Ah, thanks for your explanation - I'm with you now. I've done some shader programming myself, both "from scratch" and also in Godot, but I'm not an expert. So if you're using a 2D transform type, on the hardware it's still using a 3D/quaternion transform? Interesting.
And so even if I was careful to write shaders that efficiently operate in 2D space, those efficiencies would be trumped by the hardware converting it all to 3D space anyway?
I guess my intuition was that if you have a full 3D shader setup, eg the Unity renderer, that you add a layer of new shaders on top of to give a friendlier 2D API, that's going to be slower than just writing the 2D API on its own.
And so even if I was careful to write shaders that efficiently operate in 2D space, those efficiencies would be trumped by the hardware converting it all to 3D space anyway?
I guess my intuition was that if you have a full 3D shader setup, eg the Unity renderer, that you add a layer of new shaders on top of to give a friendlier 2D API, that's going to be slower than just writing the 2D API on its own.