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--- simulating_photosynthesis [2008-10-06 09:49] – davegriffiths
+++ simulating_photosynthesis [2008-10-09 11:08] – davegriffiths
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 ===Making plants grow towards light===
+Using lindenmayer systems and genetic algorithms to simulate plant growth.
+Plants are given a "fitness" based on their leaves -
+  * How much do they face the light?
+  * Are they too close to other leaves?
+  * Are they in shadow from another leaf?
+  * Are they below the ground?
+  * Also - the fitness drops as the plant description (a linenmayer system string) gets too long.
 {{http://www.pawfal.org/dave/images/patab-angle-s.png}}
 {{http://www.pawfal.org/dave/images/patab-close-s.png}}
 {{http://www.pawfal.org/dave/images/patab-occlude-s.png}}
+The leaf score is indicated by it's colour (red=bad, green=good).
+Using this measurement, a genetic algorithm can create populations of individual plants, score each one and iteratively create new populations by combining fit individuals.
 <html>
 <embed src="http://blip.tv/play/AdGkH4_+Sw" type="application/x-shockwave-flash" width="640" height="480" allowscriptaccess="always" allowfullscreen="true"></embed>
 </html>
+The simplest strategy is to "cheat" with one leaf :) Each frame is the fittest of a new population, the text is the current lindenmayer string.
 {{http://www.pawfal.org/dave/images/patab-long.png}}
+The result of a long run with many thousands of generations. Many leaves circle the light to get the maximum photosynthesis possible.
 {{http://www.pawfal.org/dave/images/patab-helped.png}}
+You can also evolve from a starting point - in this case a simple tree is modified to create a bigger and more suitable one for the environment.
+Code: http://www.pawfal.org/flotsam/jetsam/patabotany/scheme/
+<html>
+<embed src="http://blip.tv/play/AdGkMo_+Sw" type="application/x-shockwave-flash" width="640" height="480" allowscriptaccess="always" allowfullscreen="true"></embed>
+</html>
+Another evolutionary run, a bit more interesting than the one-leaf approach.