FSAA setting has no effect on world rendering when shaders are enabled

[Calinou]

Minetest version

5.7.0

OS / Hardware

Operating system: Linux
CPU: Intel Core i9-13900K

GPU model: GeForce RTX 4090 (NVIDIA 530.41.03)
OpenGL version: OpenGL 4.6

Summary

When shaders are enabled, the FSAA setting only affects the wieldhand rendering, not the general world rendering (regardless of which value you choose). This cannot be worked around by forcing antialiasing on the graphics driver.

After disabling shaders, toggling FSAA works on the world rendering.

I can confirm fsaa = 4 is present in my minetest.conf, so it's not an issue with the settings menu.

Steps to reproduce

Ensure shaders are enabled, set FSAA to 4 in the All Settings menu, then restart the game.

To compare with driver-forced MSAA: On Linux with the NVIDIA proprietary driver, set the __GL_FSAA_MODE environment variable to 5 to force 4× MSAA on any OpenGL application. For example, when using the Flatpak, use __GL_FSAA_MODE=5 flatpak run net.minetest.Minetest.

$ nvidia-settings --query=fsaa --verbose
[...]
      value - description
        0   -   Off
        1   -   2x (2xMS)
        5   -   4x (4xMS)
        9   -   8x (4xSS, 2xMS)
       10   -   8x (8xMS)
       11   -   16x (4xSS, 4xMS)

On Windows, you have a similar option available in the NVIDIA Control Panel.

[rubenwardy]

See #13253

[Calinou]

I was actually wrong on the exact circumstances. MSAA does work on the wieldhand rendering when shaders are enabled, and it works on the world rendering too when shaders are disabled. I've updated OP accordingly.

This sounds like an issue with a missing MSAA resolve step on the world framebuffer when shaders are enabled.

[sfan5]

ping @x2048

[x2048]

Enabling shaders enables the deferred rendering pipeline, and the 3d step is done into a renderbuffer instead of screen. FSAA does not support renderbuffers, and, for example, FXAA or some other technique can be used (there is a PR somewhere for FXAA).

If possible, I would not go back to direct rendering using shaders, too many options to maintain.

[sfan5]

If anything we should document this better but it also looks like it's gonna be solved by that pending PR.