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Add built-in sphere mesh.

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PiperOrigin-RevId: 791162850
Change-Id: I573a414727e79f1a495e0f2282b2faff48ab3443
This commit is contained in:
Yuval Tassa
2025-08-05 05:04:11 -07:00
committed by Copybara-Service
parent 5220767457
commit 996f0040fd
8 changed files with 165 additions and 8 deletions
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python/mujoco/specs.cc
+9
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@@ -1014,6 +1014,15 @@ PYBIND11_MODULE(_specs, m) {
},
py::arg("resolution") = std::array<int, 2>{0, 0},
py::arg("fov") = std::array<double, 2>{0, 0}, py::arg("gamma") = 0);
mjsMesh.def(
"make_sphere",
[](raw::MjsMesh* self, int subdivision) {
double params[1] = {static_cast<double>(subdivision)};
if (mjs_makeMesh(self, mjMESH_BUILTIN_SPHERE, params, 1)) {
throw pybind11::value_error(mjs_getError(mjs_getSpec(self->element)));
}
},
py::arg("subdivision"));
mjsMesh.def(
"make_hemisphere",
[](raw::MjsMesh* self, int subdivision) {
python/mujoco/specs_test.py
+5 -1
View File
@@ -499,12 +499,16 @@ class SpecsTest(absltest.TestCase):
mesh = spec.add_mesh(name='hemisphere')
mesh.make_hemisphere(subdivision=4)
mesh = spec.add_mesh(name='sphere')
mesh.make_sphere(subdivision=2)
model = spec.compile()
self.assertEqual(model.nmesh, 4)
self.assertEqual(model.nmesh, 5)
self.assertEqual(model.mesh_vertnum[0], 25 * 25)
self.assertEqual(model.mesh_vertnum[1], 10)
self.assertEqual(model.mesh_vertnum[2], 7)
self.assertEqual(model.mesh_vertnum[3], 2 * (4 + 1) * (4 + 2) + 2)
self.assertEqual(model.mesh_vertnum[4], 2 + 10 * 4**2)
def test_compile_errors_with_line_info(self):
spec = mujoco.MjSpec()
src/user/user_api.cc
+18
View File
@@ -524,6 +524,24 @@ int mjs_makeMesh(mjsMesh* mesh, mjtMeshBuiltin builtin, double* params, int npar
return 0;
}
case mjMESH_BUILTIN_SPHERE: {
if (nparams != 1) {
m->SetError(mjCError(0, "Sphere mesh type requires 1 parameter"));
return -1;
}
int subdiv = static_cast<int>(params[0]);
if (subdiv < 0) {
m->SetError(mjCError(0, "Sphere subdivision cannot be negative"));
return -1;
}
if (subdiv > 4) {
m->SetError(mjCError(0, "Sphere subdivision cannot be greater than 4"));
return -1;
}
meshC->MakeSphere(subdiv, /*make_faces*/ true);
return 0;
}
case mjMESH_BUILTIN_WEDGE: {
if (nparams != 5) {
m->SetError(mjCError(0, "Wedge builtin mesh types require 5 parameters"));
src/user/user_mesh.cc
+105
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@@ -22,6 +22,7 @@
#include <cstring>
#include <functional>
#include <limits>
#include <map>
#include <memory>
#include <set>
#include <string>
@@ -2178,6 +2179,110 @@ void mjCMesh::MakeHemisphere(int res, bool make_faces, bool make_cap) {
// make a mesh of a sphere using icosaheral subdivision
void mjCMesh::MakeSphere(int subdiv, bool make_faces) {
// make icosahedron
const float phi = (1.0 + std::sqrt(5.0)) / 2.0;
std::vector<float> vert = {
-1.0, phi, 0.0,
