mapgen.lua

--[[

http://people.ee.ethz.ch/~pascmu/documents/procedural_modeling_of_cities__siggraph2001.pdf

]]

--[[

from: http://www.newton64.ca/blog/?p=747#7472

initialize priority queue Q with a single entry: r(0, r0, q0)
initialize segment list S to empty

until Q is empty
  pop smallest r(ti, ri, qi) from Q (i.e., smallest ‘t’)
  accepted = localConstraints(&r)
  if (accepted) {
    add segment(ri) to S
    foreach r(tj, rj, qj) produced by globalGoals(ri, qi)
      add r(ti + 1 + tj, rj, qj) to Q
  }

]]

local R = function( ti, ri, qi ) return { t = ti, r = ri, q = qi } end

local Q = { R( 0, ??, ?? ) }
local S = {}
local r = Q:pop()

do
	accepted = localConstraints( r )
	if (accepted) then
		S:add( r )

		local potential_rs = globalGoals( r.r, r.q )

		for _,v in pairs(potential_rs) do
			Q:add( v )
		end
		
	end

	-- pop new potential road with smallest 't'
	r = Q:pop()
while (r)