libobs-opengl: Introduce the X11/EGL winsys

Introduce the EGL/X11 winsys, and use it when the OBS_USE_EGL environment
variable is defined. This variable is only temporary, for future commits
will add a proper concept of platform.

All the EGL/X11 code is authored by Ivan Avdeev <[email protected]>.

libobs-opengl/CMakeLists.txt

@@ -46,6 +46,7 @@ else() #This needs to change to be more specific to get ready for Wayland
 
 	set(libobs-opengl_PLATFORM_SOURCES
 		gl-nix.c
+		gl-x11-egl.c
 		gl-x11-glx.c)
 endif()
 

libobs-opengl/gl-nix.c

@@ -17,6 +17,7 @@
 
 #include "gl-nix.h"
 #include "gl-x11-glx.h"
+#include "gl-x11-egl.h"
 
 static const struct gl_winsys_vtable *gl_vtable = NULL;
 
@@ -24,7 +25,12 @@ static void init_winsys(void)
 {
 	assert(gl_vtable == NULL);
 
-	gl_vtable = gl_x11_glx_get_winsys_vtable();
+	if (getenv("OBS_USE_EGL")) {
+		gl_vtable = gl_x11_egl_get_winsys_vtable();
+		blog(LOG_INFO, "Using EGL/X11");
+	} else {
+		gl_vtable = gl_x11_glx_get_winsys_vtable();
+	}
 
