Add flag for disabling implicit integration of joint damping in the Euler integrator.

PiperOrigin-RevId: 559398414
Change-Id: I43b23c5e75a2830a64b1898daeaa16f19e011718

src/engine/engine_forward.c

@@ -593,16 +593,18 @@ void mj_EulerSkip(const mjModel* m, mjData* d, int skipfactor) {
   mjtNum* qfrc = mj_stackAlloc(d, nv);
   mjtNum* qacc = mj_stackAlloc(d, nv);
 
-  // check for dof damping
+  // check for dof damping if disable flag is not set
   int dof_damping = 0;
-  for (int i=0; i < nv; i++) {
-    if (m->dof_damping[i] > 0) {
-      dof_damping = 1;
-      break;
+  if (!mjDISABLED(mjDSBL_EULERDAMP)) {
+    for (int i=0; i < nv; i++) {
+      if (m->dof_damping[i] > 0) {
+        dof_damping = 1;
+        break;
+      }
     }
   }
 
-  // no damping: explicit velocity integration
+  // no damping or disabled: explicit velocity integration
   if (!dof_damping) {
     mju_copy(qacc, d->qacc, nv);
   }

src/engine/engine_support.c

@@ -56,7 +56,8 @@ const char* mjDISABLESTRING[mjNDISABLE] = {
   "Actuation",
   "Refsafe",
   "Sensor",
-  "Midphase"
+  "Midphase",
+  "Eulerdamp"
 };
 
 

src/xml/xml_native_reader.cc

@@ -103,9 +103,9 @@ static const char* MJCF[nMJCF][mjXATTRNUM] = {
         "solver", "iterations", "noslip_iterations", "mpr_iterations",
         "sdf_iterations", "sdf_initpoints"},
     {"<"},
-        {"flag", "?", "19", "constraint", "equality", "frictionloss", "limit", "contact",
+        {"flag", "?", "21", "constraint", "equality", "frictionloss", "limit", "contact",
             "passive", "gravity", "clampctrl", "warmstart",
-            "filterparent", "actuation", "refsafe", "sensor",
+            "filterparent", "actuation", "refsafe", "sensor", "midphase", "eulerdamp",
             "override", "energy", "fwdinv", "sensornoise", "multiccd", "island"},
     {">"},
 
@@ -1003,6 +1003,7 @@ void mjXReader::Option(XMLElement* section, mjOption* opt) {
     READDSBL("refsafe",      mjDSBL_REFSAFE)
     READDSBL("sensor",       mjDSBL_SENSOR)
     READDSBL("midphase",     mjDSBL_MIDPHASE)
+    READDSBL("eulerdamp",    mjDSBL_EULERDAMP)
 #undef READDSBL
 
 #define READENBL(NAME, MASK) \

src/xml/xml_native_writer.cc

@@ -836,6 +836,7 @@ void mjXWriter::Option(XMLElement* root) {
     WRITEDSBL("refsafe",        mjDSBL_REFSAFE)
     WRITEDSBL("sensor",         mjDSBL_SENSOR)
     WRITEDSBL("midphase",       mjDSBL_MIDPHASE)
+    WRITEDSBL("eulerdamp",      mjDSBL_EULERDAMP)
 #undef WRITEDSBL
 
 #define WRITEENBL(NAME, MASK) \