c++ - 矩形弹跳碰撞检测

Question

我使用 SDL 创建了一个程序，其中一个矩形在程序的墙内不断发生碰撞，但碰撞检查工作不正常。

这是代码:`

int main(int argc, char *argv[]){
//variable Initialization]
width = height = 45;
srcX = srcY = 0;
destY = destX = 0;
vlc = 1;
SDL_Init(SDL_INIT_VIDEO);
screen = SDL_SetVideoMode(640, 480, 32, SDL_SWSURFACE);
SDL_WM_SetCaption("Bouncing Balls","./ball.jpg");
backg = IMG_Load("./back.png");
ball = IMG_Load("./ball.jpg");
while (checkBounce){
    //Increase velocity
    destX += vlc;
    destY += vlc;
     //Collision Checking
        if (destX < 0){
            destX = 0;
            vlc = -vlc;
            destX += vlc;
        }
        if (destY < 0){
            destY = 0;
            vlc = -vlc;
            destY += vlc;
        }
        if (destY + height > 480){
            destY = 480 - height;
            vlc = -vlc;
            }
        if (destX + width > 640){
            destX = 640 - width;
            vlc = -vlc;
        }
    if (SDL_PollEvent(&event)){
        if (event.type == SDL_QUIT)
            checkBounce = false;
    }
//Applying Surfaces
applySurface(0, 0, backg, screen);
applyBall(srcX, srcY, destX, destY, width, height, ball, screen);
SDL_Flip(screen);
}
SDL_Quit();
return 0;
}

这是 gif 图像发生了什么:Bouncing Rectangle.gif

Answer 1

我假设预期结果是矩形从墙壁上正确反弹？

您需要将速度分为 x 和 y 分量，而不是使用单个数字。这是因为速度是二维的。

只要检测到碰撞，您的程序就会导致 x 和 y 分量都变为负值。这会导致矩形沿其路径向后反弹。

这里是一个编辑:

int main(int argc, char *argv[]){
    //variable Initialization]
    width = height = 45;
    srcX = srcY = 0;
    destY = destX = 0;
    vlcX = 1;
    vlcY = 1;
    SDL_Init(SDL_INIT_VIDEO);
    screen = SDL_SetVideoMode(640, 480, 32, SDL_SWSURFACE);
    SDL_WM_SetCaption("Bouncing Balls","./ball.jpg");
    backg = IMG_Load("./back.png");
    ball = IMG_Load("./ball.jpg");
    while (checkBounce){
        //Increase velocity
        destX += vlcX;
        destY += vlcY;
        //Collision Checking
        if (destX < 0){
            destX = 0;
            vlcX = -vlcX;
            destX += vlcX;
        }
        if (destY < 0){
            destY = 0;
            vlcY = -vlcY;
            destY += vlcY;
        }
        if (destY + height > 480){
            destY = 480 - height;
            vlcY = -vlcY;
            }
        if (destX + width > 640){
            destX = 640 - width;
            vlcX = -vlcX;
        }
        if (SDL_PollEvent(&event)){
            if (event.type == SDL_QUIT)
                checkBounce = false;
        }
        //Applying Surfaces
        applySurface(0, 0, backg, screen);
        applyBall(srcX, srcY, destX, destY, width, height, ball, screen);
        SDL_Flip(screen);
    }
    SDL_Quit();
    return 0;
}