 	assert(gl_vtable != NULL);
 }

libobs-opengl/gl-x11-egl.c

@@ -0,0 +1,651 @@
+/******************************************************************************
+    Copyright (C) 2019 by Ivan Avdeev <[email protected]>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+******************************************************************************/
+
+/* GL context initialization using EGL instead of GLX
+ * Which is essential for improved and more performant screen grabbing and
+ * VA-API feeding techniques.
+ *
+ * Note: most of x11-related functionality was taken from gl-x11.c
+ */
+
+#include <X11/Xlib.h>
+#include <X11/Xlib-xcb.h>
+
+#include <xcb/xcb.h>
+
+#include <stdio.h>
+
+#include "gl-x11-egl.h"
+
+#include <glad/glad_egl.h>
+
+typedef EGLDisplay(EGLAPIENTRYP PFNEGLGETPLATFORMDISPLAYEXTPROC)(
+	EGLenum platform, void *native_display, const EGLint *attrib_list);
+
+static const int ctx_attribs[] = {
+#ifdef _DEBUG
+	EGL_CONTEXT_OPENGL_DEBUG,
+	EGL_TRUE,
+#endif
+	EGL_CONTEXT_OPENGL_PROFILE_MASK,
+	EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT,
+	EGL_CONTEXT_MAJOR_VERSION,
+	3,
+	EGL_CONTEXT_MINOR_VERSION,
+	3,
+	EGL_NONE,
+};
+
+static int ctx_pbuffer_attribs[] = {EGL_WIDTH, 2, EGL_HEIGHT, 2, EGL_NONE};
+
+static const EGLint ctx_config_attribs[] = {EGL_STENCIL_SIZE,
+					    0,
+					    EGL_DEPTH_SIZE,
+					    0,
+					    EGL_BUFFER_SIZE,
+					    32,
+					    EGL_ALPHA_SIZE,
+					    8,
+					    EGL_RENDERABLE_TYPE,
+					    EGL_OPENGL_BIT,
+					    EGL_SURFACE_TYPE,
+					    EGL_WINDOW_BIT | EGL_PBUFFER_BIT,
+					    EGL_NONE};
+
+struct gl_windowinfo {
+	EGLConfig config;
+
+	/* Windows in X11 are defined with integers (XID).
+	 * xcb_window_t is a define for this... they are
+	 * compatible with Xlib as well.
+	 */
+	xcb_window_t window;
+	EGLSurface surface;
+
+	/* We can't fetch screen without a request so we cache it. */
+	int screen;
+};
+
+struct gl_platform {
+	Display *xdisplay;
+	EGLDisplay edisplay;
+	EGLConfig config;
+	EGLContext context;
+	EGLSurface pbuffer;
+};
+
+/* The following utility functions are copied verbatim from GLX code. */
+
+/*
+ * Since we cannot take advantage of the asynchronous nature of xcb,
+ * all of the helper functions are synchronous but thread-safe.
+ *
+ * They check for errors and will return 0 on problems
+ * with the exception of when 0 is a valid return value... in which case
+ * read the specific function comments.
+ */
+
+/* Returns -1 on invalid screen. */
+static int get_screen_num_from_xcb_screen(xcb_connection_t *xcb_conn,
+					  xcb_screen_t *screen)
+{
+	xcb_screen_iterator_t iter =
+		xcb_setup_roots_iterator(xcb_get_setup(xcb_conn));
+	int screen_num = 0;
+
+	for (; iter.rem; xcb_screen_next(&iter), ++screen_num)
+		if (iter.data == screen)
+			return screen_num;
+
+	return -1;
+}
+
+static xcb_screen_t *get_screen_from_root(xcb_connection_t *xcb_conn,
+					  xcb_window_t root)
+{
+	xcb_screen_iterator_t iter =
+		xcb_setup_roots_iterator(xcb_get_setup(xcb_conn));
+
+	while (iter.rem) {
+		if (iter.data->root == root)
+			return iter.data;
+
+		xcb_screen_next(&iter);
+	}
+
+	return 0;
+}
+
+static inline int get_screen_num_from_root(xcb_connection_t *xcb_conn,
+					   xcb_window_t root)
+{
+	xcb_screen_t *screen = get_screen_from_root(xcb_conn, root);
+
+	if (!screen)
+		return -1;
+
+	return get_screen_num_from_xcb_screen(xcb_conn, screen);
+}
+
+static xcb_get_geometry_reply_t *get_window_geometry(xcb_connection_t *xcb_conn,
