libosgearth-dev 2.5.0+dfsg-8build1 / usr / include / osgEarth / ImageUtils

/* -*-c++-*- */
/* osgEarth - Dynamic map generation toolkit for OpenSceneGraph
 * Copyright 2008-2013 Pelican Mapping
 * http://osgearth.org
 *
 * osgEarth is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

#ifndef OSGEARTH_IMAGEUTILS_H
#define OSGEARTH_IMAGEUTILS_H

#include <osgEarth/Common>
#include <osg/Image>
#include <osg/GL>

//These formats were not added to OSG until after 2.8.3 so we need to define them to use them.
#ifndef GL_EXT_texture_compression_rgtc
  #define GL_COMPRESSED_RED_RGTC1_EXT                0x8DBB
  #define GL_COMPRESSED_SIGNED_RED_RGTC1_EXT         0x8DBC
  #define GL_COMPRESSED_RED_GREEN_RGTC2_EXT          0x8DBD
  #define GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT   0x8DBE
#endif

#ifndef GL_IMG_texture_compression_pvrtc
    #define GL_COMPRESSED_RGB_PVRTC_4BPPV1_IMG      0x8C00
    #define GL_COMPRESSED_RGB_PVRTC_2BPPV1_IMG      0x8C01
    #define GL_COMPRESSED_RGBA_PVRTC_4BPPV1_IMG     0x8C02
    #define GL_COMPRESSED_RGBA_PVRTC_2BPPV1_IMG     0x8C03
#endif

namespace osgEarth
{
    class OSGEARTH_EXPORT ImageUtils
    {
    public:
        /**
         * Clones an image.
         *
         * Use this instead of the osg::Image copy construtor, which keeps the referenced to
         * its underlying BufferObject around. Calling dirty() on the new clone appears to
         * help, but just call this method instead to be sure.
         */
        static osg::Image* cloneImage( const osg::Image* image );

        /**
         * Tweaks an image for consistency. OpenGL allows enums like "GL_RGBA" et.al. to be
         * used in the internal texture format, when really "GL_RGBA8" is the proper things
         * to use. This method accounts for that. Some parts of osgEarth (like the texture-
         * array compositor) rely on the internal texture format being correct.
         * (http://http.download.nvidia.com/developer/Papers/2005/Fast_Texture_Transfers/Fast_Texture_Transfers.pdf)
         */
        static void normalizeImage( osg::Image* image );

        /**
         * Copys a portion of one image into another.
         */
        static bool copyAsSubImage(
            const osg::Image* src, 
            osg::Image* dst, 
            int dst_start_col, int dst_start_row, int dst_start_img=0 );

        /**
         * Resizes an image using nearest-neighbor resampling. Returns a new image, leaving
         * the input image unaltered.
         *
         * Note. If the output parameter is NULL, this method will allocate a new image and
         * resize into that new image. If the output parameter is non-NULL, this method will
         * assume that the output image is already allocated to the proper size, and will
         * do a resize+copy into that image. In the latter case, it is your responsibility
         * to make sure the output image is allocated to the proper size.
         *
         * If the output parameter is non-NULL, then the mipmapLevel is also considered.
         * This lets you resize directly into a particular mipmap level of the output image.
         */
        static bool resizeImage(
            const osg::Image* input, 
            unsigned int new_s, unsigned int new_t,
            osg::ref_ptr<osg::Image>& output,
            unsigned int mipmapLevel =0 );

        /**
         * Crops the input image to the dimensions provided and returns a
         * new image. Returns a new image, leaving the input image unaltered.
         * Note:  The input destination bounds are modified to reflect the bounds of the
         *        actual output image.  Due to the fact that you cannot crop in the middle of a pixel
         *        The specified destination extents and the output extents may vary slightly.
         *@param src_minx
         *       The minimum x coordinate of the input image.
         *@param src_miny
         *       The minimum y coordinate of the input image.
         *@param src_maxx
         *       The maximum x coordinate of the input image.
         *@param src_maxy
         *       The maximum y coordinate of the input image.
         *@param dst_minx
         *       The desired minimum x coordinate of the cropped image.
         *@param dst_miny
         *       The desired minimum y coordinate of the cropped image.
         *@param dst_maxx
         *       The desired maximum x coordinate of the cropped image.
         *@param dst_maxy
         *       The desired maximum y coordinate of the cropped image.
         */
        static osg::Image* cropImage(
            const osg::Image* image,
            double src_minx, double src_miny, double src_maxx, double src_maxy,
            double &dst_minx, double &dst_miny, double &dst_maxx, double &dst_maxy);

