/*
    WaterSurface class

    An OpenSceneGraph viewer for pyVolution .sww files.
    copyright (C) 2004 Geoscience Australia
*/


#include <watersurface.h>
#include <osg/AlphaFunc>
#include <osg/BlendFunc>
#include <osg/PolygonMode>
#include <osg/ShapeDrawable>
#include <osg/Texture2D>
#include <osg/TexEnv>
#include <osg/TexGen>

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

#include <osgUtil/TriStripVisitor>

#define DEF_ALPHA_THRESHOLD 0.01


// constructor
WaterSurface::WaterSurface(SWWReader* sww)
{
    // persistent
    _sww = sww;
    _node = new osg::Geode;
    _geom = new osg::Geometry;
    _stateset = new osg::StateSet;

    // construct local scenegraph hierarchy
    _node->setName("watersurface");
    _node->addDrawable(_geom);
    _node->setStateSet(_stateset);

    _geom->setUseDisplayList( false );

    // initial geometry
    setTimeStep(0);

    // environment map
    osg::Texture2D* texture = new osg::Texture2D;
    texture->setDataVariance(osg::Object::DYNAMIC);
    texture->setBorderColor(osg::Vec4(1.0f,1.0f,1.0f,0.5f));
    texture->setWrap(osg::Texture::WRAP_S, osg::Texture::REPEAT);
    texture->setImage(osgDB::readImageFile("envmap.jpg"));
    _stateset->setTextureAttributeAndModes( 1, texture, osg::StateAttribute::ON );
    _stateset->setMode( GL_LIGHTING, osg::StateAttribute::ON );

    // surface transparency
    osg::BlendFunc* osgBlendFunc = new osg::BlendFunc();
    osgBlendFunc->setFunction(osg::BlendFunc::SRC_ALPHA, osg::BlendFunc::ONE_MINUS_SRC_ALPHA);
    _stateset->setAttribute(osgBlendFunc);
    _stateset->setMode(GL_BLEND, osg::StateAttribute::ON);
    _stateset->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);

    // discard pixels with an alpha value below threshold
    osg::AlphaFunc* alphaFunc = new osg::AlphaFunc;
    alphaFunc->setFunction( osg::AlphaFunc::GREATER, DEF_ALPHA_THRESHOLD );
    _stateset->setAttributeAndModes( alphaFunc, osg::StateAttribute::ON );

    // automatically generate texture coords
    osg::TexGen* texgen = new osg::TexGen;
    texgen->setMode( osg::TexGen::SPHERE_MAP );

    osg::TexEnv* texenv = new osg::TexEnv;
    texenv->setMode( osg::TexEnv::DECAL );
    texenv->setColor( osg::Vec4(0.6f,0.6f,0.6f,0.2f) );
    _stateset->setTextureAttributeAndModes( 1, texgen, osg::StateAttribute::ON );
    _stateset->setTextureAttribute( 1, texenv );
}



WaterSurface::~WaterSurface()
{
}



void WaterSurface::setTimeStep(unsigned int ts)
{
    // delete if exists
    if( _geom->getNumPrimitiveSets() )
      _geom->removePrimitiveSet(0);  // reference counting does actual delete

    // local reference to raw height field data
    osg::ref_ptr<osg::Vec3Array> vertices = _sww->getStageVertexArray(ts);
    osg::ref_ptr<osg::Vec3Array> vertexnormals = _sww->getStageVertexNormalArray();
    osg::ref_ptr<osg::Vec4Array> colors = _sww->getStageColorArray();

    // geometry
    _geom->setVertexArray( vertices.get() );
    _geom->addPrimitiveSet( _sww->getBedslopeIndexArray().get() );

    // per vertex colors (we only modulate the alpha for transparency)
    _geom->setColorArray( colors.get() );
    _geom->setColorBinding(osg::Geometry::BIND_PER_VERTEX);

    // normals
    _geom->setNormalArray( vertexnormals.get() );
    _geom->setNormalBinding(osg::Geometry::BIND_PER_VERTEX);

    // osgUtil::TriStripVisitor* optimize = new osgUtil::TriStripVisitor();
    // optimize->stripify( *_geom );

}


void WaterSurface::toggleWireframe()
{
    osg::PolygonMode* polyModeObj = 
        dynamic_cast<osg::PolygonMode*>(_stateset->getAttribute(osg::StateAttribute::POLYGONMODE));

    if (!polyModeObj) 
    {
	    polyModeObj = new osg::PolygonMode;
	    _stateset->setAttribute(polyModeObj);
    }

    switch( polyModeObj->getMode(osg::PolygonMode::FRONT_AND_BACK) )
    {
    
      case osg::PolygonMode::FILL : polyModeObj->setMode(osg::PolygonMode::FRONT_AND_BACK,
							 osg::PolygonMode::LINE); break;
      case osg::PolygonMode::LINE : polyModeObj->setMode(osg::PolygonMode::FRONT_AND_BACK,
							 osg::PolygonMode::FILL); break;
      case osg::PolygonMode::POINT : break;
    }
}