66 lines
2.5 KiB
Plaintext
66 lines
2.5 KiB
Plaintext
## Ruleset which attempts to model retreat of ice after an iceage
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;; Limitations: because the rule language doesn't (yet) allow sophisticated
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;; arithmetic, the ice retreats north to south (southern hemisphere). Otherwise,
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;; it's pretty realistic; ice moves progressively up hillsides, and vegetation
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;; gradually re-establishes.
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## Vegetation rules
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;; rules which populate the world with plants
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;; Occasionally, passing birds plant tree seeds into grassland
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if state is grassland then 1 chance in 10 state should be heath
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;; heath below the treeline grows gradually into forest, providing browsing pressure is not to high
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if state is heath and fertility is more than 10 and altitude is less than 120 then state should be scrub
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if state is scrub and fertility is more than 20 then 1 chance in 20 state should be forest
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;; Forest on fertile land grows to climax
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if state is forest and fertility is more than 30 and altitude is less than 70 then state should be climax
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;; Climax forest occasionally catches fire (e.g. lightning strikes)
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if state is climax then 1 chance in 500 state should be fire
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;; Climax forest neighbouring fires is likely to catch fire
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if state is climax and some neighbours are fire then 1 chance in 3 state should be fire
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;; After fire we get waste
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if state is fire then state should be waste
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;; And after waste we get pioneer species; if there's a woodland seed
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;; source, it's going to be heath, otherwise grassland.
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if state is waste and some neighbours are scrub then state should be heath
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if state is waste and some neighbours are forest then state should be heath
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if state is waste and some neighbours are climax then state should be heath
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if state is waste then state should be grassland
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## Potential blockers
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;; Woody plants increase soil fertility over time.
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if state is in heath or scrub or forest or climax then fertility should be fertility + 1
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## Initialisation rules
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;; Rules which deal with state 'new' will waste less time if they're near the
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;; end of the file
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if state is new then state should be ice
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;; thaw moves gradually southwards (the distinction between 'ice' and 'snow' is
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;; just a hack because I can't do complex arithmetic in rules)
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;; below the waterline ice thaws to water.
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if state is ice and generation is more than y and altitude is less than 10 then state should be water
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;; otherwise it thaws to snow
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if state is ice and generation is more than y then state should be snow
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;; thaw moves gradually up the hills
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if state is snow and generation is more than altitude then state should be waste
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