Generic Headless support, drop server platform, enable linuxbsd build without vulkan/X11.

[Faless]

Implement a new "headless" DisplayServerDummyDisplayServerHeadless. Uses the dummy rasterizer internally, and is always compiled in (we could exclude it, but frankly, it's a bunch of empty functions).

You can run ideally any platform via --display-driver headless, e.g.:

bin/godot.linuxbsd.tools.64 --display-driver headless -s script.gd

An extra commit removes the old "server" platform, and the last one enable building the linuxbsd platform without vulkan/X11 dependencies.

$ scons p=x11 target=release_debug tools=no vulkan=no x11=no
$ ldd bin/godot.linuxbsd.opt.debug.64 
linux-vdso.so.1 (0x00007fff9e1ee000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f55142cf000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f55142c9000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f551417a000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f5513f88000)
/lib64/ld-linux-x86-64.so.2 (0x00007f5514320000)

This effectively adds the RasterizerDummy back to CI, and for all platforms. so, as mentioned above, I can also add an headless flag to scons and default it to False if that's preferred.

EDIT: Closes godotengine/godot-proposals#991 . Only tested on linuxbsd. EDIT: Also briefly tested on windows.

[YuriSizov]

Part of godotengine/godot-proposals#991?

[Faless]

Rebased and ready to go.

[reduz]

Looks good to me, up to @akien-mga to merge.

[akien-mga]

As discussed on chat, since this SCsub is removed it doesn't really make sense anymore to keep a drivers/dummy folder. Instead, we should move the respective dummy/null implementations close to their virtual class definitions (as was done already with servers/audio/audio_driver_dummy.h).

This can be done in a follow-up PR though.

[akien-mga]

I guess we'd want this capitalized to be consistent with other platforms.

And maybe the name should be "Dummy" (respectively "Null" if we do this change).

[akien-mga]

Tested on Windows, seems to work fine:

$ cat main.gd
extends MainLoop

var time_elapsed = 0

func _initialize():
        print("Sleepy Hollow is in da place")

func _process(delta):
        time_elapsed += delta
        print(time_elapsed)
        return time_elapsed > 0.1

func _finalize():
        print("The end.")

$ godot-git --display-driver headless -s main.gd
Godot Engine v4.0.dev.custom_build.0e944defc - https://godotengine.org

WARNING: Icon not supported by this display server.
     at: DisplayServer::set_icon (servers\display_server.cpp:305)
WARNING: Icon not supported by this display server.
     at: DisplayServer::set_icon (servers\display_server.cpp:305)
Sleepy Hollow is in da place
0.008333
0.012155
0.012187
0.016667
0.02
0.024167
0.028333
0.033333
0.037541
0.044585
0.051609
0.057651
0.064641
0.071662
0.078666
0.084737
0.092739
0.099784
0.106808
The end.

We could possibly silence those by replacing the default implementation with a no-op:

WARNING: Icon not supported by this display server.
     at: DisplayServer::set_icon (servers\display_server.cpp:305)
WARNING: Icon not supported by this display server.
     at: DisplayServer::set_icon (servers\display_server.cpp:305)\

[akien-mga]

Since we name it headless internally, maybe the implementation should be DisplayServerHeadless?

[Faless]

Yeah, I think that's a good idea.

[Faless]

Renamed DisplayServerDummy to DisplayServerHeadless, added set_icon function to avoid console warning spam on startup.

[akien-mga]

Needs renaming too.

[akien-mga]

I think you can do the git mv we discussed yesterday in this PR too:

drivers/dummy/display_server_headless.* -> servers/display_server_headless.*
drivers/dummy/rasterizer_dummy.* -> servers/rendering/rasterizer_dummy.*

[akien-mga]

Thanks!

[SebastianAtWork]

Hi guys, quick question. Is this commit also in 3.5.1 and if yes, how do I make a headless build with windows?

[YuriSizov]

@SebastianAtWork This is not a part of 3.x and won't be a part of 3.x, as it's a breaking change.

In 3.x you can still use the --no-window command line argument to run without spawning a window (no custom build required).