个回答

• 慕粉1470740819

  2016-08-25 17:17:18

  已采纳

  性能优化function updateBalls(){
  
      for( var i = 0 ; i < balls.length ; i ++ ){
  
          balls[i].x += balls[i].vx;
          balls[i].y += balls[i].vy;
          balls[i].vy += balls[i].g;
  
          if( balls[i].y >= WINDOW_HEIGHT-RADIUS ){
              balls[i].y = WINDOW_HEIGHT-RADIUS;
              balls[i].vy = - balls[i].vy*0.75;
          }
      }
  
      var cnt = 0
      for( var i = 0 ; i < balls.length ; i ++ )
          if( balls[i].x + RADIUS > 0 && balls[i].x -RADIUS < WINDOW_WIDTH )
              balls[cnt++] = balls[i]
  
      while( balls.length > Math.min(300,cnt) ){
          balls.pop();
      }
  }

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