code: public boolean hasVertex(float x, float y) {    	
      	if (points.length == 0) {
      		return false;
      	}
      	
      	checkPoints();
      	
      	for (int i=0;i<points.length;i+=2) {
      		if ((points[i] == x) && (points[i+1] == y)) {
      			return true;
      		}
      	}
      	
      	return false;
      }
docs: Check if a particular location is a vertex of this polygon
  
  @param x The x coordinate to check
  @param y The y coordinate to check
  @return True if the cordinates supplied are a vertex of this polygon