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Fix segfault in FuseStatic when body contains cameras or lights

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FuseStatic deletes static (joint-less) bodies and reassigns their
children to the parent body. Geoms and sites were reassigned, but
cameras and lights were not, leaving dangling body pointers that
crash in mjCCamera::Compile() / mjCLight::Compile().

Add camera and light reassignment in FuseStatic and FuseReindex.
This commit is contained in:
Kevin Zakka
2026-02-09 14:56:51 -08:00
parent a6a639003f
commit f570ab52a8
2 changed files with 67 additions and 1 deletions
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src/user/user_model.cc
+20 -1
View File
@@ -4138,6 +4138,8 @@ void mjCModel::FuseReindex(mjCBody* body) {
makelistid(joints_, body->joints);
makelistid(geoms_, body->geoms);
makelistid(sites_, body->sites);
makelistid(cameras_, body->cameras);
makelistid(lights_, body->lights);
// process children recursively
for (int i=0; i < body->bodies.size(); i++) {
@@ -4265,10 +4267,25 @@ void mjCModel::FuseStatic(void) {
mju_error("Internal error: FuseStatic: body not found");
}
//------------- assign geoms and sites to parent, change frames
//------------- assign geoms, sites, cameras, lights to parent, change frames
ReassignChild(par->geoms, body->geoms, par, body);
ReassignChild(par->sites, body->sites, par, body);
ReassignChild(par->cameras, body->cameras, par, body);
// lights have dir instead of quat, so handle separately
for (int j=0; j < body->lights.size(); j++) {
body->lights[j]->body = par;
par->lights.push_back(body->lights[j]);
// transform pos into parent frame
double qunit[4] = {1, 0, 0, 0};
changeframe(body->lights[j]->pos, qunit, body->pos, body->quat);
// rotate dir into parent frame
mjuu_rotVecQuat(body->lights[j]->dir, body->lights[j]->dir, body->quat);
}
body->lights.clear();
//------------- remove from global body list, reduce global counts
@@ -4300,6 +4317,8 @@ void mjCModel::FuseStatic(void) {
joints_.clear();
geoms_.clear();
sites_.clear();
cameras_.clear();
lights_.clear();
FuseReindex(bodies_[0]);
// recompute parent contype, conaffinity, and margin
test/user/user_model_test.cc
+47
View File
@@ -668,6 +668,53 @@ TEST_F(FuseStaticTest, FuseStaticForceSensorReferencedBody) {
mj_deleteModel(m);
}
TEST_F(FuseStaticTest, FuseStaticCameraInBody) {
static constexpr char xml[] = R"(
<mujoco>
<compiler fusestatic="true"/>
<worldbody>
<body>
<joint axis="1 0 0"/>
<geom size="0.5"/>
<body pos="1 0 0">
<site name="site1"/>
<camera name="cam1"/>
</body>
</body>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
EXPECT_EQ(m->nbody, 2) << "Static body should be fused";
EXPECT_EQ(m->ncam, 1);
mj_deleteModel(m);
}
TEST_F(FuseStaticTest, FuseStaticLightInBody) {
static constexpr char xml[] = R"(
<mujoco>
<compiler fusestatic="true"/>
<worldbody>
<body>
<joint axis="1 0 0"/>
<geom size="0.5"/>
<body pos="1 0 0">
<light name="light1" dir="0 0 -1"/>
</body>
</body>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
EXPECT_EQ(m->nbody, 2) << "Static body should be fused";
EXPECT_EQ(m->nlight, 1);
mj_deleteModel(m);
}
// ------------- test discardvisual --------------------------------------------
using DiscardVisualTest = MujocoTest;