Kept mod trees on plantable ground

- A mod biome that brings its own vegetation pays a template penalty scaled by the share of the template's top surface layer that cannot hold plants, so snow, ice, sand, and stone templates no longer swallow its trees
- The top layer palette is resolved through biome-palette snippets and weighted by palette entry weight
- Mod biomes without their own vegetation keep the closest climate template

core/src/test/java/art/arcane/iris/pack/ingest/IngestPlantableSurfaceTest.java

@@ -0,0 +1,124 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package art.arcane.iris.pack.ingest;
+
+import art.arcane.iris.pack.ingest.catalog.CatalogBiome;
+import art.arcane.iris.pack.ingest.catalog.CatalogDimensionType;
+import art.arcane.iris.pack.ingest.catalog.CatalogNamespace;
+import art.arcane.iris.pack.ingest.catalog.CatalogPlacedFeature;
+import art.arcane.iris.pack.ingest.catalog.WorldgenCatalog;
+import com.google.gson.JsonParser;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import static org.junit.Assert.assertTrue;
+
+public class IngestPlantableSurfaceTest {
+    private static final String MOD = "modtrees";
+    private static final int VEGETAL_STEP = ModIngestFixture.VEGETAL_STEP;
+
+    @Rule
+    public TemporaryFolder folder = new TemporaryFolder();
+
+    @Test
+    public void modBiomesWithTheirOwnTreesAvoidSnowCoveredTemplates() throws Exception {
+        ModIngestReport report = ingest();
+
+        assertTrue(reason(report, "snowy_maple_woods"), reason(report, "snowy_maple_woods").contains("in region tundra from template tundra/"));
+        assertTrue(reason(report, "scarlet_peaks"), reason(report, "scarlet_peaks").contains("in region tundra from template tundra/"));
+    }
+
+    @Test
+    public void modBiomesWithoutVegetationKeepTheBestClimateTemplate() throws Exception {
+        ModIngestReport report = ingest();
+
+        assertTrue(reason(report, "frost_flats"), reason(report, "frost_flats").contains("from template frozen/plains"));
+    }
+
+    private ModIngestReport ingest() throws IOException {
+        Path root = folder.newFolder().toPath();
+        Path source = root.resolve("source");
+        ModIngestFixture.write(source, "dimensions/overworld.json", """
+                {"name": "Overworld", "environment": "NORMAL", "regions": ["frozen", "tundra"], "dimensionHeight": {"min": -64, "max": 320}}
+                """);
+        ModIngestFixture.write(source, "regions/frozen.json", """
+                {"name": "Frozen", "landBiomes": ["frozen/plains", "frozen/slopes"]}
+                """);
+        ModIngestFixture.write(source, "regions/tundra.json", """
+                {"name": "Tundra", "landBiomes": ["tundra/taiga", "tundra/mountain-forest"]}
+                """);
+        ModIngestFixture.write(source, "snippet/biome-palette/snow/top.json", """
+                {"palette": [{"block": "minecraft:snow_block"}], "minHeight": 1, "maxHeight": 1}
+                """);
+        biome(source, "frozen/plains", "minecraft:snowy_plains", "\"snippet/biome-palette/snow/top\"");
+        biome(source, "frozen/slopes", "minecraft:snowy_slopes", "\"snippet/biome-palette/snow/top\"");
+        biome(source, "tundra/taiga", "minecraft:taiga", "{\"palette\": [{\"block\": \"grass_block\"}]}");
+        biome(source, "tundra/mountain-forest", "minecraft:windswept_forest", "{\"palette\": [{\"block\": \"minecraft:grass_block\", \"weight\": 3}, {\"block\": \"minecraft:snow_block\"}]}");
+        Path target = root.resolve("packs").resolve("trees");
+        return ModIngester.ingest(new ModIngestRequest(source, target, "overworld", catalog(), Set.of(MOD), Set.of(), false));
+    }
+
+    private static void biome(Path pack, String key, String derivative, String topLayer) throws IOException {
+        ModIngestFixture.write(pack, "biomes/" + key + ".json", "{\"name\": \"" + key + "\", \"derivative\": \"" + derivative
+                + "\", \"layers\": [" + topLayer + ", {\"palette\": [{\"block\": \"minecraft:dirt\"}]}]}");
+    }
+
+    private static WorldgenCatalog catalog() {
+        List<CatalogBiome> biomes = new ArrayList<>();
+        biomes.add(biome("minecraft:snowy_plains", 0.0F, 0.5F, List.of("c:is_snowy", "c:is_plains"), List.of()));
+        biomes.add(biome("minecraft:snowy_slopes", -0.3F, 0.9F, List.of("c:is_snowy", "minecraft:is_mountain"), List.of()));
+        biomes.add(biome("minecraft:taiga", 0.25F, 0.8F, List.of("minecraft:is_taiga"), List.of()));
+        biomes.add(biome("minecraft:windswept_forest", 0.2F, 0.3F, List.of("minecraft:is_mountain", "minecraft:is_forest"), List.of()));
+        biomes.add(biome(MOD + ":snowy_maple_woods", 0.0F, 0.5F, List.of("c:is_snowy"), List.of(MOD + ":maple_trees")));
+        biomes.add(biome(MOD + ":scarlet_peaks", -0.3F, 0.9F, List.of("c:is_snowy", "minecraft:is_mountain"), List.of(MOD + ":scarlet_trees")));
+        biomes.add(biome(MOD + ":frost_flats", 0.0F, 0.5F, List.of("c:is_snowy", "c:is_plains"), List.of()));
+        List<CatalogPlacedFeature> features = List.of(tree("maple_trees"), tree("scarlet_trees"));
+        return new WorldgenCatalog(WorldgenCatalog.FORMAT, "26.3", "fabric", 1L, "plantable",
+                List.of(new CatalogNamespace(MOD, "Mod Trees", "1")), biomes, features, List.of(),
+                List.of(new CatalogDimensionType("minecraft:overworld", -64, 384, 384, null)), List.of(), Map.of());
+    }
+
+    private static CatalogPlacedFeature tree(String path) {
+        String key = MOD + ":" + path;
+        return new CatalogPlacedFeature(key, key, "minecraft:tree", JsonParser.parseString("{}"),
+                JsonParser.parseString("[{\"type\": \"minecraft:count\", \"count\": 4}]"));
+    }
+
+    private static CatalogBiome biome(String key, float temperature, float downfall, List<String> tags, List<String> vegetal) {
+        List<List<String>> steps = new ArrayList<>(11);
+        for (int index = 0; index < 11; index++) {
+            steps.add(index == VEGETAL_STEP ? vegetal : List.of());
+        }
+        List<String> allTags = new ArrayList<>(tags);
+        allTags.add("minecraft:is_overworld");
+        return new CatalogBiome(key, temperature, downfall, true, allTags, steps, List.of(), null);
+    }
+
+    private static String reason(ModIngestReport report, String biome) {
+        return ModIngestFixture.item(report, MOD + ":" + biome).reason();
+    }
+}