// SimplerConvexUmbrellaSdfAlgo.h: interface for the SimplerConvexUmbrellaSdfAlgo class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_SIMPLERCONVEXUMBRELLASDFALGO_H__C48F190F_B16C_461B_9AAB_1872F1E833D1__INCLUDED_)
#define AFX_SIMPLERCONVEXUMBRELLASDFALGO_H__C48F190F_B16C_461B_9AAB_1872F1E833D1__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include "ConvexUmbrellaTriMeshSdfAlgorithm.h"

namespace SDF {

	//--------------------------------
	// 2005-12-06 UPDATE - Actually..this is unsound.  Consider the juice squeezer shape..
	//	none of its faces would lie on the convex hull..
	//
	// (Steve)
	//	This is a simpler variation of the convex umbrella algorithm.
	//	Instead of projecting umbrella edges onto p_perp, we simply
	//	look for a triangle that must be on the convex umbrella.
	//
	//	We do this by going through every triangle, and calculating other triangles'
	//	relative positions to it.  There are three possible relative positions:
	//		COPLANAR - the two triangles are co-planar
	//		B_BEHIND_A - tri B is behind A - meaning its centroid is behind A's face plane
	//		B_INFRONT_A - ditto.
	//	For any triangle A, if there exists two triangles B1 B2 such that B1 is behind
	//	and B2 is in front, then A must NOT be a face on the convex umbrella.
	//	But if B1 and B2 do not exist, then all other triangles B are either coplanar,
	//	or ALL have relative position p - where p is either BEHIND or INFRONT.
	//	If p is BEHIND, we classify the point as outside.
	//	If p is INFRONT, we classify the point as inside.
	//
	//--------------------------------
	class SimplerConvexUmbrellaSdfAlgo : public ConvexUmbrellaTriMeshSdfAlgorithm  
	{

	protected:
		enum RelativePosition {COPLANAR, B_BEHIND_A, B_INFRONT_A, RELPOS_DONT_KNOW};

		//--------------------------------
		// This assumes a and b share at least one vertex - ie. they're both part
		// of an umbrella.  We do NOT assume they share an edge.
		// NOTE: This function is NOT commutative, ie. rel_pos(a,b) != rel_pos(b,a)
		//--------------------------------
		RelativePosition calc_relative_position_of_umbrella_tris(
			const MeshTriangle &a,
			const MeshTriangle &b )
		{
			RelativePosition out = RELPOS_DONT_KNOW;
			if( a.norm == b.norm ) {
				out = COPLANAR;
			}
			else if(b.is_behind(a)) {
				out = B_BEHIND_A;
			}
			else {
				// B must be in front.
				out = B_INFRONT_A;
			}
			return out;
		}

	public:
		SimplerConvexUmbrellaSdfAlgo();
		virtual ~SimplerConvexUmbrellaSdfAlgo();

		PointClass classify_pt_by_umbrella_tris( const TriangleList &tris, const Point &x, const Point &p);	

	};

}

#endif // !defined(AFX_SIMPLERCONVEXUMBRELLASDFALGO_H__C48F190F_B16C_461B_9AAB_1872F1E833D1__INCLUDED_)