package greenfoot.collision.ibsp;




| A cache for BSP nodes, allowing object re-use. Might help reduce garbage collection
| impact.
|
| @author Davin McCall
|
public class BSPNodeCache
{       
private static final int CACHE_SIZE = 1000;
    
   
   private static BSPNode [] cache = new BSPNode[CACHE_SIZE];
   
   private static int tail = 0;
   
   private static int size = 0;
    
   
   public static BSPNode getBSPNode()
   {
      if (size == 0) {            
         return new BSPNode(new Rect(0,0,0,0), 0, 0);         
         }
       

      else {
           
      int ppos = tail - size;
      if (ppos < 0) {                
         ppos += CACHE_SIZE;             
         }

           
      BSPNode node = cache[ppos];
      node.setParent(null);
           
      size--;
           
      return node;         
      }     
   }
    
   
public static void returnNode(BSPNode node)
   {
   node.blankNode();
       
   cache[tail++] = node;
   if (tail == CACHE_SIZE) {            
      tail = 0;         
      }
   size = Math.min(size + 1, CACHE_SIZE);
        
   if (node.getLeft() != null || node.getRight() != null) {            
      throw new RuntimeException("HHHHH!");         
      }              
   } 
}