A way to destroy these blocks faster?

Questions & Answers
1

im trying to destroy the chunk of blocks as quickly as they are instantiated. Basically blocks are destroyed and instantiated depending on the player’s distance from the chunk. When blocks are instantiated, they quickly instantiate as if the entire chunk in instantiating at once. However, when it comes to destroying them, it seems that they are destroyed in flowing rows, like this (may not be a good image):

3284-unity-2012-09-05-17-23-10-14.jpg

So the questions is, how do i destroy the blocks as quickly as they are being instanced? Does it have to do with using a foreach loop and a list? Here’s the code:

		Vector3 chunkCenter = new Vector3(transform.position.x + BlockData.chunkX / 2, BlockData.chunkY, transform.position.z + BlockData.chunkZ/2);
		
		if(Vector3.Distance(chunkCenter,player.transform.position) > terrain.maxViewDistance) {
			terrain.chunksToRender.Remove(transform);
			foreach(Transform block in terrain.blockList) { 
				
				if(block != null) {
					if(block.position.x >= transform.position.x	&& block.position.x < transform.position.x + terrain.blocksX) {
						
						if(block.position.z >= transform.position.z && block.position.z < transform.position.z + terrain.blocksZ) {
							
							Destroy (block.gameObject);
							terrain.blockList.Remove(block);
							
						}
						
					}
					
				}
				
			}
			
		} else if(!terrain.chunksToRender.Contains(transform)) {
			
			terrain terrainScript = blockGenerator.GetComponent<terrain>();
			terrainScript.renderChunk(transform);
			terrain.chunksToRender.Add(transform);
			
		}
2

You should not modify the list while iterating through it with foreach - this screws up the loop control, with unpredictable results. A good work around is to use a copy of the list in the foreach - this way you can safely remove elements from the original list. The List method CopyTo seems a good choice to make this copy:

      ...
      if(Vector3.Distance(chunkCenter,player.transform.position) > terrain.maxViewDistance) {
         terrain.chunksToRender.Remove(transform);
         // create a copy of blockList:
         Transform[] blocks = new Transform[terrain.blockList.Count];
         terrain.blockList.CopyTo(blocks); // copy the list to the blocks array
         foreach (Transform block in blocks) { // use blocks in the foreach...
           ...
           // now you can safely delete blockList elements in the foreach:
           terrain.blockList.Remove(block);
           ...