// main.cs

// C:>csc /t:winexe main.cs

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

class AWindow : System.Windows.Forms.Form
{

    private int m_mouse_x;
    private int m_mouse_y;

	int[] coords0 = new int[] {1,1,0,198,299,198,298,1,280,63,285,71,283,80,279,91,271,102,276,134,273,160,265,176,252,187,231,188,209,174,203,157,215,132,227,118,228,111,209,110,188,91,171,78,152,80,146,85,146,93,158,97,179,100,191,107,198,122,191,142,172,152,154,151,135,137,128,131,105,130,101,135,100,156,88,173,67,183,41,183,24,172,16,146,21,125,36,111,46,108,64,105,70,99,66,84,50,77,33,82,30,85,21,87,15,77,19,67,41,60,60,60,78,67,89,89,87,107,80,116,65,124,48,126,34,137,34,153,44,165,70,164,83,151,85,129,94,116,114,111,134,113,149,124,160,133,170,133,178,126,168,115,143,113,127,97,131,71,154,61,179,60,195,70,210,88,214,90,234,92,245,99,246,120,233,142,222,155,222,159,239,169,248,166,256,152,256,124,251,96,254,92,264,80,264,69,270,62,278,60};

	private void OnPaint(object sender, System.Windows.Forms.PaintEventArgs e)
	{
		System.Drawing.Graphics g = e.Graphics;

		//int[] coords0 = new int[] {5,5, 80, 80 };
		
		//int[] coords0 = new int[] {30,30, 180,30,  180,180,  30,180};
        int iLen = coords0.Length;

        iLen -= 2;

		GraphicsPath path = new GraphicsPath();

		for(int i=0; i<iLen; i+=2)
		{
			path.AddLine(coords0[i+0], coords0[i+1], 
				    coords0[i+2], coords0[i+3]);
		}

		//path.AddLine(coords0[iLen-2], coords0[iLen-1], 
		//		     coords0[0], coords0[1]);

		// Create pen
		Pen redPen = new Pen( Color.Red, 1 );

		// Draw path to screen.
		g.DrawPath( redPen, path );

		// Now tidy up
		redPen.Dispose();

		// ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** //
		// Line from a fixed point to our mouse cursor position.
		double px = 400;
		double py = 500;

		g.DrawLine( new Pen(Color.Blue), (int)px, (int)py, (int)m_mouse_x, (int)m_mouse_y );

		// ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** //
/*
		int totalIntersections = 0;
		for(int i=0; i<iLen; i+=2)        
		{
			double p0x = coords0[i+0];
			double p0y = coords0[i+1];

			double p1x = coords0[i+2];
			double p1y = coords0[i+3];

			if( IntersectLines2D( p0x, p0y, p1x, p1y,
				                  px, py, m_mouse_x, m_mouse_y) > 0 ) 
				totalIntersections++;

		}

		if( (totalIntersections % 2)==0 ) // even
		    this.Text = "even";
		else
		    this.Text = "odd";
		*/

	}// End of OnPaint(..)

        // Returns positive if the point is on the positive side of the line. - clockwise direction
	bool isInsideLine(double px, double py,
                      double x0, double y0, double x1, double y1)
	{
        double dirx = x1 - x0;
        double diry = y1 - y0;


		double ang = -3.14/2.0;
		double nx = dirx*Math.Cos( ang ) - diry*Math.Sin( ang );
		double ny = dirx*Math.Sin( ang ) + diry*Math.Cos( ang );

		// Normalize our normals
		double length = Math.Sqrt(Math.Abs(nx*nx + ny*ny));

		nx = nx/length;
		ny = ny/length;


		double d = nx*x1 + ny*y1;
		double k = nx*px + ny*py;

		//this.Text = "Normal: " + px.ToString() + " " + py.ToString();
        if( k<d )
            return true;
        else
            return false;

	}//End isInsideLine(..)

	bool insidePoly( int[] coords, int x0, int y0 )
	{
		// Line far away that we can use to reference our point to.
		double px = 300;
		double py = 500;

		int iLen = coords.Length;
		iLen -= 2;

		int totalIntersections = 0;
		for(int i=0; i<iLen; i+=2)        
		{
			double p0x = coords[i+0];
			double p0y = coords[i+1];

			double p1x = coords[i+2];
			double p1y = coords[i+3];

			if( IntersectLines2D( p0x, p0y, p1x, p1y,
				                  px, py, m_mouse_x, m_mouse_y) > 0 )  totalIntersections++;

		}

		if( (totalIntersections % 2)==0 ) // even
			return true;
		else
			return false;
	}// End insidePoly(..)

	int IntersectLines2D( double p0x, double p0y, double p1x, double p1y,
		                  double p2x, double p2y, double p3x, double p3y)
	{
		// Uses parametric lines. (e.g. p = p0 + (p1-p0)*t ) where t is from 0 to 1;
		double p0vx  = p1x - p0x;
		double p0vy  = p1y - p0y;

		double p1vx  = p3x - p2x;
		double p1vy  = p3y - p2y;

        // Test -1- Check for parallel ines.  If the direction vectors are scalar
		// multiples then the lines are parallel and can't possibly intersect unless
		// the lines overlap
		double det_p0p1 = (p0vx*p1vy - p0vy*p1vx);
		if( Math.Abs( det_p0p1) <= 0.000001 )
		  return 0; // Parallel lines - hence no intersection

		// Test -2- Computer the t0 and t1 values for intersection, where we have
		// two lines of hte form
		// p = p0 + v*t
		// p1 = p10 + v1*t1

		// p1.x = p10.x + v1.x*t1
		// p1.y = p10.y + v1.y*t1

		// p2 = p20 + v2*t2

		// p2.x = p20.x + v2.x*t2
		// p2.y = p20.y + v2.y*t2
		// Solve the system when x1 = x2 and y1 = y2

		double t0 = (p1vx*(p0y - p2y) - p1vy*(p0x - p2x) ) / det_p0p1;
		double t1 = (p0vx*(p0y - p2y) - p0vy*(p0x - p2x) ) / det_p0p1;
		

		if( (t0>=0) && (t0<=1) && (t1>=0) && (t1<=1) )
			return 1; // We have an intersection
		else
			return 0; // Intersects out of bounds.

	}//End IntersectLines2D(..)

    private void OnMouseMoveEvent(object sender, System.Windows.Forms.MouseEventArgs e)
    {
		int mouse_x = e.X;
		int mouse_y = e.Y;

		m_mouse_x = mouse_x;
		m_mouse_y = mouse_y;

		if( insidePoly( coords0, mouse_x, mouse_y)  )
			this.Text = "even";
		else
		    this.Text = "odd";

		Invalidate();
		this.Update();
    }


	AWindow()
	{
		this.Paint += new System.Windows.Forms.PaintEventHandler(this.OnPaint);
        this.MouseMove += new System.Windows.Forms.MouseEventHandler(this.OnMouseMoveEvent);
	}// End of AWindow()

	// Application Entry Point
	static void Main()
	{
		System.Windows.Forms.Application.Run(new AWindow());
	}// End Main()
}// End of AWindow class