/* -*-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.
*/

#include <osgShadow/ShadowTexture>
#include <osgShadow/ShadowedScene>
#include <osg/Notify>
#include <osg/ComputeBoundsVisitor>
#include <osg/io_utils>

using namespace osgShadow;

ShadowTexture::ShadowTexture():
    _textureUnit(1)
{
}

ShadowTexture::ShadowTexture(const ShadowTexture& copy, const osg::CopyOp& copyop):
    ShadowTechnique(copy,copyop),
    _textureUnit(copy._textureUnit)
{
}

void ShadowTexture::setTextureUnit(unsigned int unit)
{
    _textureUnit = unit;
}

void ShadowTexture::init()
{
    if (!_shadowedScene) return;

    unsigned int tex_width = 512;
    unsigned int tex_height = 512;
    
    _texture = new osg::Texture2D;
    _texture->setTextureSize(tex_width, tex_height);
    _texture->setInternalFormat(GL_RGB);
    _texture->setFilter(osg::Texture2D::MIN_FILTER,osg::Texture2D::LINEAR);
    _texture->setFilter(osg::Texture2D::MAG_FILTER,osg::Texture2D::LINEAR);
    _texture->setWrap(osg::Texture2D::WRAP_S,osg::Texture2D::CLAMP_TO_BORDER);
    _texture->setWrap(osg::Texture2D::WRAP_T,osg::Texture2D::CLAMP_TO_BORDER);
    _texture->setBorderColor(osg::Vec4(1.0f,1.0f,1.0f,1.0f));

    // set up the render to texture camera.
    {
        // create the camera
        _camera = new osg::Camera;

        _camera->setClearColor(osg::Vec4(1.0f,1.0f,1.0f,1.0f));
        
        _camera->setCullCallback(new CameraCullCallback(this));

        // set viewport
        _camera->setViewport(0,0,tex_width,tex_height);

        // set the camera to render before the main camera.
        _camera->setRenderOrder(osg::Camera::PRE_RENDER);

        // tell the camera to use OpenGL frame buffer object where supported.
        _camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
        //_camera->setRenderTargetImplementation(osg::Camera::SEPERATE_WINDOW);

        // attach the texture and use it as the color buffer.
        _camera->attach(osg::Camera::COLOR_BUFFER, _texture.get());

        _material = new osg::Material;
        _material->setAmbient(osg::Material::FRONT_AND_BACK,osg::Vec4(0.0f,0.0f,0.0f,1.0f));
        _material->setDiffuse(osg::Material::FRONT_AND_BACK,osg::Vec4(0.0f,0.0f,0.0f,1.0f));
        _material->setEmission(osg::Material::FRONT_AND_BACK,osg::Vec4(0.0f,0.0f,0.0f,1.0f));
        _material->setShininess(osg::Material::FRONT_AND_BACK,0.0f);

        osg::StateSet* stateset = _camera->getOrCreateStateSet();
        stateset->setAttribute(_material.get(),osg::StateAttribute::OVERRIDE);
        
    }
    
    {
        _stateset = new osg::StateSet;        
        _stateset->setTextureAttributeAndModes(_textureUnit,_texture.get(),osg::StateAttribute::ON);
        _stateset->setTextureMode(_textureUnit,GL_TEXTURE_GEN_S,osg::StateAttribute::ON);
        _stateset->setTextureMode(_textureUnit,GL_TEXTURE_GEN_T,osg::StateAttribute::ON);
        _stateset->setTextureMode(_textureUnit,GL_TEXTURE_GEN_R,osg::StateAttribute::ON);
        _stateset->setTextureMode(_textureUnit,GL_TEXTURE_GEN_Q,osg::StateAttribute::ON);
        
        _texgen = new osg::TexGen;
    }
    
    _dirty = false;
}


void ShadowTexture::update(osg::NodeVisitor& nv)
{
    _shadowedScene->osg::Group::traverse(nv);
}

void ShadowTexture::cull(osgUtil::CullVisitor& cv)
{
    // record the traversal mask on entry so we can reapply it later.
    unsigned int traversalMask = cv.getTraversalMask();

    osgUtil::RenderStage* orig_rs = cv.getRenderStage();

    // do traversal of shadow casting scene which does not need to be decorated by the shadow texture
    {
        cv.setTraversalMask( traversalMask & 
                             getShadowedScene()->getCastsShadowTraversalMask() );

        _shadowedScene->osg::Group::traverse(cv);
    }

    // do traversal of shadow receiving scene which does need to be decorated by the shadow texture
    {
        cv.pushStateSet(_stateset.get());
    
        cv.setTraversalMask( traversalMask & 
                             getShadowedScene()->getReceivesShadowTraversalMask() );

