Move BVH active visualization flag reset after early return check in MuJoCo collision driver.

This avoids unnecessarily resetting the bvh_active flags when the collision driver returns early due to disabled constraints, disabled contacts, or having fewer than two bodies/flexes.

PiperOrigin-RevId: 959531283
Change-Id: I85caf054b06e3be1018d710f9ab762627fc3356a

src/engine/engine_collision_driver.c

@@ -599,17 +599,17 @@ void mj_collision(const mjModel* m, mjData* d) {
   resetArena(d);
   mj_clearEfc(d);
 
-  // reset the visualization flags
-  if (m->vis.global.bvactive) {
-    memset(d->bvh_active, 0, m->nbvh);
-  }
-
   // return if disabled
   if (mjDISABLED(mjDSBL_CONSTRAINT) || mjDISABLED(mjDSBL_CONTACT) || nbodyflex < 2) {
     TM_END1(mjTIMER_POS_COLLISION);
     return;
   }
 
+  // reset the visualization flags
+  if (m->vis.global.bvactive) {
+    memset(d->bvh_active, 0, m->nbvh);
+  }
+
   mj_markStack(d);
 
   // broadphase collision detector

src/engine/engine_init.c

@@ -144,7 +144,7 @@ void mj_defaultVisual(mjVisual* vis) {
   vis->global.offheight           = 480;
   vis->global.realtime            = 1.0;
   vis->global.ellipsoidinertia    = 0;
-  vis->global.bvactive            = 1;
+  vis->global.bvactive            = 0;
 
   // rendering quality
   vis->quality.shadowsize         = 4096;