/* -*-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.
*/
#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>(color.x() * 255);
			*(i->data(c, r)+1) = static_cast<unsigned char>(color.y() * 255);
			*(i->data(c, r)+2) = static_cast<unsigned char>(color.z() * 255);
			*(i->data(c, r)+3) = static_cast<unsigned char>(color.w() * 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
