OpenGL ES is the most widely supported 3D library today because of the mobile and tablet market.
It is also lagging behind the other libraries (Open GL, Direct 3D, others) by 2-3 generations, however, on December 2013 it made a huge step forward by introducing version 3.0

With this version out, any platform can now support per vertex textures, and volumetric texture handling via the GPU - something that was highly missing.

QT will benefit much by incorporating it and I would be forever in your debt