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#include <math.h>
#include "extensionmanager.h"
#include "geometryextension.h"
#include "maxwell.h"
#include "maxwellversions.h"
#ifndef DEG2RAD
#define DEG2RAD(d) ((d) * 3.14159265358979323846 / 180.0)
#endif

class SphereRenderExtension : public CgeometryProceduralExtension
{
	DECLARE_EXTENSION_METHODS( "SphereRenderExample", SphereRenderExtension, 1 )
	Cmaxwell* pMaxwellLocal;
	double radius;

public:
	SphereRenderExtension()
	{
		getExtensionData()->createDouble( "Radius", 1.00, 0, 1000000 );
	}
	~SphereRenderExtension()
	{
	}

    bool initializeForRendering ( Cmaxwell* pMaxwell )    
    {
        pMaxwellLocal = pMaxwell;
		getExtensionData()->getDouble( "Radius", radius );
        return true;
    }

    //Helper function to spit messages to maxwell.
    void printMessage( const char* text, const int code )
    {
        if( pMaxwellLocal != NULL ) 
        {
            char pMessage[ 1024 ];
            sprintf ( pMessage, "[Extension %s] %s", getName(), text );
            pMaxwellLocal->printMessage( pMessage, code );
        }
    }

    dword getNumSubVolumes( void )
    {
        return 1;//We just have one region surrounding the whole sphere
    };

	bool intersect( Cmaxwell::Cobject* object, const Cpoint& origin, const Cvector& dir, 
			real time, const dword subVolumeIndex, Cvector* pNormal, Cvector* pLocalImpact, 
			CfVector &data, Cvector& parametricUVW, Cvector& tangentU, Cvector& tangentV )
	{
		real dist, a, b, disc, t0, t1, sqr;
		dist = -1.0;
		//Assume sphere centered in ( 0, 0, 0 ) in local coordinates
		a = 2*( dir.x*origin.x + dir.y*origin.y + dir.z*origin.z );
		b = origin.x*origin.x + origin.y*origin.y + origin.z*origin.z - radius*radius;
		disc = a*a - 4*b;
		if ( disc < 0.0 )
		{
			return false;
		}
		sqr = sqrt ( disc );
		t0 = ( -a - sqr ) * 0.5;
		t1 = ( -a + sqr ) * 0.5;
		if ( t0 <= 0.0 )
		{
			if ( t1 > 0.0 )
			{
				dist = t1;
			}
			else
			{
				return false;
			}
		}
		else
		{
			if ( t0 < t1 ) dist = t0;
			else dist = t1;
		}
		Cvector p;
		p.assign( origin + dir * dist );//Point of intersection in local coordinates
		pLocalImpact->assign( p );
		Cvector normal;
		normal.assign( p );
		pNormal->assign( normal );//No need to normalize. Done later on demand.
		return true;
	}
	void getBoundingBox( Cvector& bmin, Cvector& bmax, float time )
	{
		bmin.assign( -radius, -radius, -radius );
		bmax.assign( radius, radius, radius );
	}
};
EXPORT_GEOMETRY_PROCEDURAL_EXTENSION( SphereRenderExtension )

extern "C" ALWAYSEXPORT int getSdkVersion()
{
    return MAXWELL_SDK_VERSION;
}

extern "C" ALWAYSEXPORT int StartExtension( CextensionManager& extensionManager )
{
    int i = 0;
    if ( extensionManager.registerGeometryProceduralExtension( new SphereRenderExtension ) ) i++;
    return i;
}