        _shadowedScene->osg::Group::traverse(cv);
        
        cv.popStateSet();

    }
    
    // need to compute view frustum for RTT camera.
    // 1) get the light position
    // 2) get the center and extents of the view frustum

    const osg::Light* selectLight = 0;
    osg::Vec4 lightpos;

    osgUtil::PositionalStateContainer::AttrMatrixList& aml = orig_rs->getPositionalStateContainer()->getAttrMatrixList();
    for(osgUtil::PositionalStateContainer::AttrMatrixList::iterator itr = aml.begin();
        itr != aml.end();
        ++itr)
    {
        const osg::Light* light = dynamic_cast<const osg::Light*>(itr->first.get());
        if (light)
        {
            osg::RefMatrix* matrix = itr->second.get();
            if (matrix) lightpos = light->getPosition() * (*matrix);
            else lightpos = light->getPosition();

            selectLight = light;
        }
    }
    
    osg::Matrix eyeToWorld;
    eyeToWorld.invert(*cv.getModelViewMatrix());
    
    lightpos = lightpos * eyeToWorld;

    if (selectLight)
    {

        // get the bounds of the model.    
        osg::ComputeBoundsVisitor cbbv(osg::NodeVisitor::TRAVERSE_ACTIVE_CHILDREN);
        cbbv.setTraversalMask(getShadowedScene()->getCastsShadowTraversalMask());
        
        _shadowedScene->osg::Group::traverse(cbbv);
        
        osg::BoundingBox bb = cbbv.getBoundingBox();
        
        if (lightpos[3]!=0.0)
        {
            osg::Vec3 position(lightpos.x(), lightpos.y(), lightpos.z());

            float centerDistance = (position-bb.center()).length();

            float znear = centerDistance-bb.radius();
            float zfar  = centerDistance+bb.radius();
            float zNearRatio = 0.001f;
            if (znear<zfar*zNearRatio) znear = zfar*zNearRatio;

            float top   = (bb.radius()/centerDistance)*znear;
            float right = top;

            _camera->setReferenceFrame(osg::Camera::ABSOLUTE_RF);
            _camera->setProjectionMatrixAsFrustum(-right,right,-top,top,znear,zfar);
            _camera->setViewMatrixAsLookAt(position,bb.center(),computeOrthogonalVector(bb.center()-position));
            

            // compute the matrix which takes a vertex from local coords into tex coords
            // will use this later to specify osg::TexGen..
            osg::Matrix MVPT = _camera->getViewMatrix() * 
                               _camera->getProjectionMatrix() *
                               osg::Matrix::translate(1.0,1.0,1.0) *
                               osg::Matrix::scale(0.5f,0.5f,0.5f);
                               
            _texgen->setMode(osg::TexGen::EYE_LINEAR);
            _texgen->setPlanesFromMatrix(MVPT);
        }
        else
        {
            // make an orthographic projection
            osg::Vec3 lightDir(lightpos.x(), lightpos.y(), lightpos.z());
            lightDir.normalize();

            // set the position far away along the light direction
            osg::Vec3 position = bb.center() + lightDir * bb.radius() * 2.0;

            float centerDistance = (position-bb.center()).length();

            float znear = centerDistance-bb.radius();
            float zfar  = centerDistance+bb.radius();
            float zNearRatio = 0.001f;
            if (znear<zfar*zNearRatio) znear = zfar*zNearRatio;

            float top   = bb.radius();
            float right = top;

            _camera->setReferenceFrame(osg::Camera::ABSOLUTE_RF);
            _camera->setProjectionMatrixAsOrtho(-right, right, -top, top, znear, zfar);
            _camera->setViewMatrixAsLookAt(position,bb.center(),computeOrthogonalVector(lightDir));
            

            // compute the matrix which takes a vertex from local coords into tex coords
            // will use this later to specify osg::TexGen..
            osg::Matrix MVPT = _camera->getViewMatrix() * 
                               _camera->getProjectionMatrix() *
                               osg::Matrix::translate(1.0,1.0,1.0) *
                               osg::Matrix::scale(0.5f,0.5f,0.5f);
                               
            _texgen->setMode(osg::TexGen::EYE_LINEAR);
            _texgen->setPlanesFromMatrix(MVPT);
        }


        cv.setTraversalMask( traversalMask & 
                             getShadowedScene()->getCastsShadowTraversalMask() );

        // do RTT camera traversal
        _camera->accept(cv);

        orig_rs->getPositionalStateContainer()->addPositionedTextureAttribute(_textureUnit, cv.getModelViewMatrix(), _texgen.get());
    }
    
    
    


    // reapply the original traversal mask
    cv.setTraversalMask( traversalMask );
}

void ShadowTexture::cleanSceneGraph()
{
}