+						     xcb_drawable_t drawable)
+{
+	xcb_get_geometry_cookie_t cookie;
+	xcb_generic_error_t *error;
+	xcb_get_geometry_reply_t *reply;
+
+	cookie = xcb_get_geometry(xcb_conn, drawable);
+	reply = xcb_get_geometry_reply(xcb_conn, cookie, &error);
+
+	if (error) {
+		blog(LOG_ERROR, "Failed to fetch parent window geometry!");
+		free(error);
+		free(reply);
+		return 0;
+	}
+
+	free(error);
+	return reply;
+}
+
+static const char *get_egl_error_string2(const EGLint error)
+{
+	switch (error) {
+#define OBS_EGL_CASE_ERROR(e) \
+	case e:               \
+		return #e;
+		OBS_EGL_CASE_ERROR(EGL_SUCCESS)
+		OBS_EGL_CASE_ERROR(EGL_NOT_INITIALIZED)
+		OBS_EGL_CASE_ERROR(EGL_BAD_ACCESS)
+		OBS_EGL_CASE_ERROR(EGL_BAD_ALLOC)
+		OBS_EGL_CASE_ERROR(EGL_BAD_ATTRIBUTE)
+		OBS_EGL_CASE_ERROR(EGL_BAD_CONTEXT)
+		OBS_EGL_CASE_ERROR(EGL_BAD_CONFIG)
+		OBS_EGL_CASE_ERROR(EGL_BAD_CURRENT_SURFACE)
+		OBS_EGL_CASE_ERROR(EGL_BAD_DISPLAY)
+		OBS_EGL_CASE_ERROR(EGL_BAD_SURFACE)
+		OBS_EGL_CASE_ERROR(EGL_BAD_MATCH)
+		OBS_EGL_CASE_ERROR(EGL_BAD_PARAMETER)
+		OBS_EGL_CASE_ERROR(EGL_BAD_NATIVE_PIXMAP)
+		OBS_EGL_CASE_ERROR(EGL_BAD_NATIVE_WINDOW)
+		OBS_EGL_CASE_ERROR(EGL_CONTEXT_LOST)
+#undef OBS_EGL_CASE_ERROR
+	default:
+		return "Unknown";
+	}
+}
+static const char *get_egl_error_string()
+{
+	return get_egl_error_string2(eglGetError());
+}
+
+static EGLDisplay get_egl_display(struct gl_platform *plat)
+{
+	Display *display = plat->xdisplay;
+	EGLDisplay edisplay = EGL_NO_DISPLAY;
+	const char *egl_client_extensions = NULL;
+
+	egl_client_extensions = eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);
+
+	PFNEGLGETPLATFORMDISPLAYEXTPROC eglGetPlatformDisplayEXT =
+		(PFNEGLGETPLATFORMDISPLAYEXTPROC)(
+			strstr(egl_client_extensions, "EGL_EXT_platform_base")
+				? eglGetProcAddress("eglGetPlatformDisplayEXT")
+				: NULL);
+
+	if (eglGetPlatformDisplayEXT) {
+		edisplay = eglGetPlatformDisplayEXT(EGL_PLATFORM_X11_EXT,
+						    display, NULL);
+		if (EGL_NO_DISPLAY == edisplay)
+			blog(LOG_ERROR, "Failed to get EGL/X11 display");
+	}
+
+	if (EGL_NO_DISPLAY == edisplay)
+		edisplay = eglGetDisplay(display);
+
+	return edisplay;
+}
+
+static bool gl_context_create(struct gl_platform *plat)
+{
+	Display *display = plat->xdisplay;
+	int frame_buf_config_count = 0;
+	EGLDisplay edisplay = EGL_NO_DISPLAY;
+	EGLConfig config = NULL;
+	EGLContext context = EGL_NO_CONTEXT;
+	int egl_min = 0, egl_maj = 0;
+	bool success = false;
+
+	eglBindAPI(EGL_OPENGL_API);
+
+	edisplay = get_egl_display(plat);
+
+	if (EGL_NO_DISPLAY == edisplay) {
+		blog(LOG_ERROR,
+		     "Failed to get EGL display using eglGetDisplay");
+		return false;
+	}
+
+	if (!eglInitialize(edisplay, &egl_maj, &egl_min)) {
+		blog(LOG_ERROR, "Failed to initialize EGL: %s",
+		     get_egl_error_string());
+		return false;
+	}
+
+	if (!eglChooseConfig(edisplay, ctx_config_attribs, &config, 1,
+			     &frame_buf_config_count)) {
+		blog(LOG_ERROR, "Unable to find suitable EGL config: %s",
+		     get_egl_error_string());
+		goto error;
+	}
+
+	context =
+		eglCreateContext(edisplay, config, EGL_NO_CONTEXT, ctx_attribs);
+#ifdef _DEBUG
+	if (EGL_NO_CONTEXT == context) {
+		const EGLint error = eglGetError();
+		if (error == EGL_BAD_ATTRIBUTE) {
+			/* Sometimes creation fails because debug gl is not supported */
+			blog(LOG_ERROR,
+			     "Unable to create EGL context with DEBUG attrib, trying without");
+			context = eglCreateContext(edisplay, config,
+						   EGL_NO_CONTEXT,
+						   ctx_attribs + 2);
+		} else {
