simulate: fix display of loading message

python/mujoco/simulate.cc

@@ -203,7 +203,11 @@ PYBIND11_MODULE(_simulate, pymodule) {
       }))
       .def("destroy", &SimulateWrapper::Destroy,
            py::call_guard<py::gil_scoped_release>())
+      .def("load_message", CallIfNotNull(&mujoco::Simulate::LoadMessage),
+           py::call_guard<py::gil_scoped_release>())
       .def("load", &SimulateWrapper::Load)
+      .def("load_message_clear", CallIfNotNull(&mujoco::Simulate::LoadMessageClear),
+           py::call_guard<py::gil_scoped_release>())
       .def("sync", CallIfNotNull(&mujoco::Simulate::Sync),
            py::call_guard<py::gil_scoped_release>())
 

python/mujoco/viewer.py

@@ -174,9 +174,11 @@ def _reload(
 ) -> Optional[Tuple[mujoco.MjModel, mujoco.MjData]]:
   """Internal function for reloading a model in the viewer."""
   try:
+    simulate.load_message('') # path is unknown at this point
     load_tuple = loader()
   except Exception as e:  # pylint: disable=broad-except
     simulate.load_error = str(e)
+    simulate.load_message_clear()
   else:
     m, d = load_tuple[:2]
 

simulate/main.cc

@@ -259,6 +259,7 @@ void PhysicsLoop(mj::Simulate& sim) {
   // run until asked to exit
   while (!sim.exitrequest.load()) {
     if (sim.droploadrequest.load()) {
+      sim.LoadMessage(sim.dropfilename);
       mjModel* mnew = LoadModel(sim.dropfilename, sim);
       sim.droploadrequest.store(false);
 
@@ -279,10 +280,14 @@ void PhysicsLoop(mj::Simulate& sim) {
         ctrlnoise = (mjtNum*) malloc(sizeof(mjtNum)*m->nu);
         mju_zero(ctrlnoise, m->nu);
       }
+      else {
+        sim.LoadMessageClear();
+      }
     }
 
     if (sim.uiloadrequest.load()) {
       sim.uiloadrequest.fetch_sub(1);
+      sim.LoadMessage(sim.filename);
       mjModel* mnew = LoadModel(sim.filename, sim);
       mjData* dnew = nullptr;
       if (mnew) dnew = mj_makeData(mnew);
@@ -301,6 +306,9 @@ void PhysicsLoop(mj::Simulate& sim) {
         ctrlnoise = static_cast<mjtNum*>(malloc(sizeof(mjtNum)*m->nu));
         mju_zero(ctrlnoise, m->nu);
       }
+      else {
+        sim.LoadMessageClear();
+      }
     }
 
     // sleep for 1 ms or yield, to let main thread run
@@ -404,6 +412,7 @@ void PhysicsLoop(mj::Simulate& sim) {
 void PhysicsThread(mj::Simulate* sim, const char* filename) {
   // request loadmodel if file given (otherwise drag-and-drop)
   if (filename != nullptr) {
+    sim->LoadMessage(filename);
     m = LoadModel(filename, *sim);
     if (m) d = mj_makeData(m);
     if (d) {
@@ -414,6 +423,8 @@ void PhysicsThread(mj::Simulate* sim, const char* filename) {
       free(ctrlnoise);
       ctrlnoise = static_cast<mjtNum*>(malloc(sizeof(mjtNum)*m->nu));
       mju_zero(ctrlnoise, m->nu);
+    } else {
+      sim->LoadMessageClear();
     }
   }
 

simulate/simulate.cc

@@ -1977,6 +1977,15 @@ void Simulate::Sync() {
 }
 
 //------------------------- Tell the render thread to load a file and wait -------------------------
+void Simulate::LoadMessage(const char* displayed_filename) {
+  mju::strcpy_arr(this->filename, displayed_filename);
+
+  {
+    MutexLock lock(mtx);
+    this->loadrequest = 3;
+  }
+}
+
 void Simulate::Load(mjModel* m, mjData* d, const char* displayed_filename) {
   this->mnew_ = m;
   this->dnew_ = d;
@@ -1993,6 +2002,15 @@ void Simulate::Load(mjModel* m, mjData* d, const char* displayed_filename) {
   }
 }
 
+void Simulate::LoadMessageClear(void) {
+  {
+    MutexLock lock(mtx);
+    this->loadrequest = 0;
+  }
+}
+
+
+
 //------------------------------------- load mjb or xml model --------------------------------------
 void Simulate::LoadOnRenderThread() {
   this->m_ = this->mnew_;
@@ -2167,7 +2185,7 @@ void Simulate::Render() {
 
     // label
     if (this->loadrequest) {
-      mjr_overlay(mjFONT_BIG, mjGRID_TOPRIGHT, smallrect, "loading", nullptr,
+      mjr_overlay(mjFONT_BIG, mjGRID_TOPLEFT, smallrect, "loading", nullptr,
                   &this->platform_ui->mjr_context());
     } else {
       char intro_message[Simulate::kMaxFilenameLength];
@@ -2450,7 +2468,7 @@ void Simulate::RenderLoop() {
       // load model (not on first pass, to show "loading" label)
       if (this->loadrequest==1) {
         this->LoadOnRenderThread();
-      } else if (this->loadrequest>1) {
+      } else if (this->loadrequest == 2) {
         this->loadrequest = 1;
       }
 

simulate/simulate.h

@@ -62,10 +62,18 @@ class Simulate {
   void UpdateMesh(int meshid);
   void UpdateTexture(int texid);
 
+  // Request that the Simulate UI display a "loading" message
+  // Called prior to Load or LoadMessageClear
+  void LoadMessage(const char* displayed_filename);
+
   // Request that the Simulate UI thread render a new model
-  // optionally delete the old model and data when done
   void Load(mjModel* m, mjData* d, const char* displayed_filename);
 
+  // Clear the loading message
+  // Can be called instead of Load to clear the message without
+  // requesting the UI load a model
+  void LoadMessageClear(void);
+
   // functions below are used by the renderthread
   // load mjb or xml model that has been requested by load()
   void LoadOnRenderThread();
@@ -173,6 +181,7 @@ class Simulate {
   std::atomic_int uiloadrequest = 0;
 
   // loadrequest
+  //   3: display a loading message
   //   2: render thread asked to update its model
   //   1: showing "loading" label, about to load
   //   0: model loaded or no load requested.