.\" Copyright (c) 2010-2026 Julien Nadeau Carriere <vedge@csoft.net>
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.Dd January 5, 2026
.Dt AG_INITVIDEOSDL2 3
.Os Agar 1.8
.Sh NAME
.Nm AG_InitVideoSDL2
.Nd agar SDL2 video initialization
.Sh SYNOPSIS
.Bd -literal
#include <agar/core.h>
#include <agar/gui.h>
.Ed
.Sh DESCRIPTION
.\" IMAGE(/widgets/AG_DriverSDLFB.png, "The sdlfb driver")
If Agar was compiled with SDL 2.x support (--with-sdl2), the "sdl2fb" (frame-buffer), "sdl2gl" (single-window GL)
and "sdl2mw" (multi-window GL) drivers become available.
.Sh INITIALIZATION
.nr nS 1
.Ft "int"
.Fn AG_InitVideoSDL2 "SDL_Surface *display" "Uint flags"
.Pp
.Ft "int"
.Fn AG_SetVideoSurfaceSDL2 "SDL_Surface *display"
.Pp
.nr nS 0
The
.Fn AG_InitVideoSDL
function initializes the GUI to attach to an existing SDL2 display surface.
It accepts the following
.Fa flags
options:
.Bl -tag -width "AG_VIDEO_OPENGL_OR_SDL "
.It AG_VIDEO_FULLSCREEN
Start up application in full-screen mode
.It AG_VIDEO_RESIZABLE
If a window manager is available, request that the application be resizable.
This is the default.
.It AG_VIDEO_FIXED
If a window manager is available, request that the window be non-resizable.
.It AG_VIDEO_BORDERLESS
If a window manager is available, disable window decorations.
.It AG_VIDEO_NOFRAME
Alias for
.Dv AG_VIDEO_BORDERLESS .
.It AG_VIDEO_BGPOPUPMENU
Whenever the user right-clicks on an area not covered by an Agar window,
display a standard pop-up menu with the list of active windows.
.It AG_VIDEO_OPENGL
Require OpenGL mode.
If OpenGL is not available, initialization will fail.
.It AG_VIDEO_OPENGL_OR_SDL
Try OpenGL mode if available, otherwise fallback to SDL frame-buffer mode.
.It AG_VIDEO_OVERLAY
Run in OpenGL "overlay" mode.
In this mode, Agar will never clear the background or swap GL buffers.
Before rendering itself, Agar will also save the current OpenGL state and
restore it completely once rendering is complete.
Internally, this option causes the
.Dv AG_DRIVER_SW_OVERLAY
option to be set (see
.Xr AG_DriverSw 3 ) .
.El
.Pp
Note: When creating a new SDL display (as opposed to attaching to an existing one),
consider calling
.Xr AG_InitGraphics 3
with the "<SDL2>" argument instead of using
.Fn AG_InitVideoSDL2 .
.Pp
The
.Fn AG_SetVideoSurfaceSDL2
function can be used to reattach to a different (e.g., a newly resized)
SDL display surface without reinitializing the GUI.
.Pp
Note: The
.Fn AG_InitVideoSDL2
and
.Fn AG_SetVideoSurfaceSDL2
functions are only available if Agar has been compiled with SDL2 support
(to find out at compile-time, include "<agar/config/have_sdl2.h>" and test
for
.Dv HAVE_SDL2 ) .
.Pp
.Sh SEE ALSO
.Xr AG_Core 3 ,
.Xr AG_DriverSDLFB 3 ,
.Xr AG_DriverSDLGL 3 ,
.Xr AG_DriverSDL2FB 3 ,
.Xr AG_DriverSDL2GL 3 ,
.Xr AG_DriverSDL2MW 3 ,
.Xr AG_InitGraphics 3 ,
.Xr AG_InitVideoSDL 3 ,
.Xr AG_Intro 3
.Pp
.Bl -tag -compact
.It Lk https://libsdl.org/ Simple DirectMedia Layer
.El
.Sh HISTORY
SDL1 support first appeared in Agar 1.0.
The "sdlfb" and "sdlgl" driver modules first appeared in Agar 1.4.0.
SDL2 support with the "sdl2fb", "sdl2gl" and "sdl2mw" driver modules appeared in Agar 1.7.0.