+ add support for the GLX_SGI_swap_control extension

* import all GLX procedures and functions via the glXGetProcAddress and
  glXGetProcAddressARB functions, if they are available. This is necessary,
  because not all GLX extension functions are exported statically by libGL.so

git-svn-id: trunk@20516 -

packages/opengl/src/glx.pp

@@ -300,6 +300,9 @@ var
   glXReleaseBufferMESA: function(dpy: PDisplay; d: GLXDrawable): Boolean; cdecl;
   glXCopySubBufferMESA: procedure(dpy: PDisplay; drawbale: GLXDrawable; x, y, width, height: Integer); cdecl;
 
+  // GLX_SGI_swap_control
+  glXSwapIntervalSGI: function(interval: Integer): Integer; cdecl;
+
   // GLX_SGI_video_sync
   glXGetVideoSyncSGI: function(var counter: LongWord): Integer; cdecl;
   glXWaitVideoSyncSGI: function(divisor, remainder: Integer; var count: LongWord): Integer; cdecl;
@@ -346,6 +349,7 @@ function GLX_ARB_create_context_robustness(Display: PDisplay; Screen: Integer):
 function GLX_ARB_multisample(Display: PDisplay; Screen: Integer): boolean;
 function GLX_EXT_visual_info(Display: PDisplay; Screen: Integer): boolean;
 function GLX_MESA_pixmap_colormap(Display: PDisplay; Screen: Integer): boolean;
+function GLX_SGI_swap_control(Display: PDisplay; Screen: Integer): boolean;
 function GLX_SGI_video_sync(Display: PDisplay; Screen: Integer): boolean;
 function GLX_SGIS_multisample(Display: PDisplay; Screen: Integer): boolean;
 
@@ -548,6 +552,19 @@ begin
   end;
 end;
 
+function GLX_SGI_swap_control(Display: PDisplay; Screen: Integer): boolean;
+var
+  GlxExtensions: PChar;
+begin
+  Result := GLX_version_1_1(Display);
+  if Result then
+  begin
+    GlxExtensions := glXQueryExtensionsString(Display, Screen);
+    Result := glext_ExtensionSupported('GLX_SGI_swap_control', GlxExtensions) and
+      Assigned(glXSwapIntervalSGI);
+  end;
+end;
+
 function GLX_SGI_video_sync(Display: PDisplay; Screen: Integer): boolean;
 var
   GlxExtensions: PChar;
@@ -576,7 +593,13 @@ end;
 
 function GetProc(handle: PtrInt; name: PChar): Pointer;
 begin
-  Result := GetProcAddress(handle, name);
+  if Assigned(glXGetProcAddress) then
+    Result := glXGetProcAddress(name)
+  else
+    if Assigned(glXGetProcAddressARB) then
+      Result := glXGetProcAddressARB(name)
+    else
+      Result := GetProcAddress(handle, name);
   if (Result = nil) and GLXDumpUnresolvedFunctions then
     WriteLn('Unresolved: ', name);
 end;
@@ -596,6 +619,16 @@ begin
   if OurLibGL = 0 then
     exit;
 
+  // glXGetProcAddress and glXGetProcAddressARB are imported first,
+  // so we can use them (when they are available) to resolve all the
+  // other imports
+
+  // GLX 1.4 and later
+  glXGetProcAddress := GetProc(OurLibGL, 'glXGetProcAddress');
+  // GLX_ARB_get_proc_address
+  glXGetProcAddressARB := GetProc(OurLibGL, 'glXGetProcAddressARB');
+
+  // GLX 1.0
   glXChooseVisual := GetProc(OurLibGL, 'glXChooseVisual');
   glXCreateContext := GetProc(OurLibGL, 'glXCreateContext');
   glXDestroyContext := GetProc(OurLibGL, 'glXDestroyContext');
@@ -637,11 +670,7 @@ begin
   glXQueryContext := GetProc(OurLibGL, 'glXQueryContext');
   glXSelectEvent := GetProc(OurLibGL, 'glXSelectEvent');
   glXGetSelectedEvent := GetProc(OurLibGL, 'glXGetSelectedEvent');
-  // GLX 1.4 and later
-  glXGetProcAddress := GetProc(OurLibGL, 'glXGetProcAddress');
   // Extensions
-  // GLX_ARB_get_proc_address
-  glXGetProcAddressARB := GetProc(OurLibGL, 'glXGetProcAddressARB');
   // GLX_ARB_create_context
   glXCreateContextAttribsARB := GetProc(OurLibGL, 'glXCreateContextAttribsARB');
   // GLX_MESA_pixmap_colormap
@@ -649,6 +678,8 @@ begin
   // Unknown Mesa GLX extension
   glXReleaseBufferMESA := GetProc(OurLibGL, 'glXReleaseBufferMESA');
   glXCopySubBufferMESA := GetProc(OurLibGL, 'glXCopySubBufferMESA');
+  // GLX_SGI_swap_control
+  glXSwapIntervalSGI := GetProc(OurLibGL, 'glXSwapIntervalSGI');
   // GLX_SGI_video_sync
   glXGetVideoSyncSGI := GetProc(OurLibGL, 'glXGetVideoSyncSGI');
   glXWaitVideoSyncSGI := GetProc(OurLibGL, 'glXWaitVideoSyncSGI');