Initial open sourcing of MuJoCo.

PiperOrigin-RevId: 450374687
Change-Id: Ie3225a46ce095fc28ae8e63c326a640261f562bb

src/xml/xml_base.cc

@@ -0,0 +1,60 @@
+// Copyright 2021 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "xml/xml_base.h"
+
+#include <cfloat>
+#include <cstddef>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include "user/user_model.h"
+#include "user/user_objects.h"
+#include "tinyxml2.h"
+
+namespace {
+
+using std::string;
+using tinyxml2::XMLElement;
+
+}  // namespace
+
+
+//--------------------------------- Base class, helper functions -----------------------------------
+
+// base constructor
+mjXBase::mjXBase() {
+  model = NULL;
+}
+
+
+
+// set model field
+void mjXBase::SetModel(mjCModel* _model) {
+  model = _model;
+}
+
+
+
+// read alternative orientation specification
+void mjXBase::ReadAlternative(XMLElement* elem, mjCAlternative& alt) {
+  string text;
+  ReadAttr(elem, "axisangle", 4, alt.axisangle, text);
+  ReadAttr(elem, "xyaxes", 6, alt.xyaxes, text);
+  ReadAttr(elem, "zaxis", 3, alt.zaxis, text);
+  ReadAttr(elem, "euler", 3, alt.euler, text);
+  ReadAttr(elem, "fullinertia", 6, alt.fullinertia, text);
+}