+			blog(LOG_ERROR, "Unable to create EGL context: %s",
+			     get_egl_error_string2(error));
+			goto error;
+		}
+	}
+#endif
+	if (EGL_NO_CONTEXT == context) {
+		blog(LOG_ERROR, "Unable to create EGL context: %s",
+		     get_egl_error_string());
+		goto error;
+	}
+
+	plat->pbuffer =
+		eglCreatePbufferSurface(edisplay, config, ctx_pbuffer_attribs);
+	if (EGL_NO_SURFACE == plat->pbuffer) {
+		blog(LOG_ERROR, "Failed to create OpenGL pbuffer: %s",
+		     get_egl_error_string());
+		goto error;
+	}
+
+	plat->edisplay = edisplay;
+	plat->config = config;
+	plat->context = context;
+
+	success = true;
+	blog(LOG_DEBUG, "Created EGLDisplay %p", plat->edisplay);
+
+error:
+	if (!success) {
+		if (EGL_NO_CONTEXT != context)
+			eglDestroyContext(edisplay, context);
+		eglTerminate(edisplay);
+	}
+
+	XSync(display, false);
+	return success;
+}
+
+static void gl_context_destroy(struct gl_platform *plat)
+{
+	eglMakeCurrent(plat->edisplay, EGL_NO_SURFACE, EGL_NO_SURFACE,
+		       EGL_NO_CONTEXT);
+	eglDestroyContext(plat->edisplay, plat->context);
+}
+
+static struct gl_windowinfo *
+gl_x11_egl_windowinfo_create(const struct gs_init_data *info)
+{
+	UNUSED_PARAMETER(info);
+	return bmalloc(sizeof(struct gl_windowinfo));
+}
+
+static void gl_x11_egl_windowinfo_destroy(struct gl_windowinfo *info)
+{
+	UNUSED_PARAMETER(info);
+	bfree(info);
+}
+
+static Display *open_windowless_display(void)
+{
+	Display *display = XOpenDisplay(NULL);
+	xcb_connection_t *xcb_conn;
+	xcb_screen_iterator_t screen_iterator;
+	xcb_screen_t *screen;
+	int screen_num;
+
+	if (!display) {
+		blog(LOG_ERROR, "Unable to open new X connection!");
+		return NULL;
+	}
+
+	xcb_conn = XGetXCBConnection(display);
+	if (!xcb_conn) {
+		blog(LOG_ERROR, "Unable to get XCB connection to main display");
+		goto error;
+	}
+
+	screen_iterator = xcb_setup_roots_iterator(xcb_get_setup(xcb_conn));
+	screen = screen_iterator.data;
+	if (!screen) {
+		blog(LOG_ERROR, "Unable to get screen root");
+		goto error;
+	}
+
+	screen_num = get_screen_num_from_root(xcb_conn, screen->root);
+	if (screen_num == -1) {
+		blog(LOG_ERROR, "Unable to get screen number from root");
+		goto error;
+	}
+
+	if (!gladLoadEGL()) {
+		blog(LOG_ERROR, "Unable to load EGL entry functions.");
+		goto error;
+	}
+
+	return display;
+
+error:
+	if (display)
+		XCloseDisplay(display);
+	return NULL;
+}
+
+static int x_error_handler(Display *display, XErrorEvent *error)
+{
+	char str1[512];
+	char str2[512];
+	char str3[512];
+	XGetErrorText(display, error->error_code, str1, sizeof(str1));
+	XGetErrorText(display, error->request_code, str2, sizeof(str2));
+	XGetErrorText(display, error->minor_code, str3, sizeof(str3));
+
+	blog(LOG_ERROR,
+	     "X Error: %s, Major opcode: %s, "
+	     "Minor opcode: %s, Serial: %lu",
+	     str1, str2, str3, error->serial);
+	return 0;
+}
+
+static struct gl_platform *gl_x11_egl_platform_create(gs_device_t *device,
+						      uint32_t adapter)
+{
+	/* There's some trickery here... we're mixing libX11, xcb, and EGL
+	   For an explanation see here: http://xcb.freedesktop.org/MixingCalls/
+	   Essentially, EGL requires Xlib. Everything else we use xcb. */
+	struct gl_platform *plat = bmalloc(sizeof(struct gl_platform));
+	Display *display = open_windowless_display();
+
+	if (!display) {
+		goto fail_display_open;
+	}
+
+	XSetEventQueueOwner(display, XCBOwnsEventQueue);
+	XSetErrorHandler(x_error_handler);
+
+	/* We assume later that cur_swap is already set. */
+	device->plat = plat;
