Files
Mujoco_WASM/test/user/user_flex_test.cc
T
Alessio Quaglino 7d54123303 Make flex vert0 rotation-invariant for interpolated flexes.
The `vert0` array, used for parametric vertex coordinates in flexes, is now computed in the flex's local, unrotated frame when using interpolation. This ensures that the parametric coordinates are independent of the flex's initial orientation. A new test confirms that `flex_vert0` is identical for an unrotated and a rotated flex grid.

PiperOrigin-RevId: 908196464
Change-Id: I47d6bcc2bc5df581479d485480e0e947ec6d3ffd
2026-04-30 08:41:01 -07:00

1405 lines
43 KiB
C++

// Copyright 2021 DeepMind Technologies Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Tests for user/user_model.cc.
#include <array>
#include <memory>
#include <string>
#include <gmock/gmock.h>
#include <gtest/gtest.h>
#include <mujoco/mjmodel.h>
#include <mujoco/mujoco.h>
#include "test/fixture.h"
namespace mujoco {
namespace {
using ::testing::IsNull;
using ::testing::NotNull;
using ::testing::HasSubstr;
using ::testing::Pointwise;
using UserFlexTest = MujocoTest;
TEST_F(UserFlexTest, ParentMustHaveName) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull());
EXPECT_THAT(error.data(), HasSubstr("required attribute missing: 'name'"));
}
TEST_F(UserFlexTest, InvalidDim) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" dim="4"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull());
EXPECT_THAT(error.data(), HasSubstr("Invalid dim, must be between 1 and 3"));
}
TEST_F(UserFlexTest, CountTooSmall) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" count="2 2 0"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull());
EXPECT_THAT(error.data(), HasSubstr("Count too small"));
}
TEST_F(UserFlexTest, CellnumZeroInterpolated) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<body name="b0"/>
<body name="b1"/>
<body name="b2"/>
<body name="b3"/>
</worldbody>
<deformable>
<flex name="test" cellcount="2 2 0" dof="trilinear"
dim="3" body="b0 b1 b2 b3" element="0 1 2 3"/>
</deformable>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull());
EXPECT_THAT(error.data(), HasSubstr("cellcount cannot be 0"));
}
TEST_F(UserFlexTest, SpacingGreaterThanGeometry) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" spacing="0.5 0.5 0.5" radius="1"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(),
HasSubstr("Spacing must be larger than geometry size"));
}
TEST_F(UserFlexTest, ScaleMinValue) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" scale="0 1 1"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(), HasSubstr("Scale must be larger than mjMINVAL"));
}
TEST_F(UserFlexTest, MassMinValue) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" mass="0"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(),
HasSubstr("Mass and inertiabox must be larger than mjMINVAL"));
}
TEST_F(UserFlexTest, PointSizeNotMultipleOf3) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" point="0 0 0 0"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(), HasSubstr("Point size must be a multiple of 3"));
}
TEST_F(UserFlexTest, ElementSize) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" point="0 0 0" element="0 1 2" dim="3"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(),
HasSubstr("Element size must be a multiple of dim+1"));
}
TEST_F(UserFlexTest, PointAndElementNotInDirect) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="direct"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(), HasSubstr("Point and element required"));
}
TEST_F(UserFlexTest, UnknownFlexCompType) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="unknown"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(), HasSubstr("invalid keyword: 'unknown'"));
}
TEST_F(UserFlexTest, InvalidPinid) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="direct" point="0 0 0" element="0 1 2">
<pin id="1"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(),
HasSubstr("element 1 has point id 1, number of points is 1"));
}
TEST_F(UserFlexTest, MeshFileMissing) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="mesh"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(), HasSubstr("File is required"));
}
TEST_F(UserFlexTest, VertexOrFaceDataMissing) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/malformed_flex_nofaces.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
EXPECT_THAT(m, IsNull()) << error.data();
