public boolean collision(Tetromino tetromino){
		boolean isCollision = false;
		
		//going right
		if ((tetromino.getLeft() + tetromino.getWidth() > strengthMap[0].length)){
			return true;
		}
		
		//going left
		if (tetromino.getLeft() < 0){
			return true;
		}
		
		//reached bottom
		if (tetromino.getBottom() > strengthMap.length){
			return true;
		}
		
		//overlaps another block
		for (Point p : tetromino.getPoints()){
			if (p.y < 0) break;
			if(strengthMap[p.y][p.x] != 0) isCollision = true;
		}
		
		return isCollision;
	}