+
+	plat->xdisplay = display;
+
+	if (!gl_context_create(plat)) {
+		blog(LOG_ERROR, "Failed to create context!");
+		goto fail_context_create;
+	}
+
+	if (!eglMakeCurrent(plat->edisplay, plat->pbuffer, plat->pbuffer,
+			    plat->context)) {
+		blog(LOG_ERROR, "Failed to make context current: %s",
+		     get_egl_error_string());
+		goto fail_make_current;
+	}
+
+	if (!gladLoadGL()) {
+		blog(LOG_ERROR, "Failed to load OpenGL entry functions.");
+		goto fail_load_gl;
+	}
+
+	goto success;
+
+fail_make_current:
+	gl_context_destroy(plat);
+fail_context_create:
+fail_load_gl:
+	XCloseDisplay(display);
+fail_display_open:
+	bfree(plat);
+	plat = NULL;
+success:
+	UNUSED_PARAMETER(adapter);
+	return plat;
+}
+
+static void gl_x11_egl_platform_destroy(struct gl_platform *plat)
+{
+	if (!plat)
+		return;
+
+	gl_context_destroy(plat);
+	eglTerminate(plat->edisplay);
+	bfree(plat);
+}
+
+static bool gl_x11_egl_platform_init_swapchain(struct gs_swap_chain *swap)
+{
+	const struct gl_platform *plat = swap->device->plat;
+	Display *display = plat->xdisplay;
+	xcb_connection_t *xcb_conn = XGetXCBConnection(display);
+	xcb_window_t wid = xcb_generate_id(xcb_conn);
+	xcb_window_t parent = swap->info.window.id;
+	xcb_get_geometry_reply_t *geometry =
+		get_window_geometry(xcb_conn, parent);
+	bool status = false;
+
+	int screen_num;
+	int visual;
+
+	if (!geometry)
+		goto fail_geometry_request;
+
+	screen_num = get_screen_num_from_root(xcb_conn, geometry->root);
+	if (screen_num == -1) {
+		goto fail_screen;
+	}
+
+	{
+		if (!eglGetConfigAttrib(plat->edisplay, plat->config,
+					EGL_NATIVE_VISUAL_ID,
+					(EGLint *)&visual)) {
+			blog(LOG_ERROR,
+			     "Cannot get visual id for EGL context: %s",
+			     get_egl_error_string());
+			goto fail_visual_id;
+		}
+	}
+
+	xcb_colormap_t colormap = xcb_generate_id(xcb_conn);
+	uint32_t mask = XCB_CW_BORDER_PIXEL | XCB_CW_COLORMAP;
+	uint32_t mask_values[] = {0, colormap, 0};
+
+	xcb_create_colormap(xcb_conn, XCB_COLORMAP_ALLOC_NONE, colormap, parent,
+			    visual);
+
+	xcb_create_window(xcb_conn, 24 /* Hardcoded? */, wid, parent, 0, 0,
+			  geometry->width, geometry->height, 0, 0, visual, mask,
+			  mask_values);
+
+	const EGLSurface surface =
+		eglCreateWindowSurface(plat->edisplay, plat->config, wid, 0);
+	if (EGL_NO_SURFACE == surface) {
+		blog(LOG_ERROR, "Cannot get window EGL surface: %s",
+		     get_egl_error_string());
+		goto fail_window_surface;
+	}
+
+	swap->wi->config = plat->config;
+	swap->wi->window = wid;
+	swap->wi->surface = surface;
+	swap->wi->screen = screen_num;
+
+	xcb_map_window(xcb_conn, wid);
+
+	status = true;
+	goto success;
+
+fail_window_surface:
+fail_visual_id:
+fail_screen:
+fail_geometry_request:
+success:
+	free(geometry);
+	return status;
+}
+
+static void gl_x11_egl_platform_cleanup_swapchain(struct gs_swap_chain *swap)
+{
+	UNUSED_PARAMETER(swap);
+	/* Really nothing to clean up? */
+}
+
+static void gl_x11_egl_device_enter_context(gs_device_t *device)
+{
+	const EGLContext context = device->plat->context;
+	const EGLDisplay display = device->plat->edisplay;
+	const EGLSurface surface = (device->cur_swap)
+					   ? device->cur_swap->wi->surface
+					   : device->plat->pbuffer;
+
+	if (!eglMakeCurrent(display, surface, surface, context))
+		blog(LOG_ERROR, "Failed to make context current: %s",
+		     get_egl_error_string());
+}
+
+static void gl_x11_egl_device_leave_context(gs_device_t *device)
+{
+	const EGLDisplay display = device->plat->edisplay;
+
