Node port customization - more than inputs and outputs

[aimerib]

First of all, I'd like to thank everyone in this community for this amazing library! Even if my current needs can't be addressed by it, it is a really mature starting point for me!

My specific application is a text adventure/interactive fiction editor, where rooms are going to be represented by nodes, and each cardinal exit is a port (located at top/north, right/east, bottom/south, left/west of each node) and connecting to any other port available on any other node.

Similar in idea, but not so much in execution, to what Twine does for their story flow graph:

(Note - The above is just for a visual example of nodes with connections that aren't inputs and outputs, but I don't have plans to add multiple connections to the same port for example)

I am not sure whether egui_node_graph is capable of doing that as is, unless I am missing some kind of customization, but it seems like the library itself is hard-wired for inputs on the left, and outputs on the right, suggesting a pipped workflow.

If the above is the case, do you have any suggestions on where I might start looking to modify the library for my needs? If I am missing some obvious customization that is currently possible, any help in that direction would be great as well!

[setzer22]

Hey! Thanks for reaching out 😄

it seems like the library itself is hard-wired for inputs on the left, and outputs on the right, suggesting a pipped workflow.

Yup, I'm afraid that's the case 😅. This library started out as an implementation to support my other project and is heavily inspired by Blender's node editor. People (myself included) have been adding customization options as needs arise, but the whole design is heavily oriented towards having inputs on the left and outputs on the right (with inputs and outputs being different things). Changing that would take a considerable rework of the internals.

That said, there's still lots of code in this library that you can reuse, or take inspiration from (and please do! That's why it's open source 😄). If you want to take a look at the code, most of the magic happens inside editor_ui.rs. The draw_graph_editor function there is the root of the node graph drawing code. There's also show_graph_node which handles rendering a specific node.

The thing you probably won't be able to reuse is the data model for the Graph. Using slotmaps is a great way to create a grap data structure in Rust, but the specifics would be a bit different in your case. Instead of storing inputs and outputs, you likely just want to have bidirectional connections between ports, where each node has exactly four slots for each cardinal direction. I'd suggest starting there: Define your graph data structure and then build the UI around it.

Also, when looking at the code, keep in mind that the only reason for the generics is to make things customisable. My approach was to develop this graph library alongside Blackjack for a few months before splitting it off into a separate crate. It's way faster to iterate on something when your project is not split across separate crates, trying to make things too decoupled via generics is definitely a price to pay!

Anyway. I'm sorry I can't be of more help, but I don't think what you need can be achieved simply by a layer of customisation on top of this library 😅. At least, not currently. I'm still open to accepting any PRs that might make things more customisable though 😄

Best of luck! And don't hesitate to ask any questions about the library or the code

[aimerib]

Thank you so much! I suspected as much, and was already walking down that path, but figured I’d ask before I committed too much time on this.
Your pointers are really helpful, and if I encounter any parts of the code that elucidate me, I’ll make sure to reach out.