87 lines
3.5 KiB
Clojure
87 lines
3.5 KiB
Clojure
;; Functions to apply a heightmap to a world.
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;;
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;; Heightmaps are considered only as greyscale images, so colour is redundent (will be
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;; ignored). Darker shades are higher.
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(ns mw-engine.heightmap
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(:import [java.awt.image BufferedImage])
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(:use mw-engine.utils
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mw-engine.world
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;; interestingly the imagez load-image is failing for me, while the
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;; collage version is problem free.
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[mikera.image.core :only [filter-image get-pixels]]
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[mikera.image.filters]
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[fivetonine.collage.util]
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))
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(defn- abs
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"Surprisingly, Clojure doesn't seem to have an abs function, or else I've
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missed it. So here's one of my own. Maps natural numbers onto themselves,
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and negative integers onto natural numbers. Also maps negative real numbers
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onto positive real numbers.
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* `n` a number, on the set of real numbers."
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[n]
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(cond (< n 0) (- 0 n) true n))
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(defn tag-gradient
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"Set the `gradient` property of this `cell` of this `world` to the difference in
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altitude between its highest and lowest neghbours."
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[world cell]
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(let [heights (remove nil? (map #(:altitude %) (get-neighbours world cell)))
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highest (cond (empty? heights) 0 ;; shouldn't happen
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true (apply max heights))
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lowest (cond (empty? heights) 0 ;; shouldn't
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true (apply min heights))
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gradient (- highest lowest)]
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(merge cell {:gradient gradient})))
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(defn tag-gradients
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"Set the `gradient` property of each cell in this `world` to the difference in
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altitude between its highest and lowest neghbours."
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[world]
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(map-world world tag-gradient))
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(defn transform-altitude
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"Set the altitude of this cell from the corresponding pixel of this heightmap.
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If the heightmap you supply is smaller than the world, this will break.
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* `world` not actually used, but present to enable this function to be
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passed as an argument to `mw-engine.utils/map-world`, q.v.
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* `cell` a cell, as discussed in world.clj, q.v. Alternatively, a map;
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* `heightmap` an (ideally) greyscale image, whose x and y dimensions should
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exceed those of the world of which the `cell` forms part."
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([world cell heightmap]
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(transform-altitude cell heightmap))
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([cell heightmap]
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(merge cell
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{:altitude
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(+ (get-int cell :altitude)
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(- 256
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(abs
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(mod
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(.getRGB heightmap
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(get-int cell :x)
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(get-int cell :y)) 256))))})))
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(defn apply-heightmap
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"Apply the image file loaded from this path to this world, and return a world whose
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altitudes are modified (added to) by the altitudes in the heightmap. It is assumed that
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the heightmap is at least as large in x and y dimensions as the world.
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* `world` a world, as defined in `world.clj`, q.v.; if world is not supplied,
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a world the size of the heightmap will be created.
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* `imagepath` a file path or URL which indicates an image file."
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([world imagepath]
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;; bizarrely, the collage load-util is working for me, but the imagez version isn't.
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(let [heightmap (filter-image (grayscale)(load-image imagepath))]
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(map-world
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(map-world world transform-altitude (list heightmap))
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tag-gradient)))
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([imagepath]
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(let [heightmap (filter-image (grayscale)(load-image imagepath))
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world (make-world (.getWidth heightmap) (.getHeight heightmap))]
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(map-world
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(map-world world transform-altitude (list heightmap))
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tag-gradient))))
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