EXPECT_THAT(error.data(), HasSubstr("Vertex and face data required"));
}
TEST_F(UserFlexTest, CreateBVHSuccess) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/robot_arm.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, RigidFlex) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/rigid_flex.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, FlexNotCollide) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" pos="1 0 -1" type="grid"
count="5 5 5" spacing="1 1 1" dim="3">
<contact contype="0" conaffinity="0"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, BoundingBoxCoordinates) {
#ifdef mjUSESINGLE
GTEST_SKIP() << "Float32 rounding in bounding box centering gives ~3e-8 error";
#endif
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" pos="1 0 -1" type="grid"
count="5 5 5" spacing="1 1 1" dim="3"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
mj_kinematics(m, d);
mj_flex(m, d);
EXPECT_EQ(m->nflexvert, 5*5*5);
EXPECT_EQ(m->nflexelem, 4*4*4*6);
EXPECT_EQ(m->flex_dim[0], 3);
// Cartesian coordinates
EXPECT_EQ(d->flexvert_xpos[0], -1);
EXPECT_EQ(d->flexvert_xpos[1], -2);
EXPECT_EQ(d->flexvert_xpos[2], -3);
EXPECT_EQ(d->flexvert_xpos[3*m->nflexvert-3], 3);
EXPECT_EQ(d->flexvert_xpos[3*m->nflexvert-2], 2);
EXPECT_EQ(d->flexvert_xpos[3*m->nflexvert-1], 1);
// bounding box coordinates
EXPECT_EQ(m->flex_vert0[0], 0);
EXPECT_EQ(m->flex_vert0[1], 0);
EXPECT_EQ(m->flex_vert0[2], 0);
EXPECT_EQ(m->flex_vert0[3*m->nflexvert-3], 1);
EXPECT_EQ(m->flex_vert0[3*m->nflexvert-2], 1);
EXPECT_EQ(m->flex_vert0[3*m->nflexvert-1], 1);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, TrilinearCannotDoSelfCollision) {
std::array<char, 1024> error;
static constexpr char xml_selfcoll[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="2 2 2" spacing="1 1 1" dim="3" dof="trilinear">
<contact selfcollide="auto" internal="false"/>
</flexcomp>
</worldbody>
</mujoco>
)";
mjModel* m1 = LoadModelFromString(xml_selfcoll, error.data(), error.size());
EXPECT_THAT(m1, IsNull()) << error.data();
EXPECT_THAT(error.data(),
HasSubstr("trilinear interpolation cannot do self-collision"));
static constexpr char xml_internal[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="2 2 2" spacing="1 1 1" dim="3" dof="trilinear">
<contact selfcollide="none" internal="true"/>
</flexcomp>
</worldbody>
</mujoco>
)";
mjModel* m2 = LoadModelFromString(xml_internal, error.data(), error.size());
EXPECT_THAT(m2, IsNull()) << error.data();
EXPECT_THAT(error.data(),
HasSubstr("trilinear interpolation cannot do internal"));
}
TEST_F(UserFlexTest, TrilinearInterpolation) {
static constexpr char xml_trilinear[] = R"(
<mujoco>
<worldbody>
<geom type="plane" pos="0 0 -.5" size="10 10 .1"/>
<flexcomp name="test" type="grid" count="2 2 2" spacing="1 1 1" dim="3" dof="trilinear">
<contact selfcollide="none" internal="false"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m1 = LoadModelFromString(xml_trilinear, error.data(), error.size());
ASSERT_THAT(m1, NotNull()) << error.data();
mjData* d1 = mj_makeData(m1);
mj_step(m1, d1);
static constexpr char xml_linear[] = R"(
<mujoco>
<worldbody>
<geom type="plane" pos="0 0 -.5" size="10 10 .1"/>
<flexcomp name="test" type="grid" count="2 2 2" spacing="1 1 1" dim="3">
<contact selfcollide="none" internal="false"/>
</flexcomp>
</worldbody>
</mujoco>
)";
mjModel* m2 = LoadModelFromString(xml_linear, error.data(), error.size());
ASSERT_THAT(m2, NotNull()) << error.data();
mjData* d2 = mj_makeData(m2);
mj_step(m2, d2);
EXPECT_EQ(m1->nflexvert, m2->nflexvert);
for (int i = 0; i < 3*m1->nflexvert; ++i) {
EXPECT_NEAR(m1->flex_vert[i], d2->flexvert_xpos[i], 1e-7);
EXPECT_NEAR(m1->flex_vert0[i], m2->flex_vert0[i], 1e-7);
EXPECT_NEAR(d1->flexvert_xpos[i], d2->flexvert_xpos[i], 1e-7);
}
EXPECT_EQ(m1->nM, m2->nM);
for (int i = 0; i < m1->nM; ++i) {
EXPECT_EQ(d1->qM[i], d2->qM[i]);
}
EXPECT_EQ(m1->nbody, m2->nbody);
for (int i = 0; i < m2->nbody; ++i) {
if (i == 0) {
continue;
}
EXPECT_EQ(m1->body_mass[i], m2->body_mass[i]);
for (int j = 0; j < 2; ++j) {
EXPECT_EQ(m1->body_invweight0[i*2+j], m2->body_invweight0[i*2+j]);
}
for (int j = 0; j < 10; ++j) {
EXPECT_NEAR(d1->cinert[10*i+j], d2->cinert[i*10+j], 1e-5) << i;
EXPECT_NEAR(d1->crb[10*i+j], d2->crb[i*10+j], 1e-5) << i;
}
}
EXPECT_EQ(d1->ncon, 4);
EXPECT_EQ(d2->ncon, 4);
for (int i = 0; i < d1->ncon; ++i) {
EXPECT_EQ(d1->contact[i].dist, d2->contact[i].dist);
