[1.17.1] Custom Structures (also a little bit of entity spawning)

[Goosey]

A long time ago I tried to make a Minecraft mod (key word is tried). I knew a lot less about Java back then and I mainly relied on the tutorial videos I found. Recently I decided to try and get back into it, and I found it was really fun! I've started doing things that I had no chance of figuring out how to do last time like implementing custom mobs and even bosses. The biggest problem is that there are close to no tutorials or any actual useful documentation for forge 1.17.1, but because of my increased skill level since my last modding attempt, I haven't had to rely on tutorials that much

I recently started trying to add custom entity spawning to the game, but couldn't figure out how to do it in the current forge version. Eventually I just decided to use reflection to add my own data into the vanilla map of "spawners" in net.minecraft.world.level.biome.MobSpawnSettings. This obviously isn't the intended way to add custom entity spawning to the game but because I can't find anything on this subject online, I did it and it works. Entity spawning isn't the main subject of this post, but it gives you the backstory of what I'm about to do (or more specifically, what I did).

After that, I wanted to add my own custom structure. I decided to add an RV that spawns in deserts and mesa biomes so I just looked at how vanilla adds structures.

I created all the proper java classes for the structure itself (The Feature class and the Pieces class) and created a StructureFeature field and a ConfiguredStructureFeature from that Feature. Then in a similar fashion to what I did with the entities, In biomes I wanted my structure to spawn in, I added my ConfiguredStructureFeature to "structureStarts" in net.minecraft.world.level.biome.BiomeGenerationSettings using reflection.

On top of that I also added my own StructureFeatureConfiguration to "BUILTIN_OVERWORLD" from net.minecraft.world.level.levelgen.NoiseGeneratorSettings.

If you're wondering, it works... kind of

When I create a new world, It will spawn the structures but after I exit that world it will take a long time to load the world and there are many EOFExceptions in the console. I did the best job I could do with debugging and found that the error was happening while loading the NBT data for structures in every chunk. It is having a lot of trouble when trying to do something having to do with structure references. I have done my best to try and see exactly what is going wrong in the code and how I can fix it, but frankly, I'm stumped and I have no idea of how to fix it. Honestly the way to fix it is probably to stop using reflection and to just properly register my structures, but I don't know how to do that. After I've exhausted every single solution I can think of, I finally decided to come here and ask for help.

My code for world generation:

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public class ModWorldGeneration {
    public static ImmutableList<OreConfiguration.TargetBlockState> MANHUNT_TARGET_LIST;
    public static ConfiguredFeature<?, ?> MANHUNT;

    public static StructureFeature<NoneFeatureConfiguration> RV_FEATURE = (StructureFeature<NoneFeatureConfiguration>) new RVFeature().setRegistryName("rv");
    public static ConfiguredStructureFeature<NoneFeatureConfiguration, ? extends StructureFeature<NoneFeatureConfiguration>> RV_CONFIGURED;

    @Mod.EventBusSubscriber(modid = GooseMod.MODID, bus = Mod.EventBusSubscriber.Bus.FORGE)
    public static class ForgeBus {
        private static final Logger LOGGER = LogManager.getLogger();

        public static void registerConfiguredFeatures() {
            // IGNORE NAMES
            MANHUNT_TARGET_LIST = ImmutableList.of(OreConfiguration.target(OreConfiguration.Predicates.NATURAL_STONE, ModBlocks.MANHUNT.defaultBlockState()), OreConfiguration.target(OreConfiguration.Predicates.STONE_ORE_REPLACEABLES, ModBlocks.MANHUNT.defaultBlockState()));
            MANHUNT = (ConfiguredFeature) ((ConfiguredFeature) ((ConfiguredFeature) Feature.ORE.configured(new OreConfiguration(MANHUNT_TARGET_LIST, 8)).rangeUniform(VerticalAnchor.absolute(16), VerticalAnchor.absolute(32))).squared()).count(31);
            Registry.register(BuiltinRegistries.CONFIGURED_FEATURE, new ResourceLocation(GooseMod.MODID, "manhunt"), MANHUNT);

            // rv
            RV_CONFIGURED = RV_FEATURE.configured(NoneFeatureConfiguration.INSTANCE);
            LOGGER.info("RV_FEATURE: {}", RV_CONFIGURED);
        }

