I'm working to port over a project of mine from GameMaker Studio 2 to Godot 3 currently, and one thing I developed by hand in that studio was the inventory system.
What I wish to accomplish is a dynamic inventory system that sets up individual panels within the UI based upon inventory slot count. It works similarly to how Minecraft does it - click an item and a ghost of the item will hover around the cursor. From there, you can switch the position with another item, change its position or drop it. Note that it's possible to store the items anywhere on the grid and reorganize to one's content.
The UI system with the other engine... I had no other choice but to hack in object elements onto the screen to pose as UI entities.
Making the inventory items themselves is easy, they're just dictionaries with things like weapon name, damage, fire rate, projectile name, display image, world image, etc.
I've been having trouble finding ways on getting this to work and most inventory tutorials are not very helpful. The UI system is highly confusing and has proven to be a bit painful in terms of adapting, so I've deleted my efforts and am starting from scratch again.
Does anyone have any ideas on how to get the above image going? A push in the right direction would be fantastic right now and I'm not having any luck finding much in terms of tutorials.