code: int getCornerIndex( SquareNode node , double x , double y ) {
  		for (int i = 0; i < node.square.size(); i++) {
  			Point2D_F64 c = node.square.get(i);
  			if( c.x == x && c.y == y )
  				return i;
  		}
  
  		throw new RuntimeException("BUG!");
  	}
docs: Returns the corner index of the specified coordinate