- store the last found OpenGL version in the INI so that modern GL related options can be removed when running old hardware with software rendering.

src/d_main.cpp

@@ -132,6 +132,7 @@ extern void M_SetDefaultMode ();
 extern void G_NewInit ();
 extern void SetupPlayerClasses ();
 extern void HUD_InitHud();
+void gl_PatchMenu();	// remove modern OpenGL options on old hardware.
 void DeinitMenus();
 const FIWADInfo *D_FindIWAD(TArray<FString> &wadfiles, const char *iwad, const char *basewad);
 
@@ -2639,6 +2640,7 @@ void D_DoomMain (void)
 			}
 
 			V_Init2();
+			gl_PatchMenu();
 			UpdateJoystickMenu(NULL);
 
 			v = Args->CheckValue ("-loadgame");

src/gl/compatibility/gl_20.cpp

@@ -53,6 +53,7 @@
 
 
 CVAR(Bool, gl_lights_additive, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
+CVAR(Bool, gl_legacy_mode, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG | CVAR_NOSET)
 
 //==========================================================================
 //
@@ -64,6 +65,7 @@ CVAR(Bool, gl_lights_additive, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
 void gl_PatchMenu()
 {
 	// Radial fog and Doom lighting are not available without full shader support.
+	if (!gl_legacy_mode) return;
 
 	FOptionValues **opt = OptionValues.CheckKey("LightingModes");
 	if (opt != NULL) 

src/gl/system/gl_interface.cpp

@@ -42,6 +42,8 @@ void gl_PatchMenu();
 static TArray<FString>  m_Extensions;
 RenderContext gl;
 
+EXTERN_CVAR(Bool, gl_legacy_mode)
+
 //==========================================================================
 //
 // 
@@ -311,8 +313,8 @@ void gl_LoadExtensions()
 		FUDGE_FUNC(glRenderbufferStorage, EXT);
 		FUDGE_FUNC(glBindRenderbuffer, EXT);
 		FUDGE_FUNC(glCheckFramebufferStatus, EXT);
-		gl_PatchMenu();
 	}
+	gl_legacy_mode = gl.legacyMode;
 }
 
 //==========================================================================

src/gl/system/gl_swframebuffer.cpp

@@ -92,6 +92,7 @@ EXTERN_CVAR(Float, Gamma)
 EXTERN_CVAR(Bool, vid_vsync)
 EXTERN_CVAR(Float, transsouls)
 EXTERN_CVAR(Int, vid_refreshrate)
+EXTERN_CVAR(Bool, gl_legacy_mode)
 
 CVAR(Int, vid_max_width, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
 CVAR(Int, vid_max_height, 0, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
@@ -205,6 +206,13 @@ OpenGLSWFrameBuffer::OpenGLSWFrameBuffer(void *hMonitor, int width, int height,
 	
 	const char *glversion = (const char*)glGetString(GL_VERSION);
 	bool isGLES = (glversion && strlen(glversion) > 10 && memcmp(glversion, "OpenGL ES ", 10) == 0);
+
+	// GL 3.0 is mostly broken on MESA drivers which really are the only relevant case here that doesn't fulfill the requirements based on version number alone.
+#ifdef _WIN32
+	gl_legacy_mode = !ogl_IsVersionGEQ(3, 0);
+#else
+	gl_legacy_mode = !ogl_IsVersionGEQ(3, 1);
+#endif
 	if (!isGLES && ogl_IsVersionGEQ(3, 0) == 0)
 	{
 		Printf("OpenGL acceleration requires at least OpenGL 3.0. No Acceleration will be used.\n");