def create_initial_ring( surface, points, size ): vertex_ring = VertexRing( points ) midx, midy = surface.get_width()/2.0, surface.get_height()/2.0 radius = min( surface.get_width(), surface.get_height() )*0.4 th = 2.0*math.pi*random.randint( 0, 72 )/72.0 for i in range( 0, points ): a = 2.0*math.pi*i/points + th # b = Vertex() b.position = Cartesian( midx + radius*math.sin( a ), midy + radius*math.cos( a ) ) b.velocity = Cartesian( 0, 0 ) b.reset_acceleration() b.size = size vertex_ring.append( b ) return vertex_ring