Add glXSwapIntervalMESA

client/deps/glbench/src/glx_stuff.cc

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <string.h>
 #include <GL/glx.h>
 
 #include "base/logging.h"
 #include "main.h"
 #include "xlib_window.h"
 
 static GLXContext glx_context = NULL;
 static GLXFBConfig glx_fbconfig = NULL;
 
 #define F(fun, type) type fun = NULL;
 LIST_PROC_FUNCTIONS(F)
 #undef F
+PFNGLXSWAPINTERVALMESAPROC _glXSwapIntervalMESA = NULL;
 
 bool Init() {
   return XlibInit();
 }
 
 XVisualInfo* GetXVisual() {
   if (!glx_fbconfig) {
     int screen = DefaultScreen(g_xlib_display);
     int attrib[] = {
       GLX_DOUBLEBUFFER, True,
@@ skipping 37 matching lines @@
 
   const GLubyte *str = glGetString(GL_EXTENSIONS);
   if (!str || !strstr(reinterpret_cast<const char *>(str),
                       "GL_ARB_vertex_buffer_object"))
     return false;
 
 #define F(fun, type) fun = reinterpret_cast<type>( \
     glXGetProcAddress(reinterpret_cast<const GLubyte *>(#fun)));
   LIST_PROC_FUNCTIONS(F)
 #undef F
+  _glXSwapIntervalMESA = reinterpret_cast<PFNGLXSWAPINTERVALMESAPROC>(
+    glXGetProcAddress(reinterpret_cast<const GLubyte *>(
+        "glXSwapIntervalMESA")));
 
   return true;
 }
 
 void DestroyContext() {
   glXMakeCurrent(g_xlib_display, 0, NULL);
   glXDestroyContext(g_xlib_display, glx_context);
 }
 
 void SwapBuffers() {
   glXSwapBuffers(g_xlib_display, g_xlib_window);
 }
 
 bool SwapInterval(int interval) {
-  return glXSwapIntervalSGI(interval) == 0;
+  // Strictly, glXSwapIntervalSGI only allows interval > 0, whereas
+  // glXSwapIntervalMESA allow 0 with the same semantics as eglSwapInterval.
+  if (_glXSwapIntervalMESA) {
+    return _glXSwapIntervalMESA(interval) == 0;
+  } else {
+    return glXSwapIntervalSGI(interval) == 0;
+  }
 }