Fix typos.

PiperOrigin-RevId: 710678815
Change-Id: Iab6f603f8f4d782ac7f34140add39e1f37625167

src/engine/engine_forward.c

@@ -147,7 +147,7 @@ void mj_fwdPosition(const mjModel* m, mjData* d) {
     mj_collision(m, d);  // timed internally (POS_COLLISION)
   }
 
-  // have threadpool: inertia and collision on seperate threads
+  // have threadpool: inertia and collision on separate threads
   else {
     mjTask tasks[2];
     mjFwdPositionArgs forward_args;

src/engine/engine_support.c

@@ -278,7 +278,7 @@ int mj_mergeChain(const mjModel* m, int* chain, int b1, int b2) {
     return 0;
   }
 
-  // intialize last dof address for each body
+  // initialize last dof address for each body
   da1 = m->body_dofadr[b1] + m->body_dofnum[b1] - 1;
   da2 = m->body_dofadr[b2] + m->body_dofnum[b2] - 1;
 
@@ -361,7 +361,7 @@ int mj_bodyChain(const mjModel* m, int body, int* chain) {
       return 0;
     }
 
-    // intialize last dof
+    // initialize last dof
     int da = m->body_dofadr[body] + m->body_dofnum[body] - 1;
     int NV = 0;
 

src/engine/engine_vis_interact.c

@@ -497,7 +497,7 @@ void mjv_moveModel(const mjModel* m, int action, mjtNum reldx, mjtNum reldy,
     // get current model rotation
     mju_f2n(rotate, scn->rotate, 4);
 
-    // compose rotation, normalize and and set
+    // compose rotation, normalize and set
     mju_mulQuat(result, quat, rotate);
     mju_normalize4(result);
     mju_n2f(scn->rotate, result, 4);