1.0, phi, 0.0,
-1.0, -phi, 0.0,
1.0, -phi, 0.0,
0.0, -1.0, phi,
0.0, 1.0, phi,
0.0, -1.0, -phi,
0.0, 1.0, -phi,
phi, 0.0, -1.0,
phi, 0.0, 1.0,
-phi, 0.0, -1.0,
-phi, 0.0, 1.0,
};
// normalize vertices to be on a unit sphere
const double norm = std::sqrt(1.0 + phi * phi);
for (float& v : vert) {
v /= norm;
}
std::vector<int> face = {
0, 11, 5, 0, 5, 1, 0, 1, 7, 0, 7, 10, 0, 10, 11,
1, 5, 9, 5, 11, 4, 11, 10, 2, 10, 7, 6, 7, 1, 8,
3, 9, 4, 3, 4, 2, 3, 2, 6, 3, 6, 8, 3, 8, 9,
4, 9, 5, 2, 4, 11, 6, 2, 10, 8, 6, 7, 9, 8, 1
};
// subdivision
if (subdiv > 0) {
// helper to get or create a midpoint vertex
auto get_midpoint = [&vert](
int v1_idx, int v2_idx, std::map<std::pair<int, int>, int>& cache) -> int {
// key is the pair of vertex indices, sorted
std::pair<int, int> key = std::minmax(v1_idx, v2_idx);
// if midpoint is already in cache, return its index
auto it = cache.find(key);
if (it != cache.end()) {
return it->second;
}
// otherwise, create it
const float* v1 = &vert[v1_idx * 3];
const float* v2 = &vert[v2_idx * 3];
float mid_x = (v1[0] + v2[0]) / 2.0f;
float mid_y = (v1[1] + v2[1]) / 2.0f;
float mid_z = (v1[2] + v2[2]) / 2.0f;
// normalize the new vertex to put it on the sphere
float mid_norm = std::sqrt(mid_x * mid_x + mid_y * mid_y + mid_z * mid_z);
mid_x /= mid_norm;
mid_y /= mid_norm;
mid_z /= mid_norm;
// add the new vertex to the list
int new_idx = vert.size() / 3;
vert.push_back(mid_x);
vert.push_back(mid_y);
vert.push_back(mid_z);
// add to cache
cache[key] = new_idx;
return new_idx;
};
// subdivision loop
for (int i = 0; i < subdiv; ++i) {
std::map<std::pair<int, int>, int> midpoint_cache;
std::vector<int> new_face;
new_face.reserve(face.size() * 4);
for (size_t j = 0; j < face.size(); j += 3) {
int v1 = face[j];
int v2 = face[j+1];
int v3 = face[j+2];
int m12 = get_midpoint(v1, v2, midpoint_cache);
int m23 = get_midpoint(v2, v3, midpoint_cache);
int m31 = get_midpoint(v3, v1, midpoint_cache);
new_face.insert(new_face.end(), {v1, m12, m31});
new_face.insert(new_face.end(), {v2, m23, m12});
new_face.insert(new_face.end(), {v3, m31, m23});
new_face.insert(new_face.end(), {m12, m23, m31});
}
face = std::move(new_face);
}
}
// save vertices and maybe faces
mjs_setFloat(spec.uservert, vert.data(), vert.size());
if (make_faces) mjs_setInt(spec.userface, face.data(), face.size());
}
// make a mesh of a spherical wedge
void mjCMesh::MakeWedge(int resolution[2], double fov[2], double gamma) {
std::vector<double> x_edges(resolution[0] + 1, 0);
src/user/user_objects.h
+1
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@@ -1052,6 +1052,7 @@ class mjCMesh: public mjCMesh_, private mjsMesh {
// make a mesh of a predefined shape
void MakeHemisphere(int res, bool make_faces, bool make_cap);
void MakeSphere(int subdiv, bool make_faces);
void MakeWedge(int resolution[2], double fov[2], double gamma);
void MakeRect(int resolution[2]);
void MakeCone(int nedge, double radius);
test/engine/testdata/collision_convex/perf/spheremesh.xml
Vendored
