Add fallback texture support in case of scanned-but-unknown biomes

biome_api.lua

@@ -1,8 +1,14 @@
 -- Arguments
 -- util: API for uncategorized utility methods
-local util = ...;
+local util,skin = ...
 
-local biome_lookup = {};
+local biome_lookup = {}
+local fallback_biome_lookup = {}
+
+local function match_biome_metrics (biome, height)
+    return (not biome.min_height or height >= biome.min_height)
+       and (not biome.max_height or height <= biome.max_height)
+end
 
 -- Contains functions for registering and getting biome-related mapping information
 return {
@@ -20,7 +26,22 @@ return {
             textures = textures,
             min_height = min_height,
             max_height = max_height,
-        };
+        }
+    end,
+
+    -- Register fallback biome textures to use when a biome hasn't been registered
+    --
+    -- textures: A table of texture names.
+    --           These should correspond with detail levels,
+    --           any detail level past the length of the table will return the last texture
+    -- (Optional) min_height: The minimum Y position where these textures should be used
+    -- (Optional) max_height: The maximum Y position where these textures should be used
+    add_fallback = function (textures, min_height, max_height)
+        table.insert(fallback_biome_lookup, {
+            textures = textures,
+            min_height = min_height,
+            max_height = max_height,
+        })
     end,
 
     -- Get the texture name (minus index/extension) for the given biome, height, and detail level.
@@ -29,16 +50,22 @@ return {
     -- height: A number representing the Y position of the biome
     -- detail: The detail level
     --
-    -- Returns a string with a texture name, or nil if no matching biome entry was found.
+    -- Always returns a string with a texture name, if the biome is unregistered it will fallback to other options
     get_texture = function (name, height, detail)
         for _,biome in ipairs(biome_lookup) do
-            local matches_height = (not biome.min_height or height >= biome.min_height)
-            and (not biome.max_height or height <= biome.max_height);
-            if biome.name == name and matches_height then
-                return util.get_clamped(biome.textures, detail);
+            if biome.name == name and match_biome_metrics (biome, height) then
+                return util.get_clamped(biome.textures, detail)
             end
         end
 
-        return nil;
+        -- Fallback on matching default biomes
+        for _,biome in ipairs(fallback_biome_lookup) do
+            if match_biome_metrics (biome, height) then
+                return util.get_clamped(biome.textures, detail)
+            end
+        end
+
+        -- If we don't have any registered defaults, fallback to a texture
+        return util.get_clamped(skin.default_biome_textures, detail)
     end,
-};
+}

init.lua

@@ -16,7 +16,7 @@ local gui = loadfile(modpath .. "/formspec.lua") ();
 local skin = loadfile(modpath .. "/skin_api.lua") ();
 local util = loadfile(modpath .. "/util.lua") ();
 local audio = loadfile(modpath .. "/audio.lua") ();
-local biomes = loadfile(modpath .. "/biome_api.lua") (util);
+local biomes = loadfile(modpath .. "/biome_api.lua") (util, skin);
 local markers = loadfile(modpath .. "/marker_api.lua") ();
 local scanner = loadfile(modpath .. "/scanner.lua") (map_data, chunk, settings);
 local maps = loadfile(modpath .. "/map_api.lua") (map_data, chunk);

map_formspec.lua

@@ -86,7 +86,6 @@ local function generate_map(x, y, w, h, player_x, player_y, detail, map_scale, h
                 local height = column[world_j].height;
                 local biome = biomes.get_texture(name, math.floor(height + 0.5), detail);
 
-                if biome then
                 local depth = math.min(math.max(math.floor(height / 8), -8), 0) * -1
                 height = math.max(math.min(math.floor(height / (math.max(map_scale * 0.5, 1) + 4)), 8), 0)
 
@@ -145,17 +144,6 @@ local function generate_map(x, y, w, h, player_x, player_y, detail, map_scale, h
                         animation = player_icon,
                     };
                 end
-                else
-                    local unknown_tex = util.get_clamped(skin.unknown_biome_textures, detail);
-                    str = str .. gui.image {
-                        x = fx,
-                        y = fy,
-                        w = TILE_SIZE,
-                        h = TILE_SIZE,
-
-                        image = get_variant(unknown_tex, i, j, noise),
-                    };
-                end
             end
         end
     end

skin_api.lua

@@ -6,11 +6,16 @@ return {
         "cartographer_cliff",
     };
 
-    -- The textures to use in maps for uncovered/unknown tiles
+    -- The textures to use in maps for undiscovered tiles
     unknown_biome_textures = {
         "cartographer_unknown_biome",
     };
 
+    -- The textures to use in maps for tiles with no associated biome
+    default_biome_textures = {
+        "cartographer_default_biome",
+    };
+
     -- The animated texture data to use for the player icon
     player_icons = {
         {