/* -*-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.
*/

#ifndef OSG_TEXENVFILTER
#define OSG_TEXENVFILTER 1

#include <osg/GL>
#include <osg/StateAttribute>

#ifndef GL_EXT_texture_lod_bias
#define GL_MAX_TEXTURE_LOD_BIAS_EXT       0x84FD
#define GL_TEXTURE_FILTER_CONTROL_EXT     0x8500
#define GL_TEXTURE_LOD_BIAS_EXT           0x8501
#endif

namespace osg {

/** TexEnvFilter - encapsulates the OpenGL glTexEnv (GL_TEXTURE_FILTER_CONTROL) state.*/
class OSG_EXPORT TexEnvFilter : public StateAttribute
{
  public:
    TexEnvFilter(float lodBias = 0.0f);
        
    /** Copy constructor using CopyOp to manage deep vs shallow copy.*/
    TexEnvFilter(const TexEnvFilter& texenv,const CopyOp& copyop=CopyOp::SHALLOW_COPY):
            StateAttribute(texenv,copyop),
            _lodBias(texenv._lodBias) {}

    META_StateAttribute(osg, TexEnvFilter, TEXENVFILTER);

    virtual bool isTextureAttribute() const { return true; }

    /** return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs.*/
    virtual int compare(const StateAttribute& sa) const
    {
        // check the types are equal and then create the rhs variable
        // used by the COMPARE_StateAttribute_Paramter macro's below.
        COMPARE_StateAttribute_Types(TexEnvFilter, sa)

        // compare each parameter in turn against the rhs.
        COMPARE_StateAttribute_Parameter(_lodBias)

        return 0; // passed all the above comparison macro's, must be equal.
    }

    void  setLodBias( float lodBias ) { _lodBias = lodBias; }
        
    float getLodBias() const { return _lodBias; }

    virtual void apply(State& state) const;

  protected:
    virtual ~TexEnvFilter();

    float   _lodBias;
};

}

#endif
