PONG_GAME.java

package application;

import java.util.Random;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.scene.text.TextAlignment;
import javafx.stage.Stage;
import javafx.util.Duration;

public class PONG_GAME extends Application {
	
	private static final int width=1000; // Width of the window
	private static final int height=800; // height of the window

	private static final int height_player = 100;
	private static final int width_player = 15;
	private static final double ball_radius = 15;
	//BALL SPEED
	private int ballYSpeed = 1;
	private int ballXSpeed = 1;
	// X POSITION FOR BOTH THE PLAYERS
	private int player1X = 0;
	private double player2X = width - width_player;
	// Y POSITION FOR BOTH THE PLAYERS
	private double player1Y = height / 2;
	private double player2Y = height / 2;
	//LOACATION OF BALL
	private double ballX = width / 2;
	private double ballY = height / 2;
	// SCORES
	private int scoreP1 = 0;
	private int scoreP2 = 0;
	private boolean gameStarted;

		
	public void start(Stage stage) throws Exception {
		stage.setTitle("P O N G");
		Canvas canvas = new Canvas(width, height);
		GraphicsContext gc = canvas.getGraphicsContext2D();
		
		// For Animations 
		Timeline tl = new Timeline(new KeyFrame(Duration.millis(10), e -> run(gc)));
		//number of cycles in animation INDEFINITE = repeat indefinitely
		tl.setCycleCount(Timeline.INDEFINITE);
		
		//mouse control (move and click)
		canvas.setOnMouseMoved(e ->  player1Y  = e.getY());
		canvas.setOnMouseClicked(e ->  gameStarted = true);
		stage.setScene(new Scene(new StackPane(canvas)));
		stage.show();
		tl.play();
	}

	private void run(GraphicsContext gc) {
		
		//set background color
		gc.setFill(Color.BLACK);
		gc.fillRect(0, 0, width, height);
		
		// //SET TEXT COLOR
		gc.setFill(Color.WHITE);
		gc.setFont(Font.font(25));
		
		if(gameStarted) {
			//SET BALL MOVEMENT FOR PLAYER
			ballX+=ballXSpeed;
			ballY+=ballYSpeed;
			
			//COMPUTER(OPPONENT) FOLLOWING BALL
			if(ballX < width - width  / 4) {                // if ball x-position is less than 3/4 of width
				player2Y = ballY - height_player / 2;  //then player2 will move to it
			}  else {
				player2Y =  ballY > player2Y + height_player / 2 ?player2Y += 1: player2Y - 1;
			} // if ball y position is greater than player2 y+ player height then inc player2 y by 1
			  // if not then decrease it by 1
			
			gc.fillOval(ballX, ballY, ball_radius, ball_radius);   //draw the ball
			
		} 
		else 
		{
			//set the start text if game is not Running
			gc.setStroke(Color.WHITE);
			gc.setFill(Color.AQUA);
			gc.setTextAlign(TextAlignment.CENTER);
			gc.strokeText("Click", width / 2, height / 2);
			
			//reset the ball start position 
			ballX = width / 2;
			ballY = height / 2;
			
			//reset the ball speed and the direction
			ballXSpeed = 1;
			ballYSpeed = 1;
		}
		
		//makes sure the ball stays in the canvas
		if(ballY > height || ballY < 0) ballYSpeed *=-1;
		
		//if you miss the ball, computer gets a point
		if(ballX < player1X - width_player) {
			scoreP2++;
			gameStarted = false;
		}
		
		//if the computer misses the ball, you get a point
		if(ballX > player2X + width_player) {  
			scoreP1++;
			gameStarted = false;
		}
	
		//increase the speed after the ball hits the player
		// ballX is from center so checks by adding radius of ball
		//        ||||  this is checking X part of Ball and racket       |||||||||||  these two for upper and lower part of racket with ball          
		if( ((ballX + ball_radius > player2X) && ballY >= player2Y && ballY <= player2Y + height_player) ||   // condition for hitting the ball for player 2
			((ballX < player1X + width_player) && ballY >= player1Y && ballY <= player1Y + height_player)) { // condition for hitting the ball for player 1
			// Rebounds the ball after collision
			ballXSpeed *= -1;
	       ballYSpeed *= -1;		
	       // Increase the speed of the ball
	   	ballYSpeed += 1 * Math.signum(ballYSpeed);       // in opposite sign 
		ballXSpeed += 1 * Math.signum(ballXSpeed);       //math.signum gives +1 for +ve value and -1 for -ve value 
		}
		
		//draw score
		gc.fillText(scoreP1 + "\t\t\t\t\t\t\t\t" + scoreP2, width / 2, 100);
		//draw player 1 & 2
		gc.fillRect(player2X, player2Y, width_player, height_player);
		gc.fillRect(player1X, player1Y, width_player, height_player);
	}
	
		// start the application
		public static void main(String[] args) {
		launch(args);
		}
}