Simon Brooke
9912f264fa
difference in itself - because the world is immutable, this change won't work without a different mechanism for generating the world itself.
52 lines
1.9 KiB
Clojure
52 lines
1.9 KiB
Clojure
;; Experimental, probably of no interest to anyone else; attempt to compute drainage on a world,
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;; assumed to have altitudes already set from a heighmap.
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(ns mw-engine.drainage
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(:require
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[clojure.core.reducers :as r])
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(:use mw-engine.utils
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mw-engine.world))
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(def ^:dynamic *sealevel* 10)
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(defn rain-world
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"Simulate rainfall on this `world`. TODO: Doesn't really work just now - should
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rain more on west-facing slopes, and less to the east of high ground"
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[world]
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(map-world world (fn [world cell] (merge cell {:rainfall 1}))))
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(defn flow-contributors
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"Return a list of the cells in this `world` which are higher than this
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`cell` and for which this cell is the lowest neighbour"
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[world cell]
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(remove nil?
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(into []
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(r/map
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(fn [n]
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(cond (= cell (get-least-cell (get-neighbours world n) :altitude)) n))
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(get-neighbours-with-property-value world (:x cell) (:y cell) 1
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:altitude
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(or (:altitude cell) 0) >)))))
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(defn flow
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"Compute the total flow upstream of this `cell` in this `world`, and return a cell identical
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to this one but having a value of its flow property set from that computation.
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Flow comes from a higher cell to a lower only if the lower is the lowest neighbour of the higher."
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[world cell]
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(cond
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(not (nil? (:flow cell))) cell
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(<= (or (:altitude cell) 0) *sealevel*) cell
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true
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(merge cell
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{:flow (+ (:rainfall cell)
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(apply +
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(map (fn [neighbour] (:flow (flow world neighbour)))
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(flow-contributors world cell))))})))
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(defn flow-world
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"Return a world like this `world`, but with cells tagged with the amount of
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water flowing through them."
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[world]
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(map-world (rain-world world) flow))
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