Implement custom non-trivial Visual Shader nodes

[paddy-exe]

Implement (partly) these proposals:

(RotationMatrix node and other DistanceFade modes in future PR) godotengine/godot-proposals#5106
(only as VS node): godotengine/godot-proposals#5112

• Proximity fade -> Category: Fade
• Distance fade -> Category: Fade
• Rand between two values -> Category: Random
• Polar coordinates conversion -> Category: Textures / Common
• Remap -> Category: Utility
• Linear depth -> Category: Textures / Depth

[nathanfranke]

Is M_PI exposed to the user, if so, it should be something like built_ins.glsl (not with _functions).

Also, looks like files in Godot's repository favor no spaces with builtin, so maybe builtins.glsl instead, although I admit that's harder to read.

$ find -iname '*builtin*' | wc -l
104
$ find -iname '*built_in*' | wc -l
0

[paddy-exe]

Is M_PI exposed to the user, if so, it should be something like built_ins.glsl (not with _functions).

The user can call PI in shader code since it's a global built-in now. I wasn't sure if I need to include it in the glsl file or not but I saw it in other shader files and I needed it for the polar_coordinates function.

Also, looks like files in Godot's repository favor no spaces with builtin, so maybe builtins.glsl instead, although I admit that's harder to read.

Thanks for going through the log! I will have to try it out. Since the plan is that it is automatically included anyway, the user doesn't need to include the file. (At least that's how I understood it when Clay John explained it to me)

[reduz]

I don't think adding functions to the core shaders to be used with the high level shaders is a good idea. This will increase compilation time for those shaders (and there are a lot to compile) without need.

IMO if you want to add these things for the core shaders as something to help users, this should be downloaded from the asset library, not be provided built-in.

If this is needed just for visual shaders, feel free to put those there directly, so they are used only on demand. Don't make them always available for the rest of the shaders.

[nathanfranke]

Is it possible to compile a snippet once, but still have it available everywhere? Otherwise, I agree that this should be in AssetLib, not core (knowing how many core shaders there are and how noticeable the shader compilation already is).

[paddy-exe]

Is it possible to compile a snippet once, but still have it available everywhere? Otherwise, I agree that this should be in AssetLib, not core (knowing how many core shaders there are and how noticeable the shader compilation already is).

@Chaosus had the idea for text-based shader add-ons but right now I guess we already have the shader preprocessor with include files that should do the trick.
I will be updating the PR according to Juan's feedback.👍🏻

[paddy-exe]

Polar Coordinates done for now:

[paddy-exe]

Random Range works now as well:

[paddy-exe]

Remap node also works

[Chaosus]

Need to fix the static checks and generate docs. You can generate docs by executing the following command
in the Godot's exe directory: ./godot.windows.opt.tools.64.exe.exe --doctool .. - This is for Windows, on Linux it might be a bit different.

[paddy-exe]

Rebased and should be ready to merge

[Chaosus]

Thanks!