        /**
         * Creates an Image that "blends" two images into a new image in which "primary"
         * occupies mipmap level 0, and "secondary" occupies all the other mipmap levels.
         *
         * WARNING: this method assumes that primary and seconday are the same exact size
         * and the same exact format.
         */
        static osg::Image* createMipmapBlendedImage(
            const osg::Image* primary,
            const osg::Image* secondary );

        /**
         * Blends the "src" image into the "dest" image, based on the "a" value.
         * The two images must be the same.
         */
        static bool mix( osg::Image* dest, const osg::Image* src, float a );

        /**
         * Creates and returns a copy of the input image after applying a
         * sharpening filter. Returns a new image, leaving the input image unaltered.
         */
        static osg::Image* createSharpenedImage( const osg::Image* image );

        /**
         * Gets whether the input image's dimensions are powers of 2.
         */
        static bool isPowerOfTwo(const osg::Image* image);

        /**
         * Gets a transparent, single pixel image used for a placeholder
         */
        static osg::Image* createEmptyImage();

        /**
         * Gets a transparent image used for a placeholder with the specified dimensions
         */
        static osg::Image* createEmptyImage(unsigned int s, unsigned int t);

        /**
         * Creates a one-pixel image.
         */
        static osg::Image* createOnePixelImage(const osg::Vec4& color);

        /**
         * Tests an image to see whether it's "empty", i.e. completely transparent,
         * within an alpha threshold.
         */
        static bool isEmptyImage(const osg::Image* image, float alphaThreshold =0.01);

        /**
         * Tests an image to see whether it's "single color", i.e. completely filled with a single color,
         * within an threshold (threshold is tested on each channel).
         */
        static bool isSingleColorImage(const osg::Image* image, float threshold =0.01);

        /**
         * Returns true if it is possible to convert the image to the specified 
         * format/datatype specification.
         */
        static bool canConvert(const osg::Image* image, GLenum pixelFormat, GLenum dataType);

        /**
         * Converts an image to the specified format.
         */
        static osg::Image* convert(const osg::Image* image, GLenum pixelFormat, GLenum dataType);

        /**
         *Converts the given image to RGB8
         */
        static osg::Image* convertToRGB8(const osg::Image* image);

        /**
         *Converts the given image to RGBA8
         */
        static osg::Image* convertToRGBA8(const osg::Image* image);

        /**
         *Compares the image data of two images and determines if they are equivalent
         */
        static bool areEquivalent(const osg::Image *lhs, const osg::Image *rhs);

        /**
         * Whether two colors are roughly equivalent.
         */
        static bool areRGBEquivalent( const osg::Vec4& lhs, const osg::Vec4& rhs, float epsilon =0.01f ) {
            return
                fabs(lhs.r() - rhs.r()) < epsilon &&
                fabs(lhs.g() - rhs.g()) < epsilon &&
                fabs(lhs.b() - rhs.b()) < epsilon;
        }

        /**
         * Checks whether the image has an alpha component 
         */
        static bool hasAlphaChannel( const osg::Image* image );

        /**
         * Checks whether an image has transparency; i.e. whether
         * there are any pixels with an alpha component whole value
         * falls below the specified threshold.
         */
        static bool hasTransparency(const osg::Image* image, float alphaThreshold =1.0f);

        /**
         * Finds pixels with alpha less than [maxAlpha] and sets their color
         * to match that or neighboring non-alpha pixels. This facilitates multipass
         * blending or abutting tiles by overlapping them slightly. Specify "maxAlpha"
         * as the maximum value to consider when searching for fully-transparent pixels.
         *
         * Returns false if there is no reader or writer for the image's format.
         */
        static bool featherAlphaRegions(osg::Image* image, float maxAlpha =0.0f);

        /**
         * Converts an image (in place) to premultiplied-alpha format.
         * Returns False is the conversion fails, e.g., if there is no reader
         * or writer for the image format.
         */
        static bool convertToPremultipliedAlpha(osg::Image* image);

        /**
         * Checks whether the given image is compressed
         */
        static bool isCompressed( const osg::Image* image );

        /**
         * Generated a bump map image for the input image
         */
        static osg::Image* createBumpMap( const osg::Image* input );

        /**
         * Is it a floating-point texture format?
         */
        static bool isFloatingPointInternalFormat( GLint internalFormat );

        /**
         * Reads color data out of an image, regardles of its internal pixel format.
         */
        class OSGEARTH_EXPORT PixelReader
        {
        public:
            PixelReader(const osg::Image* image);

