Question

我是SDL的初学者，我只是尝试在SDL中运行精灵。我在屏幕底部有一个矩形，您可以左右移动。但是，当你左右移动精灵时，它会“重复”，当你左右移动玩家时会产生一种类似跟踪/蛇形游戏的效果。关于如何解决这个问题的任何想法？

///the headers
#include "stdafx.h"
#include <SDL.h>
#include <SDL_image.h>
#include <string>
using namespace std;

//screen attributes
const int SCREEN_WIDTH = 800;
const int SCREEN_HEIGHT = 480;
const int SPRITE_SIZE = 32;

//the surfaces
SDL_Surface *image = NULL;
SDL_Surface *screen = NULL;

int main( int argc, char* argv[] )
{
SDL_Surface *screen, *temp,/* *temp2*/ *sprite/*, *sprite2*/;
SDL_Rect rcSprite/*, rcSprite2*/;
SDL_Event event;
Uint8 *keystate;

int gameover;

//initiailise sdl
SDL_Init(SDL_INIT_VIDEO);

SDL_WM_SetCaption("Pong Move Test", "Pong Move Test");
screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, 0, 0);

//load the sprite (paddle)
temp = SDL_LoadBMP("pongpaddle1.bmp");
sprite = SDL_DisplayFormat(temp);
SDL_FreeSurface(temp);


//set positions of sprite
rcSprite.x = 400;
rcSprite.y = 450;
gameover = 0;

//message pump
while (!gameover)
{
    //look for an event
    if (SDL_PollEvent(&event))
    {
        switch (event.type)
        {
        case SDL_QUIT:
            gameover = 1;
            break;

        case SDL_KEYDOWN:
            switch (event.key.keysym.sym)
            {
            case SDLK_ESCAPE:
            case SDLK_q:
                gameover = 1;
                break;
            }
            break;
        }
    }

    //handle sprite movement
    keystate = SDL_GetKeyState(NULL);
    if (keystate[SDLK_LEFT])
    {
        rcSprite.x -= 1;
    }
    if (keystate[SDLK_RIGHT])
    {
        rcSprite.x += 1;
    }

    //colide with edges of screen
    if (rcSprite.x < 0)
    {
        rcSprite.x =0;
    }
    else if (rcSprite.x > (SCREEN_WIDTH - SPRITE_SIZE))
    {
        rcSprite.x = (SCREEN_WIDTH - SPRITE_SIZE);
    }


    //draw the sprite

    SDL_BlitSurface(sprite, NULL, screen, &rcSprite);

    //update the screen
    SDL_UpdateRect(screen, 0, 0, 0, 0);



}

//clean up area
SDL_FreeSurface(sprite);
SDL_Quit();


return 0;

}

Answer 1

在绘制每一帧之前，你没有清除屏幕，所以你实际上正在绘制前一帧，这就是你得到“尾随”效果的原因。

您可以在绘制每个帧之前使用SDL_FillRect以背景颜色填充整个屏幕来解决此问题：

SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format, 0, 0, 0));

C ++ SDL Movement Player“重复”？

1 个答案: