Question

我试图让玩家平稳地运动，例如模拟物理重力到速度，但是效果不好。我刚刚按下的方向键会延迟一段时间才能产生效果，然后停止所有奇怪的动作。我绘制了一个红色的矩形，并尝试像飞船的月球着陆器那样进行控制，但是无法正常工作。

有人可以帮我吗？

#include <SDL.h>
#include <stdio.h>
// for random number
#include <stdlib.h>
#include <SDL_image.h>
#include <ctime>

SDL_Surface *screen = NULL;

SDL_Surface *playership = NULL;

//SDL_Renderer *renderer = NULL;

SDL_Window *window = NULL;

SDL_Event occur;

SDL_Rect PlayerShip;

//Definition Color PlayerShip 
Uint32 red;

// X and Y velocity of Ball variables
float xVelShip, yVelShip;
// dx dy momentum acel decel velocity player
float dx, dy;

int GetRandomNumber(int high, int low)
{
     return rand() % high + low;
}

void Load_Game()
{

     /*Initialize SDL*/
     SDL_Init(SDL_INIT_EVERYTHING);
     //SDL_Window* window = nullptr;
     //Create window
     window = SDL_CreateWindow( "SDL_lunarlander", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 800, 600, SDL_WINDOW_SHOWN);
     screen = SDL_GetWindowSurface( window );


     //Player setup
     PlayerShip.x = GetRandomNumber(500,200);
     PlayerShip.y = 200;
     PlayerShip.w = 10;
     PlayerShip.h = 30;

     dx = 0.0f;
     dy = 0.0f;

     //Color Player
     red = SDL_MapRGB(screen->format, 255, 0, 0);

     //ramdon number to movemment Ball
     srand((int)time(0));

}

void Draw_Level()

{
  SDL_FillRect(screen, NULL, 0);

  SDL_FillRect(screen, &PlayerShip, red);

  SDL_UpdateWindowSurface( window );

}

void Logic()
{

  dy += 0.15f;
  if ( PlayerShip.y < 558)
      {
        PlayerShip.y += dy*0.05f;
      }

  if ( PlayerShip.x < 800)
      {
        PlayerShip.x = dx;
      }
  // SDL 2.0 USES 
  //const Uint8 *keystates = SDL_GetKeyboardState(NULL);
  //if (keystates[SDL_SCANCODE_W])
  const Uint8 *keystates = SDL_GetKeyboardState(NULL);

  if (keystates[SDL_SCANCODE_UP])
  {
     dy -= 0.65f; 

  }

  if (keystates[SDL_SCANCODE_DOWN])
  {
     dy += 0.25f; 

  }

  if (keystates[SDL_SCANCODE_RIGHT])
  {
     dx += 0.2f; 

  }

  if (keystates[SDL_SCANCODE_LEFT])
  {
     dx -= 0.2f; 

  }

}

int main( int argc, char* args[] )
{    
    printf("FPS:%d", SDL_GetTicks());
    Load_Game();

    bool running = true;

    // CAP FPS to 60 may be not working 
    const int FPS=60;
    Uint32 start;
    printf("FPS:%d", SDL_GetTicks());
    while(running == true)
    {
      start = SDL_GetTicks();

      SDL_PollEvent(&occur);

      if (occur.type == SDL_QUIT)
      {
         running = false;     
      }

      Logic();  
      Draw_Level();

      // CAP FPS to 60 Maybe not working
      if (1000/FPS > SDL_GetTicks() - start)
      {
         SDL_Delay( 1000/FPS - (SDL_GetTicks() - start));   

      }

    }   
    SDL_FreeSurface(screen);
    SDL_DestroyWindow( window );
    SDL_Quit();
    return 0;
}```

如何在SDL 2中获得流畅的播放器？

0 个答案: