Creating Objects for Game in C++

Question

I'm working on coding a Pong game and am having trouble creating objects. I had working code, but it did not include a class or any objects, and since it is for an Object-Oriented Programming class, I needed to fix that. However, now I'm getting a bunch of different error messages (it stops displaying after 100). Most of them appear to be dealing with me not creating objects correctly.

I've never worked with objects in C++ (probably should've, but have just been muddling through this class and getting points deducted for this very reason), but since the semester is winding down, I really need to do well on this project.

Update I've managed to get rid of the majority of the errors, but there are still a few remaining that have me stumped. I have edited my code to reflect the changes I've made and updated the error list.

Here is my code:

My header file:

#include "stdafx.h"
#include <string>
#include <Windows.h>
#include <iostream>
//#include <conio.h>
#include <sstream>
#include <math.h>
//#include <gl\gl.h>
//#include <gl\glu.h>
#include "GL/freeglut.h"
#pragma comment(lib, "Opengl32.lib")
#define VK_W 0x57
#define VK_S 0x53
using namespace std;

class Pong {
public:
    Pong();
    std::string int2str;
    void drawText(float x, float y, std::string text);
    void drawPaddle(float x, float y, float width, float height);
    void draw();
    void enable2D(int width, int height);
    void keyboard();
    void vec2_norm(float& x, float &y);
    void updateBall();
    void gameOverCheck();
    void update(int value);

    //window size and update rate
    int width;
    int height;
    int interval; // 60 frames per-second

    //scoring
    int p1Score; //Player 1's score
    int p2Score; //Player 2's score
    int winner;

    //the paddles
    int paddleWidth;
    int paddleHeight;
    int paddleSpeed;
    float paddleLeftX;
    float paddleLeftY;
    float paddleRightX;
    float paddleRightY;

    //the ball
    float ballPositionX; 
    float ballPositionY;
    float ballDirectionX;
    float ballDirectionY;
    int ballSize;
    int ballSpeed;
};

My .cpp file:

#include "stdafx.h"
#include "PongGame.h"
#include <string>
#include <Windows.h>
#include <iostream>
//#include <conio.h>
#include <sstream>
#include <math.h>
//#include <gl\gl.h>
//#include <gl\glu.h>
#include "GL/freeglut.h"
#pragma comment(lib, "Opengl32.lib")
#define VK_W 0x57
#define VK_S 0x53
using namespace std;

Pong pong;
Pong::Pong() {
    width = 500;
    height = 300;
    interval = 1000/60;
    p1Score = 0;
    p2Score = 0;
    winner = 0;
    paddleWidth = 10;
    paddleHeight = 80;
    paddleSpeed = 3;
    paddleLeftX = 10.0f;
    paddleLeftY = 50.0f;
    paddleRightX = width - paddleWidth - 10;
    paddleRightY = 50;
    ballPositionX = width / 2;
    ballPositionY = height / 2;
    ballDirectionX = -1.0f;
    ballDirectionY = 0.0f;
    ballSize = 8;
    ballSpeed = 3;
}

std::string int2str(int x) { //used to convert an integer to a string
    std::stringstream ss;
    ss << x;

    return ss.str( );
}

void drawText(float x, float y, std::string text) {
    glRasterPos2f(x, y);
    glutBitmapString(GLUT_BITMAP_8_BY_13, (const unsigned char*)text.c_str());
}

void drawPaddle(float x, float y, float width, float height) {
    glBegin(GL_QUADS);
        glVertex2f(x, y);
        glVertex2f(x + width, y);
        glVertex2f(x + width, y + height);
        glVertex2f(x, y + height);
    glEnd();
}

void draw() {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();

    //draws the paddles
    drawPaddle(pong.paddleLeftX, pong.paddleLeftY, pong.paddleWidth, pong.paddleHeight);
    drawPaddle(pong.paddleRightX, pong.paddleRightY, pong.paddleWidth, pong.paddleHeight);

    //draws the ball
    drawPaddle(pong.ballPositionX - pong.ballSize / 2, pong.ballPositionY- pong.ballSize / 2, pong.ballSize, pong.ballSize);

    //draws the score at the top center of the screen
    drawText(pong.width / 2 - 10, pong.height - 15, int2str(pong.p1Score) + ":" + int2str(pong.p2Score));

    glutSwapBuffers();
}

void enable2D(int width, int height) {
    glViewport(0, 0, width, height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0f, width, 0.0f, height, 0.0f, 1.0f);
    glMatrixMode (GL_MODELVIEW);
    glLoadIdentity();
}

void keyboard() { //allows teh paddles to be controled from the keyboard
    //moves left paddle (player 1)
    if (GetAsyncKeyState(VK_W))
        pong.paddleLeftY += pong.paddleSpeed; //move paddle up with "W" key

    if (GetAsyncKeyState(VK_S)) 
        pong.paddleLeftY -= pong.paddleSpeed; //move paddle down with "S" key

