//C:> javac -target 1.1 pointInRegion.java

//C:> appletviewer.exe index.html

import java.awt.image.*;
import java.awt.*;
import java.applet.*;

/*********************************************************************************************/
class Point2 
{
   	public int x, y;
   	public Point2( int xx, int yy ) 
	{
      x = xx;  y = yy;
   	}// End constructor
}// End Point3 class


/*********************************************************************************************/
/*                                                                                           */
/* Program Entry Point!                                                                      */
/* Let the coding begin....                                                                  */
/*                                                                                           */
/*********************************************************************************************/

public class pointInRegion extends Applet
{
   
	int scr_width;
	int scr_height;
	
	// Mouse coords
	int mx;
	int my;
	int mb;

	public void init() 
	{
		scr_width  = getSize().width;
		scr_height = getSize().height;
		
		repaint();
	}// End init(..)

   
	 void RenderBox( Graphics g ) 
	 {
	 	
		Point2[] pts;
		pts = new Point2[ 4 ];
		pts[0] = new Point2( 10, 10);
		pts[1] = new Point2( 50, 10);
		pts[2] = new Point2( 50, 50);
		pts[3] = new Point2( 10, 50);
	 	
	 	boolean inRegion = false;
	 	
	 	inRegion = 
	 	CheckIsInRegion((float)mx, (float)my, pts);
		
		// Clear the screen
		if (inRegion)
		{
			g.setColor( Color.blue );
		}
		else
		{
			g.setColor( Color.black );
		}
		g.fillRect( 0, 0, scr_width, scr_height );
      
        
        int p0 = 0;
        int p1 = 1;
		for(int j=0; j<3; j++)
		{
			g.setColor( Color.white );
			g.drawLine( pts[p0].x, pts[p0].y,  pts[p1].x, pts[p1].y );
			p0++;
			p1++;
		}// End for loop j
		
		// Draw closing line of the shape
		g.drawLine( pts[0].x, pts[0].y,  pts[3].x, pts[3].y );
		
		g.drawLine( mx, my,  mx+1, my+1 );
      
	}// End renderWireCube(..)
   
   
    float Cross2D(float ux, float uy, float vx, float vy)
    {
    	return uy*vx - ux*vy;
    }
   
	boolean CheckIsInRegion(float px, float py, Point2[] pts)
	{
		float p0x = pts[3].x;
		float p0y = pts[3].y;
		float p1x = pts[0].x;
		float p1y = pts[0].y;
		
		float d0x = p0x - px;
		float d0y = p0y - py;
		float d1x = p1x - px;
		float d1y = p1y - py;
		
		float firstDir = Cross2D(d0x,d0y,  d1x,d1y);
		
		System.out.println("\nfirstDir " + firstDir);
		
		for (int i=0; i<3; i++)
		{
			p0x = pts[i].x;
			p0y = pts[i].y;
			p1x = pts[i+1].x;
			p1y = pts[i+1].y;
			
			d0x = p0x - px;
			d0y = p0y - py;
			d1x = p1x - px;
			d1y = p1y - py;
			
			float dir = Cross2D(d0x,d0y,  d1x,d1y);
			
			float testDir = dir * firstDir;
			
			System.out.println("dir " + dir);
			
			if (testDir < 0.0f)
			{
				return true;
			}
		}
		
		System.out.println("-");
		
		return false;
	}
	
      
	public void update( Graphics g ) 
	{
		RenderBox( g );
		showStatus("Press Mouse Button and Drag In and Out of Rectangle ");
	}// End update(..)

	public void paint( Graphics g ) 
	{
		update( g );
	}// End paint(..)


/*********************************************************************************************/
/*                                                                                           */
/*  Capture event when mouse is pressed                                                      */
/*    Parameters:                                                                            */
/*    evt is The event...                                                                    */
/*    x is the x mouse position                                                              */
/*    y is the y mouse position                                                              */
/*    return whether or not we handled the event                                             */
/*                                                                                           */
/*********************************************************************************************/

	public boolean mouseDown(Event evt, int x, int y)
	{
		mb = 1;
		return true;
	}// End of mouseDown(..)

/*********************************************************************************************/
/*                                                                                           */
/*  Capture mouse release                                                                    */
/*    Parameters:                                                                            */
/*    evt is The event...                                                                    */
/*    x is the x mouse position                                                              */
/*    y is the y mouse position                                                              */
/*    return whether or not we handled the event                                             */
/*                                                                                           */
/*********************************************************************************************/
	
	public boolean mouseUp(Event evt, int x, int y)
	{
		mb=0;
		return false;
	}// End of mouseUp(..)
	

/*********************************************************************************************/
/*                                                                                           */
/* Captures mouse movement                                                                   */
/* -> Was added so that the dagging of the wire cube was more smooth...as if you click at a  */
/* new place on the screen, there would be a sudden jump...this way its smooth right from    */
/* your first click with the mouse :)                                                        */
/*                                                                                           */
/*********************************************************************************************/

	public boolean mouseMove(Event evt, int x, int y)
	{
		// Update our old mouse pos
		mx = x;
		my = y;
		return true;
	}// End mouseMove(..)

/*********************************************************************************************/
/*                                                                                           */
/*  Capture mouse drags                                                                      */
/*    Parameters:                                                                            */
/*    evt is The event...                                                                    */
/*    x is the x mouse position                                                              */
/*    y is the y mouse position                                                              */
/*    return whether or not we handled the event                                             */
/*                                                                                           */
/*********************************************************************************************/

	public boolean mouseDrag(Event evt, int x, int y)
	{
		if( mb == 1 )
		{
			int xnew = my - y;
			int ynew = mx - x;
			
			// Update the screen
			repaint();
		}// End if(..)
		
		// Update our old mouse pos
		mx = x;
		my = y;
		
		return true;
	}// End of mouseDrag(..)

	
}// End of Applet