        @SubscribeEvent(priority = EventPriority.HIGH)
        public static void registerBiomeModification(BiomeLoadingEvent event) {
            // custom ore
            event.getGeneration().getFeatures(GenerationStep.Decoration.UNDERGROUND_ORES).add(() -> MANHUNT);
            // add the rv to biomes
            if (event.getCategory() == Biome.BiomeCategory.DESERT || event.getCategory() == Biome.BiomeCategory.MESA) {
                event.getGeneration().getStructures().add(() -> RV_CONFIGURED);
                StringBuilder s = new StringBuilder();
                for (Supplier<ConfiguredStructureFeature<?, ?>> feature : event.getGeneration().getStructures()) {
                    s.append(feature.get().feature.getRegistryName()).append(", ");
                }
                s.delete(s.length() - 2, s.length());
                LOGGER.info("structures in {}: [{}]", event.getName(), s.toString());
            }
        }
    }

    @Mod.EventBusSubscriber(modid = GooseMod.MODID, bus = Mod.EventBusSubscriber.Bus.MOD)
    public static class ModBus {
        private static final Logger LOGGER = LogManager.getLogger();

        @SubscribeEvent
        public static void loadComplete(FMLLoadCompleteEvent event) {
            // just logging here
            StringBuilder s1 = new StringBuilder();
            boolean print1 = false;
            for (StructureFeature<?> feature : ForgeRegistries.STRUCTURE_FEATURES.getValues()) {
                print1 = true;
                s1.append(feature.getRegistryName()).append(", ");
            }
            if (print1) {
                s1.delete(s1.length() - 2, s1.length());
                LOGGER.info("All structure features: [{}]", s1.toString());
            }
            LOGGER.info(ForgeRegistries.STRUCTURE_FEATURES.getValues());
            // loop over biomes
            for (Biome biome : ForgeRegistries.BIOMES) {
                // rv biome
                if (biome.getBiomeCategory() == Biome.BiomeCategory.DESERT || biome.getBiomeCategory() == Biome.BiomeCategory.MESA) {
                    // override structure starts
                    try {
                        Field field = BiomeGenerationSettings.class.getDeclaredField("structureStarts");
                        field.setAccessible(true);
                        List<Supplier<ConfiguredStructureFeature<?, ?>>> oldStructures = (List<Supplier<ConfiguredStructureFeature<?, ?>>>) field.get(biome.getGenerationSettings());
                        List<Supplier<ConfiguredStructureFeature<?, ?>>> newStructures = new ArrayList<>();
                        for (Supplier<ConfiguredStructureFeature<?, ?>> structure : oldStructures) {
                            newStructures.add(structure);
                        }
                        newStructures.add(() -> RV_CONFIGURED);
                        field.set(biome.getGenerationSettings(), newStructures);
                    } catch (NoSuchFieldException | IllegalAccessException e) {
                        e.printStackTrace();
                    }
                }
                // logging stuff here
                StringBuilder s = new StringBuilder();
                boolean print = false;
                for (Supplier<ConfiguredStructureFeature<?, ?>> feature : biome.getGenerationSettings().structures()) {
                    print = true;
                    s.append(feature.get().feature.getRegistryName()).append(", ");
                }
                if (print) {
                    s.delete(s.length() - 2, s.length());
                    LOGGER.info("structures in {}:\n [{}]", biome.getRegistryName(), s.toString());
                }
                // lemur biome
                if (biome.getBiomeCategory() == Biome.BiomeCategory.JUNGLE) {
                    // spawn lemurs
                    try {
                        // make spawn settings accessible
                        Field field = MobSpawnSettings.class.getDeclaredField("spawners");
                        field.setAccessible(true);
                        // get current spawn settings
                        Map<MobCategory, WeightedRandomList<MobSpawnSettings.SpawnerData>> oldSpawners = (Map<MobCategory, WeightedRandomList<MobSpawnSettings.SpawnerData>>) field.get(biome.getMobSettings());
                        // create a new list of old spawn settings plus the ones we want to add
                        Map<MobCategory, ArrayList<MobSpawnSettings.SpawnerData>> newSpawners = new HashMap<>();
                        // add old spawn settings to list
                        for (MobCategory category : oldSpawners.keySet()) {
                            newSpawners.put(category, Lists.newArrayList(oldSpawners.get(category).unwrap()));
                        }
                        // add new spawn settings
                        newSpawners.get(MobCategory.AMBIENT).add(new MobSpawnSettings.SpawnerData(ModEntityTypes.LEMUR, 100, 5, 10));
                        // replace old spawner settings list
                        field.set(biome.getMobSettings(), newSpawners.entrySet().stream().collect(ImmutableMap.toImmutableMap(Map.Entry::getKey, (list) -> WeightedRandomList.create(list.getValue()))));
                    } catch (NoSuchFieldException | IllegalAccessException e) {
                        e.printStackTrace();
                    }
                }
            }

