2.8 branch: Added convenience macros to Version header. This is a mer…

…ge of r10173 from trunk.

include/osg/Version

@@ -24,6 +24,18 @@ extern "C" {
 #define OPENSCENEGRAPH_PATCH_VERSION    3
 #define OPENSCENEGRAPH_SOVERSION        65
 
+/** convinience macro that can be used to decide whether a feature is present or not i.e.
+  * #if OSG_MIN_VERSION_REQUIRED(2,9,5)
+  *    your code here
+  * #endif
+  */ 
+#define OSG_MIN_VERSION_REQUIRED(MAJOR, MINOR, PATCH) ((OPENSCENEGRAPH_MAJOR_VERSION>MAJOR) || (OPENSCENEGRAPH_MAJOR_VERSION==MAJOR && (OPENSCENEGRAPH_MINOR_VERSION>MINOR || (OPENSCENEGRAPH_MINOR_VERSION==MINOR && OPENSCENEGRAPH_PATCH_VERSION>=PATCH))))
+#define OSG_VERSION_LESS_THAN(MAJOR, MINOR, PATCH) ((OPENSCENEGRAPH_MAJOR_VERSION<MAJOR) || (OPENSCENEGRAPH_MAJOR_VERSION==MAJOR && (OPENSCENEGRAPH_MINOR_VERSION<MINOR || (OPENSCENEGRAPH_MINOR_VERSION==MINOR && OPENSCENEGRAPH_PATCH_VERSION<PATCH))))
+#define OSG_VERSION_LESS_OR_EQUAL(MAJOR, MINOR, PATCH) ((OPENSCENEGRAPH_MAJOR_VERSION<MAJOR) || (OPENSCENEGRAPH_MAJOR_VERSION==MAJOR && (OPENSCENEGRAPH_MINOR_VERSION<MINOR || (OPENSCENEGRAPH_MINOR_VERSION==MINOR && OPENSCENEGRAPH_PATCH_VERSION<=PATCH))))
+#define OSG_VERSION_GREATER_THAN(MAJOR, MINOR, PATCH) ((OPENSCENEGRAPH_MAJOR_VERSION>MAJOR) || (OPENSCENEGRAPH_MAJOR_VERSION==MAJOR && (OPENSCENEGRAPH_MINOR_VERSION>MINOR || (OPENSCENEGRAPH_MINOR_VERSION==MINOR && OPENSCENEGRAPH_PATCH_VERSION>PATCH))))
+#define OSG_VERSION_GREATER_OR_EQUAL(MAJOR, MINOR, PATCH) ((OPENSCENEGRAPH_MAJOR_VERSION>MAJOR) || (OPENSCENEGRAPH_MAJOR_VERSION==MAJOR && (OPENSCENEGRAPH_MINOR_VERSION>MINOR || (OPENSCENEGRAPH_MINOR_VERSION==MINOR && OPENSCENEGRAPH_PATCH_VERSION>=PATCH))))
+
+
 /**
   * osgGetVersion() returns the library version number.
  * Numbering convention : OpenSceneGraph-1.0 will return 1.0 from osgGetVersion.