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