EXPECT_EQ(d1->contact[i].mu, d2->contact[i].mu);
for (int j = 0; j < 5; ++j) {
EXPECT_EQ(d1->contact[i].friction[j], d2->contact[i].friction[j]);
}
for (int j = 0; j < 3; ++j) {
EXPECT_EQ(d1->contact[i].pos[j], d2->contact[i].pos[j]);
}
for (int j = 0; j < 9; ++j) {
EXPECT_EQ(d1->contact[i].frame[j], d2->contact[i].frame[j]);
}
for (int j = 0; j < 36; ++j) {
EXPECT_EQ(d1->contact[i].H[j], d2->contact[i].H[j]);
}
}
EXPECT_EQ(d1->nefc, 4*(d1->contact[0].dim-1)*2);
EXPECT_EQ(d2->nefc, 4*(d2->contact[0].dim-1)*2);
EXPECT_EQ(d1->nJ, d2->nJ);
for (int i = 0; i < d1->nefc; ++i) {
EXPECT_EQ(d1->efc_diagApprox[i], d2->efc_diagApprox[i]);
EXPECT_EQ(d1->efc_D[i], d2->efc_D[i]);
}
mj_deleteModel(m1);
mj_deleteModel(m2);
mj_deleteData(d1);
mj_deleteData(d2);
}
TEST_F(UserFlexTest, StiffnessMatrix) {
#ifdef mjUSESINGLE
GTEST_SKIP() << "Stiffness matrix kernel check fails in float32 precision";
#endif
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="3 3 3" spacing="1 1 1" dim="3" dof="trilinear">
<contact selfcollide="none" internal="false"/>
<elasticity young="1"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
EXPECT_NE(m->flex_stiffness[m->flex_stiffnessadr[0]], 0);
EXPECT_EQ(m->nflexnode, 8);
// constants are in the kernel
mjtNum ones[24], zeros[24], res[24];
for (int i = 0; i < 3*m->nflexnode; ++i) {
zeros[i] = 0;
ones[i] = 1;
}
mju_mulMatVec(res, m->flex_stiffness + m->flex_stiffnessadr[0], ones,
3 * m->nflexnode, 3 * m->nflexnode);
EXPECT_THAT(res, Pointwise(MjNear(1e-8, 1e-4), zeros));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, StiffnessCacheDiffersByGeometry) {
std::array<char, 1024> error;
// Create two flexes with same material but different bounding boxes
static constexpr char xml_small[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="3 3 3" spacing="1 1 1" dim="3" dof="trilinear">
<contact selfcollide="none" internal="false"/>
<elasticity young="1" poisson="0.3"/>
</flexcomp>
</worldbody>
</mujoco>
)";
static constexpr char xml_large[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="3 3 3" spacing="2 2 2" dim="3" dof="trilinear">
<contact selfcollide="none" internal="false"/>
<elasticity young="1" poisson="0.3"/>
</flexcomp>
</worldbody>
</mujoco>
)";
mjModel* m_small = LoadModelFromString(xml_small, error.data(), error.size());
ASSERT_THAT(m_small, NotNull()) << error.data();
mjModel* m_large = LoadModelFromString(xml_large, error.data(), error.size());
ASSERT_THAT(m_large, NotNull()) << error.data();
// Same number of nodes but different stiffness due to different geometry
EXPECT_EQ(m_small->nflexnode, m_large->nflexnode);
EXPECT_NE(m_small->flex_stiffness[m_small->flex_stiffnessadr[0]],
m_large->flex_stiffness[m_large->flex_stiffnessadr[0]]);
mj_deleteModel(m_small);
mj_deleteModel(m_large);
}
TEST_F(UserFlexTest, LoadTexture) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/textured_torus_flex.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
EXPECT_THAT(m->nflextexcoord, 637);
EXPECT_THAT(m->flex_elemtexcoord[0], 0);
EXPECT_THAT(m->flex_elemtexcoord[1], 1);
EXPECT_THAT(m->flex_elemtexcoord[2], 2);
EXPECT_THAT(m->flex_elemtexcoord[3], 0);
EXPECT_THAT(m->flex_elemtexcoord[4], 2);
EXPECT_THAT(m->flex_elemtexcoord[5], 3);
mj_deleteModel(m);
}
TEST_F(UserFlexTest, LoadMSHBinary_41_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/cube_41_binary_vol_gmshApp.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
EXPECT_EQ(m->nflexvert, 14);
EXPECT_EQ(m->nflexelem, 24);
EXPECT_EQ(m->flex_dim[0], 3);
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHBinary_22_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/cube_22_binary_vol_gmshApp.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
EXPECT_EQ(m->nflexvert, 14);
EXPECT_EQ(m->nflexelem, 24);
EXPECT_EQ(m->flex_dim[0], 3);
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHSurfaceBinary_41_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/cube_41_binary_surf_gmshApp.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
mj_kinematics(m, d);
mj_flex(m, d);
EXPECT_EQ(m->nflexvert, 14);
EXPECT_EQ(m->nflexelem, 24);
EXPECT_EQ(m->flex_dim[0], 2);
// first node x y z
EXPECT_EQ(d->flexvert_xpos[0], -0.5 );
EXPECT_EQ(d->flexvert_xpos[1], -0.5 );
EXPECT_EQ(d->flexvert_xpos[2], 0 );
// first element
EXPECT_EQ(m->flex_elem[0], 9-1 );
EXPECT_EQ(m->flex_elem[1], 4-1 );
EXPECT_EQ(m->flex_elem[2], 3-1 );
