fix: reduce gltf2 export time (#5972)

* fix: reduce gltf2 export time

* fix: use std::less<> in std::map

---------

Co-authored-by: huangxinchuang <[email protected]>
Co-authored-by: Kim Kulling <[email protected]>

code/AssetLib/glTF2/glTF2Asset.h

@@ -1267,6 +1267,7 @@ private:
     size_t mBodyOffset;
     size_t mBodyLength;
     IdMap mUsedIds;
+    std::map<std::string, int, std::less<>> mUsedNamesMap;
     Ref<Buffer> mBodyBuffer;
 };
 

code/AssetLib/glTF2/glTF2Asset.inl

@@ -2195,8 +2195,10 @@ inline std::string Asset::FindUniqueID(const std::string &str, const char *suffi
     std::string id = str;
 
     if (!id.empty()) {
-        if (mUsedIds.find(id) == mUsedIds.end())
+        if (mUsedIds.find(id) == mUsedIds.end()){
+            mUsedNamesMap[id] = 0;
             return id;
+        }
 
         id += "_";
     }
@@ -2205,17 +2207,13 @@ inline std::string Asset::FindUniqueID(const std::string &str, const char *suffi
 
     Asset::IdMap::iterator it = mUsedIds.find(id);
     if (it == mUsedIds.end()) {
+        mUsedNamesMap[id] = 0;
         return id;
     }
 
-    std::vector<char> buffer;
-    buffer.resize(id.size() + 16);
-    int offset = ai_snprintf(buffer.data(), buffer.size(), "%s_", id.c_str());
-    for (int i = 0; it != mUsedIds.end(); ++i) {
-        ai_snprintf(buffer.data() + offset, buffer.size() - offset, "%d", i);
-        id = buffer.data();
-        it = mUsedIds.find(id);
-    }
+    auto key = id;
+    id += "_" + std::to_string(mUsedNamesMap[key]);
+    mUsedNamesMap[key] = mUsedNamesMap[key] + 1;
 
     return id;
 }

code/AssetLib/glTF2/glTF2Exporter.cpp

@@ -1499,6 +1499,10 @@ unsigned int glTF2Exporter::ExportNodeHierarchy(const aiNode *n) {
     Ref<Node> node = mAsset->nodes.Create(mAsset->FindUniqueID(n->mName.C_Str(), "node"));
 
     node->name = n->mName.C_Str();
+    if(n->mNumChildren > 0)
+        node->children.reserve(n->mNumChildren);
+    if(n->mNumMeshes > 0)
+        node->meshes.reserve(n->mNumMeshes);
 
     if (!n->mTransformation.IsIdentity(configEpsilon)) {
         node->matrix.isPresent = true;
@@ -1527,6 +1531,10 @@ unsigned int glTF2Exporter::ExportNode(const aiNode *n, Ref<Node> &parent) {
 
     node->parent = parent;
     node->name = name;
+    if(n->mNumChildren > 0)
+        node->children.reserve(n->mNumChildren);
+    if(n->mNumMeshes > 0)
+        node->meshes.reserve(n->mNumMeshes);
 
     ExportNodeExtras(n->mMetaData, node->extras);