WebGL sample compilation

If you've built FreeType without using CMake, then you have to extend CMake scripts for WebGL sample with FreeType search paths (similar to "adm/cmake/freetype.cmake" used for building OCCT itself).
Alterantively, you can re-build FreeType using CMake - in this case FreeType installation folder will have "lib/cmake/freetype/freetype-config.cmake" configuration file, so that freetype_DIR in WebGL sample should point to this "lib/cmake/freetype" folder.

Hi

Another issue regarding the compilation that I've had, using :

OCCT 7.6.0 dev
Emscripten 1.39.7 ( MinGW 4.6.2-32bit )

Compiling seems ok, but when it comes to linking :

Anyone found a way to get through this one ?

Thanks,

Paul

Hi and thanks for your prompt reply,

I did use the Qt 5.15.2 for WebAssembly tutorial and the recommended version for Emscripten is 1.39.7 ...

I Installed and activated Emscripten 2.0.23 and mingw-7.1.0-64bit as you indicated, and now the process goes a bit further, yet it splashes this new error :

A bit of search on the github issues indicates that it could be linked to newest version of Emscripten not handling things the same as they used to in previous releases.

I'll have a go at different versions and see which one can fit then ...

Regards,

Paul

Hi

I have another issue about the compilation.

Using:

• OCCT 7.6.0
• cmake version 3.22.1
• emsdk 2.0.11

Command:

     emcmake cmake .. -DOpenCASCADE_DIR=E:\package\opencascade\opencascade-install\cmake -G "Visual Studio 16 2019" -A x64

Error:

CMakeOutput.log:

 The target system is: Emscripten - 1 - x86_64
The host system is: Windows - 10.0.19043 - AMD64

Edited files

webgl/CMakeLists.txt

# FreeType
set(freetype_DIR E:/package/thrid-part/freetype-2.5.5)
# find_package(freetype REQUIRED NO_DEFAULT_PATH)
# if(freetype_FOUND)
#   message (STATUS "Using FreeType from \"${freetype_DIR}\"" )
# else()
#   message(WARNING "Could not find FreeType, please set freetype_DIR variable." )
# endif()

# Open CASCADE Technology
find_package(OpenCASCADE REQUIRED)

 Emscripten.cmake

# Advertise Emscripten as a 32-bit platform (as opposed to
# CMAKE_SYSTEM_PROCESSOR=x86_64 for 64-bit platform), since some projects (e.g.
# OpenCV) use this to detect bitness.

# set(CMAKE_SYSTEM_PROCESSOR x86)
set(CMAKE_SYSTEM_PROCESSOR x86_64)

I found a similar error. link.

You are trying to build a x86 (32bit) program saying that you want to link it to a 64bit library. Then the mess.
Just check the script that you are using to trigger the build, there lies the problem :)

I edited "set(CMAKE_SYSTEM_PROCESSOR x86)" to "set(CMAKE_SYSTEM_PROCESSOR x86_64)" in Emscripten.cmake, but it didn't work.

Anyone found a way to get through this one ?

Thanks,

Vrainy

Hi everyone,

I'm trying to build the WebGL sample project on macOS 13, and I'm stumbling on the same problems but also new ones. Maybe someone will be able to give me some directions.

First, I had the same problem with the freetype_DIR as everyone above. I modified webgl/CMakeLists.txt to provide the path to the Freetype directory.

Now when using emcmake ccmake then [c]configure, I get a number of errors

  CMake Deprecation Warning at CMakeLists.txt:1 (cmake_minimum_required):
   Compatibility with CMake < 3.5 will be removed from a future version of
   CMake.

   Update the VERSION argument <min> value or use a ...<max> suffix to tell
   CMake that the project does not need compatibility with older versions.

