Calibrated converted decorator density

- Patch decorators converted from features that snap to a leaf-blocked heightmap lose the share of placements that land on tree canopy in the declaring biomes
- Canopy is estimated from the tree-like features that run before the decoration in each declaring biome's vegetal step, using their expected per-chunk count and a typical crown footprint
- Patches that snap below leaves or run before the trees keep their full density

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

@@ -0,0 +1,66 @@
+/*
+ * 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.CatalogNamespace;
+import art.arcane.iris.pack.ingest.catalog.CatalogPlacedFeature;
+import art.arcane.iris.pack.ingest.catalog.WorldgenCatalog;
+import art.arcane.iris.pack.ingest.catalog.WorldgenCatalogIndex;
+import com.google.gson.JsonParser;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+import static org.junit.Assert.assertEquals;
+
+public class CanopyEstimateTest {
+    private static final double CANOPY = 1D - Math.exp(-10D * CanopyEstimate.CROWN_COLUMNS / 256D);
+
+    @Test
+    public void flowersPlacedAfterTreesSeeTheTreeCanopy() {
+        CanopyEstimate estimate = new CanopyEstimate(WorldgenCatalogIndex.of(catalog()));
+
+        assertEquals(CANOPY, estimate.occlusion("mod:flowers_after", Set.of("mod:woods")), 0.000001D);
+        assertEquals(0D, estimate.occlusion("mod:flowers_before", Set.of("mod:woods")), 0.000001D);
+        assertEquals(CANOPY / 2D, estimate.occlusion("mod:flowers_after", Set.of("mod:woods", "mod:meadow")), 0.000001D);
+    }
+
+    private static WorldgenCatalog catalog() {
+        List<CatalogBiome> biomes = List.of(
+                biome("mod:woods", List.of("mod:flowers_before", "mod:oak_trees", "mod:flowers_after")),
+                biome("mod:meadow", List.of("mod:flowers_after")));
+        List<CatalogPlacedFeature> features = new ArrayList<>();
+        features.add(new CatalogPlacedFeature("mod:oak_trees", "mod:oak_trees", "minecraft:tree", JsonParser.parseString("{}"),
+                JsonParser.parseString("[{\"type\": \"minecraft:count\", \"count\": 10}, {\"type\": \"minecraft:in_square\"},"
+                        + "{\"type\": \"minecraft:surface_water_depth_filter\", \"max_water_depth\": 0}, {\"type\": \"minecraft:biome\"}]")));
+        return new WorldgenCatalog(WorldgenCatalog.FORMAT, "26.3", "fabric", 1L, "canopy", List.of(new CatalogNamespace("mod", "Mod", "1")),
+                biomes, features, List.of(), List.of(), List.of());
+    }
+
+    private static CatalogBiome biome(String key, List<String> vegetal) {
+        List<List<String>> steps = new ArrayList<>(11);
+        for (int index = 0; index < 11; index++) {
+            steps.add(index == ModIngestFixture.VEGETAL_STEP ? vegetal : List.of());
+        }
+        return new CatalogBiome(key, 0.7F, 0.8F, true, List.of("minecraft:is_overworld"), steps, List.of(), null);
+    }
+}

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

@@ -114,12 +114,29 @@ public class FeatureConverterFormatTest {
                         + "{\"type\": \"minecraft:heightmap\", \"heightmap\": \"WORLD_SURFACE_WG\"}, {\"type\": \"minecraft:biome\"},"
                         + "{\"type\": \"minecraft:count\", \"count\": 96}," + PATCH_TAIL + "]");
 
-        JsonObject decorator = PatchDecoratorConverter.convert(lavender, index());
+        JsonObject decorator = PatchDecoratorConverter.convert(lavender, index(), 0D);
 
         assertEquals(1.0D - Math.exp(-(15.0D * 96.0D * 0.25D) / 256.0D), decorator.get("chance").getAsDouble(), 0.000001D);
         assertTrue(decorator.get("chance").getAsDouble() < 1.0D);
     }
 
+    @Test
+    public void leafBlockedHeightmapsLoseTheCanopyShareOfTheirPlacements() throws Exception {
+        CatalogPlacedFeature lavender = feature(PatchDecoratorConverter.SIMPLE_BLOCK,
+                "{\"type\": \"minecraft:simple_block\", \"to_place\": {\"id\": \"examplemod:lavender\"}}",
+                "[{\"type\": \"minecraft:count\", \"count\": 4}, {\"type\": \"minecraft:in_square\"},"
+                        + "{\"type\": \"minecraft:heightmap\", \"heightmap\": \"MOTION_BLOCKING\"}, {\"type\": \"minecraft:biome\"}]");
+        CatalogPlacedFeature underLeaves = feature(PatchDecoratorConverter.SIMPLE_BLOCK,
+                "{\"type\": \"minecraft:simple_block\", \"to_place\": {\"id\": \"examplemod:lavender\"}}",
+                "[{\"type\": \"minecraft:count\", \"count\": 4}, {\"type\": \"minecraft:in_square\"},"
+                        + "{\"type\": \"minecraft:heightmap\", \"heightmap\": \"MOTION_BLOCKING_NO_LEAVES\"}, {\"type\": \"minecraft:biome\"}]");
+
+        assertEquals(1.0D - Math.exp(-(4.0D * 0.5D) / 256.0D),
+                PatchDecoratorConverter.convert(lavender, index(), 0.5D).get("chance").getAsDouble(), 0.000001D);
+        assertEquals(1.0D - Math.exp(-4.0D / 256.0D),
+                PatchDecoratorConverter.convert(underLeaves, index(), 0.5D).get("chance").getAsDouble(), 0.000001D);
+    }
+
     @Test
     public void unnamespacedTypesAndClampedCountsConvert() throws Exception {
         CatalogPlacedFeature flowers = feature("simple_block", "{\"type\": \"simple_block\", \"to_place\": {\"id\": \"minecraft:poppy\"}}", """
@@ -134,7 +151,7 @@ public class FeatureConverterFormatTest {
                  {"type": "minecraft:biome"}]
                 """);
 
-        JsonObject decorator = PatchDecoratorConverter.convert(flowers, index());
+        JsonObject decorator = PatchDecoratorConverter.convert(flowers, index(), 0D);
 
         assertEquals(1.0D - Math.exp(-(0.5D * 0.2D * 0.25D) / 256.0D), decorator.get("chance").getAsDouble(), 0.000001D);
         assertEquals("minecraft:grass_block", decorator.getAsJsonArray("whitelist").get(0).getAsJsonObject().get("block").getAsString());
@@ -149,8 +166,8 @@ public class FeatureConverterFormatTest {
                 "{\"type\": \"minecraft:simple_block\", \"to_place\": \"minecraft:flower_plain\"}",
                 "[{\"type\": \"minecraft:heightmap\", \"heightmap\": \"MOTION_BLOCKING\"}]");
 
-        assertThrows(IngestConversionException.class, () -> PatchDecoratorConverter.convert(seagrass, index()));
-        IngestConversionException reference = assertThrows(IngestConversionException.class, () -> PatchDecoratorConverter.convert(plains, index()));
+        assertThrows(IngestConversionException.class, () -> PatchDecoratorConverter.convert(seagrass, index(), 0D));
+        IngestConversionException reference = assertThrows(IngestConversionException.class, () -> PatchDecoratorConverter.convert(plains, index(), 0D));
         assertTrue(reference.getMessage(), reference.getMessage().contains("minecraft:flower_plain"));
     }
 

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

@@ -123,7 +123,9 @@ public class ModIngesterFeatureTest {
         assertNotNull(mapleFlowers);
         assertNotNull(forestFlowers);
         assertEquals(2, forest.getAsJsonArray("decorators").size());
-        assertEquals(1.0D - Math.exp(-(1.0D / 4.0D * 32.0D * 0.25D) / 256.0D), forestFlowers.get("chance").getAsDouble(), 0.000001D);
+        double mapleCanopy = 1.0D - Math.exp(-CanopyEstimate.CROWN_COLUMNS / 256.0D);
+        double openShare = 1.0D - mapleCanopy / 2.0D;
+        assertEquals(1.0D - Math.exp(-(1.0D / 4.0D * 32.0D * 0.25D * openShare) / 256.0D), forestFlowers.get("chance").getAsDouble(), 0.000001D);
         JsonArray palette = forestFlowers.getAsJsonArray("palette");
         assertEquals(3, palette.get(0).getAsJsonObject().get("weight").getAsInt());
         assertEquals("examplemod:glowbell", palette.get(1).getAsJsonObject().get("block").getAsString());