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

doc/XMLreference.rst

@@ -9321,10 +9321,10 @@ is effectively a miscellaneous subsection.
 
 .. _visual-global-bvactive:
 
-:at:`bvactive`: :at-val:`[false, true], "true"`
+:at:`bvactive`: :at-val:`[false, true], "false"`
    This attribute specifies whether collision and raycasting code should mark elements of Bounding Volume Hierarchies
-   as intersecting, for the purpose of visualization. Setting this attribute to "false" can speed up simulation for
-   models with high-resolution meshes.
+   as intersecting, for the purpose of visualization. Setting this attribute to "true" can slow down simulation for
+   models with high-resolution meshes, due to the O(N) cost of clearing visualization flags at each step.
 
 .. _visual-quality:
 

doc/changelog.rst

@@ -47,6 +47,9 @@ Engine
      of the effective-metric Cholesky factor, which no longer exists; ``mjData.efm_L`` now holds dense 3x3 blocks,
      9 numbers per covered vertex. ``mjData.efm_active`` no longer takes the value 2: nothing selects a solve path on
      preconditioner exactness, so it is now a plain 0/1 flag.
+   - Changed the default value of :ref:`bvactive<visual-global-bvactive>` from "true" to "false". This avoids
+     unnecessarily clearing bounding volume hierarchy visualization flags at every simulation step, which can be a
+     bottleneck for models with large meshes.
 
 Models
 ^^^^^^

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;

src/xml/generated/mjcf.xsd

@@ -1193,7 +1193,7 @@
       </xs:simpleType>
     </xs:attribute>
     <xs:attribute name="ellipsoidinertia" type="kw_bool" default="false"/>
-    <xs:attribute name="bvactive" type="kw_bool" default="true"/>
+    <xs:attribute name="bvactive" type="kw_bool" default="false"/>
   </xs:complexType>
 
   <xs:complexType name="quality">

src/xml/generated/mjcf_default_table.inc

@@ -122,7 +122,7 @@ static const mjXDefaultEntry kDefaults_mjVisual_global[] = {
   {"offheight", (int)offsetof(mjVisual, global.offheight), 2, 1, 1, 0, {480.0}},
   {"realtime", (int)offsetof(mjVisual, global.realtime), 1, 1, 1, 0, {1.0}},
   {"ellipsoidinertia", (int)offsetof(mjVisual, global.ellipsoidinertia), 2, 1, 1, 0, {0}},
-  {"bvactive", (int)offsetof(mjVisual, global.bvactive), 2, 1, 1, 0, {1}},
+  {"bvactive", (int)offsetof(mjVisual, global.bvactive), 2, 1, 1, 0, {0}},
 };
 
 static const mjXDefaultEntry kDefaults_mjVisual_headlight[] = {

src/xml/mjcf.schema

@@ -687,7 +687,7 @@ element global : mjVisual (field=global) {
   offheight          : int = 480
   realtime           : float = 1 (positive)
   ellipsoidinertia   : bool = false
-  bvactive           : bool = true
+  bvactive           : bool = false
 }
 
 element quality : mjVisual (field=quality) {

test/testdata/flex.xml

@@ -14,7 +14,7 @@
     <map force="0.1" zfar="30"/>
     <rgba haze="0.15 0.25 0.35 1"/>
     <quality shadowsize="4096"/>
-    <global offwidth="800" offheight="800"/>
+    <global offwidth="800" offheight="800" bvactive="true"/>
   </visual>
 
   <worldbody>

test/testdata/model.xml

@@ -26,6 +26,10 @@
     <material name="grid" texture="grid" texrepeat="1 1" texuniform="true" reflectance=".2"/>
   </asset>
 
+  <visual>
+    <global bvactive="true"/>
+  </visual>
+
   <default>
     <site rgba=".5 .5 .5 .5"/>
     <joint armature="1" damping="10"/>