sphere.cpp

蒙特卡罗方法可以有效地解决复杂的工程问题

// Sphere.cpp: implementation of the CSphere class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "RayTrace.h"
#include "Sphere.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CSphere::CSphere()
{

}

CSphere::CSphere(CVector center, double radius)
	:
	vecCenter ( center ),
	dRadius ( radius )
{
}

CSphere::~CSphere()
{

}

double CSphere::Intersect()
{
	//求交测试，场景原点O(0,0,0),入射光线HitRay方向向量为单位向量
	CVector temp = vecCenter;
	double dintersect;
	double I_b,I_c,I_disc;
	
	temp -= HitRay->StartPoint;
	I_b = -2.0 * (temp*HitRay->Direction);
	I_c = temp*temp - dRadius*dRadius;
	I_disc = I_b*I_b - 4.0*I_c;

	if( !( I_disc > 0.0 ) )
		dintersect=0.0;
	else
	{
		double I_sqrt,I_t1,I_t2;
		I_sqrt = sqrt(I_disc);
		I_t1 = ( -I_b - I_sqrt ) * 0.5;
		I_t2 = ( -I_b + I_sqrt ) * 0.5;
	
		if(( !( I_t1 > SMALL ) ) && ( !( I_t2 > SMALL ) ))
			dintersect = 0.0;
		else
		{
			if( I_t1 > I_t2 )
			{
				if( I_t2 < SMALL )
				I_t2 = I_t1;
			}
			else
			{
		      if( I_t1 > SMALL )
				I_t2 = I_t1;
			}
			dintersect = I_t2;
		}
	}
	if( dintersect != 0.0 )
	{
		IntersectPoint = HitRay->Direction;
		IntersectPoint *= dintersect;
		IntersectPoint += HitRay->StartPoint;
	}
	return dintersect;
}

CVector CSphere::GetNormalVec()
{
	CVector N = IntersectPoint;
	N -= vecCenter;
	N.Normalize();

	return N;
}

CVector CSphere::Mapping()
{
	double theta,phi;
	double x,y,z;

	x = IntersectPoint.GetX() - vecCenter.GetX();
	y = IntersectPoint.GetY() - vecCenter.GetY();
	z = IntersectPoint.GetZ() - vecCenter.GetZ();

	phi = acos( z / dRadius );
	theta = acos( x / ( dRadius * sin( phi ) ) );

	if( y < 0 )
		theta = 2.0 * PI - theta;

	double u,v;

	u = theta / PI / 2.0;
	v = 1.0 - phi / PI;

	return Texture->GetColor(u,v);
}


void CSphere::Transform(CVector offset, CVector rotate)
{
	vecCenter.Rotate( rotate );
	vecCenter.Translate( offset );
}