Sort DeferredObject.

src/ifcconvert/ColladaSerializer.cpp

@@ -352,6 +352,7 @@ void ColladaSerializer::ColladaExporter::endDocument() {
 	// only at this point all objects are written to the stream.
 	materials.write();
 	std::set<std::string> geometries_written;
+	std::sort(deferreds.begin(), deferreds.end());
 	for (std::vector<DeferredObject>::const_iterator it = deferreds.begin(); it != deferreds.end(); ++it) {
 		if (geometries_written.find(it->representation_id) != geometries_written.end()) {
 			continue;

src/ifcconvert/ColladaSerializer.h

@@ -121,6 +121,10 @@ private:
             ColladaEffects effects;
 		};
 		class DeferredObject {
+		friend bool operator < (const DeferredObject & def_obj1, const DeferredObject & def_obj2)
+		{
+			return (def_obj1.parent < def_obj2.parent ? true : false);
+		}
 		public:
 			std::string unique_id, representation_id, type;
 			std::vector<real_t> matrix;