PongExample/main.cpp

#define OLC_PGE_APPLICATION
#include "olcPixelGameEngine.h"

enum state{
	TITLE_SCREEN,
	RUNNING_GAME,
	WIN_GAME,
	LOSE_GAME
};

class Example : public olc::PixelGameEngine
{
	float ballx = 200;
	float bally = 200;
	float ballXSpd = -80;
	float ballYSpd = 80;
	float ballRadius = 10;

	float paddlex = 20;
	float paddley;
	float paddleWidth = 30;
	float paddleHeight = 100;

	float enemyPaddleX = 20;
	float enemyPaddleY;
	float enemyPaddleWidth = 30;
	float enemyPaddleHeight = 100;

	int playerScore = 0;
	int enemyScore = 0;

	state GameState = TITLE_SCREEN;

public:
	Example()
	{
		sAppName = "Example";
	}

public:
	bool OnUserCreate() override
	{
		// Called once at the start, so create things here
		
		paddley = ScreenHeight()/2;
		enemyPaddleX = ScreenWidth()-20;
		enemyPaddleY = ScreenHeight()/2;

		srand(time(NULL));

		return true;
	}

	bool OnUserUpdate(float fElapsedTime) override
	{
		// called once per frame

		Clear(olc::VERY_DARK_GREY);

		if (GameState == TITLE_SCREEN) {
			std::string titleText = "PONG";
			std::string spacebarText = "Press <SPACE> to Begin!";

			DrawString(ScreenWidth() / 2 - GetTextSize(titleText).x/2*6, 80 - GetTextSize(titleText).y/2*6, titleText, olc::BLACK, 6);
			DrawString(ScreenWidth() / 2 - GetTextSize(spacebarText).x/2*3, 240 - GetTextSize(spacebarText).y/2*3, spacebarText, olc::BLACK, 3);

			if (GetKey(olc::SPACE).bPressed) {
				GameState = RUNNING_GAME;
				playerScore = 0;
				enemyScore = 0;
			}
		} else
		if (GameState == WIN_GAME) {
			Clear(olc::DARK_BLUE);
			std::string winText = "YOU WIN!";
			std::string spacebarText = "Press <SPACE> to Play Again!";

			DrawString(ScreenWidth() / 2 - GetTextSize(winText).x/2*6, 80 - GetTextSize(winText).y/2*6, winText, olc::WHITE, 6);
			DrawString(ScreenWidth() / 2 - GetTextSize(spacebarText).x/2*2, 240 - GetTextSize(spacebarText).y/2*2, spacebarText, olc::WHITE, 2);

			if (GetKey(olc::SPACE).bPressed) {
				GameState = TITLE_SCREEN;
			}
		} else
		if (GameState == LOSE_GAME) {
			Clear(olc::DARK_RED);
			std::string loseText = "YOU LOSE!";
			std::string spacebarText = "Press <SPACE> to Play Again!";

			DrawString(ScreenWidth() / 2 - GetTextSize(loseText).x/2*6, 80 - GetTextSize(loseText).y/2*6, loseText, olc::WHITE, 6);
			DrawString(ScreenWidth() / 2 - GetTextSize(spacebarText).x/2*2, 240 - GetTextSize(spacebarText).y/2*2, spacebarText, olc::WHITE, 2);

			if (GetKey(olc::SPACE).bPressed) {
				GameState = TITLE_SCREEN;
			}
		} else
		if (GameState == RUNNING_GAME) {

			ballx += ballXSpd * fElapsedTime; // move the ball horizontally
			bally += ballYSpd * fElapsedTime; // move the ball vertically

			//Related to Ball Horizontal Collision Checking
			float ballLeft = ballx - ballRadius;
			float ballRight = ballx + ballRadius;
			float paddleRight = paddlex + paddleWidth/2;
			float enemyPaddleLeft = enemyPaddleX - enemyPaddleWidth/2;

