/* OpenSceneGraph example, osgtexture3D.
*
*  Permission is hereby granted, free of charge, to any person obtaining a copy
*  of this software and associated documentation files (the "Software"), to deal
*  in the Software without restriction, including without limitation the rights
*  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
*  copies of the Software, and to permit persons to whom the Software is
*  furnished to do so, subject to the following conditions:
*
*  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
*  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
*  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
*  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
*  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
*  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
*  THE SOFTWARE.
*/

#include <osg/Node>
#include <osg/Geometry>
#include <osg/Notify>
#include <osg/Texture3D>
#include <osg/TexGen>
#include <osg/Geode>

#include <osgDB/Registry>
#include <osgDB/ReadFile>

#include <osgViewer/Viewer>

#include <iostream>

//
// A simple demo demonstrating different texturing modes, 
// including using of texture extensions.
//


typedef std::vector< osg::ref_ptr<osg::Image> > ImageList;


class MyGraphicsContext {
    public:
        MyGraphicsContext()
        {
            osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
            traits->x = 0;
            traits->y = 0;
            traits->width = 1;
            traits->height = 1;
            traits->windowDecoration = false;
            traits->doubleBuffer = false;
            traits->sharedContext = 0;
            traits->pbuffer = true;

            _gc = osg::GraphicsContext::createGraphicsContext(traits.get());

            if (!_gc)
            {
                traits->pbuffer = false;
                _gc = osg::GraphicsContext::createGraphicsContext(traits.get());
            }

            if (_gc.valid()) 
            {
                _gc->realize();
                _gc->makeCurrent();
            }
        }
        
        bool valid() const { return _gc.valid() && _gc->isRealized(); }
        
    private:
        osg::ref_ptr<osg::GraphicsContext> _gc;
};


osg::StateSet* createState()
{
    MyGraphicsContext gc;
    if (!gc.valid()) 
    {
        osg::notify(osg::NOTICE)<<"Unable to create the graphics context required to build 3d image."<<std::endl;
        return 0;
    }

    // read 4 2d images
    osg::ref_ptr<osg::Image> image_0 = osgDB::readImageFile("Images/lz.rgb");
    osg::ref_ptr<osg::Image> image_1 = osgDB::readImageFile("Images/reflect.rgb");
    osg::ref_ptr<osg::Image> image_2 = osgDB::readImageFile("Images/tank.rgb");
    osg::ref_ptr<osg::Image> image_3 = osgDB::readImageFile("Images/skymap.jpg");

    if (!image_0 || !image_1 || !image_2 || !image_3)
    {
        std::cout << "Warning: could not open files."<<std::endl;
        return new osg::StateSet;
    }

    if (image_0->getPixelFormat()!=image_1->getPixelFormat() || image_0->getPixelFormat()!=image_2->getPixelFormat() || image_0->getPixelFormat()!=image_3->getPixelFormat())
    {
        std::cout << "Warning: image pixel formats not compatible."<<std::endl;
        return new osg::StateSet;
    }

    // get max 3D texture size
    GLint textureSize = osg::Texture3D::getExtensions(0,true)->maxTexture3DSize();
    if (textureSize > 256)
        textureSize = 256;

    // scale them all to the same size.
    image_0->scaleImage(textureSize,textureSize,1);
    image_1->scaleImage(textureSize,textureSize,1);
    image_2->scaleImage(textureSize,textureSize,1);
    image_3->scaleImage(textureSize,textureSize,1);


    // then allocated a 3d image to use for texturing.
    osg::Image* image_3d = new osg::Image;
    image_3d->allocateImage(textureSize,textureSize,4,
                            image_0->getPixelFormat(),image_0->getDataType());

    // copy the 2d images into the 3d image.
    image_3d->copySubImage(0,0,0,image_0.get());
    image_3d->copySubImage(0,0,1,image_1.get());
    image_3d->copySubImage(0,0,2,image_2.get());
    image_3d->copySubImage(0,0,3,image_3.get());

    image_3d->setInternalTextureFormat(image_0->getInternalTextureFormat());        

    // set up the 3d texture itself,
    // note, well set the filtering up so that mip mapping is disabled,
    // gluBuild3DMipsmaps doesn't do a very good job of handled the
    // inbalanced dimensions of the 256x256x4 texture.
    osg::Texture3D* texture3D = new osg::Texture3D;
    texture3D->setFilter(osg::Texture3D::MIN_FILTER,osg::Texture3D::LINEAR);
    texture3D->setFilter(osg::Texture3D::MAG_FILTER,osg::Texture3D::LINEAR);
    texture3D->setWrap(osg::Texture3D::WRAP_R,osg::Texture3D::REPEAT);
    texture3D->setImage(image_3d);


