VTK 9.x without hardware OpenGL acceleration on Windows

Is there a prescription for VTK 9.x and OpenGL1 (Mesa) now that the OpenGL1 backend in VTK has been removed? The build instructions at https://gitlab.kitware.com/vtk/vtk/-/blob/master/Documentation/dev/build.md really only discuss Mesa wrt Linux. Do we simply drop the Mesa dll(s) in the bin folder and run? Or do we configure the CMake build to use it somehow?

The docs on this are pretty thin.

Thanks!

If you get a Mesa build on Windows, you’ll want to point VTK’s build at its SDK and libraries (that is, anything FindOpenGL wants should get the Mesa answers). If you’re doing Qt stuff, you’ll run into this issue and need to tell Mesa to ignore compat bits (workaround is discussed in that issue).

Can you explain why this is necessary? A lot of documentation suggests just carefully naming and place dlls to make sure that mesa is loaded - and this seems to work. Does pointing VTK at Mesa’s SDK/libs result in a better (or faster) connection?

Our deployment scenario is one where most of our customer have sufficient support for OpenGL2, but some won’t and we want the code to switch to mesa in those limited cases. We do NOT want to deal with 2 different builds of VTK for this.

If that works, sure, it’s worth doing. But it’s not something I would necessarily trust to work in such a way without actual testing. It’s more about making sure that nothing is “leaking” around the “this is what OpenGL is” barriers and causing symbol mismatches or such.

As for getting a Mesa build on Windows, in the distant past I found this to be extremely helpful. GitHub - pal1000/mesa-dist-win: Pre-built Mesa3D drivers for Windows

hth