From Sohey Yamamoto, added support for GL_TEXTURE_FILTER_CONTROL/GL_TEXTURE_LOD_BIAS.

src/osg/TexEnvFilter.cpp

@@ -0,0 +1,38 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 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/GLExtensions>
+#include <osg/TexEnvFilter>
+
+using namespace osg;
+
+TexEnvFilter::TexEnvFilter(float lodBias) :
+        _lodBias(lodBias)
+{
+}
+
+
+TexEnvFilter::~TexEnvFilter()
+{
+}
+
+void TexEnvFilter::apply(State&) const
+{
+    // note from RO, need to adapt to do testing per graphics context.
+    static float glVersion = atof( (const char *)glGetString( GL_VERSION ) );
+    static bool s_isTexLodBias = glVersion>=1.4 || isGLExtensionSupported("GL_EXT_texture_lod_bias");
+
+    if (s_isTexLodBias)
+    {
+        glTexEnvf(GL_TEXTURE_FILTER_CONTROL_EXT, GL_TEXTURE_LOD_BIAS_EXT, _lodBias);
+    }
+}