    // create a texgen to generate a R texture coordinate, the geometry
    // itself will supply the S & T texture coordinates.
    // in the animateStateSet callback well alter this R value to
    // move the texture through the 3d texture, 3d texture filtering
    // will do the blending for us.
    osg::TexGen* texgen = new osg::TexGen;
    texgen->setMode(osg::TexGen::OBJECT_LINEAR);
    texgen->setPlane(osg::TexGen::R, osg::Plane(0.0f,0.0f,0.0f,0.2f));

    // create the StateSet to store the texture data
    osg::StateSet* stateset = new osg::StateSet;
    stateset->setTextureMode(0,GL_TEXTURE_GEN_R,osg::StateAttribute::ON);
    stateset->setTextureAttribute(0,texgen);
    stateset->setTextureAttributeAndModes(0,texture3D,osg::StateAttribute::ON);

    return stateset;
}


class UpdateStateCallback : public osg::NodeCallback
{
    public:
        UpdateStateCallback() {}
        
        void animateState(osg::StateSet* stateset)
        {
            // here we simply get any existing texgen, and then increment its
            // plane, pushing the R coordinate through the texture.
            osg::StateAttribute* attribute = stateset->getTextureAttribute(0,osg::StateAttribute::TEXGEN);
            osg::TexGen* texgen = dynamic_cast<osg::TexGen*>(attribute);
            if (texgen)
            {
                texgen->getPlane(osg::TexGen::R)[3] += 0.001f;
            }

        }

        virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
        { 

            osg::StateSet* stateset = node->getStateSet();
            if (stateset)
            {
                // we have an exisitng stateset, so lets animate it.
                animateState(stateset);
            }

            // note, callback is repsonsible for scenegraph traversal so
            // should always include call the traverse(node,nv) to ensure 
            // that the rest of cullbacks and the scene graph are traversed.
            traverse(node,nv);
        }      
};

/** create 2,2 square with center at 0,0,0 and aligned along the XZ plan */
osg::Drawable* createSquare(float textureCoordMax=1.0f)
{
    // set up the Geometry.
    osg::Geometry* geom = new osg::Geometry;

    osg::Vec3Array* coords = new osg::Vec3Array(4);
    (*coords)[0].set(-1.0f,0.0f,1.0f);
    (*coords)[1].set(-1.0f,0.0f,-1.0f);
    (*coords)[2].set(1.0f,0.0f,-1.0f);
    (*coords)[3].set(1.0f,0.0f,1.0f);
    geom->setVertexArray(coords);

    osg::Vec3Array* norms = new osg::Vec3Array(1);
    (*norms)[0].set(0.0f,-1.0f,0.0f);
    geom->setNormalArray(norms);
    geom->setNormalBinding(osg::Geometry::BIND_OVERALL);

    osg::Vec2Array* tcoords = new osg::Vec2Array(4);
    (*tcoords)[0].set(0.0f,textureCoordMax);
    (*tcoords)[1].set(0.0f,0.0f);
    (*tcoords)[2].set(textureCoordMax,0.0f);
    (*tcoords)[3].set(textureCoordMax,textureCoordMax);
    geom->setTexCoordArray(0,tcoords);
    
    geom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS,0,4));

    return geom;
}

osg::Node* createModel()
{

    // create the geometry of the model, just a simple 2d quad right now.    
    osg::Geode* geode = new osg::Geode;
    geode->addDrawable(createSquare());

    // normally we'd create the stateset's to contain all the textures
    // etc here, but, the above technique uses osg::Image::scaleImage and
    // osg::Image::copySubImage() which are implemented with OpenGL utility
    // library, which unfortunately can't be used until we have a valid
    // OpenGL context, and at this point in initilialization we don't have
    // a valid OpenGL context, so we have to delay creation of state until
    // there is a valid OpenGL context.  I'll manage this by using an
    // app callback which will create the state during the first traversal.
    // A bit hacky, and my plan is to reimplement the osg::scaleImage and
    // osg::Image::copySubImage() without using GLU which will get round
    // this current limitation.
    geode->setUpdateCallback(new UpdateStateCallback());
    geode->setStateSet(createState());
    
    return geode;

}


int main(int , char **)
{
    // construct the viewer.
    osgViewer::Viewer viewer;

    // create a model from the images and pass it to the viewer.
    viewer.setSceneData(createModel());

    return viewer.run();
}
