Added NvOptimusEnablement.

CMakeLists.txt

@@ -18,6 +18,7 @@ option(GLFW_DOCUMENT_INTERNALS "Include internals in documentation" OFF)
 
 if (WIN32)
     option(GLFW_USE_DWM_SWAP_INTERVAL "Set swap interval even when DWM compositing is enabled" OFF)
+    option(GLFW_USE_OPTIMUS_HPG "Force use of high-performance GPU on Optimus systems" OFF)
 endif()
 
 if (APPLE)
@@ -159,6 +160,9 @@ if (_GLFW_WIN32)
     if (GLFW_USE_DWM_SWAP_INTERVAL)
         set(_GLFW_USE_DWM_SWAP_INTERVAL 1)
     endif()
+    if (GLFW_USE_OPTIMUS_HPG)
+        set(_GLFW_USE_OPTIMUS_HPG 1)
+    endif()
 endif()
 
 #--------------------------------------------------------------------

README.md

@@ -173,6 +173,10 @@ static library version of the Visual C++ runtime library.
 when DWM compositing is enabled.  This can lead to severe jitter and is not
 usually recommended.
 
+`GLFW_USE_OPTIMUS_HPG` determines whether to export the `NvOptimusEnablement`
+symbol, which forces the use of the high-performance GPU on nVidia Optimus
+systems.
+
 
 #### EGL specific options
 
@@ -204,6 +208,8 @@ See the [GLFW documentation](http://www.glfw.org/docs/latest/).
  - Bugfix: The default for `GLFW_ALPHA_BITS` was set to zero
  - [Win32] Added `_GLFW_USE_DWM_SWAP_INTERVAL` for forcing the swap interval
            to be set even when DWM compositing is enabled
+ - [Win32] Added support for forcing the use of the high-performance GPU
+           on nVidia Optimus systems
  - [Win32] Bugfix: The clipboard string was not freed on terminate
  - [Win32] Bugfix: Entry points for OpenGL 1.0 and 1.1 functions were not
                    returned by `glfwGetProcAddress`

src/config.h.in

@@ -55,6 +55,8 @@
 #cmakedefine _GLFW_NO_DLOAD_WINMM
 // Define this to 1 if glfwSwapInterval should ignore DWM compositing status
 #cmakedefine _GLFW_USE_DWM_SWAP_INTERVAL
+// Define this to 1 to force use of high-performance GPU on Optimus systems
+#cmakedefine _GLFW_USE_OPTIMUS_HPG
 
 // Define this to 1 if glXGetProcAddress is available
 #cmakedefine _GLFW_HAS_GLXGETPROCADDRESS

src/win32_init.c

@@ -36,6 +36,15 @@
 #endif // __BORLANDC__
 
 
+#if defined(_GLFW_USE_OPTIMUS_HPG)
+
+// Applications exporting this symbol with this value will be automatically
+// directed to the high-performance GPU on nVidia Optimus systems
+//
+GLFWAPI DWORD NvOptimusEnablement = 0x00000001;
+
+#endif // _GLFW_USE_OPTIMUS_HPG
+
 #if defined(_GLFW_BUILD_DLL)
 
 // GLFW DLL entry point