I think you can make Viewports transparent by setting the transparent_bg property to true. That said, it has been awhile since I've messed with Viewports in Godot, so maybe things have changed.
I have made a prototype game akin to INK in both Godot 2 and Godot 3 before. I can briefly explain how I managed the (potentially) massive amount of ink splats. I'm not 100% sure if like what you are looking for, but maybe it will help?
Here is the breakdown of how I handled creating the ink splats:
-| Make a Node2D node/scene that will handle be the 'manager' that all of the scripts that need to spawn splats will call. This node will need to have a list to keep track of 'workers', which will be responsible for rendering the splats.
-| Make another Node2D node/scene that will be the workers. These nodes will have a list that will hold the position and other data needed for your splats. These nodes will draw the splats in the _draw function whenever a new splat is added.
-| In the 'manager', always have a variable that will hold a single worker. We'll refer to this worker as the "current worker". You will also need to make the worker list empty initially.
-| In the 'manager', make a function to add splat(s). When a splat(s) is added, have the manager send the new splat data to the "current worker" and then call the update function on the "current worker" so the _draw function will be called and the new splat(s) will be rendered. I used draw_circle and draw_texture primarily, but any of the drawing related functions should work.
-| Have the 'manager', or the "current_worker", check to see how many splats are in the "current worker" splat list after you have added splats. If the number of splats is over a certain amount, make/instance a new worker, add the "current worker" to the list of workers in 'manager', and then make the newly created worker the new "current worker"
-| Rense and repeat every time a new splat is added. This way, workers will only have N many splats. Because the _draw function is only called when the update function is called, and until the update function is called a Node2D will keep its visuals, this allows you to add many splats without running into performance issues.
Hopefully that helps! I tried to outline how I made a splat system as best I could. Hopefully it will be of some help :smile:
One day, I'll get around to making the INK prototype Godot tutorial on RandomMomentania, and then I can share the code that makes, renders, and manages the ink splats.
As for the GodotEngine.org help section being dead, I have no idea. It might just be that everyone is busy and so it appears to be dead, or maybe the servers are having issues. Last I knew though, the help section of GodotEngine.org is alive and well.