+	if (!eglMakeCurrent(display, EGL_NO_SURFACE, EGL_NO_SURFACE,
+			    EGL_NO_CONTEXT)) {
+		blog(LOG_ERROR, "Failed to reset current context: %s",
+		     get_egl_error_string());
+	}
+}
+
+static void *gl_x11_egl_device_get_device_obj(gs_device_t *device)
+{
+	return device->plat->context;
+}
+
+static void gl_x11_egl_getclientsize(const struct gs_swap_chain *swap,
+				     uint32_t *width, uint32_t *height)
+{
+	xcb_connection_t *xcb_conn =
+		XGetXCBConnection(swap->device->plat->xdisplay);
+	xcb_window_t window = swap->wi->window;
+
+	xcb_get_geometry_reply_t *geometry =
+		get_window_geometry(xcb_conn, window);
+	if (geometry) {
+		*width = geometry->width;
+		*height = geometry->height;
+	}
+
+	free(geometry);
+}
+
+static void gl_x11_egl_update(gs_device_t *device)
+{
+	Display *display = device->plat->xdisplay;
+	xcb_window_t window = device->cur_swap->wi->window;
+
+	uint32_t values[] = {device->cur_swap->info.cx,
+			     device->cur_swap->info.cy};
+
+	xcb_configure_window(XGetXCBConnection(display), window,
+			     XCB_CONFIG_WINDOW_WIDTH | XCB_CONFIG_WINDOW_HEIGHT,
+			     values);
+}
+
+static void gl_x11_egl_clear_context(gs_device_t *device)
+{
+	Display *display = device->plat->edisplay;
+
+	if (!eglMakeCurrent(display, EGL_NO_SURFACE, EGL_NO_SURFACE,
+			    EGL_NO_CONTEXT)) {
+		blog(LOG_ERROR, "Failed to reset current context.");
+	}
+}
+
+static void gl_x11_egl_device_load_swapchain(gs_device_t *device,
+					     gs_swapchain_t *swap)
+{
+	if (device->cur_swap == swap)
+		return;
+
+	device->cur_swap = swap;
+
+	device_enter_context(device);
+}
+
+enum swap_type {
+	SWAP_TYPE_NORMAL,
+	SWAP_TYPE_EXT,
+	SWAP_TYPE_MESA,
+	SWAP_TYPE_SGI,
+};
+
+static void gl_x11_egl_device_present(gs_device_t *device)
+{
+	Display *display = device->plat->xdisplay;
+
+	xcb_connection_t *xcb_conn = XGetXCBConnection(display);
+	xcb_generic_event_t *xcb_event;
+	while ((xcb_event = xcb_poll_for_event(xcb_conn))) {
+		free(xcb_event);
+	}
+
+	if (!eglSwapBuffers(device->plat->edisplay,
+			    device->cur_swap->wi->surface))
+		blog(LOG_ERROR, "Cannot swap EGL buffers: %s",
+		     get_egl_error_string());
+}
+
+static const struct gl_winsys_vtable egl_x11_winsys_vtable = {
+	.windowinfo_create = gl_x11_egl_windowinfo_create,
+	.windowinfo_destroy = gl_x11_egl_windowinfo_destroy,
+	.platform_create = gl_x11_egl_platform_create,
+	.platform_destroy = gl_x11_egl_platform_destroy,
+	.platform_init_swapchain = gl_x11_egl_platform_init_swapchain,
+	.platform_cleanup_swapchain = gl_x11_egl_platform_cleanup_swapchain,
+	.device_enter_context = gl_x11_egl_device_enter_context,
+	.device_leave_context = gl_x11_egl_device_leave_context,
+	.device_get_device_obj = gl_x11_egl_device_get_device_obj,
+	.getclientsize = gl_x11_egl_getclientsize,
+	.clear_context = gl_x11_egl_clear_context,
+	.update = gl_x11_egl_update,
+	.device_load_swapchain = gl_x11_egl_device_load_swapchain,
+	.device_present = gl_x11_egl_device_present,
+};
+
+const struct gl_winsys_vtable *gl_x11_egl_get_winsys_vtable(void)
+{
+	return &egl_x11_winsys_vtable;
+}

libobs-opengl/gl-x11-egl.h

@@ -0,0 +1,22 @@
+/******************************************************************************
+    Copyright (C) 2019 by Ivan Avdeev <[email protected]>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+******************************************************************************/
+
+#pragma once
+
+#include "gl-nix.h"
+
+const struct gl_winsys_vtable *gl_x11_egl_get_winsys_vtable(void);