+1 -4
View File
@@ -7,6 +7,7 @@
</visual>
<asset>
<mesh name="sphere" builtin="sphere" params="3" scale=".08 .08 .08"/>
<texture type="skybox" builtin="gradient" rgb1="0.3 0.5 0.7" rgb2="0 0 0" width="64" height="64"/>
<texture name="texplane" type="2d" builtin="checker" rgb1=".2 .3 .4" rgb2=".1 0.15 0.2" width="512" height="512" mark="cross" markrgb=".8 .8 .8"/>
<material name="matplane" reflectance="0.3" texture="texplane" texrepeat="1 1" texuniform="true"/>
@@ -38,8 +39,4 @@
</replicate>
</replicate>
</worldbody>
<asset>
<mesh name="sphere" builtin="wedge" params="25 25 180 90 0" scale=".08 .08 .08"/>
</asset>
</mujoco>
test/user/testdata/makemesh.xml
Vendored
+3 -1
View File
@@ -1,5 +1,6 @@
<mujoco model="makemesh">
<asset>
<mesh name="sphere" builtin="sphere" params="2" scale=".8 .8 .8"/>
<mesh name="hemisphere" builtin="hemisphere" params="4" scale=".8 .8 .8"/>
<mesh name="wedge" builtin="wedge" params="10 10 60 60 0"/>
<mesh name="prism3" builtin="cone" params="3 1" scale=".3 .3 .3"/>
@@ -10,7 +11,8 @@
<worldbody>
<light pos="0 0 10"/>
<geom mesh="hemisphere" type="mesh" pos="-2 0 0"/>
<geom mesh="sphere" type="mesh" pos="-3 0 0"/>
<geom mesh="hemisphere" type="mesh" pos="-1 0 0"/>
<geom mesh="wedge" type="mesh" euler="90 -90 0"/>
<geom mesh="prism5" type="mesh" pos="2 0 0" euler="90 0 0"/>
<geom mesh="prism3" type="mesh" pos="3 0 0"/>
test/user/user_mesh_test.cc
+23 -2
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@@ -15,6 +15,7 @@
// Tests for user/user_objects.cc.
#include <array>
#include <cmath>
#include <cstddef>
#include <limits>
#include <memory>
@@ -732,7 +733,6 @@ TEST_F(MjCMeshTest, VolumeTooSmall) {
EXPECT_THAT(model, testing::IsNull());
EXPECT_THAT(error.data(), HasSubstr("mesh volume is too small"));
mj_deleteModel(model);
}
TEST_F(MjCMeshTest, VisualVolumeTooSmall) {
@@ -760,7 +760,6 @@ TEST_F(MjCMeshTest, VisualVolumeTooSmall) {
EXPECT_THAT(model, testing::IsNull());
EXPECT_THAT(error.data(), HasSubstr("mesh volume is too small"));
mj_deleteModel(model);
}
TEST_F(MjCMeshTest, VisualVolumeSmallAllowedShell) {
@@ -1310,5 +1309,27 @@ TEST_F(MjCMeshTest, HemisphereSizes) {
mj_deleteModel(model);
}
TEST_F(MjCMeshTest, SphereSizes) {
static constexpr char xml[] = R"(
<mujoco model="makemesh">
<asset>
<mesh name="h0" builtin="sphere" params="0"/>
<mesh name="h1" builtin="sphere" params="1"/>
<mesh name="h2" builtin="sphere" params="2"/>
</asset>
</mujoco>
)";
std::array<char, 1024> error;
mjModel* model = LoadModelFromString(xml, error.data(), error.size());
ASSERT_THAT(model, NotNull()) << error.data();
EXPECT_EQ(model->mesh_vertnum[0], 2 + 10 * std::pow(4, 0));
EXPECT_EQ(model->mesh_vertnum[1], 2 + 10 * std::pow(4, 1));
EXPECT_EQ(model->mesh_vertnum[2], 2 + 10 * std::pow(4, 2));
EXPECT_EQ(model->mesh_facenum[0], 20 * std::pow(4, 0));
EXPECT_EQ(model->mesh_facenum[1], 20 * std::pow(4, 1));
EXPECT_EQ(model->mesh_facenum[2], 20 * std::pow(4, 2));
mj_deleteModel(model);
}
} // namespace
} // namespace mujoco