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHSurfaceBinary_22_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/cube_22_binary_surf_gmshApp.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
mj_kinematics(m, d);
mj_flex(m, d);
EXPECT_EQ(m->nflexvert, 14);
EXPECT_EQ(m->nflexelem, 24);
EXPECT_EQ(m->flex_dim[0], 2);
// first node x y z
EXPECT_EQ(d->flexvert_xpos[0], -0.5 );
EXPECT_EQ(d->flexvert_xpos[1], -0.5 );
EXPECT_EQ(d->flexvert_xpos[2], 0 );
// first element
EXPECT_EQ(m->flex_elem[0], 9-1 );
EXPECT_EQ(m->flex_elem[1], 4-1 );
EXPECT_EQ(m->flex_elem[2], 3-1 );
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHBinaryFTETWILD_22_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/shark_22_binary_vol_fTetWild.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
EXPECT_EQ(m->nflexvert, 429);
EXPECT_EQ(m->nflexelem, 1073);
EXPECT_EQ(m->flex_dim[0], 3);
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHASCII_41_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/cube_41_ascii_vol_gmshApp.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
EXPECT_EQ(m->nflexvert, 14);
EXPECT_EQ(m->nflexelem, 24);
EXPECT_EQ(m->flex_dim[0], 3);
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHASCII_22_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/cube_22_ascii_vol_gmshApp.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
EXPECT_EQ(m->nflexvert, 14);
EXPECT_EQ(m->nflexelem, 24);
EXPECT_EQ(m->flex_dim[0], 3);
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHSurfaceASCII_41_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/cube_41_ascii_surf_gmshApp.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
mj_kinematics(m, d);
mj_flex(m, d);
EXPECT_EQ(m->nflexvert, 14);
EXPECT_EQ(m->nflexelem, 24);
EXPECT_EQ(m->flex_dim[0], 2);
// first node x y z
EXPECT_EQ(d->flexvert_xpos[0], -0.5 );
EXPECT_EQ(d->flexvert_xpos[1], -0.5 );
EXPECT_EQ(d->flexvert_xpos[2], 0 );
// first element
EXPECT_EQ(m->flex_elem[0], 9-1 );
EXPECT_EQ(m->flex_elem[1], 4-1 );
EXPECT_EQ(m->flex_elem[2], 3-1 );
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHSurfaceASCII_22_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/cube_22_ascii_surf_gmshApp.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
mj_kinematics(m, d);
mj_flex(m, d);
EXPECT_EQ(m->nflexvert, 14);
EXPECT_EQ(m->nflexelem, 24);
EXPECT_EQ(m->flex_dim[0], 2);
// first node x y z
EXPECT_EQ(d->flexvert_xpos[0], -0.5 );
EXPECT_EQ(d->flexvert_xpos[1], -0.5 );
EXPECT_EQ(d->flexvert_xpos[2], 0 );
// first element
EXPECT_EQ(m->flex_elem[0], 9-1 );
EXPECT_EQ(m->flex_elem[1], 4-1 );
EXPECT_EQ(m->flex_elem[2], 3-1 );
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHASCIIFTETWILD_22_Success) {
const std::string xml_path =
GetTestDataFilePath("user/testdata/shark_22_ascii_vol_fTetWild.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
EXPECT_EQ(m->nflexvert, 425);
EXPECT_EQ(m->nflexelem, 1070);
EXPECT_EQ(m->flex_dim[0], 3);
mj_step(m, d);
mj_deleteModel(m);
mj_deleteData(d);
}
TEST_F(UserFlexTest, LoadMSHASCII_41_MissingNodeHeader_Fail) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/malformed_cube_41_ascii_missing_node_header.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
EXPECT_THAT(error.data(), HasSubstr(
"XML Error: Error: All nodes must be in single block"));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, LoadMSHASCII_41_MissingNodeIndex_Fail) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/malformed_cube_41_ascii_missing_node_index.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
EXPECT_THAT(error.data(), HasSubstr(
"XML Error: Error: Node tags must be sequential"));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, LoadMSHASCII_41_MissingElementHeader_Fail) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/malformed_cube_41_ascii_missing_element_header.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
EXPECT_THAT(error.data(), HasSubstr(
"XML Error: Error: All elements must be in single block"));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, LoadMSHASCII_41_MissingElement_Fail) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/malformed_cube_41_ascii_missing_element.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
EXPECT_THAT(error.data(), HasSubstr(
"XML Error: Error: Error reading Elements"));
mj_deleteModel(m);
}
TEST_F(UserFlexTest,
