The way how things work at the moment is the only reliable way to create the images under Windows with Qt5. So, in case for Linux some fixes are needed the code for Windows must not be changed.- I still don't get file thumbnails on linux, unless I apply the GL_RGB32F_ARB -> GL_RGBA32F_ARB fix.
The thumbnail function uses View3DInventorViewer::imageFromFramebuffer which actually works well for me under Windows and Linux.- Tools -> Save picture... still doesn't work for me (no image produced, no error). It seems however to use a different mechanism than the above.
The Save picture function uses View3DInventorViewer::savePicture which internally can be controlled with a user parameter to either use:
- Coin's implementation of the off-screen renderer (SoFCOffscreenRenderer)
- FreeCAD's implementation of the off-screen renderer (SoQtOffscreenRenderer) which e.g. supports anti-aliasing. For Qt4 it can also be set to either use FBO or pixel buffers.