Merge pull request #23 from RyanGlScott/master

Allow building with freeglut on Windows

Author: svenpanne

GLUT.cabal

@@ -46,7 +46,7 @@ extra-source-files:
 flag UseNativeWindowsLibraries
   description:
     When compiling under Windows, use the native libraries instead of e.g. the
-    ones coming with Cygwin.
+    ones coming with Cygwin or MSYS.
 
 flag BuildExamples
   description: Build various OpenGL/GLUT examples.
@@ -100,7 +100,6 @@ library
     else
       cpp-options: "-DCALLCONV=ccall"
     cc-options: "-DUSE_GETPROCADDRESS"
-    extra-libraries: glut32
   else
     cpp-options: "-DCALLCONV=ccall"
     cc-options: "-DUSE_DLSYM"

cbits/HsGLUT.c

@@ -86,6 +86,16 @@ hs_GLUT_getProcAddress(const char *name)
   if (firstTime) {
     firstTime = 0;
     handle = LoadLibrary(TEXT("glut32"));
+
+    // If glut32 isn't present, try freeglut instead
+    if (!handle) {
+      handle = LoadLibrary(TEXT("freeglut"));
+    }
+
+    // The MinGW-w64 version of freeglut prefixes "lib" onto the DLL name
+    if (!handle) {
+      handle = LoadLibrary(TEXT("libfreeglut"));
+    }
   }
 
   return handle ? GetProcAddress(handle, name) : NULL;