[Freeciv-Dev] (PR#9799) PATCH: rewrited adjust_map()

["Marcelo Burda" <mburda@xxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=9799 >

Best comment and names

diff -ruN -Xfreeciv/diff_ignore freeciv/common/map.h freeciv_/common/map.h
--- freeciv/common/map.h        2004-08-26 20:37:52.000000000 +0200
+++ freeciv_/common/map.h       2004-09-01 09:00:52.100705080 +0200
@@ -229,7 +229,7 @@
 void reset_move_costs(int x, int y);
 
 /* Maximum value of index (for sanity checks and allocations) */
-#define MAX_MAP_INDEX map.xsize * map.ysize
+#define MAX_MAP_INDEX (map.xsize * map.ysize)
 
 #ifdef DEBUG
 #define CHECK_MAP_POS(x,y) assert(is_normal_map_pos((x),(y)))
diff -ruN -Xfreeciv/diff_ignore freeciv/server/mapgen.c freeciv_/server/mapgen.c
--- freeciv/server/mapgen.c     2004-08-28 18:50:49.000000000 +0200
+++ freeciv_/server/mapgen.c    2004-09-01 09:28:54.889882240 +0200
@@ -63,7 +63,7 @@
 static void mapgenerator4(void);
 static void mapgenerator5(void);
 static void smooth_map(void);
-static void adjust_map(void);
+static void adjust_hmap(void);
 static void adjust_terrain_param(void);
 
 #define RIVERS_MAXTRIES 32767
@@ -75,8 +75,18 @@
    A value of 2 means river.                            -Erik Sigra */
 static int *river_map;
 
+/*******************************************************************
+ * Height map information
+ ******************************************************************/
 static int *height_map;
-static int maxval=0;
+/* maximum value for height_map after be adjusted */
+static const int hmap_max_level = 1000;
+/* after call make_land(), this is the level of sea in height_map */
+static int hmap_shore_level = 0;
+/* after call make_mountains(), this the minimum level where mountains and hill
+   probably will placed */
+static int  hmap_mountain_level = 0;
+
 static int forests=0;
 
 struct isledata {
@@ -106,6 +116,17 @@
    ? MAX_TEMP * (3 + 2 * SQSIZE) / (100 * SQSIZE)              \
    : 5 * MAX_TEMP / 100  /* 5% for all maps */)
 
+/********************************************************************
+ * used to initialize a array with some value
+ ********************************************************************/
+#define INITIALIZE_ARRAY(_a, _size, _val)                            \
+  { \
+    int _ini_index = 0; \
+    for(; _ini_index < (_size);_ini_index++) { \
+      (_a)[_ini_index] = (_val); \
+     } \
+  } 
+
 /****************************************************************************
   Returns the temperature of this map position.  This is a value in the
   range of 0 to MAX_TEMP (inclusive).
@@ -293,28 +314,12 @@
   the map.mountains value, so increase map.mountains and you'll get more 
   hills and mountains (and vice versa).
 **************************************************************************/
-static void make_mountains(int thill)
+static void make_mountains(void)
 {
-  int mount;
-  int j;
-
-  for (j = 0; j < 10; j++) {
-    mount = 0;
-    whole_map_iterate(x, y) {
-      if (hmap(x, y) > thill) {
-       mount++;
-      }
-    } whole_map_iterate_end;
-    if (mount < (map_num_tiles() * map.mountains) / 1000) {
-      thill *= 95;
-    } else {
-      thill *= 105;
-    }
-    thill /= 100;
-  }
-  
+  hmap_mountain_level = ((hmap_max_level - hmap_shore_level)
+                        * (100 - map.mountains)) / 100 + hmap_shore_level;
   whole_map_iterate(x, y) {
-    if (hmap(x, y) > thill && !is_ocean(map_get_terrain(x,y))) { 
+    if (hmap(x, y) > hmap_mountain_level && !is_ocean(map_get_terrain(x,y))) { 
       /* Randomly place hills and mountains on "high" tiles.  But don't
        * put hills near the poles (they're too green). */
       if (myrand(100) > 75 
@@ -527,7 +532,7 @@
     }
     rand_map_pos(&x, &y);
     if (not_placed(x, y)
-       && hmap(x, y) < (maxval * 60) / 100) {
+       && hmap(x, y) < (hmap_max_level * 60) / 100) {
       map_set_terrain(x, y, T_SWAMP);
       cardinal_adjc_iterate(x, y, x1, y1) {
        if (myrand(10) > 5 && !is_ocean(map_get_terrain(x1, y1)) 
@@ -1135,37 +1140,20 @@
 **************************************************************************/
 static void make_land(void)
 {
-  int tres;
-  int count=0;
-  int total = (map_num_tiles() * map.landpercent) / 100;
-  int forever=0;
-
-  adjust_map();
+  adjust_hmap();
   normalize_hmap_poles();
-  tres = (maxval * map.landpercent) / 100;
-
-  do {
-    forever++;
-    if (forever>50) break; /* loop elimination */
-    count=0;
-    whole_map_iterate(x, y) {
-      if (hmap(x, y) < tres)
-       map_set_terrain(x, y, T_OCEAN);
-      else {
-       map_set_terrain(x, y, T_NOT_PLACED);
-       count++;
-      }
-    } whole_map_iterate_end;
-    if (count>total)
-      tres*=11;
-    else
-      tres*=9;
-    tres/=10;
-  } while (abs(total-count)> maxval/40);
+  hmap_shore_level = (hmap_max_level *(100 - map.landpercent)) / 100;
+  whole_map_iterate(x, y) {
+    if (hmap(x, y) < hmap_shore_level) {
+      map_set_terrain(x, y, T_OCEAN);
+    } else {
+      map_set_terrain(x, y, T_NOT_PLACED);
+    }
+  } whole_map_iterate_end;
 
