#include "Polygon3.h"
#include "Mesh.h"

Polygon3::Polygon3()
{}

Polygon3::Polygon3(const VertexContainer &vertices): mVertices(vertices) 
{}

Polygon3::Polygon3(Face *face, Mesh *parent)
{
	VertexIndexContainer::const_iterator it;

	for (it = face->mVertexIndices.begin(); it != face->mVertexIndices.end(); ++ it)
	{
		mVertices.push_back(parent->mVertices[*it]);
	}
}

Plane3 Polygon3::GetSupportingPlane()
{
	return Plane3(mVertices[0], mVertices[1], mVertices[2]);
}

void Polygon3::DeletePolygons(PolygonQueue *polys)
{
	// don't need to store polygon information = delete polygons
	while(!polys->empty())
	{
		Polygon3 *poly = polys->front();
		polys->pop();
		DEL_PTR(poly);
	}
}

void Polygon3::Split(Plane3 *partition, Polygon3 *front, Polygon3 *back, int &splits)
{
	splits = 0;
	Vector3 ptA = mVertices[mVertices.size() - 1];;
	
	int sideA = partition->Side(ptA);
	
	VertexContainer::const_iterator it;

	// find line - plane intersections
	for (it = mVertices.begin(); it != mVertices.end(); ++ it)
	{
		Vector3 ptB = (*it);
		int sideB = partition->Side(ptB);

		// vertices on different sides => split
		if ((sideA != 0) && (sideB != 0) && (sideA != sideB)) 
		{
			Vector3 v = ptB - ptA; // line from A to B
			float dv = DotProd(partition->mNormal, v);
			float t = 0;
			
			if (dv)
			{
				t = - partition->Distance(ptA) / dv;
			}

			++ splits;
		}
		if (sideB >= 0)
		{
			back->mVertices.push_back(ptB);
		}
		else if (sideB <= 0)
		{
			front->mVertices.push_back(ptB);
		}

		ptA = ptB;
		sideA = sideB;
	}
}

int Polygon3::Side(Plane3 *plane)
{
	VertexContainer::const_iterator it;

	bool onFrontSide = false;
	bool onBackSide = false;

	// find line - plane intersections
	for (it = mVertices.begin(); it != mVertices.end(); ++ it)
	{
		int side = plane->Side(*it);
		
		if (side > 0)
		{
			onFrontSide = true;
		}
		else if (side < 0)
		{
			onBackSide = true;
		}

		if (onFrontSide && onBackSide) // split
		{
			return SPLIT;
		}
	}

	if (onBackSide)
	{
		return BACK_SIDE;
	}
	else if (onFrontSide)
	{
		return FRONT_SIDE;
	}

	return COINCIDENT;
}