Add compute_density_function to replace removed `sample_noise (#1591)

src/main/java/carpet/script/api/WorldAccess.java

@@ -3,6 +3,7 @@ package carpet.script.api;
 import carpet.CarpetSettings;
 import carpet.fakes.ChunkGeneratorInterface;
 import carpet.fakes.ChunkTicketManagerInterface;
+import carpet.fakes.RandomStateVisitorAccessor;
 import carpet.fakes.ServerChunkManagerInterface;
 import carpet.fakes.ServerWorldInterface;
 import carpet.fakes.SpawnHelperInnerInterface;
@@ -41,15 +42,22 @@ import it.unimi.dsi.fastutil.longs.LongSet;
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.Direction;
 import net.minecraft.core.Holder;
+import net.minecraft.core.HolderLookup;
 import net.minecraft.core.HolderSet;
 import net.minecraft.core.QuartPos;
 import net.minecraft.core.Registry;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.tags.TagKey;
+import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.chunk.PalettedContainer;
+import net.minecraft.world.level.levelgen.DensityFunction;
+import net.minecraft.world.level.levelgen.NoiseBasedChunkGenerator;
+import net.minecraft.world.level.levelgen.NoiseRouter;
+import net.minecraft.world.level.levelgen.RandomState;
 import net.minecraft.world.level.levelgen.structure.Structure;
 import net.minecraft.world.level.levelgen.structure.StructureType;
+import net.minecraft.world.level.levelgen.synth.NormalNoise;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
@@ -1626,23 +1634,68 @@ public class WorldAccess {
     }
 
     @ScarpetFunction(maxParams = -1)
-    public Value sample_noise(Context c, @Locator.Block BlockPos pos, String... noiseQueries) {
-        return Value.NULL;
-        /*
-        int mappedX = QuartPos.fromBlock(pos.getX());
-        int mappedY = QuartPos.fromBlock(pos.getY());
-        int mappedZ = QuartPos.fromBlock(pos.getZ());
-        Climate.Sampler mns = ((CarpetContext) c).s.getLevel().getChunkSource().getGenerator().climateSampler();
-        Map<Value, Value> ret = new HashMap<>();
+    public Value compute_density_function(Context c, @Locator.Block BlockPos pos, String... densityFunctionQueries) {
 
-        if (noiseQueries.length == 0) {
-            noiseQueries = new String[]{"continentalness", "erosion", "weirdness", "temperature", "humidity", "depth"};
+        Map<Value, Value> result = new HashMap<>();
+
+        ServerLevel level = ((CarpetContext) c).level();
+        Registry<DensityFunction> densityFunctionRegistry = level.registryAccess().registryOrThrow(Registries.DENSITY_FUNCTION);
+
+        if (densityFunctionQueries.length == 0) {
+            return ListValue.wrap(densityFunctionRegistry.keySet().stream().map(ValueConversions::of));
         }
 
-        for (String noise : noiseQueries) {
-            double noiseValue = ((NoiseColumnSamplerInterface) mns).getNoiseSample(noise, mappedX, mappedY, mappedZ);
-            ret.put(new StringValue(noise), new NumericValue(noiseValue));
+        ChunkGenerator chunkGenerator = level.getChunkSource().getGenerator();
+        if (!(chunkGenerator instanceof NoiseBasedChunkGenerator generator)) {
+            return MapValue.wrap(result);
         }
-        return MapValue.wrap(ret);*/
+
+        RandomState randomState = RandomState.create(
+            generator.generatorSettings().value(),
+            level.registryAccess().lookupOrThrow(Registries.NOISE), level.getSeed()
+        );
+
+        DensityFunction.Visitor visitor = ((RandomStateVisitorAccessor) (Object) randomState).getVisitor();
+        DensityFunction.SinglePointContext singlePointContext = new DensityFunction.SinglePointContext(pos.getX(), pos.getY(), pos.getZ());
+        NoiseRouter router = generator.generatorSettings().value().noiseRouter();
+
+        for (String densityFunctionQuery : densityFunctionQueries) {
+            DensityFunction densityFunction = switch (densityFunctionQuery) {
+                case "barrier_noise" -> router.barrierNoise();
+                case "fluid_level_floodedness_noise" -> router.fluidLevelFloodednessNoise();
+                case "fluid_level_spread_noise" -> router.fluidLevelSpreadNoise();
+                case "lava_noise" -> router.lavaNoise();
+                case "temperature" -> router.temperature();
+                case "vegetation" -> router.vegetation();
+                case "continents" -> router.continents();
+                case "erosion" -> router.erosion();
+                case "depth" -> router.depth();
+                case "ridges" -> router.ridges();
+                case "initial_density_without_jaggedness" -> router.initialDensityWithoutJaggedness();
+                case "final_density" -> router.finalDensity();
+                case "vein_toggle" -> router.veinToggle();
+                case "vein_ridged" -> router.veinRidged();
+                case "vein_gap" -> router.veinGap();
+                default -> {
+                    ResourceLocation densityFunctionKey = InputValidator.identifierOf(densityFunctionQuery);
+
+                    if (densityFunctionRegistry.containsKey(densityFunctionKey)) {
+                        yield densityFunctionRegistry.get(densityFunctionKey);
+                    }
+
+                    throw new InternalExpressionException(
+                        "Density function '" + densityFunctionQuery + "' doesn't exist. " +
+                        "Please check the spelling or use with full 'namespace:value' if its custom defined."
+                    );
+                }
+            };
+
+            if (densityFunction == null) // IDE thinks may be null as Registry.get is Nullable, but we checked it
+                throw new IllegalStateException("density function can't be null here"); 
+
+            double value = densityFunction.mapAll(visitor).compute(singlePointContext);
+            result.put(StringValue.of(densityFunctionQuery), new NumericValue(value));
+        }
+        return MapValue.wrap(result);
     }
 }