LoadMSHASCII_41_MismatchBetweenMaxNodesAndNodesInBlock_Fail) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/malformed_cube_41_ascii_mismatch_between_max_nodes_and_nodes_in_block.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
EXPECT_THAT(error.data(), HasSubstr(
"XML Error: Error: Maximum number of nodes must be equal to number of nodes in a block\nElement 'flexcomp', line 22\n"));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, LoadMSHASCII_22_MissingNumNodes_Fail) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/malformed_cube_22_ascii_missing_num_nodes.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
// TODO(mohammadhamid): Replace with an assertion about the error message. For
// some reason, on Windows the error message is different on GH Actions
EXPECT_THAT(m, IsNull());
mj_deleteModel(m);
}
TEST_F(UserFlexTest, LoadMSHASCII_22_MissingNode_Fail) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/malformed_cube_22_ascii_missing_node.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
EXPECT_THAT(error.data(), HasSubstr(
"XML Error: Error: Error reading node tags"));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, LoadMSHASCII_22_MissingNumElements_Fail) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/malformed_shark_22_ascii_missing_num_elements.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
// TODO(mohammadhamid): Replace with an assertion about the error message. For
// some reason, on Windows the error message is different on GH Actions
EXPECT_THAT(m, IsNull());
mj_deleteModel(m);
}
TEST_F(UserFlexTest, LoadMSHASCII_22_MissingElement_Fail) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/malformed_cube_22_ascii_missing_element.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
EXPECT_THAT(error.data(), HasSubstr(
"XML Error: Error: Error reading Elements"));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, LoadMSHASCII_dim_missing_in_xml) {
const std::string xml_path =
GetTestDataFilePath(
"user/testdata/cube_22_ascii_vol_gmshApp_missing_dim.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
EXPECT_EQ(m->flex_dim[0], 3);
mj_deleteModel(m);
}
TEST_F(UserFlexTest, TrilinearUnusedVertices_Crash) {
// This XML defines 5 points but only uses 4 in the element.
// The last point (2 2 2) is unused.
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="direct"
point="0 0 0 1 0 0 0 1 0 0 0 1 2 2 2"
element="0 1 2 3"
dof="trilinear" dim="3">
<contact selfcollide="none"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, testing::NotNull()) << error.data();
mj_deleteModel(m);
}
TEST_F(UserFlexTest, MeshNodePinning) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="direct"
point="0 0 0 1 0 0 0 1 0 0 0 1 2 2 2"
element="0 1 2 3"
dof="trilinear" dim="3">
<contact selfcollide="none"/>
<pin id="0"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, testing::NotNull()) << error.data();
// Verify that node 0 (corner) is pinned
// Trilinear 3D has 8 nodes.
// If 0 are pinned, we get 8 bodies.
// If 1 is pinned, we get 7 bodies (created) + 1 existing (the parent).
// m->nbody should reflect this. Flex bodies are added to the model.
// Model has 1 world body + flex bodies.
EXPECT_EQ(m->nbody, 1 + 7); // 1 world + 7 flex nodes (1 pinned)
mj_deleteModel(m);
}
TEST_F(UserFlexTest, FlexcompMeshLoadsFromVFS) {
// read cube.stl from testdata into a buffer
const std::string stl_path =
GetTestDataFilePath("user/testdata/cube.stl");
FILE* f = fopen(stl_path.c_str(), "rb");
ASSERT_THAT(f, NotNull()) << "Could not open " << stl_path;
fseek(f, 0, SEEK_END);
long stl_size = ftell(f);
fseek(f, 0, SEEK_SET);
std::string stl_data(stl_size, '\0');
fread(stl_data.data(), 1, stl_size, f);
fclose(f);
// add the STL data to a VFS
mjVFS vfs;
mj_defaultVFS(&vfs);
mj_addBufferVFS(&vfs, "cube.stl", stl_data.data(), stl_size);
// XML that uses flexcomp type="mesh" referencing the VFS file
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<body name="flex_body" pos="0 0 1">
<flexcomp name="flex_object" type="mesh" file="cube.stl" rigid="true">
<contact contype="1" conaffinity="1"/>
</flexcomp>
</body>
</worldbody>
</mujoco>
)";
// cleanup
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size(), &vfs);
ASSERT_THAT(m, NotNull()) << error.data();
mjData* d = mj_makeData(m);
mj_step(m, d);
mj_deleteData(d);
mj_deleteModel(m);
mj_deleteVFS(&vfs);
}
// Test that flex constraints are preserved when attaching a model
