OpenGL: FXAA antialiasing is not reimplemented yet

[Calinou]

Godot version

4.0.beta7

System information

Fedora 36, GL Compatibility, AMD Radeon RX 6900 XT

Issue description

FXAA is missing in 3D rendering in the OpenGL renderer. In comparison, Godot 3.x's GLES3 renderer supports FXAA.

Steps to reproduce

• Set Screen Space AA to FXAA in the advanced project settings.
• Run the project.

Minimal reproduction project

demo-fxaa.zip

[clayjohn]

We don't have any immediate plans to re-implement FXAA in the OpenGL renderer as we are working to avoid doing any post-processing at all. The post-processing pass required for FXAA can be a killer on mobile devices.

Moving the milestone as this definitely won't be added for 4.0. We can consider adding it in later releases as we expose more performance trade-offs to users (i.e. we could make the post processing pass optional)

[EzraT]

I suggest adding a warning message when trying to enable FXAA in the Compatibility renderer, for clarity, as long as this isn't implemented.