fix enable per-variant custom model caching

src/frontend/ContentGfxCache.cpp

@@ -62,7 +62,7 @@ void ContentGfxCache::refreshVariant(
                 }
             }
         }
-        models[def.rt.id] = std::move(model);
+        models[modelKey(def.rt.id, variantIndex)] = std::move(model);
     }
 }
 
@@ -94,8 +94,8 @@ void ContentGfxCache::refresh() {
 
 ContentGfxCache::~ContentGfxCache() = default;
 
-const model::Model& ContentGfxCache::getModel(blockid_t id) const {
-    const auto& found = models.find(id);
+const model::Model& ContentGfxCache::getModel(blockid_t id, uint8_t variant) const {
+    const auto& found = models.find(modelKey(id, variant));
     if (found == models.end()) {
         throw std::runtime_error("model not found");
     }

src/frontend/ContentGfxCache.hpp

@@ -27,7 +27,11 @@ class ContentGfxCache {
 
     // array of block sides uv regions (6 per block)
     std::unique_ptr<UVRegion[]> sideregions;
-    std::unordered_map<blockid_t, model::Model> models;
+    std::unordered_map<uint64_t, model::Model> models;
+    
+    static inline uint64_t modelKey(blockid_t id, uint8_t variant) {
+        return (uint64_t(id) << 8) | uint64_t(variant & 0xFF);
+    }
 
     void refreshVariant(
         const Block& def,
@@ -53,7 +57,7 @@ public:
         return sideregions[getRegionIndex(id, variant, side, !dense)];
     }
 
-    const model::Model& getModel(blockid_t id) const;
+    const model::Model& getModel(blockid_t id, uint8_t variant) const;
 
     void refresh(const Block& block, const Atlas& atlas);