TEST_F(UserFlexTest, FlexAttachConstraintPreserved) {
// Child model with flex and strain constraint
static constexpr char flex_xml[] = R"(
<mujoco>
<worldbody>
<body name="flex_parent">
<flexcomp name="test" type="box"
spacing=".1 .1 .1" radius="0.001"
dof="trilinear" mass="1" dim="3">
<contact selfcollide="none"/>
<edge equality="strain"/>
</flexcomp>
</body>
</worldbody>
</mujoco>
)";
// Parent model that attaches the flex model
static constexpr char parent_xml[] = R"(
<mujoco>
<asset>
<model name="flex" file="flex.xml"/>
</asset>
<worldbody>
<frame pos="0 0 0.3">
<attach model="flex" prefix="flex_"/>
</frame>
</worldbody>
</mujoco>
)";
// Set up VFS with both XML files
auto vfs = std::make_unique<mjVFS>();
mj_defaultVFS(vfs.get());
mj_addBufferVFS(vfs.get(), "flex.xml", flex_xml, sizeof(flex_xml));
// First verify the standalone flex model has constraints
std::array<char, 1024> error;
mjModel* m_standalone =
LoadModelFromString(flex_xml, error.data(), error.size(), vfs.get());
ASSERT_THAT(m_standalone, NotNull()) << error.data();
mjData* d_standalone = mj_makeData(m_standalone);
mj_forward(m_standalone, d_standalone);
int standalone_neq = m_standalone->neq;
EXPECT_GT(standalone_neq, 0) << "Standalone flex should have constraints";
mj_deleteData(d_standalone);
mj_deleteModel(m_standalone);
// Now load the parent model which attaches the flex
mjModel* m_attached =
LoadModelFromString(parent_xml, error.data(), error.size(), vfs.get());
ASSERT_THAT(m_attached, NotNull()) << error.data();
mjData* d_attached = mj_makeData(m_attached);
mj_forward(m_attached, d_attached);
// THE BUG: flex constraints disappear when attached
EXPECT_GT(m_attached->neq, 0)
<< "Attached flex should preserve strain constraints";
EXPECT_EQ(m_attached->neq, standalone_neq)
<< "Attached flex should have same number of constraints as standalone";
mj_deleteData(d_attached);
mj_deleteModel(m_attached);
mj_deleteVFS(vfs.get());
}
TEST_F(UserFlexTest, FlexNoConstraintsWarning) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="4 4 1" spacing=".2 .2 .2"
dim="2" radius=".1"/>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
EXPECT_THAT(error.data(),
HasSubstr("no equality constraints or passive forces"));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, EmptyCellNodePinning) {
// A 2x2x2 grid with a box mesh that fills all cells.
// No nodes should be pinned.
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="box" spacing=".1 .1 .1" dim="3"
dof="trilinear" mass="1" cellcount="2 2 2">
<contact selfcollide="none"/>
<elasticity young="1"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
// A 2x2x2 grid with trilinear order has (2+1)^3 = 27 node positions.
int nadr = m->flex_nodeadr[0];
int nnode = m->flex_nodenum[0];
EXPECT_EQ(nnode, 27);
// All cells are occupied by the box, so no node should be pinned.
int pinned = 0;
for (int n = nadr; n < nadr + nnode; n++) {
int bid = m->flex_nodebodyid[n];
if (m->body_jntnum[bid] == 0) {
pinned++;
}
}
EXPECT_EQ(pinned, 0);
// Verify simulation works
mjData* d = mj_makeData(m);
for (int i = 0; i < 10; i++) {
mj_step(m, d);
}
mj_deleteData(d);
mj_deleteModel(m);
}
TEST_F(UserFlexTest, EmptyCellNodePinningMesh) {
// Load bunny_multicell.xml which has a 3x3x3 grid.
// The bunny mesh only occupies some cells, so many nodes should be pinned.
const std::string xml_path =
GetModelPath("flex/bunny_multicell.xml");
std::array<char, 1024> error;
mjModel* m = mj_loadXML(xml_path.c_str(), 0, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
// 3x3x3 grid, order=1: (3+1)^3 = 64 node positions
int nadr = m->flex_nodeadr[0];
int nnode = m->flex_nodenum[0];
EXPECT_EQ(nnode, 64);
// Count pinned nodes (no joints)
int pinned = 0;
int free_nodes = 0;
for (int n = nadr; n < nadr + nnode; n++) {
int bid = m->flex_nodebodyid[n];
if (m->body_jntnum[bid] == 0) {
pinned++;
} else {
free_nodes++;
}
}
// At least some nodes should be pinned since the bunny doesn't fill all cells
EXPECT_GT(pinned, 0) << "Expected some nodes to be pinned from empty cells";
EXPECT_GT(free_nodes, 0) << "Expected some nodes to remain free";
EXPECT_EQ(pinned + free_nodes, nnode);
// Verify the model can simulate
mjData* d = mj_makeData(m);
mj_forward(m, d);
for (int i = 0; i < 10; i++) {
mj_step(m, d);
}
mj_deleteData(d);
mj_deleteModel(m);
}
TEST_F(UserFlexTest, EmptyCellNodePinningQuadratic) {
// Regression test for ci_min calculation with order=2.
