How can one implement splitscreen UI in such a way that players cannot control each others' UI?

organicpencil

I've attached a sample made with Godot 3.1 beta 1. "Player 1 Button" must only respond to the keyboard/mouse, while "Player 2 Button" must only respond to the controller.

It's looking like I'll have to re-invent the UI system, or perhaps refactor things engine side...

Any tips appreciated!

wombatstampede

Didn't check your sample. But you could define additional input actions and call the buttons "_input" methods passing the required event. At least I would try this. Handling the mouse would be probably more complicated but you could disable the controls mouse handling.

But it also depends on the platform. Keyboard input won't help much on mobile devices. The touch screen interface doesn't apply well to the UI in terms of multitouch (no simultaneous button presses).

organicpencil

Got it! Drawing inspiration from your suggestions:

extends Node

func _ready():
	$Viewport0/Control/Button.grab_focus()
	$Viewport1/Control/Button.grab_focus()

func _input(event):
	if event is InputEventKey or event is InputEventMouse:
		# Keyboard/mouse
		$Viewport0.input(event)
	elif event.device == 0:
		# Controller 0
		$Viewport1.input(event)

This won't work in a stock build because Godot only allows 1 focused UI element in the tree. But that was easy to patch.

diff --git a/scene/main/viewport.cpp b/scene/main/viewport.cpp
index 7f5dd3930..df072aa4f 100644
--- a/scene/main/viewport.cpp
+++ b/scene/main/viewport.cpp
@@ -2473,7 +2473,7 @@ void Viewport::_gui_control_grab_focus(Control *p_control) {
        //no need for change
        if (gui.key_focus && gui.key_focus == p_control)
                return;
-       get_tree()->call_group_flags(SceneTree::GROUP_CALL_REALTIME, "_viewports", "_gui_remove_focus");
+       _gui_remove_focus();
        gui.key_focus = p_control;
        p_control->notification(Control::NOTIFICATION_FOCUS_ENTER);
        p_control->update();