   renormalize_hmap_poles();
   make_polar_land(); /* make extra land at poles*/
-  make_mountains(maxval*8/10);
+  make_mountains();
   make_arctic();
   make_tundra();
   make_forests();
@@ -1643,25 +1631,47 @@
 }
 
 /**************************************************************************
-  Adjust the map so that its minimum height is 0.  This raises or lowers
-  every position by a fixed amount and sets the "maxval" global variable
-  to hold the maximum height.
+  Change the values of height map, so that they contain ranking of each 
+  tile scaled to [0 .. hmap_max_level].
+  The lowest 20% of tiles will have values lower than 0.2 * hmap_max_level.
+  slope can globaly be estiamted as
+        hmap_max_level * sqrt(number_of_islands) / linear_size_of_map
 **************************************************************************/
-static void adjust_map(void)
+static void adjust_hmap(void)
 {
-  int minval = maxval = hnat(0, 0);
+  int  min = hnat(0, 0), max = min;
 
   /* Determine minimum and maximum heights. */
   whole_map_iterate(x, y) {
-    maxval = MAX(maxval, hmap(x, y));
-    minval = MIN(minval, hmap(x, y));
+    max = MAX(max, hmap(x, y));
+    min = MIN(min, hmap(x, y));
   } whole_map_iterate_end;
 
-  /* Translate heights so the minimum height is 0. */
-  maxval -= minval;
-  whole_map_iterate(x, y) {
-    hmap(x, y) -= minval;
-  } whole_map_iterate_end;
+  {
+    int const size = 1 + max - min;
+    int i, count = 0, frequencies[size];
+
+    INITIALIZE_ARRAY(frequencies, size, 0);
+
+    /* Translate heights so the minimum height is 0
+       and count the number of accurnecies in all values to initialise the 
+       frequencies[] (frequency is the right word in probability for it)   */
+    whole_map_iterate(x, y) {
+      hmap(x, y) = (hmap(x, y) - min);
+      frequencies[hmap(x, y)]++;
+    } whole_map_iterate_end;
+
+    /* create the linearize function as "incremental" frequencies */
+    for(i =  0; i < size; i++) {
+      count += frequencies[i]; 
+      frequencies[i] = (count * hmap_max_level ) / MAX_MAP_INDEX;
+    }
+
+    /* apply the linearize function */
+    whole_map_iterate(x, y) {
+      hmap(x, y) = frequencies[hmap(x, y)];
+    } whole_map_iterate_end; 
+  }
 }
 
 /**************************************************************************