// A 2x1x1 quadratic grid has nodes at gi=0..4 (5 nodes per axis).
// We place mesh vertices only in cell 0 (x in [0, 0.5]), so cell 1 is empty.
//
// Node gi=3 belongs only to cell 1 (1*2 <= 3 <= 2*2).
// With the old formula (gi-order)/order = (3-2)/2 = 0, it would also check
// cell 0 (non-empty), incorrectly marking gi=3 as non-pinned.
// Single hex element at x=[0,0.3], well inside cell 0 of a 3x1x1 grid.
// Anchor vertex at x=1.0 extends the bounding box to [0,1]^3.
// The 3x1x1 quadratic grid splits at x=0.33, 0.67.
// Cell 0 has vertices, cells 1 and 2 are empty.
// Interior nodes for cells 1,2 should be pinned to the parent body.
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<body name="parent">
<freejoint/>
<inertial mass="0.01" pos="0 0 0"
diaginertia="0.001 0.001 0.001"/>
<flexcomp name="test" type="direct" dim="3"
dof="quadratic" mass="1" cellcount="3 1 1"
point="0.0 0.0 0.0 0.3 0.0 0.0
0.0 1.0 0.0 0.3 1.0 0.0
0.0 0.0 1.0 0.3 0.0 1.0
0.0 1.0 1.0 0.3 1.0 1.0
1.0 0.5 0.5"
element="0 1 3 2 4 5 7 6">
<contact selfcollide="none"/>
<elasticity young="1"/>
</flexcomp>
</body>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
// 3x1x1 quadratic grid: (3*2+1) * (1*2+1) * (1*2+1) = 7*3*3 = 63 nodes
int nadr = m->flex_nodeadr[0];
int nnode = m->flex_nodenum[0];
EXPECT_EQ(nnode, 63);
// Count pinned nodes: pinned nodes are assigned to the parent body.
int parent_bid = mj_name2id(m, mjOBJ_BODY, "parent");
ASSERT_GT(parent_bid, 0);
int pinned = 0;
for (int n = nadr; n < nadr + nnode; n++) {
if (m->flex_nodebodyid[n] == parent_bid) {
pinned++;
}
}
// Cells 1 and 2 are empty, so nodes exclusively in those cells are pinned.
// Nodes at gi=3..6 (with any gj, gk) are only in cells 1 and/or 2.
// That's 4 * 3 * 3 = 36 nodes.
EXPECT_EQ(pinned, 36);
mj_deleteData(mj_makeData(m));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, EmptyCellDetectsElements) {
// A cube surface mesh (dim=2, 12 triangles) spanning [0,1]^3.
// With cellcount="6 6 6" (216 cells), only 8 corner cells contain
// mesh vertices.
//
// Bug: MarkEmptyCells only checked vertices, so 208/216 cells are
// marked empty, causing most interior nodes to be incorrectly pinned.
// Fix: check element AABBs to correctly identify occupied cells.
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<body name="parent">
<freejoint/>
<inertial mass="0.01" pos="0.5 0.5 0.5"
diaginertia="0.001 0.001 0.001"/>
<flexcomp name="test" type="direct" dim="2"
dof="trilinear" mass="1" cellcount="6 6 6"
point="0 0 0 1 0 0 1 1 0 0 1 0
0 0 1 1 0 1 1 1 1 0 1 1"
element="0 1 2 0 2 3 4 6 5 4 7 6
0 5 1 0 4 5 2 7 3 2 6 7
0 3 7 0 7 4 1 5 6 1 6 2">
<contact selfcollide="none"/>
</flexcomp>
</body>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
// 6x6x6 trilinear grid: (6+1)^3 = 343 nodes
int nadr = m->flex_nodeadr[0];
int nnode = m->flex_nodenum[0];
ASSERT_EQ(nnode, 343);
// Count pinned nodes: those assigned to the parent body.
int parent_bid = mj_name2id(m, mjOBJ_BODY, "parent");
ASSERT_GT(parent_bid, 0);
int pinned = 0;
for (int n = nadr; n < nadr + nnode; n++) {
if (m->flex_nodebodyid[n] == parent_bid) {
pinned++;
}
}
// The cube surface fills the entire bounding box. The element-AABB
// marks all boundary cells as surface cells (152/216). The interior
// flood-fill finds no exterior seeds (all boundary cells are surface),
// so the remaining 64 cells are classified as interior (non-empty).
// No cells are empty → 0 nodes pinned.
