SlimeDream/addons/receive-input-in-editor/ReceiveInputInEditorPlugin.cs

#if TOOLS
[Tool]
public partial class ReceiveInputInEditorPlugin
	: EditorPlugin
{
	public override bool _Handles(GodotObject obj)
		=> true;

	public override int _Forward3DGuiInput(Camera3D camera, InputEvent ev)
	{
		var root = (Node3D)EditorInterface.Singleton.GetEditedSceneRoot();

		var viewport = root.GetViewport();
		// Don't know about any negative effect of changing these and leaving them like that.
		viewport.GuiDisableInput    = false; // Re-enable input, required for `PushInput` to work at all.
		viewport.HandleInputLocally = true;  // Let sub-viewport handle its own input, makes `SetInputAsHandled` work as expected?

		// This will propagate input events into the edited scene,
		// including regular, GUI, shortcut, unhandled key and unhandled.
		viewport.PushInput(ev);

		// Enabling `PhysicsObjectPicking` causes `IsInputHandled()` to always
		// return true, and object picking isn't immediate anyway, so let's just
		// do it ourselves. This doesn't support touch input, though.
		if (!viewport.IsInputHandled() && (ev is InputEventMouse { Position: var mouse })) {
			// Ray is cast from the editor camera's view.
			var from = camera.ProjectRayOrigin(mouse);
			var to   = from + camera.ProjectRayNormal(mouse) * camera.Far;

			// Actual collision is done in the edited scene though.
			var space = root.GetWorld3D().DirectSpaceState;
			var query = PhysicsRayQueryParameters3D.Create(from, to);

			var result = space.IntersectRay(query);
			// The collider object isn't necessarily a `CollisionObject3D`.
			var collider = (GodotObject)result.GetValueOrDefault("collider");
			if (collider is CollisionObject3D { Visible: true } obj) {
				var pos    = (Vector3)result["position"];
				var normal = (Vector3)result["normal"];
				var shape  = (int)result["shape"];
				obj._InputEvent(camera, ev, pos, normal, shape);
			}
		}

		// If any node calls `SetInputAsHandled()`, the event is not passed on to other editor gizmos / plugins.
		return viewport.IsInputHandled() ? (int)AfterGuiInput.Stop : (int)AfterGuiInput.Pass;
	}
}
#endif