Add variant alias for item models not loaded via blockstate (#5025)

src/main/java/net/minecraftforge/client/model/ModelLoader.java

@@ -300,6 +300,7 @@ public final class ModelLoader extends ModelBakery
                     try
                     {
                         model = ModelLoaderRegistry.getModel(file);
+                        ModelLoaderRegistry.addAlias(memory, file);
                     }
                     catch (Exception normalException)
                     {

src/main/java/net/minecraftforge/client/model/ModelLoaderRegistry.java

@@ -52,6 +52,8 @@ public class ModelLoaderRegistry
     private static final Map<ResourceLocation, IModel> cache = Maps.newHashMap();
     private static final Deque<ResourceLocation> loadingModels = Queues.newArrayDeque();
     private static final Set<ResourceLocation> textures = Sets.newHashSet();
+    private static final Map<ResourceLocation, ResourceLocation> aliases = Maps.newHashMap();
+
     private static IResourceManager manager;
 
     // Forge built-in loaders
@@ -95,7 +97,10 @@ public class ModelLoaderRegistry
     public static IModel getModel(ResourceLocation location) throws Exception
     {
         IModel model;
-        if(cache.containsKey(location)) return cache.get(location);
+
+        IModel cached = cache.get(location);
+        if (cached != null) return cached;
+
         for(ResourceLocation loading : loadingModels)
         {
             if(location.getClass() == loading.getClass() && location.equals(loading))
@@ -106,6 +111,9 @@ public class ModelLoaderRegistry
         loadingModels.addLast(location);
         try
         {
+            ResourceLocation aliased = aliases.get(location);
+            if (aliased != null) return getModel(aliased);
+
             ResourceLocation actual = getActualLocation(location);
             ICustomModelLoader accepted = null;
             for(ICustomModelLoader loader : loaders)
@@ -227,9 +235,16 @@ public class ModelLoaderRegistry
         return model;
     }
 
+    static void addAlias(ResourceLocation from, ResourceLocation to)
+    {
+        aliases.put(from, to);
+    }
+
     public static void clearModelCache(IResourceManager manager)
     {
         ModelLoaderRegistry.manager = manager;
+        aliases.clear();
+        textures.clear();
         cache.clear();
         // putting the builtin models in
         cache.put(new ResourceLocation("minecraft:builtin/generated"), ItemLayerModel.INSTANCE);