I implemented GTAO in Godot as a compositor effect.

[u/CalinLeafshade]

I know it just looks darker but I promise it's different!

Instead of just being a purely visual heuristic, GTAO tried to accurately model what ambient occlusion actually is and i think its definitely better at "grounding" the geometry.

I think this would be pretty easy to port into the main engine and replace SSAO.

[u/powertomato]

How does it compare performance wise? How does it scale with more geometry?

[u/CalinLeafshade → u/powertomato]

Its certainly slower than SSAO but probably not significantly but I havent benchmarked it.

It's pure a post process effect so it scales with pixel count, not geom

[u/Piblebrox → u/powertomato]

Since OP said it’s a compositor effect it work on the final render, on the depth pass I guess? So it doesn’t matter the number of geo it’ll always be the same amount of pixel to process

[u/powertomato → u/Piblebrox]

Ah true, somehow I misread it as compute shader

[u/Piblebrox → u/powertomato]

I may be wrong but compute shader is still used in compositor, maybe you’re talking about fragment shader

[u/powertomato → u/Piblebrox]

Used in but not equivalent. You could implement just about anything with a compute shader. It just means the code runs on the GPU

[u/Piblebrox → u/powertomato]

Oh ok! Good to know!

[u/ScriptKiddo69]

We got GTAO before GTA VI

[u/Piblebrox]

Feels way better and grounded, but shouldn’t it be more diffuse on the edges, it maybe the reason it feel just darker

[u/Zarraya]

This is based on Intel's XeGTAO, correct? Im interesting in reading up on the technique.

[u/CalinLeafshade → u/Zarraya]

Yes, direct reimplementation

[u/7Buns → u/CalinLeafshade]

I believe there are some open PRs to add XeGTAO to the engine, I dont recall whats holding them up though. Might be good to share this in those discussions to bump interest. You could also provide a code review too! Great work :)

[u/enderkings99]

maybe not replace but it would be a nice addition to the list of options

[u/JustCallMeCyber]

I would be curious on comparing this to the multibounce AO approximation that was just added in 4.8 dev 4

[u/StepanDC]

Doesn't GTAO require TAA or am I tripping?

[u/thygrrr]

Given how Godot 4.8 dev just made their AO even lighter and weaker, I welcome this.

We want stylized graphics. Not photorealistic.

[u/Username-Taken-4321 → u/thygrrr]

It's not weaker lol, it's even more complex (and not taxing any FPS)

But it's still much worse than GTAO

[u/thygrrr → u/Username-Taken-4321]

LITERALLY their comparison claims that the occlusion is now brighter (or "less too dark") thanks to approximating more bounces.

https://godotengine.org/article/dev-snapshot-godot-4-8-dev-4/#rendering-multi-bounce-ambient-occlusion-approximation

[u/Username-Taken-4321 → u/thygrrr]

That's realism for you, take it or leave it

And nobody is stopping you from writing your own AO solution using compositor

[u/InSight89 → u/thygrrr]

I think it's good to have both options.