/* -*-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_TEXTURETRIBUTE
#define OSG_TEXTURETRIBUTE 1

#include <osg/StateAttribute>

namespace osg {

// forward declare
class StateSet;

class TextureAttribute : public StateAttribute
{
    public:
        TextureAttribute():
            _textureUnit(0) {}

        TextureAttribute(const TextureAttribute& ta, const CopyOp& copyop=CopyOp::SHALLOW_COPY):
            StateAttribute(ta, copyop),
            _textureUnit(0) {}

        virtual bool isTextureAttribute() const { return true; }

        virtual unsigned int getMember() const { return _textureUnit; }

    protected:
        virtual ~TextureAttribute() {}

        // called when the TextureAttribute is assigned to a StateSet;
        virtual void setTextureUnit(unsigned int unit)
        {
            if (unit!=_textureUnit)
            {
                _textureUnit = unit;

                // configure the uniform names to reflect new texture unit value
                configureUniformNames();
            }
        }

        // TextureAttribute subclasses that manage uniforms will need to override configureUniformNames() and adjust uniform names to reflect texture unit that the attribute is assigned to.
        virtual void configureUniformNames() {}

        friend class StateSet;

        unsigned int _textureUnit;
};

}
#endif
