Got most things resolved - NeoForge fully working

common/src/main/java/com/girafi/waddles/CommonClass.java

@@ -1,7 +1,12 @@
 package com.girafi.waddles;
 
+import com.girafi.waddles.init.PenguinRegistry;
+import com.girafi.waddles.init.WaddlesSounds;
+
 public class CommonClass {
 
     public static void init() {
+        WaddlesSounds.load();
+        PenguinRegistry.load();
     }
 }

common/src/main/java/com/girafi/waddles/init/PenguinRegistry.java

@@ -2,6 +2,9 @@
 
 import com.girafi.waddles.Constants;
 import com.girafi.waddles.entity.AdeliePenguinEntity;
+import com.girafi.waddles.registration.RegistrationProvider;
+import com.girafi.waddles.registration.RegistryObject;
+import net.minecraft.core.registries.BuiltInRegistries;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.entity.EntityType;
 import net.minecraft.world.entity.MobCategory;
@@ -15,23 +18,24 @@
 
 public class PenguinRegistry {
     public static final Collection<Supplier<Item>> SPAWN_EGGS = new ArrayList<>();
-    public static final HashMap<String, Supplier<EntityType<? extends AdeliePenguinEntity>>> PENGUINS = new HashMap<>();
-    public static final HashMap<Supplier<EntityType<? extends AdeliePenguinEntity>>, Float> PENGUIN_WIDTHS = new HashMap<>();
-    public static final HashMap<Supplier<EntityType<? extends AdeliePenguinEntity>>, Float> PENGUIN_HEIGHTS = new HashMap<>();
-    public static final HashMap<Supplier<EntityType<? extends AdeliePenguinEntity>>, Integer> PENGUIN_EGG_PRIMARY = new HashMap<>();
-    public static final HashMap<Supplier<EntityType<? extends AdeliePenguinEntity>>, Integer> PENGUIN_EGG_SECONDARY = new HashMap<>();
+    public static final RegistrationProvider<EntityType<?>> ENTITIES = RegistrationProvider.get(BuiltInRegistries.ENTITY_TYPE, Constants.MOD_ID);
+    public static final HashMap<RegistryObject<EntityType<? extends AdeliePenguinEntity>>, String> PENGUINS = new HashMap<>();
+    public static final HashMap<RegistryObject<EntityType<? extends AdeliePenguinEntity>>, Integer> PENGUIN_EGG_PRIMARY = new HashMap<>();
+    public static final HashMap<RegistryObject<EntityType<? extends AdeliePenguinEntity>>, Integer> PENGUIN_EGG_SECONDARY = new HashMap<>();
 
-    public static final Supplier<EntityType<? extends AdeliePenguinEntity>> ADELIE_PENGUIN = registerPenguin("adelie_penguin", () -> AdeliePenguinEntity::new, 0.4F, 0.95F, 0x000000, 0xFFFFFF);
+    public static final RegistryObject<EntityType<? extends AdeliePenguinEntity>> ADELIE_PENGUIN = registerPenguin("adelie_penguin", () -> AdeliePenguinEntity::new, 0.4F, 0.95F, 0x000000, 0xFFFFFF);
 
-    private static <T extends AdeliePenguinEntity> Supplier<EntityType<? extends AdeliePenguinEntity>> registerPenguin(String name, Supplier<EntityType.EntityFactory<T>> factory, float width, float height, int eggPrimary, int eggSecondary) {
+    private static <T extends AdeliePenguinEntity> RegistryObject<EntityType<? extends AdeliePenguinEntity>> registerPenguin(String name, Supplier<EntityType.EntityFactory<T>> factory, float width, float height, int eggPrimary, int eggSecondary) {
         ResourceLocation location = new ResourceLocation(Constants.MOD_ID, name);
-        Supplier<EntityType<? extends AdeliePenguinEntity>> entityType = () -> EntityType.Builder.of(factory.get(), MobCategory.CREATURE).sized(width, height).clientTrackingRange(64).updateInterval(1).build(location.toString());
+        RegistryObject<EntityType<? extends AdeliePenguinEntity>> entityType = ENTITIES.register(name, () -> EntityType.Builder.of(factory.get(), MobCategory.CREATURE).sized(width, height).clientTrackingRange(64).updateInterval(1).build(location.toString()));
 
