Controls intercept hidden mouse input events

[Gibbz]

Godot version: 3.2

OS/device including version: Linux

Issue description:
I have some free look camera code which uses Input.set_mouse_mode(Input.MOUSE_MODE_CAPTURED);

The problem is this would seemingly "lockup" and become unresponsive. I managed to find that the problem was that the Control elements I had on screen would take the input even when though the mouse was not visible!

Steps to reproduce:
Enable Input.set_mouse_mode(Input.MOUSE_MODE_CAPTURED); which will force the mouse to the centre of the viewport.
Then display a control on the centre of the screen that doesn't have mouse_filter set to MOUSE_FILTER_IGNORE

I have worked around the problem for now by ensuring I set mouse filter to MOUSE_FILTER_IGNORE when I go enable Input.set_mouse_mode(Input.MOUSE_MODE_CAPTURED);

[KoBeWi]

Can anyone still reproduce this bug in Godot 3.2.3 rc5 or any later release?

If yes, please ensure that an up-to-date Minimal Reproduction Project (MRP) is included in this report (a MRP is a zipped Godot project with the minimal elements necessary to reliably trigger the bug). You can upload ZIP files in an issue comment with a drag and drop.

[bruvzg]

It's still relevant in both 3.2 and master, if there's a control in the center of the window, it will grab input events.

MRP: _test_mcap.zip - click CheckButton in the center to capture mouse, click again and CheckButton will be toggled again.

[akien-mga]

This is still reproducible in 4.0 RC 1 with @bruvzg's MRP.

It only happens if the mouse is not moved after hiding it. Any mouse motion before clicking again fixes the issue.

CC @Sauermann

[Sauermann]

This is a tricky problem, because during MOUSE_MODE_CAPTURED basically mouse-events shouldn't have a position, but all InputEventMouse have a position.

Not sure, if this is an appropriate solution and I also didn't test it, but I am putting it here as an idea.
Edit: actually it is not a viable solution, as explained in the posts below.

diff --git a/scene/main/viewport.cpp b/scene/main/viewport.cpp
index 23b7c072be..13edd17955 100644
--- a/scene/main/viewport.cpp
+++ b/scene/main/viewport.cpp
@@ -2813,7 +2813,9 @@ void Viewport::push_input(const Ref<InputEvent> &p_event, bool p_local_coords) {
        }
 
        if (!is_input_handled()) {
-               _gui_input_event(ev);
+               if (Input::get_singleton()->get_mouse_mode() != Input::MOUSE_MODE_CAPTURED) {
+                       _gui_input_event(ev);
+               }
        } else {
                // Cleanup internal GUI state after accepting event during _input().
                _gui_cleanup_internal_state(ev);

[KoBeWi]

Note that when you outright remove all events, some things will not work, e.g. SpinBox dragging (because it hides mouse and uses motion events).

[Sauermann]

@KoBeWi oh, thanks, I just looked at your PR and my idea above will also cause the same problems.

[KoBeWi]

Maybe instead of blocking events, we could change the function that determines whether a cursor is within control's rect and make it always return false when mouse is hidden?
Not sure if that fixes the issue though.

[Sauermann]

Other ideas:

• use NaN as mouse position
• Create separate events InputEventNoPositionMouseButton, InputEventNoPositionMouseMotion

[Sauermann]

I have tried the following approach:

diff --git a/scene/main/viewport.cpp b/scene/main/viewport.cpp
index e6ebaba79e..e713cf46e1 100644
--- a/scene/main/viewport.cpp
+++ b/scene/main/viewport.cpp
@@ -1610,6 +1610,11 @@ void Viewport::_gui_call_notification(Control *p_control, int p_what) {
 
 Control *Viewport::gui_find_control(const Point2 &p_global) {
        ERR_MAIN_THREAD_GUARD_V(nullptr);
+
+       if (Input::get_singleton()->get_mouse_mode() == Input::MOUSE_MODE_CAPTURED) {
+               return nullptr;
+       }
+
        // Handle subwindows.
        _gui_sort_roots();
 
@@ -2974,7 +2979,7 @@ void Viewport::push_input(const Ref<InputEvent> &p_event, bool p_local_coords) {
        }
 
        Ref<InputEventMouse> me = ev;
-       if (me.is_valid()) {
+       if (me.is_valid() && Input::get_singleton()->get_mouse_mode() != Input::MOUSE_MODE_CAPTURED) {
                gui.last_mouse_pos = me->get_position();
        }

I am not yet entirely convinced if this is the correct approach. We would likely need an additional state in the form of gui.last_mouse_pos == invalid, but this would make additional tests in a lot of places necessary.