CubeMapGenerator

/* -*-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 OSGUTIL_CUBEMAPGENERATOR_
#define OSGUTIL_CUBEMAPGENERATOR_

#include <osgUtil/Export>

#include <osg/Vec3>
#include <osg/Vec4>
#include <osg/CopyOp>
#include <osg/Referenced>
#include <osg/TextureCubeMap>
#include <osg/Image>
#include <osg/Notify>

#include <vector>

namespace osgUtil
{

    /** This is the base class for cube map generators. 
        It exposes the necessary interface to access the six generated images;
        descendants should only override the compute_color() method.
    */
    class OSGUTIL_EXPORT CubeMapGenerator: public osg::Referenced {
    public:
        explicit CubeMapGenerator(int texture_size = 64);
        CubeMapGenerator(const CubeMapGenerator &copy, const osg::CopyOp &copyop = osg::CopyOp::SHALLOW_COPY);

        inline osg::Image *getImage(osg::TextureCubeMap::Face face);
        inline const osg::Image *getImage(osg::TextureCubeMap::Face face) const;

        /** Generate the six cube images. 
            If use_osg_system is true, then the OSG's coordinate system is used instead 
            of the default OpenGL one.
        */
        void generateMap(bool use_osg_system = true);

    protected:
        virtual ~CubeMapGenerator() {}
        CubeMapGenerator &operator=(const CubeMapGenerator &) { return *this; }

        inline void set_pixel(int index, int c, int r, const osg::Vec4 &color);
        inline static osg::Vec4 vector_to_color(const osg::Vec3 &vec);        

        /** Override this method to define how colors are computed. 
            The parameter R is the reflection vector, pointing from the center of the cube.
            The return value should be the RGBA color associated with that reflection ray.
        */
        virtual osg::Vec4 compute_color(const osg::Vec3 &R) const = 0;

    private:
        int texture_size_;

        typedef std::vector<osg::ref_ptr<osg::Image> > Image_list;
        Image_list images_;        
    };

    // INLINE METHODS

    inline osg::Image *CubeMapGenerator::getImage(osg::TextureCubeMap::Face face)
    {
        switch (face) {
            case osg::TextureCubeMap::POSITIVE_X: return images_[0].get();
            case osg::TextureCubeMap::NEGATIVE_X: return images_[1].get();
            case osg::TextureCubeMap::POSITIVE_Y: return images_[2].get();
            case osg::TextureCubeMap::NEGATIVE_Y: return images_[3].get();
            case osg::TextureCubeMap::POSITIVE_Z: return images_[4].get();
            case osg::TextureCubeMap::NEGATIVE_Z: return images_[5].get();            
            default: return 0;
        }
    }

    inline const osg::Image *CubeMapGenerator::getImage(osg::TextureCubeMap::Face face) const
    {
        switch (face) {
            case osg::TextureCubeMap::POSITIVE_X: return images_[0].get();
            case osg::TextureCubeMap::NEGATIVE_X: return images_[1].get();
            case osg::TextureCubeMap::POSITIVE_Y: return images_[2].get();
            case osg::TextureCubeMap::NEGATIVE_Y: return images_[3].get();
            case osg::TextureCubeMap::POSITIVE_Z: return images_[4].get();
            case osg::TextureCubeMap::NEGATIVE_Z: return images_[5].get();            
            default: return 0;
        }
    }

    inline void CubeMapGenerator::set_pixel(int index, int c, int r, const osg::Vec4 &color)
    {
        osg::Image *i = images_[index].get();
        if (i) {
            *(i->data(c, r)+0) = static_cast<unsigned char>(osg::clampBetween(color.x(),0.0f,1.0f) * 255);
            *(i->data(c, r)+1) = static_cast<unsigned char>(osg::clampBetween(color.y(),0.0f,1.0f) * 255);
            *(i->data(c, r)+2) = static_cast<unsigned char>(osg::clampBetween(color.z(),0.0f,1.0f) * 255);
            *(i->data(c, r)+3) = static_cast<unsigned char>(osg::clampBetween(color.w(),0.0f,1.0f) * 255);            
        } else {
            osg::notify(osg::WARN) << "Warning: CubeMapGenerator::set_pixel(): invalid image index\n";
        }
    }

    inline osg::Vec4 CubeMapGenerator::vector_to_color(const osg::Vec3 &vec)
    {
        return osg::Vec4(
            vec.x() / vec.length() / 2 + 0.5f,
            vec.y() / vec.length() / 2 + 0.5f,
            vec.z() / vec.length() / 2 + 0.5f,
            1);
    }

}

#endif