            // add rv to vanilla overworld
            try {
                Field field = NoiseGeneratorSettings.class.getDeclaredField("BUILTIN_OVERWORLD");
                field.setAccessible(true);
                NoiseGeneratorSettings BUILTIN_OVERWORLD = (NoiseGeneratorSettings) field.get(null);
                // I don't know what I should actually make the salt so imma just pick 15000000
                BUILTIN_OVERWORLD.structureSettings().structureConfig().put(RV_FEATURE, new StructureFeatureConfiguration(32, 8, 15000000));
            } catch (NoSuchFieldException | IllegalAccessException e) {
                e.printStackTrace();
            }
        }
    }

}

 

[Luis_ST]

you can use BiomeLoadingEvent instead of Reflection, which version of forge do you exactly using 1.17.x.x.x because the first version throws an EOFException

[Goosey]

  On 10/15/2021 at 4:34 AM, Luis_ST said:

which version of forge do you exactly using 1.17.x.x.x because the first version throws an EOFException

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My mod is for minecraft 1.17.1, forge 37.0.67. Should I move my project to 37.0.95?

  Quote

you can use BiomeLoadingEvent instead of Reflection

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I utilize BiomeLoadingEvent at line 68 in my code, but that alone did not add structures to the game. I also had to use reflection to add my own StructureFeatureConfiguration.

[Luis_ST]

  On 10/16/2021 at 12:45 AM, Goosey said:

I utilize BiomeLoadingEvent at line 68 in my code, but that alone did not add structures to the game. I also had to use reflection to add my own StructureFeatureConfiguration.

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show the code of your Structure, if possible via a git repo 

[Goosey]

  On 10/16/2021 at 8:55 AM, Luis_ST said:

show the code of your Structure, if possible via a git repo 

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The code which utilizes BiomeLoadingEvent I have already shown above but here it is again:

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@SubscribeEvent(priority = EventPriority.HIGH)
        public static void registerBiomeModification(BiomeLoadingEvent event) {
            // custom ore
            event.getGeneration().getFeatures(GenerationStep.Decoration.UNDERGROUND_ORES).add(() -> MANHUNT);
            // add the rv to biomes
            if (event.getCategory() == Biome.BiomeCategory.DESERT || event.getCategory() == Biome.BiomeCategory.MESA) {
                event.getGeneration().getStructures().add(() -> RV_CONFIGURED);
                StringBuilder s = new StringBuilder();
                for (Supplier<ConfiguredStructureFeature<?, ?>> feature : event.getGeneration().getStructures()) {
                    s.append(feature.get().feature.getRegistryName()).append(", ");
                }
                s.delete(s.length() - 2, s.length());
                LOGGER.info("structures in {}: [{}]", event.getName(), s.toString());
            }
        }

 

This code for the feature is this:

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public class RVFeature extends StructureFeature<NoneFeatureConfiguration> {
    public RVFeature() {
        super(NoneFeatureConfiguration.CODEC);
    }

    public StructureFeature.StructureStartFactory<NoneFeatureConfiguration> getStartFactory() {
        return RVFeature.FeatureStart::new;
    }

    @Override
    public GenerationStep.Decoration step() {
        return GenerationStep.Decoration.SURFACE_STRUCTURES;
    }

    @Override
    public String getFeatureName() {
        return super.getFeatureName();
    }

    public static class FeatureStart extends StructureStart<NoneFeatureConfiguration> {
        public FeatureStart(StructureFeature<NoneFeatureConfiguration> p_159550_, ChunkPos p_159551_, int p_159552_, long p_159553_) {
            super(p_159550_, p_159551_, p_159552_, p_159553_);
        }

        public void generatePieces(RegistryAccess registry, ChunkGenerator generator, StructureManager manager, ChunkPos chunkPos, Biome biome, NoneFeatureConfiguration codec, LevelHeightAccessor height) {
            BlockPos blockpos = new BlockPos(chunkPos.getMinBlockX(), 90, chunkPos.getMinBlockZ());
            Rotation rotation = Rotation.getRandom(this.random);
            RVPiece rvpiece = new RVPiece(manager, RVPiece.STRUCTURE_LOCATION, blockpos, rotation);
            this.addPiece(rvpiece);
        }
    }
}

 

And the code for the structure piece is this:

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public class RVPiece extends TemplateStructurePiece {
    public static final StructurePieceType RV = StructurePieceType.setPieceId(RVPiece::new, "GMBbRv");
    static final ResourceLocation STRUCTURE_LOCATION = new ResourceLocation(GooseMod.MODID, "rv/rv");

    public RVPiece(StructureManager manager, ResourceLocation nbt, BlockPos pos, Rotation rotation) {
        super(RV, 0, manager, nbt, nbt.toString(), makeSettings(rotation, nbt), pos);
    }

    public RVPiece(ServerLevel p_162441_, CompoundTag p_162442_) {
        super(RV, p_162442_, p_162441_, (p_162451_) -> makeSettings(Rotation.valueOf(p_162442_.getString("Rot")), p_162451_));
    }

    private static StructurePlaceSettings makeSettings(Rotation p_162447_, ResourceLocation p_162448_) {
        return (new StructurePlaceSettings()).setRotation(p_162447_).setMirror(Mirror.NONE).setRotationPivot(new BlockPos(0, 0, 0)).addProcessor(BlockIgnoreProcessor.STRUCTURE_BLOCK);
    }

    protected void addAdditionalSaveData(ServerLevel p_162444_, CompoundTag p_162445_) {
        super.addAdditionalSaveData(p_162444_, p_162445_);
        p_162445_.putString("Rot", this.placeSettings.getRotation().name());
    }

    protected void handleDataMarker(String p_71260_, BlockPos p_71261_, ServerLevelAccessor p_71262_, Random p_71263_, BoundingBox p_71264_) {
        if ("chest".equals(p_71260_)) {
            p_71262_.setBlock(p_71261_, Blocks.AIR.defaultBlockState(), 3);
            BlockEntity blockentity = p_71262_.getBlockEntity(p_71261_.below());
            if (blockentity instanceof ChestBlockEntity) {
                ((ChestBlockEntity)blockentity).setLootTable(BuiltInLootTables.IGLOO_CHEST, p_71263_.nextLong());
            }

        }
    }

    public boolean postProcess(WorldGenLevel p_71250_, StructureFeatureManager p_71251_, ChunkGenerator p_71252_, Random p_71253_, BoundingBox p_71254_, ChunkPos p_71255_, BlockPos p_71256_) {
        ResourceLocation resourcelocation = new ResourceLocation(this.templateName);
        StructurePlaceSettings structureplacesettings = makeSettings(this.placeSettings.getRotation(), resourcelocation);
        BlockPos blockpos1 = this.templatePosition.offset(StructureTemplate.calculateRelativePosition(structureplacesettings, new BlockPos(3, 0, 0)));
        int i = p_71250_.getHeight(Heightmap.Types.WORLD_SURFACE_WG, blockpos1.getX(), blockpos1.getZ());
        BlockPos blockpos2 = this.templatePosition;
        this.templatePosition = this.templatePosition.offset(0, i - 90 - 1, 0);
        boolean flag = super.postProcess(p_71250_, p_71251_, p_71252_, p_71253_, p_71254_, p_71255_, p_71256_);
        if (resourcelocation.equals(RVPiece.STRUCTURE_LOCATION)) {
            BlockPos blockpos3 = this.templatePosition.offset(StructureTemplate.calculateRelativePosition(structureplacesettings, new BlockPos(3, 0, 5)));
            BlockState blockstate = p_71250_.getBlockState(blockpos3.below());
            if (!blockstate.isAir()) {
                p_71250_.setBlock(blockpos3, Blocks.AIR.defaultBlockState(), 3);
            }
        }

        this.templatePosition = blockpos2;
        return flag;
    }
}

 

I mainly took advantage of the many examples in vanilla to make the above two classes

[Cratthorax]

WorldGen you ask? I'd have examples for Decorations, BiomeHandlers, and Features as well. You can refer to post 3 in this thread for some input.

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Edited October 16, 2021 by Cratthorax

[Goosey]

  On 10/16/2021 at 3:45 PM, Cratthorax said:

WorldGen you ask? I'd have examples for Decorations, BiomeHandlers, and Features as well. You can refer to post 3 in this thread for some input.

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The post you linked is for 1.16, I doubt the code would work for 1.17

[Cratthorax]

  On 10/16/2021 at 6:04 PM, Goosey said:

The post you linked is for 1.16, I doubt the code would work for 1.17

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It does with minor changes. I've tested myself. You'll figure.

[Goosey]

I figured it out, thanks.

It turns out I had to use event.getGeneration().addStructureStart() instead of event.getGeneration().getStructures().add() among a few other things like updating my version of forge.