int ClipLine(int &x1, int &y1, int &x2, int &y2)
{

#define CLIP_CODE_C	0x0000

#define CLIP_CODE_N	0x0008

#define CLIP_CODE_S	0x0004

#define CLIP_CODE_E	0x0002

#define CLIP_CODE_W	0x0001

#define CLIP_CODE_NE	0x000a

#define CLIP_CODE_SE	0x0006

#define CLIP_CODE_NW	0x0009

#define CLIP_CODE_SW	0x0005


	int ClippedX1; // init. varibles to clip line to

	int ClippedY1;
	int ClippedX2;
	int ClippedY2;

	//init. clip codes

	int Point1Code = 0;
	int Point2Code = 0;

	//figrue out these codes

	
	//point 1 y value

	if(y1 < ClipMinY)
		Point1Code |= CLIP_CODE_N;
	
	else if(y1 > ClipMaxY)
		Point1Code |= CLIP_CODE_S;

	//point 1 x value

	if(x1 < ClipMinX)
		Point1Code |= CLIP_CODE_W;
	
	else if(x1 > ClipMaxX)
		Point1Code |= CLIP_CODE_E;

	//point 2 y value

	if(y2 < ClipMinY)
		Point2Code |= CLIP_CODE_N;

	else if(y2 > ClipMaxY)
		Point2Code |= CLIP_CODE_S;

	//point 2 x value


	if(x2 < ClipMinX)
		Point2Code |= CLIP_CODE_W;

	else if(x2 > ClipMaxX)
		Point2Code |= CLIP_CODE_E;

	//trival rejection

	if((Point1Code & Point2Code))	//if both points are off screen

		return 2;					//in the same manner

									//(both north, south, east or west)


	if((Point1Code == 0 && Point2Code == 0))
		return 1; //they are both on screen


	//ok, now we know that one of the two points needs to be clipped.

	//do point one first, then point two, clipping them to the

	//predefined clipping thing

	
	switch(Point1Code)
	{
	case CLIP_CODE_C:
		//it's inside the clipper

		break;

	case CLIP_CODE_N:
		//it's above the clipper.  Bring it down.

		 ClippedY1 = ClipMinY; //known B/C of geometry

		 ClippedX1 = x1 + 0.5 + (ClipMinY-y1)*(x2-x1)/(y2-y1);
		break;

	case CLIP_CODE_S:
		ClippedY1 = ClipMaxY; //known because of geometry

		ClippedX1 = x1 + 0.5 + (ClipMaxY-y1)*(x2-x1)/(y2-y1);
		break;

	case CLIP_CODE_W:
		ClippedX1 = ClipMinX;
		ClippedY1 =  y1 + 0.5 + (ClipMinX-x1)*(y2-y1)/(x2-x1); 
		break;

	case CLIP_CODE_E:
		ClippedX1 = ClipMaxX;
		ClippedY1 =  y1 + 0.5 + (ClipMaxX-x1)*(y2-y1)/(x2-x1);
		break;

	//ok, if we're still in this switch-case thing by now,then

	//there is more than one line intersection, in which case we'll

	//need to calculate both intersections. (How fun!)

		//remember you're still in a switch statement


	case CLIP_CODE_NE:
		//calculate the north HLine intersection

		
		ClippedY1 = ClipMinY; //easy enough

		ClippedX1 = x1 + 0.5 + (ClipMinY-y1)*(x2-x1)/(y2-y1);

		//ok, now if that worked, we don't need to clip it again.

		//if it didn't, we should.


		if(ClippedX1 < ClipMinX || ClippedX1 > ClipMaxX)
		{
			//there is a east VLine intersection

			ClippedX1 = ClipMaxX;
			ClippedY1 =  y1 + 0.5 + (ClipMaxX-x1)*(y2-y1)/(x2-x1);
		}

		break; //end CLIP_CODE_NE


	case CLIP_CODE_SE:
		//South HLine intersection

		ClippedY1 = ClipMaxY; //known because of geometry

		ClippedX1 = x1 + 0.5 + (ClipMaxY-y1)*(x2-x1)/(y2-y1);

		//if it works, great. if not, nuts.


		if(ClippedX1 < ClipMinX || ClippedX1 > ClipMaxX)
		{
			//east VLine intersection

			ClippedX1 = ClipMaxX;
			ClippedY1 =  y1 + 0.5 + (ClipMaxX-x1)*(y2-y1)/(x2-x1);
		}

		break;

	case CLIP_CODE_NW:

		// North HLine intersection

		ClippedY1 = ClipMinY; //easy enough

		ClippedX1 = x1 + 0.5 + (ClipMinY-y1)*(x2-x1)/(y2-y1);
		
		if(ClippedX1 < ClipMinX || ClippedX1 > ClipMaxX)
		{
			//west VLine intersection