EXPECT_EQ(pinned, 0);
mj_deleteData(mj_makeData(m));
mj_deleteModel(m);
}
TEST_F(UserFlexTest, TotalMassTrilinear) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="2 2 2" spacing="1 1 1"
dim="3" dof="trilinear" mass="1.5">
<contact selfcollide="none" internal="false"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
double total_mass = 0;
for (int i = 1; i < m->nbody; ++i) {
total_mass += m->body_mass[i];
}
EXPECT_NEAR(total_mass, 1.5, 1e-5);
mj_deleteModel(m);
}
TEST_F(UserFlexTest, TotalMassQuadratic) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="3 2 2" spacing="1 1 1"
dim="3" dof="quadratic" mass="2.0">
<contact selfcollide="none" internal="false"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(m, NotNull()) << error.data();
double total_mass = 0;
for (int i = 1; i < m->nbody; ++i) {
total_mass += m->body_mass[i];
}
EXPECT_NEAR(total_mass, 2.0, 1e-5);
mj_deleteModel(m);
}
TEST_F(UserFlexTest, Dof2d) {
// 3x3 grid with dof="2d": 9 vertices, 2 DOFs each -> nv = 18
static constexpr char xml_2d[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="3 3 1" spacing=".1 .1 .1"
dim="2" radius=".01" dof="2d">
<edge equality="true"/>
</flexcomp>
</worldbody>
</mujoco>
)";
// same model with dof="full" for comparison: 9 vertices, 3 DOFs each -> nv = 27
static constexpr char xml_full[] = R"(
<mujoco>
<worldbody>
<flexcomp name="test" type="grid" count="3 3 1" spacing=".1 .1 .1"
dim="2" radius=".01">
<edge equality="true"/>
</flexcomp>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
// load 2d model
mjModel* m_2d = LoadModelFromString(xml_2d, error.data(), error.size());
ASSERT_THAT(m_2d, NotNull()) << error.data();
mjData* d_2d = mj_makeData(m_2d);
// load full model
mjModel* m_full = LoadModelFromString(xml_full, error.data(), error.size());
ASSERT_THAT(m_full, NotNull()) << error.data();
mjData* d_full = mj_makeData(m_full);
// verify DOF counts
EXPECT_EQ(m_2d->nv, 18); // 9 vertices * 2 DOFs
EXPECT_EQ(m_full->nv, 27); // 9 vertices * 3 DOFs
// same number of vertices and elements
EXPECT_EQ(m_2d->nflexvert, m_full->nflexvert);
EXPECT_EQ(m_2d->nflexelem, m_full->nflexelem);
// each body has 2 DOFs in 2d mode, 3 in full mode
for (int i = 1; i < m_2d->nbody; i++) {
EXPECT_EQ(m_2d->body_dofnum[i], 2) << "body " << i;
}
for (int i = 1; i < m_full->nbody; i++) {
EXPECT_EQ(m_full->body_dofnum[i], 3) << "body " << i;
}
// simulate a few steps to make sure nothing crashes
for (int i = 0; i < 10; i++) {
mj_step(m_2d, d_2d);
mj_step(m_full, d_full);
}
mj_deleteModel(m_2d);
mj_deleteModel(m_full);
mj_deleteData(d_2d);
mj_deleteData(d_full);
}
TEST_F(UserFlexTest, Vert0RotationInvariant) {
// unrotated trilinear grid
static constexpr char xml_unrotated[] = R"(
<mujoco>
<worldbody>
<body name="parent">
<flexcomp name="test" type="grid" count="2 2 2" spacing="1 1 1"
dim="3" dof="trilinear">
<contact selfcollide="none" internal="false"/>
</flexcomp>
</body>
</worldbody>
</mujoco>
)";
// same grid rotated 45 degrees around Z via parent body quaternion
static constexpr char xml_rotated[] = R"(
<mujoco>
<worldbody>
<body name="parent" quat="0.9238795 0 0 0.3826834">
<flexcomp name="test" type="grid" count="2 2 2" spacing="1 1 1"
dim="3" dof="trilinear">
<contact selfcollide="none" internal="false"/>
</flexcomp>
</body>
</worldbody>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* m1 = LoadModelFromString(xml_unrotated, error.data(), error.size());
ASSERT_THAT(m1, NotNull()) << error.data();
mjModel* m2 = LoadModelFromString(xml_rotated, error.data(), error.size());
ASSERT_THAT(m2, NotNull()) << error.data();
// same number of vertices
ASSERT_EQ(m1->nflexvert, m2->nflexvert);
// vert0 must be identical regardless of rotation
for (int i = 0; i < 3 * m1->nflexvert; ++i) {
EXPECT_NEAR(m1->flex_vert0[i], m2->flex_vert0[i], 1e-10)
<< "vert0 mismatch at index " << i;
}
mj_deleteModel(m1);
mj_deleteModel(m2);
}
} // namespace
} // namespace mujoco