From 62462d2734a16c2b355216b98089f405f6a8163f Mon Sep 17 00:00:00 2001
From: Wolfgang Draxinger <Wolfgang.Draxinger@draxit.de>
Date: Thu, 5 Jan 2012 21:01:19 +0100
Subject: OpenGL 3 context creation

---
 samples/OpenGL/x11argb_opengl/x11argb_opengl.c | 68 ++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 3 deletions(-)

(limited to 'samples/OpenGL/x11argb_opengl/x11argb_opengl.c')

diff --git a/samples/OpenGL/x11argb_opengl/x11argb_opengl.c b/samples/OpenGL/x11argb_opengl/x11argb_opengl.c
index f7f4c58..77565f0 100644
--- a/samples/OpenGL/x11argb_opengl/x11argb_opengl.c
+++ b/samples/OpenGL/x11argb_opengl/x11argb_opengl.c
@@ -69,6 +69,37 @@ GLX_DEPTH_SIZE, 16,
 None
 };
 
+static int isExtensionSupported(const char *extList, const char *extension)
+{
+ 
+  const char *start;
+  const char *where, *terminator;
+ 
+  /* Extension names should not have spaces. */
+  where = strchr(extension, ' ');
+  if ( where || *extension == '\0' )
+    return 0;
+ 
+  /* It takes a bit of care to be fool-proof about parsing the
+     OpenGL extensions string. Don't be fooled by sub-strings,
+     etc. */
+  for ( start = extList; ; ) {
+    where = strstr( start, extension );
+ 
+    if ( !where )
+      break;
+ 
+    terminator = where + strlen( extension );
+ 
+    if ( where == start || *(where - 1) == ' ' )
+      if ( *terminator == ' ' || *terminator == '\0' )
+        return 1;
+ 
+    start = terminator;
+  }
+  return 0;
+}
+
 static Bool WaitForMapNotify(Display *d, XEvent *e, char *arg)
 {
 	return d && e && arg && (e->type == MapNotify) && (e->xmap.window == *(Window*)arg);
@@ -222,9 +253,40 @@ static void createTheRenderContext()
 		fatalError("OpenGL not supported by X server\n");
 	}
 
-	render_context = glXCreateNewContext(Xdisplay, fbconfig, GLX_RGBA_TYPE, 0, True);
-	if (!render_context) {
-		fatalError("Failed to create a GL context\n");
+#if USE_GLX_CREATE_CONTEXT_ATTRIB
+	#define GLX_CONTEXT_MAJOR_VERSION_ARB       0x2091
+	#define GLX_CONTEXT_MINOR_VERSION_ARB       0x2092
+	render_context = NULL;
+	if( isExtensionSupported( glXQueryExtensionsString(Xdisplay, DefaultScreen(Xdisplay)), "GLX_ARB_create_context" ) ) {
+		typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*);
+		glXCreateContextAttribsARBProc glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc)glXGetProcAddressARB( (const GLubyte *) "glXCreateContextAttribsARB" );
+		if( glXCreateContextAttribsARB ) {
+			int context_attribs[] =
+			{
+				GLX_CONTEXT_MAJOR_VERSION_ARB, 3,
+				GLX_CONTEXT_MINOR_VERSION_ARB, 0,
+				//GLX_CONTEXT_FLAGS_ARB        , GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB,
+				None
+			};
+
+			render_context = glXCreateContextAttribsARB( Xdisplay, fbconfig, 0, True, context_attribs );
+			fputs("glXCreateContextAttribsARB failed", stderr);
+		} else {
+			fputs("glXCreateContextAttribsARB could not be retrieved", stderr);
+		}
+	} else {
+			fputs("glXCreateContextAttribsARB not supported", stderr);
+	}
+
+	if(!render_context)
+	{
+#else
+	{
+#endif
+		render_context = glXCreateNewContext(Xdisplay, fbconfig, GLX_RGBA_TYPE, 0, True);
+		if (!render_context) {
+			fatalError("Failed to create a GL context\n");
+		}
 	}
 
 	if (!glXMakeContextCurrent(Xdisplay, glX_window_handle, glX_window_handle, render_context)) {
-- 
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