最初的《毁灭战士》拥有一个带有静态墙壁的引擎，但却不能移动;结果，所有的门都是垂直打开的;任何东西都不可能水平移动。当源代码发布后，我在查看代码时，在处理门的源文件中看到了这个，在一大块注释掉的代码的开头:

// UNUSED
// Separate into p_slidoor.c?

#if 0           // ABANDONED TO THE MISTS OF TIME!!!
//
// EV_SlidingDoor : slide a door horizontally
// (animate midtexture, then set noblocking line)
//

从《雷神之锤III》的资料中，我在一些随机的帖子中偶然发现了这一点。该文件的完整源代码可以在这里找到。这是一种非常快速的求平方根倒数的方法。至于最好的评论呢?当然，这是一种常见的方法，但考虑到它附着在直线上，它的神奇之处在于它的伟大之处。

float Q_rsqrt( float number )
{
  long i;
  float x2, y;
  const float threehalfs = 1.5F;

  x2 = number * 0.5F;
  y  = number;
  i  = * ( long * ) &y;  // evil floating point bit level hacking
  i  = 0x5f3759df - ( i >> 1 ); // what the fuck?
  y  = * ( float * ) &i;
  y  = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration
  // y  = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed

  #ifndef Q3_VM
  #ifdef __linux__
    assert( !isnan(y) ); // bk010122 - FPE?
  #endif
  #endif
  return y;
}

看这个:

'On Error Goto Hell.

在1983年的COBOL中见过:

   C   I don't know what this next bit does so I'll jump around it
       GOTO DONE.

//休斯顿，我们有麻烦了

 * ...and don't just declare it volatile and think you've solved
 * the problem. You young punks think you know what volatile
 * means... why in my day we had to cast it volatile uphill
 * both ways, and the code still didn't work! Whippersnappers...