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我正在使用 Allegro 4 和 C++ 制作一个简单版本的俄罗斯方块。我已经准备好大部分代码，除了用户输入之外一切正常。游戏仅在少数随机情况下检测到按键。我担心这是一个时间问题，但我似乎无法抓住它。这是相关的代码位...

//Tetris.h


//Tetris class definition...

volatile long tet_counter = 0;

void increment_tet_counter()
{
  tet_counter++;
}
END_OF_FUNCTION(increment_tet_counter);

//this function gets called by the menu class when the user selects the Tetris option
//contains main loop, calls all other functions etc.
void Tetris::show(BITMAP* buffer, int& scr)
{
  LOCK_VARIABLE(tet_counter);
LOCK_FUNCTION(increment_tet_counter);
install_int_ex(increment_tet_counter, BPS_TO_TIMER(120));

while(tet_counter > 0)
{
   if(tet_scr == 1)  //welcome screen logic
   {
     if(key[KEY_E])
     {
       game_init();  //initialize game variables, etc.
       tet_scr = 2;  // go to main game screen
     }
     else if(key[KEY_I])   
     {
       tet_scr = 3;  //go to instructions screen
     }
     else if(key[KEY_Q])  //quit tetris
     {
       scr = 5;  //reference to a variable in the main.cpp, basically reverting the 
                 //main screen to the menu screen upon return
       return;
       }
   }  
   else if(tet_scr == 2)   //main game screen
   {
     if(cannot_move())   //managing auto-block movement, making the last line of blocks 
      {                  //permanent, etc... all of this works fine
       put_block();
       update_score(remove_filled_line());
       get_next_block();
      }
     move_block();  //handles auto-block movement and user input

   if(is_game_over())
    {textprintf_ex(screen, font, 500, 300, WHITE, -1, "GAME OVER!");
     rest(2000);
     tet_scr = 5;
     }

    if(key[KEY_P])  //pause game
      tet_scr = 4;

    if(key[KEY_Q])   //quit game
      tet_scr = 5;
   }

   //else ifs for other screens of the game... all work fine

  tet_counter--;                
}

//drawing functions ... work fine

}

//handles block movement... CPU-generated movement works, user input not detected mot of the time 
void Tetris::move_block()
{ 
 timer = (timer+1) % time_factor; 
 if(timer == time_factor-1)  //move block every couple of seconds
    block_y += 20;
 int k;
 if(keypressed())   //this is where the problem is (i think)
 {                  //the game only picks up the keypresses some of the times
 k = readkey();     //and sometimes when I keep the keypressed for a long time it work
  if(k >> 8 == KEY_DOWN)    //but it's very buggy and erratic and no way to predict
     block_y+=20;           //when it'll work and when it won't
  else if(k >> 8 == KEY_LEFT)
    block_x-=20;
  else if(k >> 8 == KEY_RIGHT)
    block_x+=20;
  else if(k >> 8 == KEY_UP)
    rotate_block();
 } 

 if(block_x < BOARD_X)
    block_x = BOARD_X;
 if(block_x > x_lim)
    block_x = x_lim;

 if(block_y < BOARD_Y)
    block_y = BOARD_Y;
 if(block_y > y_lim)
    block_y = y_lim;

}

//various other functions handling game logic/drawing etc are all working fine

我之前以完全相同的方式实现了俄罗斯方块，但没有任何总体菜单类。只需运行 .exe，您就会遇到俄罗斯方块游戏。那个时候没有这样的问题。因此，Tetris.h 文件之外的代码显然与游戏有关。我使用'keypressed（）'的唯一其他地方主要是这样......

while (counter > 0)
   {
         if(keypressed())
         {
           switch(readkey() >> 8)
           {
             case KEY_DOWN:
                  option++;
                  break;
             case KEY_UP:
                  option--;
                  break;
           }
         }

         if (option < 0)
             option = 5;
         else if (option > 5)
             option = 0;

         screen_handler(option, done);  //updates a variable using which the appropriate game is called in show_screen(), pong, breakout, snake are the other games

         counter--;
   }

   show_screen();  //this is where Tetris::show() is called
   blit(main_buffer, screen, 0, 0, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
   clear_bitmap(main_buffer);

任何和所有的帮助来解决这个混乱将不胜感激。谢谢。

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1 回答 1

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我的评论最终解决了 OP 的问题。填写答案表以供将来参考：

如果 main() 中的 keyPressed() 函数在每一帧都被意外调用，那么在某种意义上它可能会导致第二个 keyPressed() 调用出现故障。如果对 keyPressed 的调用查找自上次调用以来按下的最后一个键，则第一个调用可能是“接收”该键，然后您实际想要接收该键的第二个调用正在获取 nada。有时虽然你很幸运，并且在 keyPressed() 调用编号 1 和调用编号 2 之间按下了那个键。如果这是一个紧密的循环，这可能是一个简短的窗口，它解释了你有时会“工作”的行为。

于 2013-06-29T16:55:10.900 回答