			ClippedX1 = ClipMinX;
			ClippedY1 =  y1 + 0.5 + (ClipMinX-x1)*(y2-y1)/(x2-x1); 
		}

		break;

	case CLIP_CODE_SW:
		//south HLine intersection

		ClippedY1 = ClipMaxY; //known because of geometry

		ClippedX1 = x1 + 0.5 + (ClipMaxY-y1)*(x2-x1)/(y2-y1);

		if(ClippedX1 < ClipMinX || ClippedX1 > ClipMaxX)
		{
			//west VLine intersection

			ClippedX1 = ClipMinX;
			ClippedY1 =  y1 + 0.5 + (ClipMinX-x1)*(y2-y1)/(x2-x1);

		}
		break;

	default: break;
	
	}//end point1


	//now roll right into point2

	//(ya!!)


	//determine the clip point for point2

	//(this will look alot like the thing above for point1)


	switch(Point2Code)
	{
	case CLIP_CODE_C:
		break;

	case CLIP_CODE_N:
		ClippedY2 = ClipMinY;
		ClippedX2 = x2 + (ClipMinY - y2)*(x1-x2)/(y1/y2);
		break;
		
	case CLIP_CODE_S:
		ClippedY2 = ClipMaxY;
		ClippedX2 = x2 + (ClipMinY - y2)*(x1-x2)/(y1/y2);
		break;

	case CLIP_CODE_W:
		ClippedX2 = ClipMinX;
		ClippedY2 = y2 + (ClipMinX - x2)*(y1-y2)/(x1-x2); 
		break;
		
	case CLIP_CODE_E:
		ClippedX2 = ClipMaxY;
		ClippedY2 =  y2 + (ClipMaxX - x2)*(y1-y2)/(x1-x2);
		break;

		//ok, now for the hard part..


	case CLIP_CODE_NE:
		//north HLine intersection

		ClippedY2 = ClipMinY;
		ClippedX2 = x2 + (ClipMinY - y2)*(x1-x2)/(y1/y2);
		
		//IF

		if(ClippedX2 < ClipMinX || ClippedX2 > ClipMaxX)
		{
			//east VLine intersection

			ClippedX2 = ClipMaxY;
			ClippedY2 =  y2 + (ClipMaxX - x2)*(y1-y2)/(x1-x2);
			
		}
		break;

	case CLIP_CODE_SE:
		//south HLine intersection

		ClippedY2 = ClipMaxY;
		ClippedX2 = x2 + (ClipMinY - y2)*(x1-x2)/(y1/y2);

		if(ClippedX2 < ClipMinX || ClippedX2 > ClipMaxX)
		{
			//east VLine intersection

			ClippedX2 = ClipMaxY;
			ClippedY2 =  y2 + (ClipMaxX - x2)*(y1-y2)/(x1-x2);

		}
		break;

	case CLIP_CODE_NW:
		//north HLine intersection

		ClippedY2 = ClipMinY;
		ClippedX2 = x2 + (ClipMinY - y2)*(x1-x2)/(y1/y2);

		if(ClippedX2 < ClipMinX || ClippedX2 > ClipMaxX)
		{
			//west VLine intersection

			ClippedX2 = ClipMinX;
			ClippedY2 = y2 + (ClipMinX - x2)*(y1-y2)/(x1-x2); 

		}
		break;

	case CLIP_CODE_SW:
		//south HLine

		ClippedY2 = ClipMaxY;
		ClippedX2 = x2 + (ClipMinY - y2)*(x1-x2)/(y1/y2);
		
		if(ClippedX2 < ClipMinX || ClippedX2 > ClipMaxX)
		{
			//west VLine

			ClippedX2 = ClipMinX;
			ClippedY2 = y2 + (ClipMinX - x2)*(y1-y2)/(x1-x2); 

		}
		
		break;



	default: break;
	}//end switch

	

	//well that was relitively painless...now do a bounds check


	if( (ClippedX1 < ClipMinX) || (ClippedX1 > ClipMaxX) ||
		(ClippedY1 < ClipMinY) || (ClippedY1 > ClipMaxY) ||
		(ClippedX2 < ClipMinX) || (ClippedX2 > ClipMaxX) ||
		(ClippedY2 < ClipMinY) || (ClippedY2 > ClipMaxY) )
	{
		//oops.  there are still points outside the clipping region

		//give up

		return 0;
	}

//restore varibles


	x1 = ClippedX1;
	y1 = ClippedY1;
	x2 = ClippedX2;
	y2 = ClippedY2;
	
	return 1;
}//end Clipline()