Hello,
I want to use a mesh that makes up some sort of 2D line path, and I need the vertices indices to start from the vertex closest to 0,0, move towards an edge that is in the Y-up direction, until the last vertex in the mesh…
Now the problem is, if the vertices were not created in this order, how can I store the vertex closest to 0,0 the first in a list, move up(Y axis-up), and continue storing the linked vertices in a list till the last one? 
I hope I wasn’t confusing… >.<
I think I made it… I have never done anything too serious with python thought, so this code probably sucks.
I’m using it for a racing game driveline, maybe someone else will find it useful, and won’t have to go through all this stuff just to order a bunch of vertices…
def WriteLeftDriveLine(obj, filename):
"Write the .drvl file"
mesh = obj.getData()
mesh.transform(obj.getMatrix())
for f in mesh.faces:
if len(f.v) != 2:
print "Can't export Drive Line .drvl file: invalid mesh."
print "The mesh must be made of linked line segments only."
return
filename = Blender.sys.splitext(filename)[0]
filename += '.drvl'
drvfile = file(filename, "w")
print "Writing drive line file: %s" % filename
verts = mesh.verts
shortest_distance = 100000
for v in verts:
#find vertex closest to 0,0
distance = sqrt(v[0]**2 + v[1]**2)
if distance < shortest_distance:
shortest_distance = distance
first_vertex = v
#Find the two vertex that are linked to the first vertex
e_v = []
edges = mesh.edges
for e in edges:
if first_vertex == e.v1:
e_v.append(e.v2)
elif first_vertex == e.v2:
e_v.append(e.v1)
second_vertex = first_vertex
#Find the vertex which has the higher Y value
for v in e_v:
if v[1] > second_vertex[1]:
second_vertex = v
if second_vertex == first_vertex:
print "Can't export Drive Line .drvl file: invalid mesh."
print "The mesh only has one point."
return
sorted_vertex = [first_vertex, second_vertex]
prev_vertex = first_vertex
curr_vertex = second_vertex
count = 2
#Find the edge that contains the second vertex but does not has first vertex
while count != len(verts):
for e in edges:
if prev_vertex != e.v1 and prev_vertex != e.v2:
#Find which vertex is the next_vertex
if curr_vertex == e.v1:
prev_vertex = curr_vertex
curr_vertex = e.v2
sorted_vertex.append(curr_vertex)
count = count + 1
break
elif curr_vertex == e.v2:
prev_vertex = curr_vertex
curr_vertex = e.v1
sorted_vertex.append(curr_vertex)
count = count + 1
break
for v in sorted_vertex:
drvfile.write('%f,%f
' % (v[0], v[1]))
drvfile.close()
Theres a script in blenders CVS that converts a mesh into a polyline