/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2013 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.
*/

// -*-c++-*-

#ifndef OSG_TEXTUREBUFFEROBJECT
#define OSG_TEXTUREBUFFEROBJECT 1

#include <osg/Texture>
#include <osg/BufferObject>

#ifndef GL_ARB_texture_buffer_object
    #define GL_TEXTURE_BUFFER_ARB                    0x8C2A
    #define GL_MAX_TEXTURE_BUFFER_SIZE_ARB           0x8C2B
    #define GL_TEXTURE_BINDING_BUFFER_ARB            0x8C2C
    #define GL_TEXTURE_BUFFER_DATA_STORE_BINDING_ARB 0x8C2D
    #define GL_TEXTURE_BUFFER_FORMAT_ARB             0x8C2E
#endif

namespace osg {

/** Encapsulates OpenGL texture buffer functionality.
*/
class OSG_EXPORT TextureBuffer : public Texture
{

    public :

        TextureBuffer();

        TextureBuffer(Image* image);

        /** Copy constructor using CopyOp to manage deep vs shallow copy. */
        TextureBuffer(const TextureBuffer& text,const CopyOp& copyop=CopyOp::SHALLOW_COPY);

        META_StateAttribute(osg, TextureBuffer, TEXTURE);

        /** Return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs. */
        virtual int compare(const StateAttribute& rhs) const;

        virtual GLenum getTextureTarget() const { return GL_TEXTURE_BUFFER_ARB; }

        /** Sets the texture image. */
        void setImage(Image* image);

        /** Gets the texture image. */
        Image* getImage() { return _image.get(); }

        /** Gets the const texture image. */
        inline const Image* getImage() const { return _image.get(); }

        inline unsigned int& getModifiedCount(unsigned int contextID) const
        {
            // get the modified count for the current contextID.
            return _modifiedCount[contextID];
        }


        /** Sets the texture image, ignoring face. */
        virtual void setImage(unsigned int, Image* image) { setImage(image); }

        /** Gets the texture image, ignoring face. */
        virtual Image* getImage(unsigned int) { return _image.get(); }

        /** Gets the const texture image, ignoring face. */
        virtual const Image* getImage(unsigned int) const { return _image.get(); }

        /** Gets the number of images that can be assigned to the Texture. */
        virtual unsigned int getNumImages() const { return 1; }


        /** Sets the texture width. If width is zero, calculate the value
          * from the source image width. */
        inline void setTextureWidth(int width) { _textureWidth = width; }

        /** Gets the texture width. */
        virtual int getTextureWidth() const { return _textureWidth; }
        virtual int getTextureHeight() const { return 1; }
        virtual int getTextureDepth() const { return 1; }

        inline void setUsageHint( GLenum usageHint ) { _usageHint=usageHint; }
        inline GLenum getUsageHint() const { return _usageHint; }

        virtual void allocateMipmap(State& /*state*/) const {};

        /** Bind the texture buffer.*/
        virtual void apply(State& state) const;

        /** Bind buffer to different target. */
        void bindBufferAs(unsigned int contextID, GLenum target);
        void unbindBufferAs(unsigned int contextID, GLenum target);

    protected :

        virtual ~TextureBuffer();

        virtual void computeInternalFormat() const;

        ref_ptr<Image> _image;

        mutable GLsizei _textureWidth;
        GLenum _usageHint;

        typedef buffered_value<unsigned int> ImageModifiedCount;
        mutable ImageModifiedCount _modifiedCount;

        class TextureBufferObject : public osg::Referenced
        {
        public:
            TextureBufferObject(unsigned int contextID, GLenum usageHint) :
                _id(0),
                _usageHint(usageHint)
            {
                _extensions = osg::GL2Extensions::Get(contextID, true);
            }

            void bindBuffer(GLenum target);
            void unbindBuffer(GLenum target);

            void texBuffer(GLenum internalFormat);
            void bufferData( osg::Image* image );
            void bufferSubData( osg::Image* image );

        public:
            GLuint _id;
            GLenum _usageHint;
            osg::GL2Extensions* _extensions;
        };

        typedef osg::buffered_object<osg::ref_ptr<TextureBufferObject> > TextureBufferObjectList;
        mutable TextureBufferObjectList _textureBufferObjects;
};

}

#endif