			//Related to Ball Vertical Collision Checking
			float ballTop = bally - ballRadius;
			float ballBottom = bally + ballRadius;
			float paddleTop = paddley - paddleHeight/2;
			float paddleBottom = paddley + paddleHeight/2;
			float enemyPaddleTop = enemyPaddleY - enemyPaddleHeight/2;
			float enemyPaddleBottom = enemyPaddleY + enemyPaddleHeight/2;

			if (
				ballLeft < paddleRight &&
				ballTop < paddleBottom &&
				ballBottom > paddleTop
			) { //If the ball collides with the paddle.
				ballXSpd *= -1.1;
				ballYSpd *= 1.1;
				ballx=paddleRight+ballRadius;
			}

			if (
				ballRight > enemyPaddleLeft &&
				ballTop < enemyPaddleBottom &&
				ballBottom > enemyPaddleTop
			) { //If the ball collides with the paddle.
				ballXSpd *= -1.1;
				ballYSpd *= 1.1;
				ballx=enemyPaddleLeft-ballRadius;
			}

			if (ballBottom > ScreenHeight()) { //If the ball touches the bottom edge, reverse its Y direction.
				ballYSpd *= -1;
				bally = ScreenHeight()-ballRadius;
			}
			if ( //If the ball touches the top edge, reverse its Y direction.
				ballTop < 0
			) {
				ballYSpd *= -1;
				bally = ballRadius;
			}

			if (ballRight > ScreenWidth()) { //If the ball touches the right edge, award a point to the player.
				playerScore += 1;
				ballx = ScreenWidth()/2;
				bally = ScreenHeight()/2;

				ballXSpd = 80;
				ballYSpd = 80;
				
				int randomNumber = rand() % 2; //Get a random number that is 0 or 1.
				if (randomNumber == 0) {
					ballXSpd *= -1;
				}

				randomNumber = rand() % 2;
				if (randomNumber == 0) {
					ballYSpd *= -1;
				}
			}
			if (ballLeft < 0) { //If the ball touches the left edge, award a point to the enemy.
				enemyScore += 1;
				ballx = ScreenWidth()/2;
				bally = ScreenHeight()/2;

				ballXSpd = 80;
				ballYSpd = 80;
				
				int randomNumber = rand() % 2; //Get a random number that is 0 or 1.
				if (randomNumber == 0) {
					ballXSpd *= -1;
				}

				randomNumber = rand() % 2;
				if (randomNumber == 0) {
					ballYSpd *= -1;
				}
			}

			if (GetKey(olc::UP).bHeld) {
				paddley -= 120 * fElapsedTime; //move the paddle up at 120 pixels / s
			}
			if (GetKey(olc::DOWN).bHeld) {
				paddley += 120 * fElapsedTime; //move the paddle down at 120 pixels / s
			}

			if (bally < enemyPaddleY) {
				enemyPaddleY -= 100 * fElapsedTime;
			}
			if (bally > enemyPaddleY) {
				enemyPaddleY += 100 * fElapsedTime;
			}

			if (playerScore >= 5) {
				GameState = WIN_GAME;
			}
			if (enemyScore >= 5) {
				GameState = LOSE_GAME;
			}

			
			DrawCircle(ballx,bally,ballRadius,olc::YELLOW);
			FillRect(paddlex - paddleWidth/2, paddley - paddleHeight/2, paddleWidth, paddleHeight, olc::GREEN); //Draw a paddle centered at the paddle position.
			FillRect(enemyPaddleX - enemyPaddleWidth/2, enemyPaddleY - enemyPaddleHeight/2, enemyPaddleWidth, enemyPaddleHeight, olc::DARK_RED); //Draw a paddle centered at the paddle position.

			DrawString(30,30,std::to_string(playerScore),olc::WHITE,4);

			std::string enemyScoreText = std::to_string(enemyScore);

			DrawString(ScreenWidth() - 30 - GetTextSize(enemyScoreText).x*4 , 30, enemyScoreText,olc::WHITE, 4);

		}

		return true;
	}
};


int main()
{
	Example demo;
	if (demo.Construct(640, 480, 4, 4))
		demo.Start();

	return 0;
}