Problem in VTK 8.2 with defaultFormat() and QVTKOpenGLWidget on Windows 10/Intel

[estan (Elvis Stansvik)]

@Adam_Hendry

I’m not sure what is the impact of enabling QSurfaceFormat::CompatibilityProfile. Could we just enable it on all configurations?

Compatibility Profile is legacy OpenGL (version <= 2) where you only have fixed functions (no shaders; software rendering only), while core profile is modern OpenGL (includes shaders; render on gpu). Most OS’s ship with legacy OpenGL to handle the case where you don’t have dedicated rendering hardware.

I don’t recommend enabling it on all configurations because then you’re turning off hardware rendering.

Hm I don’t think this is the case. Even if the compatibility profile includes fixed-function APIs that were deprecated in OpenGL 3.0, while the core profile does not, surely those fixed-function APIs are hardware accelerated by the common OpenGL implementations (Intel, NVIDIA, AMD, …)?

And in any case, the question is more how VTK will react to running under compatibility profile vs core profile, which I think is up to VTK. Everything in core profile is also available in compatibility profile, so in theory it could run the exact same code. But I did find back when struggling with this issue that it seemingly “fixed” itself when using a compatibility profile.

I haven’t looked back at this issue in a long time, but as far as I know we are still using QVTKOpenGLNativeWidget everywhere (note QVTKOpenGLWidget), partly because of this.