            /** Whether PixelReader supports a given format/datatype combiniation. */
            static bool supports( GLenum pixelFormat, GLenum dataType );

            /** Whether PixelReader can read from the specified image. */
            static bool supports( const osg::Image* image ) {
                return image && supports(image->getPixelFormat(), image->getDataType() );
            }

            /** Reads a color from the image */
            osg::Vec4 operator()(int s, int t, int r=0, int m=0) const {
                return (*_reader)(this, s, t, r, m);
            }

            // internals:
            const unsigned char* data(int s=0, int t=0, int r=0, int m=0) const {
                return m == 0 ?
                    _image->data() + s*_colMult + t*_rowMult + r*_imageSize :
                    _image->getMipmapData(m) + s*_colMult + t*(_rowMult >> m) + r*(_imageSize>>m) ;
            }

            typedef osg::Vec4 (*ReaderFunc)(const PixelReader* ia, int s, int t, int r, int m);
            ReaderFunc _reader;
            const osg::Image* _image;
            unsigned _colMult;
            unsigned _rowMult;
            unsigned _imageSize;
        };
        
        /**
         * Writes color data to an image, regardles of its internal pixel format.
         */
        class OSGEARTH_EXPORT PixelWriter
        {
        public:
            PixelWriter(osg::Image* image);

            /** Whether PixelWriter can write to an image with the given format/datatype combo. */
            static bool supports( GLenum pixelFormat, GLenum dataType );

            /** Whether PixelWriter can write to non-const version of an image. */
            static bool supports( const osg::Image* image ) {
                return image && supports(image->getPixelFormat(), image->getDataType() );
            }

            /** Writes a color to a pixel. */
            void operator()(const osg::Vec4& c, int s, int t, int r=0, int m=0) {
                (*_writer)(this, c, s, t, r, m );
            }

            // internals:
            osg::Image* _image;
            unsigned _colMult;
            unsigned _rowMult;
            unsigned _imageSize;

            unsigned char* data(int s=0, int t=0, int r=0, int m=0) const {
                return m == 0 ?
                    _image->data() + s*_colMult + t*_rowMult + r*_imageSize :
                    _image->getMipmapData(m) + s*_colMult + t*(_rowMult >> m) + r*(_imageSize>>m);
            }

            typedef void (*WriterFunc)(const PixelWriter* iw, const osg::Vec4& c, int s, int t, int r, int m);
            WriterFunc _writer;
        };

        /**
         * Functor that visits every pixel in an image
         */
        template<typename T>
        struct PixelVisitor : public T
        {
            /**
             * Traverse an image, and call this method on the superclass:
             *
             *   bool operator(osg::Vec4& pixel);
             *
             * If that method returns true, write the value back at the same location.
             */
            void accept( osg::Image* image ) {
                PixelReader _reader( image );
                PixelWriter _writer( image );
                for( int r=0; r<image->r(); ++r ) {
                    for( int t=0; t<image->t(); ++t ) {
                        for( int s=0; s<image->s(); ++s ) {
                            osg::Vec4f pixel = _reader(s,t,r);
                            if ( (*this)(pixel) )
                                _writer(pixel,s,t,r);
                        }
                    }
                }
            }          

            /**
             * Traverse an image, and call this method on the superclass:
             *
             *   bool operator(const osg::Vec4& srcPixel, osg::Vec4& destPixel);
             *
             * If that method returns true, write destPixel back at the same location
             * in the destination image.
             */
            void accept( const osg::Image* src, osg::Image* dest ) {
                PixelReader _readerSrc( src );
                PixelReader _readerDest( dest );
                PixelWriter _writerDest( dest );
                for( int r=0; r<src->r(); ++r ) {
                    for( int t=0; t<src->t(); ++t ) {
                        for( int s=0; s<src->s(); ++s ) {
                            const osg::Vec4f pixelSrc = _readerSrc(s,t,r);
                            osg::Vec4f pixelDest = _readerDest(s,t,r);
                            if ( (*this)(pixelSrc, pixelDest) )
                                _writerDest(pixelDest,s,t,r);
                        }
                    }
                }
            }
        };

        /**
         * Simple functor to copy pixels from one image to another.
         *
         * Usage:
         *    PixelVisitor<CopyImage>().accept( fromImage, toImage );
         */
        struct CopyImage {
            bool operator()( const osg::Vec4f& src, osg::Vec4f& dest ) {
                dest = src;
                return true;
            }
        };
    };
}

#endif //OSGEARTH_IMAGEUTILS_H