A Matrix-Based 2-D Polygon Clipping Class

// PolygonClip.h: interface for the CPolygonClip class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_POLYGONCLIP_H__3410F6D8_11EC_11D7_8CED_00C0F0172654__INCLUDED_)
#define AFX_POLYGONCLIP_H__3410F6D8_11EC_11D7_8CED_00C0F0172654__INCLUDED_

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

#define MAX_NUM_VERTICIES 100	// Maximum number of verticies allowed
#define MaxDetChanges 50        // Max number of determinant changes per line
#define DotSize 3				// Size of the intersection dot
#define PenSize 1				// Size of the pen
		
class CPolygonClip : public CObject  
{
public:
	void Draw(CDC* pDC);
	unsigned int FindArrayMax(unsigned int* pNumChanges);
	bool CalculateIntersections(double* LineX1, double* LineX2, 
								double* LineY1, double* LineY2, 
								double* PolyVertexX, double* PolyVertexY, 
								unsigned int nMaxNumSignChanges);
	unsigned int* CalcSiDeterm(double* LineX1, double* LineY1, 
						   	   double* LineX2, double* LineY2, 
							   double* PolyVertexX, double* PolyVertexY);
	CPolygonClip(unsigned int nNumVerticies, unsigned int nNumLines);
	virtual ~CPolygonClip();

protected:
	double** m_ppdTempIntrY;						// Temp arrays for sorting
	double** m_ppdTempIntrX;
	bool** m_ppbSignChangeTable;					// The sign change table
	unsigned int* m_pnNumSignChanges;				// Number of determinant sign changes per line
	unsigned int* m_pnIntersectsPerLine;			// The number of intersections for a given line
	unsigned int* m_pnUniquesPerLine;				// Holds the number of unique intersections per line
	int** m_ppnDetSignTable;						// Determinant sign table
	double** m_ppdIntersectionY;					// Polygon and line intersection point y coordinates
	double** m_ppdIntersectionX;					// Polygon and line intersection point x coordinates
	
	CPolygonClip(){};								// Default constructor - do not use

private:
	bool CheckValidPoint(CPoint* lpVertexPoints, int nCount, CPoint aPoint);
	bool m_bIntersectionFlag;
	bool m_bDetermCalcFlag;
	double TurboDeterm(double Elem11, double Elem12, double Elem13,
					   double Elem21, double Elem22, double Elem23);
	unsigned int m_nNumVerticies;			// Number of polygon verticies
	unsigned int m_nNumLines;				// Number of lines

	// Temp arrays to hold spanning verticies 
	double dTempVertex[MAX_NUM_VERTICIES][MAX_NUM_VERTICIES];
	double dTempVertexPrior[MAX_NUM_VERTICIES][MAX_NUM_VERTICIES];
	double dVertex[MAX_NUM_VERTICIES][MAX_NUM_VERTICIES];
	double dVertexPrior[MAX_NUM_VERTICIES][MAX_NUM_VERTICIES];
};

#endif // !defined(AFX_POLYGONCLIP_H__3410F6D8_11EC_11D7_8CED_00C0F0172654__INCLUDED_)