Figure out OpenGL support

[dmik]

This ticket is to collect which OpenGL options we have on OS/2 and also how exactly OpenGL is used in Qt and how much it will be affected by disabling or ripping off OpenGL support.

IIRC, there is IBM OpenGL 1.0 for OS/2, IBM OpenGL 1.1 (gold?), SciTech MGL 5.0 and Mesa3D 5.1 for OS/2. We need to figure out which one is the most complete in terms of OpenGL API and OS/2 hardware support.

My idea is that if we only (mostly) have software OpenGL under OS/2, we should better rip it off of Qt (i.e. build Qt w/o any OpenGL dependency) rather than try to align the Qt code to such OpenGL. IIRC, in 2D Qt OpenGL is mostly used for acceleration of rendering operations which is questionable in case of software OpenGL emulation (and therefore pointless).

The Qt 3D module is a different story but it's beyond the scope of qtbase. The OpenGL requirement for Chromium (used by the Qt web engine module) is also mostly for 2D rendering so we should get rid of it as well (the latest Qt builds should support this).

Any generic information on OpenGL support for OS/2 is very welcome here. We will decide upon it.

For now, OpenGL in qtbase may be simply disabled with the -no-opengl configure switch.

[dryeo]

Sometime back I cleaned up the WarpMesaGL build system and merged the couple of versions that were floating around. https://github.com/OS2World/WarpMesaGL Currently only tested with VACPP 3.08. This probably the latest OpenGL, roughly OpenGL ver 1.4
Performance is surprisingly good for a software emulation.

[dmik]

@dryeo Thanks for the info, I will study it.

[SilvanScherrer]

It might be worth to look at https://github.com/Think-Silicon/GLOVE