-        PENGUINS.put(name, entityType);
-        PENGUIN_WIDTHS.put(entityType, width);
-        PENGUIN_HEIGHTS.put(entityType, height);
+        PENGUINS.put(entityType, name);
         PENGUIN_EGG_PRIMARY.put(entityType, eggPrimary);
         PENGUIN_EGG_SECONDARY.put(entityType, eggSecondary);
+
         return entityType;
     }
+
+    //Needed to statically initialize fields
+    public static void load() {}
 }

common/src/main/java/com/girafi/waddles/init/WaddlesSounds.java

@@ -1,23 +1,28 @@
 package com.girafi.waddles.init;
 
 import com.girafi.waddles.Constants;
+import com.girafi.waddles.registration.RegistrationProvider;
+import com.girafi.waddles.registration.RegistryObject;
+import net.minecraft.core.registries.BuiltInRegistries;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.sounds.SoundEvent;
+import net.minecraft.world.entity.EntityType;
 
 import java.util.HashMap;
 import java.util.function.Supplier;
 
 public class WaddlesSounds {
-    public static final HashMap<String, Supplier<SoundEvent>> SOUND_MAP = new HashMap<>();
-    public static final Supplier<SoundEvent> ADELIE_AMBIENT = createSound("adelie.ambient");
-    public static final Supplier<SoundEvent> ADELIE_BABY_AMBIENT = createSound("adelie.baby.ambient");
-    public static final Supplier<SoundEvent> ADELIE_DEATH = createSound("adelie.death");
-    public static final Supplier<SoundEvent> ADELIE_HURT = createSound("adelie.hurt");
+    public static final RegistrationProvider<SoundEvent> SOUNDS = RegistrationProvider.get(BuiltInRegistries.SOUND_EVENT, Constants.MOD_ID);
+    public static final RegistryObject<SoundEvent> ADELIE_AMBIENT = createSound("adelie.ambient");
+    public static final RegistryObject<SoundEvent> ADELIE_BABY_AMBIENT = createSound("adelie.baby.ambient");
+    public static final RegistryObject<SoundEvent> ADELIE_DEATH = createSound("adelie.death");
+    public static final RegistryObject<SoundEvent> ADELIE_HURT = createSound("adelie.hurt");
 
-    private static Supplier<SoundEvent> createSound(String name) {
+    private static RegistryObject<SoundEvent> createSound(String name) {
         ResourceLocation resourceLocation = new ResourceLocation(Constants.MOD_ID, name);
-        Supplier<SoundEvent> soundEvent = () -> SoundEvent.createVariableRangeEvent(resourceLocation);
-        SOUND_MAP.put(name, soundEvent);
-        return soundEvent;
+        return SOUNDS.register(name, () -> SoundEvent.createVariableRangeEvent(resourceLocation));
     }
+
+    //Needed to statically initialize fields
+    public static void load() {}
 }

