[OSM-talk] colour fills in osmarender

[Raphael Jacquot]

Etienne wrote:

> Yes.  In fact, I'm sure the current model is wrong.
> 
> A way should be made up of an ordered list of nodes, not segments.
> This would remove all the problems with segment directionality and
> would speed up processing as well.

how about a way be composed of a linear set of segments, and 
directionality is defined by the first and last node ?

if a way contains the following nodes and segments :

1  a  2  c  3  d  5  b  4
+-----+-----+-----+-----+

the segments can be ordered automatically, and the nodes too.
now, directionality is defined by "you can travel from 1 to 4" and "you 
can travel from 4 to 1
there's an other solution though which may be better even (see below)
furthermore, it's very easy to also automatically create ways, as 
there's a simple set of rules

a node with 0 segments does not currently belong to a way
a node with exactly 2 segments is within a way
all other nodes are the beginning or end of a way

for instance

+-----+-----+
       |
       +----+

can be described by 3 ways from the above set of rules.

furthermore. we could tack information about what is possible to do at a 
particular interection. for instance

    a     b
+-----+-----+
       | c
       +

imagine c is a one way street getting into the intersection, but there's 
a bike lane that allows going the other way in c.
the node at the intersection could have information like

cars:
from b you can go to a
from c you can go to a
from c you can go to b
bikes
from a you can go to b
from a you can go to c
from b you can go to a
from b you can go to c
from c you can go to a
from c you can go to b

this of course could be represented by some sort of variable size bitmap 
  (a 64 bit integer should be enough for each category, I don't imagine 
an intersection with 8 streets ;D) and can be used easily by routing 
algorithms.

what do you think ?