Replace map variant randomness with perlin noise

map_formspec.lua

@@ -1,9 +1,26 @@
 local TILE_SIZE = 0.25;
 local TILE_OFFSET = 0.24; -- Slightly smaller than TILE_SIZE. We overlap tiles slightly to minimize seams
 
-local variant_odds = { 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4 };
+-- NoiseParams table for tile variations
-local function get_variant(random)
+local MAP_NOISE = {
-    return variant_odds[random:next(1, 12)];
+    offset = 0,
+    scale = 1,
+    spread = {x = 2, y = 2, z = 2},
+    seed = minetest.get_mapgen_setting("seed"),
+    octaves = 2,
+    persist = 0.63,
+    lacunarity = 2.0,
+    flags = "defaults, absvalue",
+};
+
+-- Get the variant of the tile at a given position
+-- x: The X position of the tile (in map coordinates)
+-- z: The Z position of the tile (in map coordinates)
+-- noise: A 2d lookup table of perlin noise. Must contain the position [x + 1][y + 1]
+--
+-- Returns a number from 1 to 4
+local function get_variant(x, z, noise)
+    return math.floor(math.min(noise[x + 1][z + 1] * 3, 3)) + 1;
 end
 
 local map_formspec_prefix = [[
@@ -43,7 +60,7 @@ end
 -- Returns a formspec string
 local function generate_map(data, x, y, w, h, player_x, player_y, detail, map_scale, is_visible, get_marker, user)
     local str = "";
-    local random = PcgRandom(x + y + w + h); -- TODO: Better seed
+    local noise = PerlinNoiseMap(MAP_NOISE, { x=w + 1, y=h + 1, z=1}):get_2d_map({ x=x, y=y});
     player_x = math.floor(player_x / map_scale + 0.5);
     player_y = math.floor(player_y / map_scale + 0.5);
 
@@ -53,7 +70,7 @@ local function generate_map(data, x, y, w, h, player_x, player_y, detail, map_sc
         for j = y + h,y,-1 do
             local fy = (y + h - j) * TILE_OFFSET;
             if column == nil or column[j * map_scale] == nil or (is_visible and not is_visible(user, i, j)) then
-                str = str .. unknown_biome_tile(fx, fy, get_variant(random));
+                str = str .. unknown_biome_tile(fx, fy, get_variant(i - x, j - y, noise));
             else
                 local name = minetest.get_biome_name(column[j * map_scale].biome);
                 local height = column[j * map_scale].height;
@@ -73,7 +90,7 @@ local function generate_map(data, x, y, w, h, player_x, player_y, detail, map_sc
                         mod = "^[colorize:#1f1f34:"..tostring(depth * 10)
                     end
 
-                    str = str..tile:format(fx, fy - height, TILE_SIZE, TILE_SIZE, biome .. "." .. tostring(get_variant(random)) .. ".png" .. mod)
+                    str = str..tile:format(fx, fy - height, TILE_SIZE, TILE_SIZE, biome .. "." .. tostring(get_variant(i - x, j - y, noise)) .. ".png" .. mod)
 
                     if get_marker then
                         local marker = cartographer.get_marker_texture(get_marker(user, i, j), detail);
@@ -90,7 +107,7 @@ local function generate_map(data, x, y, w, h, player_x, player_y, detail, map_sc
                                                  cartographer.skin.player_icon.frame_duration);
                     end
                 else
-                    str = str .. unknown_biome_tile(fx, fy, get_variant(random));
+                    str = str .. unknown_biome_tile(fx, fy, get_variant(i - x, j - y, noise));
                 end
             end
         end