common/src/main/java/com/girafi/waddles/registration/RegistrationProvider.java

@@ -0,0 +1,113 @@
+package com.girafi.waddles.registration;
+
+import com.girafi.waddles.platform.Services;
+import net.minecraft.core.Registry;
+import net.minecraft.resources.ResourceKey;
+
+import java.util.Collection;
+import java.util.function.Supplier;
+
+/**
+ * Utility class for multiloader registration.
+ * <p>
+ * Example usage:
+ * <pre>{@code
+ * public static final RegistrationProvider<Test> PROVIDER = RegistrationProvider.get(Test.REGISTRY, "modid");
+ * public static final RegistryObject<Test> OBJECT = PROVIDER.register("object", () -> new Test());
+ *
+ * // The purpose of this method is to be called in the mod's constructor, in order to assure that the class is loaded, and that objects can be registered.
+ * public static void loadClass(){}
+ * }</pre>
+ *
+ * @param <T> the type of the objects that this class registers
+ */
+public interface RegistrationProvider<T> {
+
+    /**
+     * Gets a provider for specified {@code modId} and {@code resourceKey}. <br>
+     * It is <i>recommended</i> to store the resulted provider in a {@code static final} field to
+     * the {@link Factory#INSTANCE factory} creating multiple providers for the same resource key and mod id.
+     *
+     * @param resourceKey the {@link ResourceKey} of the registry of the provider
+     * @param modId       the mod id that the provider will register objects for
+     * @param <T>         the type of the provider
+     * @return the provider
+     */
+    static <T> RegistrationProvider<T> get(ResourceKey<? extends Registry<T>> resourceKey, String modId) {
+        return Factory.INSTANCE.create(resourceKey, modId);
+    }
+
+    /**
+     * Gets a provider for specified {@code modId} and {@code registry}. <br>
+     * It is <i>recommended</i> to store the resulted provider in a {@code static final} field to
+     * the {@link Factory#INSTANCE factory} creating multiple providers for the same resource key and mod id.
+     *
+     * @param registry the {@link Registry} of the provider
+     * @param modId    the mod id that the provider will register objects for
+     * @param <T>      the type of the provider
+     * @return the provider
+     */
+    static <T> RegistrationProvider<T> get(Registry<T> registry, String modId) {
+        return Factory.INSTANCE.create(registry, modId);
+    }
+
+    /**
+     * Registers an object.
+     *
+     * @param name     the name of the object
+     * @param supplier a supplier of the object to register
+     * @param <I>      the type of the object
+     * @return a wrapper containing the lazy registered object. <strong>Calling {@link RegistryObject#get() get} too early
+     * on the wrapper might result in crashes!</strong>
+     */
+    <I extends T> RegistryObject<I> register(String name, Supplier<? extends I> supplier);
+
+    /**
+     * Gets all the objects currently registered.
+     *
+     * @return an <strong>immutable</strong> view of all the objects currently registered
+     */
+    Collection<RegistryObject<T>> getEntries();
+
+    /**
+     * Gets the mod id that this provider registers objects for.
+     *
+     * @return the mod id
+     */
+    String getModId();
+
+    /**
+     * Factory class for {@link RegistrationProvider registration providers}. <br>
+     * This class is loaded using {@link java.util.ServiceLoader Service Loaders}, and only one
+     * should exist per mod loader.
+     */
+    interface Factory {
+
+        /**
+         * The singleton instance of the {@link Factory}. This is different on each loader.
+         */
+        Factory INSTANCE = Services.load(Factory.class);
+
+        /**
+         * Creates a {@link RegistrationProvider}.
+         *
+         * @param resourceKey the {@link ResourceKey} of the registry to create this provider for
+         * @param modId       the mod id for which the provider will register objects
+         * @param <T>         the type of the provider
+         * @return the provider
+         */
+        <T> RegistrationProvider<T> create(ResourceKey<? extends Registry<T>> resourceKey, String modId);
+
+        /**
+         * Creates a {@link RegistrationProvider}.
+         *
+         * @param registry the {@link Registry} to create this provider for
+         * @param modId    the mod id for which the provider will register objects
+         * @param <T>      the type of the provider
+         * @return the provider
+         */
+        default <T> RegistrationProvider<T> create(Registry<T> registry, String modId) {
+            return create(registry.key(), modId);
+        }
+    }
+}

common/src/main/java/com/girafi/waddles/registration/RegistryObject.java

@@ -0,0 +1,45 @@
+package com.girafi.waddles.registration;
+
+import net.minecraft.core.Holder;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+
+import java.util.function.Supplier;
+
+/**
+ * Represents a lazy wrapper for registry object.
+ *
+ * @param <T> the type of the object
+ */
+public interface RegistryObject<T> extends Supplier<T> {
+
+    /**
+     * Gets the {@link ResourceKey} of the registry of the object wrapped.
+     *
+     * @return the {@link ResourceKey} of the registry
+     */
+    ResourceKey<T> getResourceKey();
+
+    /**
+     * Gets the id of the object.
+     *
+     * @return the id of the object
+     */
+    ResourceLocation getId();
+
+    /**
+     * Gets the object behind this wrapper. Calling this method too early
+     * might result in crashes.
+     *
+     * @return the object behind this wrapper
+     */
+    @Override
+    T get();
+
+    /**
+     * Gets this object wrapped in a vanilla {@link Holder}.
+     *
+     * @return the holder
+     */
+    Holder<T> asHolder();
+}

