Introduced new osg::PatchParameter StateAttribute class to wrap up glPatchParameter associated state.

Note, osg::Program::setParameter(GL_PATCH_VERTICES,num); is nolonger support and should be replaced by using the new PatchParameter class.

src/osg/PatchParameter.cpp

@@ -0,0 +1,42 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
+ *
+ * This library is open source and may be redistributed and/or modified under
+ * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
+ * (at your option) any later version.  The full license is in LICENSE file
+ * included with this distribution, and on the openscenegraph.org website.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * OpenSceneGraph Public License for more details.
+*/
+#include <osg/PatchParameter>
+#include <osg/State>
+#include <osg/Notify>
+#include <osg/io_utils>
+
+using namespace osg;
+
+PatchParameter::PatchParameter(GLint vertices):
+    _vertices(vertices),
+    _patchDefaultInnerLevel(1.0f,1.0f),
+    _patchDefaultOuterLevel(1.0f,1.0f,1.0f,1.0f)
+{
+}
+
+
+PatchParameter::~PatchParameter()
+{
+}
+
+void PatchParameter::apply(State& state) const
+{
+    GL2Extensions* extensions = GL2Extensions::Get( state.getContextID(), true );
+    if (extensions->areTessellationShadersSupported() )
+    {
+        
+        extensions->glPatchParameteri( GL_PATCH_VERTICES, _vertices );
+        extensions->glPatchParameterfv( GL_PATCH_DEFAULT_INNER_LEVEL, _patchDefaultInnerLevel.ptr() );
+        extensions->glPatchParameterfv( GL_PATCH_DEFAULT_OUTER_LEVEL, _patchDefaultOuterLevel.ptr() );
+    }
+}