ureishi
I would like to request support for passing values directly from uGUI to Udon, by providing public fields or properties in Udon for types commonly used by standard uGUI events.
## Background
Currently, passing values from uGUI into Udon is not always straightforward.
If the UI is static and predefined, this can be handled by assigning references from Udon to specific uGUI elements in advance.
However, problems arise when UI elements need to be created dynamically.
In my case, when dealing with such dynamic UI, I end up using workarounds such as:
keeping references from uGUI to Udon, which still requires locating the relevant UI element from the Udon side
identifying the calling object indirectly via MeshRenderer.probeAnchor (since Transform can be assigned from uGUI events)
These approaches are technically possible, but they do not lead to a natural or scalable implementation.
They often require indirect patterns or additional setup, especially when working with dynamically instantiated UI.
Another possible approach is to attach a separate Udon behaviour to each UI element.
However, using Udon components only to pass UI values introduces unnecessary overhead and does not scale well.
## Proposal
I propose adding public fields or properties in Udon for types supported by standard uGUI events, such as:
  • string (Input Field)
  • bool (Toggle, )
  • int (Dropdown)
  • float (Slider, Scrollbar)
  • Vector2 (Scroll View)
  • UnityEngine.Object
This would allow a uGUI event to:
  1. write a value directly into a Udon behaviour
  2. call a CustomEvent
  3. let Udon read the value from the assigned input field or property
## Why UnityEngine.Object should be included
I would also like UnityEngine.Object to be supported.
This would allow a uGUI element to pass a reference to itself, making it much easier for Udon to identify the source of the event.
Compared to current indirect methods, this provides a more direct and understandable way to determine which UI element triggered the interaction.
## Example of the intended flow
A typical flow would look like this:
  • A uGUI event assigns a value to a Udon behaviour
  • The same event calls SendCustomEvent
  • The Udon behaviour reads the value and handles it
Conceptually:
using UdonSharp;
using UnityEngine;
public class UiReceiver : UdonSharpBehaviour
{
// These are assumed to be provided by Udon itself
// public string InputString { get; set; }
// public UnityEngine.Object InputObject { get; set; }
public void _OnUiTriggered()
{
Debug.Log(InputString);
if (InputObject != null)
{
Debug.Log(InputObject.name);
}
}
}