common/src/main/resources/data/waddles/tags/worldgen/biome/spawn_include.json

@@ -1,5 +1,9 @@
 {
   "values": [
-    "#forge:is_snowy"
+    "#forge:is_snowy",
+    {
+      "id": "#c:snowy",
+      "required": false
+    }
   ]
 }

fabric/src/main/java/com/girafi/waddles/Waddles.java

@@ -9,7 +9,7 @@ public class Waddles implements ModInitializer {
 
     @Override
     public void onInitialize() {
-        ForgeConfigRegistry.INSTANCE.register(Constants.MOD_ID, ModConfig.Type.COMMON, ConfigurationHandler.spec);
         CommonClass.init();
+        ForgeConfigRegistry.INSTANCE.register(Constants.MOD_ID, ModConfig.Type.COMMON, ConfigurationHandler.spec);
     }
 }

fabric/src/main/java/com/girafi/waddles/platform/FabricRegistrationFactory.java

@@ -0,0 +1,94 @@
+package com.girafi.waddles.platform;
+
+import com.girafi.waddles.registration.RegistrationProvider;
+import com.girafi.waddles.registration.RegistryObject;
+import net.minecraft.core.Holder;
+import net.minecraft.core.Registry;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.function.Supplier;
+
+public class FabricRegistrationFactory implements RegistrationProvider.Factory {
+
+    @Override
+    public <T> RegistrationProvider<T> create(ResourceKey<? extends Registry<T>> resourceKey, String modId) {
+        return new Provider<>(modId, resourceKey);
+    }
+
+    @Override
+    public <T> RegistrationProvider<T> create(Registry<T> registry, String modId) {
+        return new Provider<>(modId, registry);
+    }
+
+    private static class Provider<T> implements RegistrationProvider<T> {
+        private final String modId;
+        private final Registry<T> registry;
+
+        private final Set<RegistryObject<T>> entries = new HashSet<>();
+        private final Set<RegistryObject<T>> entriesView = Collections.unmodifiableSet(entries);
+
+        @SuppressWarnings({"unchecked"})
+        private Provider(String modId, ResourceKey<? extends Registry<T>> key) {
+            this.modId = modId;
+
+            final var reg = BuiltInRegistries.REGISTRY.get(key.location());
+            if (reg == null) {
+                throw new RuntimeException("Registry with name " + key.location() + " was not found!");
+            }
+            registry = (Registry<T>) reg;
+        }
+
+        private Provider(String modId, Registry<T> registry) {
+            this.modId = modId;
+            this.registry = registry;
+        }
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public <I extends T> RegistryObject<I> register(String name, Supplier<? extends I> supplier) {
+            final var rl = new ResourceLocation(modId, name);
+            final var obj = Registry.register(registry, rl, supplier.get());
+            final var ro = new RegistryObject<I>() {
+                final ResourceKey<I> key = ResourceKey.create((ResourceKey<? extends Registry<I>>) registry.key(), rl);
+
+                @Override
+                public ResourceKey<I> getResourceKey() {
+                    return key;
+                }
+
+                @Override
+                public ResourceLocation getId() {
+                    return rl;
+                }
+
+                @Override
+                public I get() {
+                    return obj;
+                }
+
+                @Override
+                public Holder<I> asHolder() {
+                    return (Holder<I>) registry.getHolderOrThrow((ResourceKey<T>) this.key);
+                }
+            };
+            entries.add((RegistryObject<T>) ro);
+            return ro;
+        }
+
+        @Override
+        public Collection<RegistryObject<T>> getEntries() {
+            return entriesView;
+        }
+
+        @Override
+        public String getModId() {
+            return modId;
+        }
+    }
+}

fabric/src/main/resources/META-INF/services/com.girafi.waddles.registration.RegistrationProvider$Factory

@@ -0,0 +1 @@
+com.girafi.waddles.platform.FabricRegistrationFactory