Add mjData flags marking lazily evaluated pipeline stages

PiperOrigin-RevId: 861763477
Change-Id: Ib613c56949264573a16306800658f868d2aa7665

include/mujoco/mjdata.h

@@ -233,6 +233,12 @@ struct mjData_ {
   int     nparent_awake;     // number of bodies with awake parents
   int     nv_awake;          // number of awake dofs
 
+  // flags marking lazily evaluated stages
+  mjtByte flg_energypos;     // has mj_energyPos been called
+  mjtByte flg_energyvel;     // has mj_energyVel been called
+  mjtByte flg_subtreevel;    // has mj_subtreeVel been called
+  mjtByte flg_rnepost;       // has mj_rnePostConstraint been called
+
   // global properties
   mjtNum  time;              // simulation time
   mjtNum  energy[2];         // potential, kinetic energy

include/mujoco/mjxmacro.h

@@ -915,6 +915,10 @@
     X( int,       nbody_awake        ) \
     X( int,       nparent_awake      ) \
     X( int,       nv_awake           ) \
+    X( mjtByte,   flg_energypos      ) \
+    X( mjtByte,   flg_energyvel      ) \
+    X( mjtByte,   flg_subtreevel     ) \
+    X( mjtByte,   flg_rnepost        ) \
     X( mjtNum,    time               ) \
     X( uintptr_t, threadpool         )