/*
   BouncingBallSimpleFX.java Copyright (c) Kari Laitinen

   http://www.naturalprogramming.com/

   2014-12-18 File created.
   2014-12-29 Last modification.

   This program has a Bouncer but it can't rotate or explode.

   A better program is BouncingBallFX.java.

*/


import javafx.animation.* ;  // AnimationTimer, etc.
import javafx.util.Duration;
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.paint.Color;
import javafx.scene.shape.*;  // Arc, Circle, etc.
import javafx.geometry.* ; // Point2D, etc.
import javafx.stage.Stage;

class Bouncer extends Circle
{
   // bouncer_velocity specifies the number of pixels the object
   // will be moved in a single movement operation.
   double bouncer_velocity   =  4.0 ;

   // bouncer_direction is an angle in radians. This angle specifies
   // the direction where the bouncer will be moved next.
   double bouncer_direction  =  Math.random() * Math.PI * 2 ;

   Rectangle  bouncing_area ;

   public Bouncer( Point2D   given_position,
                   Color     given_color,
                   Rectangle given_bouncing_area )
   {
      super( given_position.getX(), given_position.getY(),
             64, given_color ) ;

      bouncing_area  =  given_bouncing_area ;
   }


   public void shrink()
   {
      //  The if-construct ensures that the ball does not become
      //  too small.

      if ( getRadius()  > 5 )
      {
         setRadius( getRadius() - 3 ) ;
      }
   }


   public void enlarge()
   {
      setRadius( getRadius() + 3 ) ;
   }



   public void move()
   {
      //  In the following statement a minus sign is needed when the
      //  y coordinate is calculated. The reason for this is that the
      //  y direction in the graphical coordinate system is 'upside down'.

      setCenterX( 
          getCenterX() + bouncer_velocity * Math.cos(bouncer_direction ) ) ;
      setCenterY(
          getCenterY() - bouncer_velocity * Math.sin(bouncer_direction ) ) ;

      //  Now, after we have moved this bouncer, we start finding out whether
      //  or not it has hit a wall or some other obstacle. If a hit occurs,
      //  a new direction for the bouncer must be calculated.

      //  The following four if constructs must be four separate ifs.
      //  If they are replaced with an if - else if - else if - else if
      //  construct, the program will not work when the bouncer enters
      //  a corner in an angle of 45 degrees (i.e. Math.PI / 4).

      if ( getCenterY() - getRadius() <=  bouncing_area.getY() )
      {
         //  The bouncer has hit the northern 'wall' of the bouncing area.

         bouncer_direction = 2 * Math.PI - bouncer_direction ;
      }

      if ( getCenterX() - getRadius() <=  bouncing_area.getX() )
      {
         //  The western wall has been reached.

         bouncer_direction = Math.PI - bouncer_direction ;
      }

      if ( ( getCenterY()  +  getRadius() )  >=
                   ( bouncing_area.getY()  +  bouncing_area.getHeight() ) )
      {
         //  Southern wall has been reached.

         bouncer_direction = 2 * Math.PI - bouncer_direction ;
      }

      if ( ( getCenterX()  +  getRadius() )  >=
                          ( bouncing_area.getX()  +  bouncing_area.getWidth() ) )
      {
         //  Eastern wall reached.

         bouncer_direction = Math.PI - bouncer_direction ;
      }
   }

}


public class BouncingBallSimpleFX extends Application
{
   static final int SCENE_WIDTH   =  800 ;
   static final int SCENE_HEIGHT  =  680 ;

   AnimationTimer animation_timer ;


   public void start( Stage stage )
   {
      Group group_for_balls = new Group() ;

      stage.setTitle( "BouncingBallSimpleFX.java" ) ;

      Scene scene = new Scene( group_for_balls, SCENE_WIDTH, SCENE_HEIGHT ) ;

      scene.setFill( Color.LIGHTYELLOW ) ;

      Rectangle  bouncing_area  =  new Rectangle(
                                   0, 0, SCENE_WIDTH, SCENE_HEIGHT ) ;


      Bouncer ball_on_screen = new Bouncer( new Point2D( SCENE_WIDTH / 2,
                                                         SCENE_HEIGHT / 2 ),
                                            Color.RED,
                                            bouncing_area ) ;

      group_for_balls.getChildren().add( ball_on_screen ) ;
           
      stage.setScene( scene ) ;
      stage.show() ;


      animation_timer = new AnimationTimer()
      {
            
            public void handle(long l)
            {
               ball_on_screen.move() ;
            }
 
      };
 

      animation_timer.start() ;
   }

   public static void main( String[] command_line_parameters )
   {
      launch( command_line_parameters ) ;
   }
}


/*  NOTES:



The following were useful pages to develop this program:

https://docs.oracle.com/javase/8/javafx/api/javafx/geometry/Point2D.html

http://docs.oracle.com/javase/8/javafx/api/javafx/scene/shape/Circle.html

http://docs.oracle.com/javase/8/javafx/api/javafx/scene/shape/Rectangle.html

*/