将图像添加到乒乓球游戏

Question

第一篇文章在这里:)

我正在编写一个乒乓球游戏，碰壁了。我的代码有效，但我想把它花哨一点。我想使用3张图片（每个球拍一张，球一张）。由于代码是现在编写的，我只有用于球拍的矩形和一个用于球的正方形。

这是我的代码：

// pongGame.cpp 
#include "stdafx.h"
#include <string>
#include <Windows.h>
#include <iostream>
#include <conio.h>
#include <sstream>
#include <math.h>
#include <glgl.h>
#include <glglu.h>
#include "GL/freeglut.h"
#pragma comment(lib, "Opengl32.lib")
#define VK_W 0x57
#define VK_S 0x53
using namespace std;
//window size and update rate
int width = 500;
int height = 300;
int interval = 1000 / 60; // 60 frames per-second
//scoring
int p1Score = 0; //Player 1's score
int p2Score = 0; //Player 2's score
int winner = 0;
//the paddles
int paddleWidth = 10;
int paddleHeight = 80;
int paddleSpeed = 3;
float paddleLeftX = 10.0f;
float paddleLeftY = 50.0f;
float paddleRightX = width - paddleWidth - 10;
float paddleRightY = 50;
//the ball
float ballPositionX = width / 2; 
float ballPositionY = height / 2;
float ballDirectionX = -1.0f;
float ballDirectionY = 0.0f;
int ballSize = 8;
int ballSpeed = 4;
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(paddleLeftX, paddleLeftY, paddleWidth, paddleHeight);
    drawPaddle(paddleRightX, paddleRightY, paddleWidth, paddleHeight);
    //draws the ball
    drawPaddle(ballPositionX - ballSize / 2, ballPositionY- ballSize / 2, ballSize, ballSize);
    //draws the score at the top center of the screen
    drawText(width / 2 - 10, height - 15, int2str(p1Score) + ":" + int2str(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))
        paddleLeftY += paddleSpeed; //move paddle up with "W" key
    if (GetAsyncKeyState(VK_S)) 
        paddleLeftY -= paddleSpeed; //move paddle down with "S" key
    //moves right paddle (player 2)
    if (GetAsyncKeyState(VK_UP)) 
        paddleRightY += paddleSpeed; //move paddle up with "up" arrow
    if (GetAsyncKeyState(VK_DOWN)) 
        paddleRightY -= 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
    ballPositionX += ballDirectionX * ballSpeed;
    ballPositionY += ballDirectionY * ballSpeed;
    if(ballPositionX < paddleLeftX + paddleWidth && ballPositionX > paddleLeftX && ballPositionY < paddleLeftY + paddleHeight && ballPositionY > paddleLeftY) { //if ball is hit by player 1's paddle
        float t = ((ballPositionY - paddleLeftY) / paddleHeight) - 0.5f;
        ballDirectionX = fabs(ballDirectionX); 
        ballDirectionY = t;
    }
    if (ballPositionX > paddleRightX && ballPositionX < paddleRightX + paddleWidth && ballPositionY < paddleRightY + paddleHeight && ballPositionY > paddleRightY) { //if ball is hit by player 2's paddle
        float t = ((ballPositionY - paddleRightY) / paddleHeight) - 0.5f;
        ballDirectionX = -fabs(ballDirectionX); 
        ballDirectionY = t;
    }
    if (ballPositionX < 0) { //if ball hits the top wall
        ++p2Score;
        ballPositionX = width / 2;
        ballPositionY = height / 2;
        ballDirectionX = fabs(ballDirectionX); 
        ballDirectionY = 0;
    }
    if (ballPositionX > width) { //if ball hits the right wall
        ++p1Score;
        ballPositionX = width / 2;
        ballPositionY = height / 2;
        ballDirectionX = -fabs(ballDirectionX); 
        ballDirectionY = 0;
    }
    if (ballPositionY > height) { //ball hits top wall
        ballDirectionY = -fabs(ballDirectionY); 
    }
    if (ballPositionY < 0) { //ball hits bottom wall
        ballDirectionY = fabs(ballDirectionY); 
    }
    vec2_norm(ballDirectionX, ballDirectionY);
}

void gameOverCheck() {
    const int maxScore = 10;
    if(p1Score == maxScore) {
        cout << "Player 1 Wins!" << endl;
        winner = 1;
    }
    else if(p2Score == maxScore) {
        cout << "Player 2 Wins!" << endl;
        winner = 2;
    }
}
void update(int value) {
   keyboard();
   if(winner == 0) {
        updateBall();
        glutTimerFunc(interval, update, 0);
        glutPostRedisplay();
        gameOverCheck();
    }
}
int _tmain(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 200);
    glutCreateWindow("Pong");
    glutDisplayFunc(draw);
    glutTimerFunc(interval, update, 0);
    enable2D(width, height);
    glColor3f(1.0f, 0.0f, 0.0f);
    glutMainLoop();
    return 0;
}

同样，如果有人能帮我弄清楚如何为游戏窗口添加背景，那也很棒:)

Answer 1

将纹理放在四边形上。

灵感：http://www.opengl-tutorial.org/beginners-tutorials/tutorial-5-a-textured-cube/