Add compiler C API for mjmSite.

PiperOrigin-RevId: 604573450
Change-Id: I6ba7fcece0942ddc0d109413ba5684b2df3fab96

src/user/user_api.cc

@@ -0,0 +1,110 @@
+// 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 "user/user_api.h"
+#include <string>
+#include <vector>
+
+#include <mujoco/mujoco.h>
+#include "user/user_model.h"
+#include "user/user_objects.h"
+
+
+
+// create model
+void* mjm_createModel() {
+  mjCModel* modelC = new mjCModel();
+  return modelC;
+}
+
+
+
+// delete model
+void mjm_deleteModel(void* model) {
+  mjCModel* modelC = static_cast<mjCModel*>(model);
+  delete modelC;
+}
+
+
+
+// add body to body
+void* mjm_addBody(void* body, void* def) {
+  mjCDef* defC = static_cast<mjCDef*>(def);
+  mjCBody* bodyC = static_cast<mjCBody*>(body);
+  return bodyC->AddBody(defC);
+}
+
+
+
+// add site to body
+mjmSite* mjm_addSite(void* body, void* def) {
+  mjCDef* defC = static_cast<mjCDef*>(def);
+  mjCSite* siteC = static_cast<mjCBody*>(body)->AddSite(defC);
+  return &siteC->spec;
+}
+
+
+
+// get object of given type
+void* mjm_findObject(void* model, mjtObj type, const char* name) {
+  mjCModel* modelC = static_cast<mjCModel*>(model);
+  return modelC->FindObject(type, std::string(name));
+}
+
+
+
+// set parent frame of dest
+void mjm_setFrame(void* dest, void* frame) {
+  mjCFrame* frameC = static_cast<mjCFrame*>(frame);
+  mjCBase* baseC = static_cast<mjCBase*>(dest);
+  baseC->SetFrame(frameC);
+}
+
+
+
+// set string
+void mjm_setString(mjString dest, const char* text) {
+  std::string* str = reinterpret_cast<std::string*>(dest);
+  *str = std::string(text);
+}
+
+
+
+// set double array
+void mjm_setDouble(mjDouble dest, const double* array, int size) {
+  std::vector<double>* v = reinterpret_cast<std::vector<double>*>(dest);
+  v->assign(size, 0.0);
+  for (int i = 0; i < size; ++i) {
+    (*v)[i] = array[i];
+  }
+}
+
+
+
+// get string
+const char* mjm_getString(const mjString source) {
+  std::string* str = reinterpret_cast<std::string*>(source);
+  return str->c_str();
+}
+
+
+
+// get double array
+const double* mjm_getDouble(const mjDouble source, int* size) {
+  std::vector<double>* v = reinterpret_cast<std::vector<double>*>(source);
+  if (size) {
+    *size = v->size();
+  }
+  return v->data();
+}