including MinGW. Assuming the folder structure described above, here's what I had to do.

cd boost
bootstrap.bat mingw
.\b2 toolset=gcc
cd ..

If you've download the skeleton archive, you'll find the build-boost.bat script will do this for you. This will build a whole load of boost libraries inside the boost\stage\lib folder. As we'll see later, the ones you'll need are libboost_system-mgw48-mt-1_58 and libboost_iostreams-mgw48-mt-1_58.

Building ilmbase

Actually, we don't need all of ilmbase; we only need the Half.cpp file. Here's what I did to build it into the library needed.

cd ilmbase\Half
g++ -UOPENEXR_DLL -DHALF_EXPORTS=\"1\" -c -I"." -I"..\" Half.cpp
cd ..\..
ar rcs libhalf.a ilmbase\Half\*.o

This will leave you with a library libhalf.a in the root folder, which is just where you need it.

Building TBB

TBB comes with a makefile you can use straight away, which is handy. This means you can build it with this.

cd tbb
mingw32-make compiler=gcc arch=ia32 runtime=mingw tbb
cd ..

Now copy the files you need into the root.

copy tbb\build\windows_ia32_gcc_mingw_release\tbb.dll .
copy tbb\build\windows_ia32_gcc_mingw_release\tbb.def .

Building OpenVDB

Phew. If everything's gone to plan so far, you're now ready to build OpenVDB. However, there are a few changes you need to make to the code first.

Following the steps from Nick's VC++ instructions, I made these changes:

  1. Add #define NOMINMAX in Coord.h and add #define ZLIB_WINAPI in
  2. Change the include path in Types.h from <OpenEXR/half.h> to <half.h>
  3. Add #include "mkstemp.h" to the top of openvdb\io\ This is to add in the mkstemp function supplied in the skeleton archive, which for some reason isn't included as part of MinGW.

The following should now do the trick.

cd openvdb
g++ -DOPENVDB_OPENEXR_STATICLIB=\"1\" -UOPENEXR_DLL -DHALF_EXPORTS=\"1\" -c -w -mwindows -mms-bitfields -I"..\..\libzip\lib" -I".." -I"..\boost" -I"..\ilmbase\Half" -I"..\tbb\include" *.cc io\*.cc math\*.cc util\*.cc metadata\*.cc ..\mkstemp.cpp
cd ..
ar rcs libopenvdb.a openvdb\*.o

And bingo! You should have a fresh new libopenvdb.a library file in the root folder of your project.

Testing the Library

Okay, what now?

You want to use your new creation? No problemo! The skeleton archive has a couple of test programs taken from the OpenVDB cookbook.

These tests also provide a great opportunity to demonstrate how the libraries can be integrated into the MinGW build process. Here are the commands I used to build them.

g++ -DOPENVDB_OPENEXR_STATICLIB=\"1\" -UOPENEXR_DLL -DHALF_EXPORTS=\"1\" -w -c -I"." -I"boost" -I"ilmbase\Half" -I"tbb\include" test\test1.cpp
g++ -DOPENVDB_OPENEXR_STATICLIB=\"1\" -UOPENEXR_DLL -DHALF_EXPORTS=\"1\" -w -c -I"." -I"boost" -I"ilmbase\Half" -I"tbb\include" test\test2.cpp
g++ -g -O2 -static test1.o tbb.dll zlib1.dll -Wl,-luuid -L"." -o test1.exe -lhalf -lopenvdb -L"boost\stage\lib" -lboost_system-mgw48-mt-1_58 -lboost_iostreams-mgw48-mt-1_58
g++ -g -O2 -static test2.o tbb.dll zlib1.dll -Wl,-luuid -L"." -o test2.exe -lhalf -lopenvdb -L"boost\stage\lib" -lboost_system-mgw48-mt-1_58 -lboost_iostreams-mgw48-mt-1_58

The key points are the pre-processor defines for compilation:

  2. Define: HALF_EXPORTS
  3. Undefine: OPENEXR_DLL

the include folders needed also for compilation:

  1. boost
  2. ilmbase\Half
  3. tbb\include

and the library folders needed during linking:

  1. tbb.dll
  2. zlib1.dll (can be found inside the MinGW folder C:\MinGW\bin
  3. libhalf.a
  4. libopenvdb.a
  5. libboost_system-mgw48-mt-1_58.a
  6. libboost_iostreams-mgw48-mt-1_58.a

Finally you should be left with two executables test1.exe and test2.exe to try out your new creation.