Add ctrl to attached keyframes.

PiperOrigin-RevId: 662878508
Change-Id: Ie273fae0220c8b257766cbbd90a880d44b901725

src/user/user_objects.cc

@@ -5394,6 +5394,7 @@ mjCActuator& mjCActuator::operator=(const mjCActuator& other) {
 
 void mjCActuator::ForgetKeyframes() {
   act_.clear();
+  ctrl_.clear();
 }
 
 
@@ -5413,6 +5414,15 @@ std::vector<mjtNum>& mjCActuator::act() {
 
 
 
+mjtNum& mjCActuator::ctrl() {
+  if (ctrl_.find(model->state_name_) == ctrl_.end()) {
+    ctrl_[model->state_name_] = mjNAN;
+  }
+  return ctrl_.at(model->state_name_);
+}
+
+
+
 void mjCActuator::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
   spec.name = &name;