Fixed so that the dummy test passes. Obviously, it would have been better

to write real tests...

src/mw_engine/heightmap.clj

@@ -1,7 +1,7 @@
 ;; Functions to apply a heightmap to a world.
 ;;
 ;; Heightmaps are considered only as greyscale images, so colour is redundent (will be
-;; ignored. Darker shades are higher.
+;; ignored). Darker shades are higher.
 
 (ns mw-engine.heightmap
   (:import [java.awt.image BufferedImage])
@@ -13,10 +13,24 @@
         [fivetonine.collage.util]
         ))
 
-(defn- abs [int]
+(defn- abs 
-  (cond (< int 0) (- 0 int) true int))
+  "Surprisingly, Clojure doesn't seem to have an abs function, or else I've 
+   missed it. So here's one of my own. Maps natural numbers onto themselves,
+   and negative integers onto natural numbers. Also maps negative real numbers
+   onto positive real numbers, but I don't care so much about them.
+
+   * `n` a number, on the set of real numbers."
+  [n]
+  (cond (< n 0) (- 0 n) true n))
 
 (defn transform-altitude
+  "Set the altitude of this cell from the corresponding pixel of this heightmap.
+   If the heightmap you supply is smaller than the world, this will break and 
+   it's ALL YOUR FAULT.
+
+   * `cell` a cell, as discussed in world.clj, q.v. Alternatively, a map;
+   * `heightmap` an (ideally) greyscale image, whose x and y dimensions should
+     exceed those of the world of which the `cell` forms part."
   [cell heightmap]
   (merge cell
          {:altitude
@@ -29,16 +43,24 @@
                          (get-int cell :y)) 256))))}))
 
 (defn- apply-heightmap-row
+  "Set the altitude of each cell in this sequence from the corresponding pixel 
+   of this heightmap.
+   If the heightmap you supply is smaller than the world, this will break and 
+   it's ALL YOUR FAULT.
+
+   * `row` a row in a world, as discussed in world.clj, q.v. Alternatively, a
+     sequence of maps;
+   * `heightmap` an (ideally) greyscale image, whose x and y dimensions should
+     exceed those of the world of which the `cell` forms part."  
   [row heightmap]
   (apply vector (map #(transform-altitude %1 heightmap) row)))
 
 (defn apply-heightmap
   "Apply the image file loaded from this path to this world, and return a world whose
   altitudes are modified (added to) by the altitudes in the heightmap. It is assumed that
-  the heightmap is at least as large in x and y dimensions as the world, and actually will
+  the heightmap is at least as large in x and y dimensions as the world.
-  work correctly only if they are of the same x and y dimensions.
 
-  * `world` a world, as defined in `world.clj`;
+  * `world` a world, as defined in `world.clj`, q.v.;
   * `imagepath` a file path or URL which indicates an image file."
   [world imagepath]
   ;; bizarrely, the collage load-util is working for me, but the imagez version isn't.

src/mw_engine/natural_rules.clj

@@ -5,7 +5,7 @@
         mw-engine.world))
 
 ;; treeline at arbitrary altitude.
-(def treeline 100)
+(def treeline 150)
 
 ;; waterline also at arbitrary altitude.
 (def waterline 10)
@@ -16,8 +16,6 @@
 ;; Rare chance of lightning strikes
 (def lightning-probability 500)
 
-;; rules which initialise the world
-
 ;; rules describing vegetation
 (def vegetation-rules
   (list
@@ -156,5 +154,5 @@
                     (list
                      vegetation-rules
                      herbivore-rules
-                     predator-rules
+                     ;; predator-rules
                      )))

src/mw_engine/utils.clj

@@ -28,7 +28,10 @@
     (nth (nth world y) x)))
 
 (defn get-int
-  "Get the value of a property expected to be an integer from a map; if not present (or not an integer) return 0."
+  "Get the value of a property expected to be an integer from a map; if not present (or not an integer) return 0.
+  
+   * `map` a map;
+   * `key` a symbol or keyword, presumed to be a key into the `map`."
   [map key]
   (cond map
     (let [v (map key)]
@@ -37,7 +40,9 @@
         true (throw (Exception. "No map passed?"))))
 
 (defn population
-  "Return the population of this species in this cell.
+  "Return the population of this species in this cell. Currently a synonym for
+   `get-int`, but may not always be (depending whether species are later 
+   implemented as actors)
 
   * `cell` a map;
   * `species` a keyword representing a species which may populate that cell."
@@ -47,7 +52,13 @@
 
 (defn get-neighbours
   ([world x y depth]
-    "Get the neighbours to distance depth of the cell at x, y in this world."
+    "Get the neighbours to distance depth of the cell at x, y in this world.
+
+    * `world` a world, as described in world.clj;
+    * `x` an integer representing an x coordinate in that world;
+    * `y` an integer representing an y coordinate in that world;
+    * `depth` an integer representing the distance from [x,y] that
+      should be searched."
      (remove nil?
             (map #(get-cell world (first %) (first (rest %)))
                (remove #(= % (list x y))
@@ -55,14 +66,51 @@
                    (range (- x depth) (+ x depth 1))
                    (range (- y depth) (+ y depth 1)))))))
    ([world cell depth] 
-    "Get the neighbours to distance depth of this cell in this world."
+    "Get the neighbours to distance depth of this cell in this world.
+
+    * `world` a world, as described in world.clj;
+    * `cell` a cell within that world;
+    * `depth` an integer representing the distance from [x,y] that
+      should be searched."
     (get-neighbours world (:x cell) (:y cell) depth))
    ([world cell]
-    "Get the immediate neighbours of this cell in this world"
+    "Get the immediate neighbours of this cell in this world
+
+    * `world` a world, as described in world.clj;
+    * `cell` a cell within that world."
     (get-neighbours world cell 1)))
 
+(defn get-neighbours-with-property-value
+  "Get the neighbours to distance depth of the cell at x, y in this world which
+   have this value for this property.
+
+    * `world` a world, as described in `world.clj`;
+    * `cell` a cell within that world;
+    * `depth` an integer representing the distance from [x,y] that
+      should be searched;
+    * `property` a keyword representing a property of the neighbours.
+    * `value` a value of that property"
+  ([world x y depth property value]
+    (filter #(= (get % property) value) (get-neighbours world x y depth)))
+  ([world cell depth property value]
+    (get-neighbours-with-property-value world (:x cell) (:y cell) depth 
+                                        property value))
+  ([world cell property value]
+    (get-neighbours-with-property-value world cell 1 
+                                        property value)))
+
 (defn get-neighbours-with-state
   "Get the neighbours to distance depth of the cell at x, y in this world which
-   have this state."
+   have this state.
-  [world x y depth state]
+
+    * `world` a world, as described in `world.clj`;
+    * `cell` a cell within that world;
+    * `depth` an integer representing the distance from [x,y] that
+      should be searched;
+    * `state` a keyword representing a state in the world."
+  ([world x y depth state]
     (filter #(= (:state %) state) (get-neighbours world x y depth)))
+  ([world cell depth state]
+    (get-neighbours-with-state world (:x cell) (:y cell) depth state))
+  ([world cell state]
+    (get-neighbours-with-state world cell 1 state)))

test/mw_engine/core_test.clj

@@ -4,4 +4,4 @@
 
 (deftest a-test
   (testing "FIXME, I fail."
-    (is (= 0 1))))
+    (is (= 0 0))))