Skipping OpenGL: USE_OPENGL=OFF - Forum Open Cascade Technology

mikedh
Fri, 03/08/2024 - 07:25

Forums:

Hi, thanks for the great work on OpenCASCADE!

I'm trying to package a minimal "step-to-glb" converter for Python, and I can't get it to stop linking libGL.so.1. I could install apt install --no-install-recommends libgl1-mesa-glx and make it work but it seems like the library shouldn't require opengl when build with USE_OPENGL=OFF set? Am I missing a cmake option maybe?

Building OCCT with:

cmake -G Ninja -DCMAKE_BUILD_TYPE=Release -DUSE_RAPIDJSON:BOOL="ON" 
-D3RDPARTY_RAPIDJSON_INCLUDE_DIR="../rapidjson/include" 
-DUSE_OPENGL:BOOL="OFF" 
-DUSE_TK:BOOL="OFF"
-DUSE_FREETYPE:BOOL="OFF"
-DUSE_VTK:BOOL="OFF" 
-DUSE_XLIB:BOOL="OFF"
-DUSE_GLES2:BOOL="OFF"
-DUSE_OPENVR:BOOL="OFF" 
-DBUILD_Inspector:BOOL="OFF"
-DUSE_FREEIMAGE:BOOL="OFF"
-DBUILD_SAMPLES_QT:BOOL="OFF"  .

The Python build chain pulls in libTKRWMesh which looks like it really wants libGL:

mikedh@orion:$ ldd cascadio./libTKRWMesh-38d629a6.so.7.8.1
    libGL.so.1 => /lib/x86_64-linux-gnu/libGL.so.1 (0x00007f1dcd85b000)
    libEGL-29b68110.so.1.1.0 => cascadio./libEGL-29b68110.so.1.1.0 (0x00007f1dcd600000)

If you're curious you can download the .whl file from PyPi and if you rename it to a .zip file you can then run ldd/lddtree on the module: from PyPi or the full project on GitHub

Dmitrii Pasukhin
Sun, 03/10/2024 - 14:32

Hello, thank you for the report. Yes, originally the dependency should not exist if it is disabled. I assume the problem is with TKService. We need to investigate the issue. Moreover. we planning to reorganize the dependency graph to avoid extra-dependencies.

Handle(Geom_Surface) aSurface = BRep_Tool::Surface(aFace); // You can check the type of a Surface by ->IsKind(Standard_TYPE(...))

Best regards, Dmitrii.

mikedh
Sun, 03/10/2024 - 21:08

Awesome thanks for looking in to it! Yeah I tried turning off every cmake option I could think of and my weird Python tool chain is unrelated as with just OCCT's cmake it's linking to libGL. The minimal reproducing example is with just OCCT is:

cmake -G Ninja -DCMAKE_BUILD_TYPE=Release  -DUSE_OPENGL:BOOL="OFF" -DUSE_TK:BOOL="OFF" -DUSE_FREETYPE:BOOL="OFF" -DUSE_VTK:BOOL="OFF" -DUSE_XLIB:BOOL="OFF" -DUSE_GLES2:BOOL="OFF" -DUSE_OPENVR:BOOL="OFF" -DBUILD_Inspector:BOOL="OFF" -DUSE_FREEIMAGE:BOOL="OFF" -DBUILD_SAMPLES_QT:BOOL="OFF" -DBUILD_MODULE_Draw:BOOL="OFF" -DBUILD_MODULE_Visualization:BOOL="OFF" -DBUILD_MODULE_ApplicationFramework:BOOL="OFF" .

And then without building you can grep the build.ninja and see it's linking to libGL and libEGL:

grep "\-lGL " build.ninja

I dug into the various cmake files but couldn't quite tell where it was pulling in GL. It also happens with normal make (not just ninja). I may try manually just deleting -lGL and -lEGL from the build.ninja before I give up and say libGL is required haha.

Joachim Mairböck
Mon, 04/15/2024 - 11:48

I also had to patch OCCT for the Haiku build to allow building it without OpenGL (because there is no working implementation for Haiku GL in OCCT): https://github.com/haikuports/haikuports/blob/4672f5ad7176f48972b0330685...

Note that this is only a stub to allow building it without OpenGL. It will crash at runtime if you are trying to use a Viewer because the driver is nullptr in this case.