// NeL - MMORPG Framework <http://dev.ryzom.com/projects/nel/>
// Copyright (C) 2010  Winch Gate Property Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program 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
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#include "stdmisc.h"

#include "nel/misc/plane.h"
#include "nel/misc/uv.h"


namespace	NLMISC
{


//============================================================
void	CPlane::make(const CVector &normal, const CVector &p)
{
	CVector	v= normal.normed();
	a= v.x;
	b= v.y;
	c= v.z;
	d=-(v*p);		// d=- (ax+by+cz).
}
void	CPlane::make(const CVector &p0, const CVector &p1, const CVector &p2)
{
	CVector v;

	v=(p1-p0)^(p2-p1);
	make(v,p1);
}


//============================================================
bool	CPlane::clipSegmentBack(CVector &p0, CVector &p1) const
{
	float	d0,d1,decal;
	CVector	proj;

	d0= (*this)*p0;
	d1= (*this)*p1;
	if(d0<0 && d1<0)
		return true;
	if(d0>=0 && d1>=0)
		return false;
	// Clip line.
	decal= (0-d0) / (d1-d0);
	proj= p0+ (p1-p0)*decal;
	if(d0>=0)
		p0=proj;
	else
		p1=proj;
	return true;
}
bool	CPlane::clipSegmentFront(CVector &p0, CVector &p1) const
{
	float	d0,d1,decal;
	CVector	proj;

	d0= (*this)*p0;
	d1= (*this)*p1;
	if(d0>=0 && d1>=0)
		return true;
	if(d0<0 && d1<0)
		return false;
	// Clip line.
	decal= (0-d0) / (d1-d0);
	proj= p0+ (p1-p0)*decal;
	if(d0<0)
		p0=proj;
	else
		p1=proj;
	return true;
}

//============================================================
sint	CPlane::clipPolygonBack(CVector in[], CVector out[], sint nIn) const
{
	sint nOut=0,s,p,i;
	if(nIn<=2) return 0;

	s=nIn-1;

	for (i=0;i<nIn;i++)
	{
		p=i;
		if ( (*this)*in[p] < 0 )
		{
			if ( (*this)*in[s] >= 0 )
				out[nOut++]= intersect(in[s],in[p]);
			out[nOut++]=in[p];
		}
		else
		{
			if ( (*this)*in[s] < 0 )
				out[nOut++]= intersect(in[s],in[p]);
		}
		s=p;
	}

	return nOut;
}

//============================================================
sint CPlane::clipPolygonBack(const CVector in[], const CUV inUV[], CVector out[], CUV outUV[], sint nIn) const
{
	sint nOut=0,s,p,i;
	if(nIn<=2) return 0;

	s=nIn-1;

	for (i=0;i<nIn;i++)
	{
		p=i;
		float dp3Curr = (*this)*in[p];
		float dp3Prev = (*this)*in[s];
		if ( dp3Curr < 0 )
		{
			if (dp3Prev >= 0 )
			{
				float lambda = favoid0((float) ((double) dp3Prev / ((double) dp3Prev - (double) dp3Curr)));
				out[nOut] = blend(in[s], in[p], lambda);
				outUV[nOut++] = blend(inUV[s], inUV[p], lambda);
			}
			out[nOut]=in[p];
			outUV[nOut++]=inUV[p];
		}
		else
		{
			if (dp3Prev < 0 )
			{
				float lambda = favoid0((float) ((double) dp3Prev / ((double) dp3Prev - (double) dp3Curr)));
				out[nOut] = blend(in[s], in[p], lambda);
				outUV[nOut++] = blend(inUV[s], inUV[p], lambda);
			}
		}
		s=p;
	}

	return nOut;
}

//============================================================
sint	CPlane::clipPolygonFront(CVector in[], CVector out[], sint nIn) const
{
	sint nOut=0,s,p,i;
	if(nIn<=2) return 0;

	s=nIn-1;

	for (i=0;i<nIn;i++)
	{
		p=i;
		if ( (*this)*in[p] > 0 )
		{
			if ( (*this)*in[s] <= 0 )
				out[nOut++]= intersect(in[s],in[p]);
			out[nOut++]=in[p];
		}
		else
		{
			if ( (*this)*in[s] > 0 )
				out[nOut++]= intersect(in[s],in[p]);
		}
		s=p;
	}

	return nOut;
}


//============================================================
CPlane  CPlane::inverted() const
{
	return CPlane(-a, -b, -c, -d);
}

//============================================================
void	CPlane::invert()
{
	a = -a;
	b = -b;
	c = -c;
	d = -d;
}




}