Add documentation pages on 2D and 3D antialiasing

[Calinou]

Images on the new pages were generated using https://github.com/Calinou/godot-antialiasing-comparison.

Some of this information is relevant for 3.x, so this PR could be remade for the 3.6 branch and cherry-picked to 3.5 (with mentions of alpha to coverage, TAA and 3D resolution scaling removed).

[clayjohn]

This is great!

One thing I noticed but couldn't comment on is that the TAA photo looks like there is no antialising (in many places the aliasing is worse than with no-antialising). It looks significantly worse than FXAA in these screenshots. How are you capturing the images for it? Are you using something automated that saves the first frame?

[Calinou]

Are you using something automated that saves the first frame?

The demo project waits for 30 frames to be rendered before taking the TAA screenshot. It's strange that it looks bad, but maybe this is due to the low input resolution (348×348, so the image can be displayed at a pixel-perfect size in the online docs on desktop).

[mhilbrunner]

Reviewed, didn't spot anything (aside from the above discussion).
Feel free to merge once you have figured out what to do with that :P

Good work!

[snailrhymer]

Some little changes, and highlighted some points where terminology wasn't clear to me (intermediate dev, very limited exerience with rendering).

[clayjohn]

@Calinou Looks like you forgot to remove the FSR reference under anti-aliasing, after that it should be good!

[Calinou]

@Calinou Looks like you forgot to remove the FSR reference under anti-aliasing, after that it should be good!

Done 🙂

I've created a documentation page dedicated to 3D resolution scaling: #6331

[mhilbrunner]

Want to convert the pngs to webps? :) Otherwise this looks mergeable

[clayjohn]

This is getting very close to being ready to merge!

[Calinou]

Want to convert the pngs to webps? :) Otherwise this looks mergeable

Done. For reference, I used parallel cwebp -z 9 {} {.}.webp ::: 3d_antialiasing_*.png for lossless compression with the smallest possible file size. New images are on average 30% smaller compared to their PNG equivalents, but with the same quality.

[akien-mga]

Thanks!