Description

Simple example of a cone rendering in the browser using VTK and Emscripten.

Build using docker

Execute to build the emvtk image:

docker build . -t emvtk

Run to start web server on port 6931:

docker run --rm -it -p 6931:6931 emvtk

Result should now be accesible at:

http://localhost:6931

Build without docker

Before the build following requirements should be met:

• Install Emscripten
• Activate Emscripten environment (i.e. source ./emsdk_env.sh for Bash)
• CMAKE_TOOLCHAIN_FILE environment variable should be set to <emsdk install path>/upstream/ emscripten/cmake/Modules/Platform/Emscripten.cmake
• Compil VTK, using Emscripten (how to build VTK)
• VTK_BUILD_DIR environment variable should be set to VTK build directory

Use make build-local command to build and run the example. Result should be accesible at: http://localhost:6931.

How to build VTK using Emscripten

Build requires the following branch of VTK https://github.com/dicehub/VTK/tree/emscripten.

First of all, freetype port should be enabled for Emscripten compiler. It can be done by setting the CXXFLAGS environment variable, for example:

export CXXFLAGS='-s USE_FREETYPE=1'

Then, ninja build files should be generated, using CMake:

    cmake -G Ninja \
    -DCMAKE_BUILD_TYPE:STRING=Release \
    -DBUILD_SHARED_LIBS:BOOL=OFF \
    -DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE} \
    -DCMAKE_INSTALL_PREFIX:PATH=./install \
    -DBUILD_EXAMPLES:BOOL=OFF \
    -DBUILD_TESTING:BOOL=OFF \
    -DVTK_NO_PLATFORM_SOCKETS:BOOL=ON \
    -DVTK_OPENGL_USE_GLES:BOOL=ON \
    -DModule_vtkRenderingContextOpenGL2:BOOL=OFF \
    -DVTK_USE_SYSTEM_FREETYPE:BOOL=ON \
    -DH5_HAVE_GETPWUID:BOOL=OFF \
    -DFREETYPE_INCLUDE_DIRS:PATH='include' \
    -DFREETYPE_LIBRARY:STRING='freetype' \
    ../VTK

And build it with:

    ninja -j "$(nproc)"

In the command above, freetype library is faked using cmake options FREETYPE_INCLUDE_DIRS and FREETYPE_LIBRARY. Also, getpwuid is disabled because currently it is missing in Emscripten. Full example can be found in the Dockerfile.