我正在编写 Pong 游戏的代码，但在创建对象时遇到了问题。我有工作代码，但它不包含类或任何对象，因为它是面向对象编程类，我需要修复它。但是，现在我收到了一堆不同的错误消息(它在 100 后停止显示)。他们中的大多数人似乎都在处理我没有正确创建对象的问题。
我从来没有使用过 C++ 中的对象(可能应该使用过，但刚刚在这门课上蒙混过关，并因此而被扣分)，但由于学期即将结束，我真的需要好好表现在这个项目上。
更新 我已经设法摆脱了大部分错误，但仍然有一些让我感到难过。我已编辑我的代码以反射(reflect)我所做的更改并更新了错误列表。
这是我的代码:
我的头文件:
#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;
};
我的 .cpp 文件:
#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();
}
}
我的主文件:
//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;
}
我敢肯定你们会因此而讨厌我，但这是我在编译时遇到的错误:
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''
我很清楚没有人会阅读所有这些消息(我知道我肯定不会)，但您能否浏览一下它们，看看是否能找出我做错了什么？就像我说的，我几乎 100% 肯定其中很多问题与我没有正确创建对象和正确使用它的成员有关。
最佳答案
1.
Pong Pong;
是非法的:您不能将类型名称声明为标识符的对象。这可能是 Pong pong。
2.
Pong::enable2D()
是非法的:enable2D 不是静态函数，而是成员(每个实例)函数，因此您必须通过对象调用它，例如 pong.enable2D( );。
3.
extern Pong pong; // in the header
Pong pong; // and both of these in the source
Pong Pong;
这绝对是错误的。你想做什么？无论是否为全局，您都不能声明类型为 Pong 的名为 Pong 的对象，如上文 (1) 所述。此外，您可能不想要一个全局变量，而只想在 main 函数中使用一个自动变量。
错误
error C2143: syntax error : missing ';' before '.'
如果编译器没有标识符的声明，它将无法接受 token 。 并且会期待一个 ;。
error C2248: 'Pong::height' : cannot access private member declared in class 'Pong'
这就像 C++ 编译器错误一样清晰。
请阅读a good C++ beginner book并解决此类后勤问题。互联网不是一个好老师，它是一个很好的引用资料库，但它大多不能代替一本好书。
关于c++ - 在 C++ 中为游戏创建对象，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27035522/