    //moves right paddle (player 2)
    if (GetAsyncKeyState(VK_UP)) 
        pong.paddleRightY += pong.paddleSpeed; //move paddle up with "up" arrow

    if (GetAsyncKeyState(VK_DOWN)) 
        pong.paddleRightY -= pong.paddleSpeed; //move paddle down with "down" arrow
}

void vec2_norm(float& x, float &y) {
    float length = sqrt((x * x) + (y * y));

    if(length != 0.0f) {
        length = 1.0f / length;
        x *= length;
        y *= length;
    }
}

void updateBall() { //allows teh ball to move
    pong.ballPositionX += pong.ballDirectionX * pong.ballSpeed;
    pong.ballPositionY += pong.ballDirectionY * pong.ballSpeed;

    if(pong.ballPositionX < pong.paddleLeftX + pong.paddleWidth && pong.ballPositionX > pong.paddleLeftX && pong.ballPositionY < pong.paddleLeftY + pong.paddleHeight && pong.ballPositionY > pong.paddleLeftY) { //if ball is hit by player 1's paddle
        float t = ((pong.ballPositionY - pong.paddleLeftY) / pong.paddleHeight) - 0.5f;
        pong.ballDirectionX = fabs(pong.ballDirectionX); 
        pong.ballDirectionY = t;
    }

    if (pong.ballPositionX > pong.paddleRightX && pong.ballPositionX < pong.paddleRightX + pong.paddleWidth && pong.ballPositionY < pong.paddleRightY + pong.paddleHeight && pong.ballPositionY > pong.paddleRightY) { //if ball is hit by player 2's paddle
        float t = ((pong.ballPositionY - pong.paddleRightY) / pong.paddleHeight) - 0.5f;
        pong.ballDirectionX = -fabs(pong.ballDirectionX); 
        pong.ballDirectionY = t;
    }

    if (pong.ballPositionX < 0) { //if ball hits the top wall
        ++pong.p2Score;
        pong.ballPositionX = pong.width / 2;
        pong.ballPositionY = pong.height / 2;
        pong.ballDirectionX = fabs(pong.ballDirectionX); 
        pong.ballDirectionY = 0;
    }

    if (pong.ballPositionX > pong.width) { //if ball hits the right wall
        ++pong.p1Score;
        pong.ballPositionX = pong.width / 2;
        pong.ballPositionY = pong.height / 2;
        pong.ballDirectionX = -fabs(pong.ballDirectionX); 
        pong.ballDirectionY = 0;
    }

    if (pong.ballPositionY > pong.height) { //ball hits top wall
        pong.ballDirectionY = -fabs(pong.ballDirectionY); 
    }

    if (pong.ballPositionY < 0) { //ball hits bottom wall
        pong.ballDirectionY = fabs(pong.ballDirectionY); 
    }

    vec2_norm(pong.ballDirectionX, pong.ballDirectionY);
}

void gameOverCheck() {
    const int maxScore = 10;
    if(pong.p1Score == maxScore) {
        cout << "Player 1 Wins!" << endl;
        pong.winner = 1;
    }
    else if(pong.p2Score == maxScore) {
        cout << "Player 2 Wins!" << endl;
        pong.winner = 2;
    }
}

void update(int value) {
   keyboard();

   if(pong.winner == 0) {
        updateBall();
        glutTimerFunc(pong.interval, update, 0);
        glutPostRedisplay();
        gameOverCheck();
    }
}

My main file:

//PongGameTest.cpp
#include "stdafx.h"
#include "PongGame.h"
#include <string>
#include <Windows.h>
#include <iostream>
//#include <conio.h>
#include <sstream>
#include <math.h>
//#include <gl\gl.h>
//#include <gl\glu.h>
#include "GL/freeglut.h"
#pragma comment(lib, "Opengl32.lib")
#define VK_W 0x57
#define VK_S 0x53
using namespace std;

int _tmain(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 200);
    glutCreateWindow("Pong");

    glutDisplayFunc(pong.draw);
    glutTimerFunc(pong.interval, pong.update, 0);

    pong.enable2D(pong..width, pong.height);
    glColor3f(1.0f, 0.0f, 0.0f);

    glutMainLoop();

    return 0;
}

And I'm sure y'all will hate me for this, but here are the errors I'm getting when I compile:

1>  PongGameTest.cpp
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(25): error C2065: 'pong' : undeclared identifier
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(25): error C2228: left of '.draw' must have class/struct/union
1>          type is ''unknown-type''
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(26): error C2065: 'pong' : undeclared identifier
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(26): error C2228: left of '.interval' must have class/struct/union
1>          type is ''unknown-type''
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(26): error C2065: 'pong' : undeclared identifier
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(26): error C2228: left of '.update' must have class/struct/union
1>          type is ''unknown-type''
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(28): error C2065: 'pong' : undeclared identifier
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(28): error C2228: left of '.enable2D' must have class/struct/union
1>          type is ''unknown-type''
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(28): error C2065: 'pong' : undeclared identifier
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(28): error C2059: syntax error : '.'
1>c:\users\hitechredneck\desktop\fall 2014\object-oriented programming\game\ponggame\ponggame\ponggametest.cpp(29): error C2228: left of '.glColor3f' must have class/struct/union
1>          type is ''unknown-type''

I'm well aware that nobody is going to read all of those messages (I know I sure wouldn't) but could you possibly skim them and see if you might can figure out what I'm doing wrong? Like I said, I'm almost 100% sure that many of them have to do with me not creating the object correctly and using it's members properly.

Answer 1

1.

Pong Pong;

is illegal: you can't declare an object with a type name as identifier. This could've been Pong pong.

2.

Pong::enable2D()

is illegal: enable2D isn't a static function, but a member (per-instance) function and thus you've to call it via an object, like pong.enable2D();.

3.

extern Pong pong;  // in the header
Pong pong;         // and both of these in the source
Pong Pong;

This is definitely wrong. What are you trying to do? Global or not, you can't declare an object named Pong of type Pong as explained above (1). Also you perhaps don't want a global but just an automatic variable in the main function.

Errors

error C2143: syntax error : missing ';' before '.'

If the compiler doesn't have the declaration of an identifier that it'll be unable to accept the token . and will be expecting a ; instead.

error C2248: 'Pong::height' : cannot access private member declared in class 'Pong'

This is as clear as C++ compiler errors get to be.

Please read a good C++ beginner book and get such logistical issues out of your way. Internet is not a good teacher, it's a good reference library, but it can't replace a good book mostly.