Load GLX dynamically with GLAD

This is accomplished through the addition of a GLAD GLX loader in the
`thirdparty` directory.

This is another step towards a nice Wayland/X11 interoperation.

3 files changed, 26 insertions, 27 deletions

diff --git a/platform/linuxbsd/x11/SCsub b/platform/linuxbsd/x11/SCsub
index 974ad98fb9..30c6080355 100644
--- a/platform/linuxbsd/x11/SCsub
+++ b/platform/linuxbsd/x11/SCsub
@@ -11,7 +11,7 @@ if env["vulkan"]:
     source_files.append("vulkan_context_x11.cpp")
 
 if env["opengl3"]:
-    source_files.append(["gl_manager_x11.cpp", "detect_prime_x11.cpp"])
+    source_files.append(["gl_manager_x11.cpp", "detect_prime_x11.cpp", "#thirdparty/glad/glx.c"])
 
 objects = []
 
diff --git a/platform/linuxbsd/x11/detect_prime_x11.cpp b/platform/linuxbsd/x11/detect_prime_x11.cpp
index 78a10fa2b0..ed046432d8 100644
--- a/platform/linuxbsd/x11/detect_prime_x11.cpp
+++ b/platform/linuxbsd/x11/detect_prime_x11.cpp
@@ -38,8 +38,9 @@
 
 #include <stdlib.h>
 
-#include <GL/gl.h>
-#include <GL/glx.h>
+#include "thirdparty/glad/glad/gl.h"
+#include "thirdparty/glad/glad/glx.h"
+
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 
@@ -77,8 +78,6 @@ void create_context() {
 	Window x11_window;
 	GLXContext glx_context;
 
-	GLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB = (GLXCREATECONTEXTATTRIBSARBPROC)glXGetProcAddress((const GLubyte *)"glXCreateContextAttribsARB");
-
 	static int visual_attribs[] = {
 		GLX_RENDER_TYPE, GLX_RGBA_BIT,
 		GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
@@ -101,7 +100,7 @@ void create_context() {
 
 	GLXFBConfig *fbc = glXChooseFBConfig(x11_display, DefaultScreen(x11_display), visual_attribs, &fbcount);
 	if (!fbc) {
-		exit(1);
+		quick_exit(1);
 	}
 
 	vi = glXGetVisualFromFBConfig(x11_display, fbc[0]);
@@ -122,7 +121,7 @@ void create_context() {
 	x11_window = XCreateWindow(x11_display, RootWindow(x11_display, vi->screen), 0, 0, 10, 10, 0, vi->depth, InputOutput, vi->visual, valuemask, &swa);
 
 	if (!x11_window) {
-		exit(1);
+		quick_exit(1);
 	}
 
 	glXMakeCurrent(x11_display, x11_window, glx_context);
@@ -189,8 +188,20 @@ int detect_prime() {
 			if (i) {
 				setenv("DRI_PRIME", "1", 1);
 			}
+
+			if (gladLoaderLoadGLX(NULL, 0) == 0) {
+				print_verbose("Unable to load GLX, GPU detection skipped.");
+				quick_exit(1);
+			}
+
 			create_context();
 
+			PFNGLGETSTRINGPROC glGetString = (PFNGLGETSTRINGPROC)glXGetProcAddressARB((GLubyte *)"glGetString");
+			if (!glGetString) {
+				print_verbose("Unable to get glGetString, GPU detection skipped.");
+				quick_exit(1);
+			}
+
 			const char *vendor = (const char *)glGetString(GL_VENDOR);
 			const char *renderer = (const char *)glGetString(GL_RENDERER);
 
diff --git a/platform/linuxbsd/x11/gl_manager_x11.cpp b/platform/linuxbsd/x11/gl_manager_x11.cpp
index 893a22e75e..4d8d63c64a 100644
--- a/platform/linuxbsd/x11/gl_manager_x11.cpp
+++ b/platform/linuxbsd/x11/gl_manager_x11.cpp
@@ -37,9 +37,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 
-#define GLX_GLXEXT_PROTOTYPES
-#include <GL/glx.h>
-#include <GL/glxext.h>
+#include "thirdparty/glad/glad/glx.h"
 
 #define GLX_CONTEXT_MAJOR_VERSION_ARB 0x2091
 #define GLX_CONTEXT_MINOR_VERSION_ARB 0x2092
@@ -324,11 +322,14 @@ void GLManager_X11::swap_buffers() {
 }
 
 Error GLManager_X11::initialize() {
+	if (!gladLoaderLoadGLX(nullptr, 0)) {
+		return ERR_CANT_CREATE;
+	}
+
 	return OK;
 }
 
 void GLManager_X11::set_use_vsync(bool p_use) {
-	static bool setup = false;
 	static PFNGLXSWAPINTERVALEXTPROC glXSwapIntervalEXT = nullptr;
 	static PFNGLXSWAPINTERVALSGIPROC glXSwapIntervalMESA = nullptr;
 	static PFNGLXSWAPINTERVALSGIPROC glXSwapIntervalSGI = nullptr;
@@ -345,25 +346,12 @@ void GLManager_X11::set_use_vsync(bool p_use) {
 	}
 	const GLDisplay &disp = get_current_display();
 
-	if (!setup) {
-		setup = true;
-		String extensions = glXQueryExtensionsString(disp.x11_display, DefaultScreen(disp.x11_display));
-		if (extensions.find("GLX_EXT_swap_control") != -1) {
-			glXSwapIntervalEXT = (PFNGLXSWAPINTERVALEXTPROC)glXGetProcAddressARB((const GLubyte *)"glXSwapIntervalEXT");
-		}
-		if (extensions.find("GLX_MESA_swap_control") != -1) {
-			glXSwapIntervalMESA = (PFNGLXSWAPINTERVALSGIPROC)glXGetProcAddressARB((const GLubyte *)"glXSwapIntervalMESA");
-		}
-		if (extensions.find("GLX_SGI_swap_control") != -1) {
-			glXSwapIntervalSGI = (PFNGLXSWAPINTERVALSGIPROC)glXGetProcAddressARB((const GLubyte *)"glXSwapIntervalSGI");
-		}
-	}
 	int val = p_use ? 1 : 0;
-	if (glXSwapIntervalMESA) {
+	if (GLAD_GLX_MESA_swap_control) {
 		glXSwapIntervalMESA(val);
-	} else if (glXSwapIntervalSGI) {
+	} else if (GLAD_GLX_SGI_swap_control) {
 		glXSwapIntervalSGI(val);
-	} else if (glXSwapIntervalEXT) {
+	} else if (GLAD_GLX_EXT_swap_control) {
 		GLXDrawable drawable = glXGetCurrentDrawable();
 		glXSwapIntervalEXT(disp.x11_display, drawable, val);
 	} else {