Add a post-process shader template for CompositorEffect

[Chaosus]

I guess this should ease up the creation of CompositorEffect (code borrowed from https://docs.godotengine.org/en/latest/tutorials/rendering/compositor.html).

[Chaosus]

@dalexeev, @AThousandShips Please check again

[AThousandShips]

Approving on style

[dalexeev]

GDScript code style looks good to me.

[Chaosus]

After some thinking, I decided to divide it to two templates: one for simple CompositorEffect and one for CompositorEffect with inline code insertion, both without any comments (I think they will irritate the advanced users of this class).

[demolen]

only manually entering CompositorEffect as the parent class in the new script dialog would provide the templates. clicking on the inherit object Icon (the one that looks like a tree view) and looking for "CompositorEffect" doesn't provide any results. I don't know if this is related to this PR per se. but I spent quite a while trying to figure this out.

[Chaosus]

I don't know if this is related to this PR per se. but I spent quite a while trying to figure this out.

That's because it only shows Node-based classes, and CompositorEffect is a Resource-based class. That may be fixed, but not on this PR.

[demolen]

I also get this error in a freshly made project when instantiating the Default CompositorEffect template, I looked up on the code and internal_size() seems to be a method of RenderSceneBuffersConfiguration

[Chaosus]

I also get this error in a freshly made project when instantiating the Default CompositorEffect template, I looked up on the code and internal_size() seems to be a method of RenderSceneBuffersConfiguration

Ah, thank you for checking, I forgot to check it with enabled type hints, my fault.. Fixed

[akien-mga]

CC @BastiaanOlij

[BastiaanOlij]

I'm personally not a big fan of this. CompositorEffects in its current form was always meant as a foundation that could be used by experienced users, ontop of which things could be build that hide the complexity (but also limit its functionality to specific use cases).

For the use case here I made the shader example just as that, an example that shows how this could be used but which would need to be further worked out to become a good base.

To be exact, I raised this proposal for a much better alternative some months ago: godotengine/godot-proposals#7849
This would introduce a new material type and a new CompositorEffects subclass, and a number of hints that allow us to automatically bind the needed inputs and outputs and have people write proper shaders for this type of compositor effect.

The biggest issue that still needs to be worked out for that however is proper support for chaining effects where effects can read from the color buffer and write into a pong buffer, and visa versa.

[Chaosus]

Alright, if it's not desired, then closed.