Took a bit of a break.

Simulated annealing is having some issues geometrically determining an elements neighbors.  In the mean time I have cleaned up the grammar implementation to handle non-terminal symbols in the middle of a string.  This has allowed me to create symmetric grammars and building.

grammar:
s gh
g bdf
f bbwf

h bob
h wow
o bzozb
o bxoxb
end

Rendered out in ambient occlusion: