Allow more than 1 activation state per actuator, but only for dyntype user.

Fixes #305.

PiperOrigin-RevId: 486597273
Change-Id: I3eb806f60949e68ebe6cbe35a6e66218a167ed45

src/user/user_model.cc

@@ -929,7 +929,7 @@ void mjCModel::SetSizes(void) {
       nu++;
     } else {
       nu++;
-      na++;
+      na += actuators[i]->actdim;
     }
   }
 
@@ -1834,7 +1834,9 @@ void mjCModel::CopyObjects(mjModel* m) {
     m->actuator_biastype[i] = pac->biastype;
     m->actuator_trnid[2*i] = pac->trnid[0];
     m->actuator_trnid[2*i+1] = pac->trnid[1];
-    m->actuator_actadr[i] = pac->dyntype == mjDYN_NONE ? -1 : adr++;
+    m->actuator_actadr[i] = pac->dyntype == mjDYN_NONE ? -1 : adr;
+    adr += pac->actdim;
+    m->actuator_actnum[i] = pac->actdim;
     m->actuator_group[i] = pac->group;
     m->actuator_ctrllimited[i] = pac->ctrllimited;
     m->actuator_forcelimited[i] = pac->forcelimited;

src/user/user_objects.cc

@@ -3390,6 +3390,7 @@ mjCActuator::mjCActuator(mjCModel* _model, mjCDef* _def) {
   ctrllimited = 2;
   forcelimited = 2;
   actlimited = 2;
+  actdim = -1;
   trntype = mjTRN_UNDEFINED;
   dyntype = mjDYN_NONE;
   gaintype = mjGAIN_FIXED;
@@ -3474,6 +3475,23 @@ void mjCActuator::Compile(void) {
                    name.c_str(), id);
   }
 
+  // check and set actdim
+  if (actdim > 1 && dyntype != mjDYN_USER) {
+    throw mjCError(this, "actdim > 1 is only allowed for dyntype 'user' in actuator '%s' (id = %d)",
+                   name.c_str(), id);
+  }
+  if (actdim == 1 && dyntype == mjDYN_NONE) {
+    throw mjCError(this, "invalid actdim 1 in stateless actuator '%s' (id = %d)", name.c_str(), id);
+  }
+  if (actdim == 0 && dyntype != mjDYN_NONE) {
+    throw mjCError(this, "invalid actdim 0 in stateful actuator '%s' (id = %d)", name.c_str(), id);
+  }
+
+  // set actdim
+  if (actdim < 0) {
+    actdim = (dyntype != mjDYN_NONE);
+  }
+
   // check muscle parameters
   for (int i=0; i<2; i++) {
     // select gain or bias

src/user/user_objects.h

@@ -873,9 +873,10 @@ class mjCActuator : public mjCBase {
  public:
   // variables set by user or API
   int group;                      // group for visualization
-  int ctrllimited;               // are control limits defined: 0 false, 1 true, 2 auto
-  int forcelimited;              // are force limits defined: 0 false, 1 true, 2 auto
-  int actlimited;                // are activation limits defined: 0 false, 1 true, 2 auto
+  int ctrllimited;                // are control limits defined: 0 false, 1 true, 2 auto
+  int forcelimited;               // are force limits defined: 0 false, 1 true, 2 auto
+  int actlimited;                 // are activation limits defined: 0 false, 1 true, 2 auto
+  int actdim;                     // dimension of associated activations
   mjtDyn dyntype;                 // dynamics type
   mjtTrn trntype;                 // transmission type
   mjtGain gaintype;               // gain type