Experimental support for windows with per-pixel transparency.

[bruvzg]

Supports:

• macOS support (Using NSOpenGLCPSurfaceOpacity)
• Windows support (Using UpdateLayeredWindow)
• X11 support (Selecting XVisualInfo with alpha)

New APIs:

• Project setting display/window/allow_per_pixel_transparency (default value: false) - enables per-pixel transparency support (this should be enabled in project settings and can't be changed at runtime)

• Project setting display/window/per_pixel_transparency (default value: false) - sets initial window transparency state

• Project setting display/window/per_pixel_transparency_splash (default value: false) - sets splash screen transparency state (set boot splash to custom .png with alpha channel)

• bool OS::window_per_pixel_transparency_enabled property
  Enables/Disables per pixel transparency, when transparency is enabled window mode is switched to borderless.

Usage:

• Set window/allow_per_pixel_transparency = true in project settings.
• Set OS.window_per_pixel_transparency_enabled = true or display/window/per_pixel_transparency project setting to enable transparency.
• In most cases you want to disable main viewport background rendering by calling get_tree().get_root().set_transparent_background(true), or change Environment->Default Clear Color alpha value.

Video:

https://streamable.com/ukpxq

Screenshots:

macOS

Windows 10

Linux/X11

Demo:

physics_platformer_transp.zip (Updated)

Note:

I have removed get_absolute_mouse_position API from this PR since it was buggy on some Linux distros and there's more advanced and convenient PR for window movement/resizing: #16512

Here's its code if someone needs it

Point2 OS_OSX::get_absolute_mouse_position() const {

	const NSPoint mouse_pos = [NSEvent mouseLocation];

	for (NSScreen *screen in [NSScreen screens]) {
		NSRect frame = [screen frame];
		if (NSMouseInRect(mouse_pos, frame, NO)) {
			return Vector2((int)mouse_pos.x, (int)-mouse_pos.y);
		}
	}

	WARN_PRINTS(TTR("No mouse found."));
	return Vector2();
}

Point2 OS_Windows::get_absolute_mouse_position() const {

	POINT pos = { 0, 0 };
	GetCursorPos(&pos);

	return Vector2((int)pos.x, (int)pos.y);
}

Point2 OS_X11::get_absolute_mouse_position() const {

	int number_of_screens = XScreenCount(x11_display);
	for (int i = 0; i < number_of_screens; i++) {
		Window root, child;
		int root_x, root_y, win_x, win_y;
		unsigned int mask;
		if (XQueryPointer(x11_display, XRootWindow(x11_display, i), &root, &child, &root_x, &root_y, &win_x, &win_y, &mask)) {
			XWindowAttributes root_attrs;
			XGetWindowAttributes(x11_display, root, &root_attrs);

			return Vector2(root_attrs.x + root_x, root_attrs.y + root_y);
		}
	}

	WARN_PRINTS(TTR("No mouse found."));
	return Vector2();
}

---

Fixes #18009, and partially #6511

[MarianoGnu]

Point2 Input::get_absolute_mouse_position()
I'm curious about how this works with several monitors, is there a way to get the current monitor wich mouse is in and therefore it's resolution? Not thinking in any special usecase

[bruvzg]

@MarianoGnu Works with multiple monitors (Tested with two monitors on macOS and Windows).

I don't know any way to get monitor where mouse is in directly and get resolution, but it is possible to get current monitor using OS::get_screen_position(int p_screen) and OS::get_screen_size(int p_screen).

[MarianoGnu]

so Input::get_absolute_mouse_position() will return the position of the current monitor or the position relative to the main monitor? (if you have secondary monitor on the right and mouse is there position.x would be monitor1.width+monitor2.current_x)

[bruvzg]

so Input::get_absolute_mouse_position() will return the position of the current monitor or the position relative to the main monitor?

Relative to main monitor.

if you have secondary monitor on the right and mouse is there position.x would be monitor1.width+monitor2.current_x

Yes.

[blurymind]

NICE!! :D

[bruvzg]

Update: added X11 support.

[akien-mga]

Thanks a lot for your contribution!
We are now entering a strict release freeze for Godot 3.0 and will only consider major bug fixes. We won't merge new features and enhancements anymore until 3.0 is released.

Moving this PR to the 3.1 milestone, to be reviewed once the release freeze is lifted. It could eventually be cherry-picked for a future 3.0.1 maintenance release if it doesn't change the user-facing APIs and doesn't compromise the engine's stability.

[silverkorn]

For UWP, I guess you already checked that:
https://docs.microsoft.com/en-us/windows/uwp/design/style/acrylic#custom-acrylic-brush ?

[Timofffee]

Bump

[hpvb]

X11 code looks good.

[FransGerards]

Hi there, I tried this script but the background doesn't get transparent. Is there something I need to change in this script?

[akien-mga]

You have to set OS.window_allow_per_pixel_transparency_enabled to true too.

[bruvzg]

I need to change in this script?

Names of the settings were changed in #26087.

Open Project Setting and make sure that “display > window > per pixel transparency > allowed” and “display > window > per pixel transparency > splash” are selected.

[FransGerards]

I checked the project settings. Both the options are selected.
and I changed the name settings. Still this doesn't work.

[bruvzg]

There's no OS.window_allow_per_pixel_transparency_enabled, allow should be checked in setting and can't be changed at runtime (it's controlling gl context creation).

If it is project created before #26087, make sure it's one under per pixel transparency subsection not the one on the top of the list.

Then you can use OS.window_per_pixel_transparency_enabled = true/false to control window transparency and get_tree().get_root().set_transparent_background(true/false) to enable/disable viewport background (in most cases you want both).

[bruvzg]

Here's minimal test project with up to date settings - tranp.zip

[FransGerards]

I tried to open the test project but it won't open.

I have now checked the boxes.

[bruvzg]

I tried to open the test project but it won't open.

Which Godot version are you using?

[FransGerards]

Im using Godot_v3.0.6-stable_win64

[bruvzg]

Im using Godot_v3.0.6

Per-pixel transparency is 3.1 feature, it's not available in 3.0.

[FransGerards]

Im using Godot_v3.0.6

Per-pixel transparency is 3.1 feature, it's not available in 3.0.

Where can i find the 3.1 version?

[bruvzg]

Where can i find the 3.1 version?

It's not released, latest beta is available at https://godotengine.org/article/dev-snapshot-godot-3-1-beta-8

[FransGerards]

Thanks, I downloaded the beta. Now I can open you test project.

This is the result I get when opening

When I put it on its a black background

I opent the gamefile again and this one is transparent.

I'm know figuring out why. Thanks for the help!

[ducklin5]

So it not possible to have transparency and the OS borders? I've tried this:

func _ready():
	OS.window_per_pixel_transparency_enabled = true
	get_tree().get_root().set_transparent_background(true)
	OS.window_borderless = false # Black instead of transparent

[Ashesh3]

So it not possible to have transparency and the OS borders? I've tried this:

func _ready():
	OS.window_per_pixel_transparency_enabled = true
	get_tree().get_root().set_transparent_background(true)
	OS.window_borderless = false # Black instead of transparent

+1 having the same issue @bruvzg , any updates on this?