When changing window mouse passthrough only area inside the polygon is rendered

[earlroxas]

Godot version

3.4.stable, 3.4.2.stable, 3.4.3.rc1

System information

Windows 10, GLES2, GLES3, nVidia 1030

Issue description

When changing the window mouse passthrough using OS.set_window_mouse_passthrough only area inside the polygon is being rendered. Also this only happen on Windows. I'm using Linux now, so it doesn't happen, also I dont know is it happen on macOS or not, because I dont have mac.

This is the screenshot on Linux (this is the correct one)

Here all elements are rendered. The text on top left also white rect in the middle.

This is the screenshot on Windows 10

Notice that the text is gone. The white rect also half gone.

On windows only half of the rect is gone because I set the polygon to that area. You can see the polygon area by pressing "I".
With OS.set_window_mouse_passthrough It should render all thing be it inside the polygon or not. It only control what the mouse can interact with, like when it executed on linux.

Steps to reproduce

1. Open project below
2. Run On Windows
3. Press T to turn on transparent background
4. Press P to change the passthrough area

Minimal reproduction project

TransBGBug.zip

[bruvzg]

This is not a bug, but a Windows OS limitation, which is also documented here https://docs.godotengine.org/en/stable/classes/class_os.html#class-os-method-set-window-mouse-passthrough.

Note: On Windows, the portion of a window that lies outside the region is not drawn, while on Linux and macOS it is.
Note: This method is implemented on Linux, macOS and Windows.

AFAIK we can't do anything with it, the only way for mouse passthrough is to set part of the window fully transparent.

[Calinou]

Closing per @bruvzg's comment.

[earlroxas]

Sorry, I didnt see that note.
@bruvzg do you know, is it windows thing or OpenGL thing? I mean if I export my app using Vulkan on Godot4 is it going to work?
Sorry for followup question while this already closed, because at this rate I can't deploy my app on Windows.

[bruvzg]

is it windows thing or OpenGL thing? I mean if I export my app using Vulkan on Godot4 is it going to work?

It's a Windows thing.

Godot 4.0 do not have window transparency support implemented at all, and probably won't have in for Vulkan backend, since most of Vulkan drivers seems to lack required features.

[coderedart]

This is not a bug, but a Windows OS limitation, which is also documented here docs.godotengine.org/en/stable/classes/class_os.html#class-os-method-set-window-mouse-passthrough.

Note: On Windows, the portion of a window that lies outside the region is not drawn, while on Linux and macOS it is.
Note: This method is implemented on Linux, macOS and Windows.

AFAIK we can't do anything with it, the only way for mouse passthrough is to set part of the window fully transparent.

I was wondering if passthrough can be enabled via another feature. I know that shapes already exists to make "parts" of the window passthrough, but it would be useful to make the full window passthrough, because that way we can bypass this limitation atleast.

glfw has https://github.com/glfw/glfw/blob/955fbd9d265fa95adf9cb94896eb9a516aa50420/src/win32_window.c#L1953 which just sets the full window passthrough, and now it is possible to render whatever you want to the full window without the present limitation. very fast too.

the only issue is that the user loses input events when window is passthrough, and user needs to just get the mouse position and decide himself when he wants the window to be passthrough or not.

usually with integrations like godot_egui have a function called "fn needs_input(&self) -> bool" which returns true when it wants input based whether the cursor is hovering over its areas and other factors, which can be used by user to decide whether they want to disable passthrough.
even without such integration, the user can simply create two windows, one is a transparent with full passthrough to render content and the second window is the transparent window with shapes where he can just set the shapes based on his own user interface rectangle positions/sizes.

not saying this needs to be priority as godot 4.0 is more important, but just wanted to say this somewhere because it could be useful for a Guild Wars 2 Overlay AsherGlick/Burrito#9 and it would be absolutely wonderful if we could get this feature because godot has EVERYTHING that you could ask for making an overlay application like easy scripting, adding runtime plugins via scenes/gdscripts and basically the full game engine package.

[earlroxas]

Hello, since someone might need it.

It seems the passthrough is work best in Godot 3.2.1 after that it get broken on Windows.
In 3.2.1 you dont even need to set polygon to set the interact-able area. It just works!

This is some article I found.
http://aureagames.rf.gd/2021/05/15/godot-advanced-transparent-bg

[Nukiloco]

This used to work below 3.2.1 on Windows and was very useful for some for some potential applications to make with Godot. Does anyone know in what ways this has broke and why window pass through doesn't render half of the screen?
Does 4.0 window pass through work on Windows or does it have the same issues as 3.5?

I don't see how this is a Windows limitation if it used to work 100% back in 3.2.1?