///////////////////////////////////////////////////////////////////////////////
//
// Name:		Bound.cpp
// Author:		Rich Cross
// Contact:		rich@wildfiregames.com
//
///////////////////////////////////////////////////////////////////////////////

#include "precompiled.h"

// necessary includes
#include <assert.h>
#include <float.h>
#include "Bound.h"

///////////////////////////////////////////////////////////////////////////////
// operator+=: extend this bound to include given bound
CBound& CBound::operator+=(const CBound& b)
{
#define CMPT(c) if (b[0].c < m_Data[0].c) m_Data[0].c = b[0].c; \
           else if (b[1].c > m_Data[1].c) m_Data[1].c = b[1].c
	CMPT(X);
	CMPT(Y);
	CMPT(Z);
#undef CMPT

	return *this;
}

///////////////////////////////////////////////////////////////////////////////
// operator+=: extend this bound to include given point
CBound& CBound::operator+=(const CVector3D& pt)
{
#define CMPT(c) if (pt.c < m_Data[0].c) m_Data[0].c = pt.c; \
           else if (pt.c > m_Data[1].c) m_Data[1].c = pt.c
	CMPT(X);
	CMPT(Y);
	CMPT(Z);
#undef CMPT

	return *this;
}

///////////////////////////////////////////////////////////////////////////////
// RayIntersect: intersect ray with this bound; return true
// if ray hits (and store entry and exit times), or false
// otherwise
// note: incoming ray direction must be normalised
bool CBound::RayIntersect(const CVector3D& origin,const CVector3D& dir,
            float& tmin,float& tmax) const
{
	float t1,t2;
    float tnear,tfar;

    if (dir[0]==0) {
        if (origin[0]<m_Data[0][0] || origin[0]>m_Data[1][0])
	        return false;
        else {
            tnear=(float) FLT_MIN;
            tfar=(float) FLT_MAX;
        }
    } else {
        t1=(m_Data[0][0]-origin[0])/dir[0];
        t2=(m_Data[1][0]-origin[0])/dir[0];

        if (dir[0]<0) {
       	    tnear = t2;
            tfar = t1;
        } else {
	    	tnear = t1;
		    tfar = t2;
        }
        
        if (tfar<0) 
		    return false;
    } 

    if (dir[1]==0 && (origin[1]<m_Data[0][1] || origin[1]>m_Data[1][1])) 
		return false;
    else {
		t1=(m_Data[0][1]-origin[1])/dir[1];
        t2=(m_Data[1][1]-origin[1])/dir[1];
        
		if (dir[1]<0) { 
            if (t2>tnear) 
			    tnear = t2;
            if (t1<tfar) 
			    tfar = t1;
        } else {
            if (t1>tnear) 
		    	tnear = t1;
            if (t2<tfar) 
			    tfar = t2;
        }

        if (tnear>tfar || tfar<0) 
			return false;
    }

    if (dir[2]==0 && (origin[2]<m_Data[0][2] || origin[2]>m_Data[1][2])) 
    	return false;
    else {
        t1=(m_Data[0][2]-origin[2])/dir[2];
        t2=(m_Data[1][2]-origin[2])/dir[2];
        
		if (dir[2]<0) { 
            if (t2>tnear) 
			    tnear = t2;
            if (t1<tfar) 
			    tfar = t1;
        } else {
            if (t1>tnear) 
		    	tnear = t1;
            if (t2<tfar) 
			    tfar = t2;
        }

        if (tnear>tfar || tfar<0) 
		  return false;
    }

    tmin=tnear;
    tmax=tfar;

    return true;
}

///////////////////////////////////////////////////////////////////////////////
// SetEmpty: initialise this bound as empty
void CBound::SetEmpty()
{
	m_Data[0]=CVector3D(FLT_MAX,FLT_MAX,FLT_MAX);
	m_Data[1]=CVector3D(FLT_MIN,FLT_MIN,FLT_MIN);
}

///////////////////////////////////////////////////////////////////////////////
// Transform: transform this bound by given matrix; return transformed bound
// in 'result' parameter - slightly modified version of code in Graphic Gems
// (can't remember which one it was, though)
void CBound::Transform(const CMatrix3D& m,CBound& result) const
{
	assert(this!=&result);

    for (int i=0;i<3;++i) {
        // handle translation 
        result[0][i]=result[1][i]=m(i,3);
		
        // Now find the extreme points by considering the product of the 
        // min and max with each component of matrix  
        for(int j=0;j<3;j++) {
            float a=m(j,i)*m_Data[0][j];
            float b=m(j,i)*m_Data[1][j];

            if (a<b) {
                result[0][i]+=a;
                result[1][i]+=b;
            } else {
                result[0][i]+=b;
                result[1][i]+=a;
            }
        }
    }
}