Add body/simple attribute to control simple body optimization.

PiperOrigin-RevId: 942164766
Change-Id: I1e83bb99b6a1955917eb9b2e9bed0dc7b8e6a161

src/user/user_init.c

@@ -82,6 +82,9 @@ void mjs_defaultBody(mjsBody* body) {
   body->ipos[0] = mjNAN;
   body->iquat[0] = 1;
   body->fullinertia[0] = mjNAN;
+
+  // simple optimization: auto
+  body->simple = 1;
 }
 
 

src/user/user_model.cc

@@ -1002,6 +1002,11 @@ void mjCModel::ComputeSparseSizes() {
                            bodies_[parentid]->parent          &&
                            bodies_[parentid]->parent->id == 0 &&
                            bodies_[parentid]->dofnum == 0)));
+
+    // user override: disable simple optimization
+    if (!pb->simple) {
+      body_simple_pre[i] = 0;
+    }
   }
 
   // a parent body is never simple (unless world)
@@ -2816,6 +2821,11 @@ void mjCModel::CopyTree(mjModel* m) {
                           (m->body_parentid[parentid] == 0 &&
                            m->body_dofnum[parentid] == 0)));
 
+    // user override: disable simple optimization
+    if (!pb->simple) {
+      m->body_simple[i] = 0;
+    }
+
     // a parent body is never simple (unless world)
     if (m->body_parentid[i] > 0) {
       m->body_simple[m->body_parentid[i]] = 0;