 CMake Error at ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEConfig.cmake:100 (include):
   include could not find requested file:

     ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEFoundationClassesTargets.cmake
 Call Stack (most recent call first):
   CMakeLists.txt:52 (find_package)

 CMake Error at ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEConfig.cmake:100 (include):
   include could not find requested file:

     ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEModelingDataTargets.cmake
 Call Stack (most recent call first):
   CMakeLists.txt:52 (find_package)

 CMake Error at ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEConfig.cmake:100 (include):
   include could not find requested file:

     ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEModelingAlgorithmsTargets.cmake
 Call Stack (most recent call first):
   CMakeLists.txt:52 (find_package)

 CMake Error at ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEConfig.cmake:100 (include):
   include could not find requested file:

     ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEVisualizationTargets.cmake
 Call Stack (most recent call first):
   CMakeLists.txt:52 (find_package)

 CMake Error at ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEConfig.cmake:100 (include):
   include could not find requested file:

     ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEApplicationFrameworkTargets.cmake
 Call Stack (most recent call first):
   CMakeLists.txt:52 (find_package)

 CMake Error at ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEConfig.cmake:100 (include):
   include could not find requested file:

     ~/Documents/OpenCascade/opencascade-7.7.0/OpenCASCADEDataExchangeTargets.cmake
 Call Stack (most recent call first):
   CMakeLists.txt:52 (find_package)

 Using OpenCASCADE from "../.."
 Configuring incomplete, errors occurred!

And indeed these files are not in the opencascade-7.7.0 directory.

Any help will be greatly appreciated, Thanks,

Renaud

I finally managed to build and run the example and run it on my Mac. I'm going to explain each steps given in the ReadMe.md file, which is laconic and outdated. My instructions should mostly work on other Unix's and might help Windows users as well.

Install Emscripten SDK and activate minimal configuration (Python, Java and CLang) following emsdk documentation. Activate also MinGW when building sample on Windows host.

Just install Emscripten. Make sure it works by compiling a simple example.

Build (using emsdk) or download FreeType static library.

Download the latest version of FreeType.

cd freetype-2.13.2
mkdir build
cd build
emcmake cmake ..
emmake make install

Configure CMake for building Open CASCADE Technology (OCCT) static libraries (BUILD_LIBRARY_TYPE="Static"). For this, activate emsdk command prompt, configure CMake for building OCCT using cross-compilation toolchain, disable BUILD_MODULE_Draw.

First, let's talk about the weird behaviour of ccmake. If it is invoked before cmake was invoked, then the infamous "EMPTY CACHE" message will show. I would have thought that ccmake used CMakeLists.txt to establish its list of options, but visibly, it uses CMakeCache.txt instead.

Back to the steps:

cd opencascade-7.7.0
emcmake cmake
emcmake ccmake

In ccmake, set the options as indicated:

• BUILD_LIBRARY_TYPE= Static
• BUILD_MODULE_Draw = OFF

then press c to configure.

Launch the build:

emmake make install

It takes more than one hour on my machine.

Files are generated in ~/Documents/emsdk/upstream/emscripten/cache/sysroot/lib/cmake/opencascade If this is not the case, check the INSTALL_DIR of OpenCascade.

Perform building and installation steps. ${EMSDK}/fastcomp/emscripten/cmake/Modules/Platform/Emscripten.cmake Configure CMake for building this WebGL sample using emsdk with paths to OCCT and FreeType. Perform building and installation steps.

cd opencascade-7.7.0/samples/webgl
emcmake cmake
emcmake ccmake

At this stage, you are going to have a problem, because the CMakeLists.txt file of the WebGL sample expects the FreeType build directory to contain a freetypeConfig.cmake file but this is no longer the case in recent versions.

A solution proposed above is to modify CMakeLists.txt:

# FreeType
set(freetype_DIR <Path to FreeType build directory>)
#find_package(freetype REQUIRED NO_DEFAULT_PATH)
#if(freetype_FOUND)
#  message (STATUS "Using FreeType from \"${freetype_DIR}\"" )
#else()
#  message(WARNING "Could not find FreeType, please set freetype_DIR variable." )
#endif()

Launch emcmake ccmake again, and now you may configure

• OpencCASCADE_DIR = installation directory of OpenCascade (~/Documents/emsdk/upstream/emscripten/cache/sysroot/lib/cmake/opencascade)

emmake make install
make: make install

This time, the WebGL sample should build.

Copy data/occ/Ball.brep from OCCT into "samples" folder within WebGL sample installation path.

Create a samples directory into sample/webgl/. Copy Ball.brep to it.

Navigate to installation folder and start web server from it; Python coming with emsdk can be used for this purpose: python -m SimpleHTTPServer 8080

emrun occt-webgl-sample.html

Open compatible browser and enter path taking into account your web server settings: http://localhost:8080/occt-webgl-sample.html

See in the console at which URL the web server listens. For me, it's http://0.0.0.0:6931.