From f04c5c8c36381c373d42579a414b7907dff17ea4 Mon Sep 17 00:00:00 2001
From: aki <aki.petit@icloud.com>
Date: Wed, 9 Sep 2026 17:55:56 +0800
Subject: [PATCH] fix(robotics): enable collider for mesh-bearing URDF
 collision links

The URDF importer fills `shapeFile`/shape transforms for mesh-bearing
<collision> geometry but leaves `colliderType` at the prefab default
(ColliderType::None). The resulting bot has no collision representation:
mochi contact queries (TotalContactForce / ContactPoints) are refused
("Contact queries are only supported for actors with contact sample
points") and no contact is generated with other actors.

Set ColliderType::Auto when a collision mesh resolves, so imported URDF
bots participate in contact. Links without a mesh collision keep the
default unchanged.

Regression tests: mesh collision -> Auto, primitive-only collision ->
None.
---
 .../src/utils/urdf_import_utils.cpp           |  3 +
 .../test/urdf_mesh_resolution_test.cpp        | 67 +++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/superdex_robotics/src/utils/urdf_import_utils.cpp b/superdex_robotics/src/utils/urdf_import_utils.cpp
index c816e9ee..3bf5245a 100644
--- a/superdex_robotics/src/utils/urdf_import_utils.cpp
+++ b/superdex_robotics/src/utils/urdf_import_utils.cpp
@@ -481,6 +481,9 @@ void PopulateFromParsedModel(
           ParsedMesh const& mesh = *parsedLink.collision;
           if (auto const resolved = ResolveMeshPath(mesh.filename, meshBasePath)) {
             link->shapeFile = DynamicString{*resolved};
+            // Enable the collider for mesh-bearing links: ColliderType::None is
+            // the prefab default, which leaves the robot contactless.
+            link->colliderType = ColliderType::Auto;
           }
           if (meshRefs != nullptr) {
             meshRefs->links[iLink].collision = DynamicString{mesh.filename};
diff --git a/superdex_robotics/test/urdf_mesh_resolution_test.cpp b/superdex_robotics/test/urdf_mesh_resolution_test.cpp
index 3eb82dad..ae4236c0 100644
--- a/superdex_robotics/test/urdf_mesh_resolution_test.cpp
+++ b/superdex_robotics/test/urdf_mesh_resolution_test.cpp
@@ -69,6 +69,37 @@ class UrdfMeshResolutionTest : public testing::Test {
 )";
   }
 
+  // Same, but the mesh is the <collision> geometry instead of <visual>.
+  static std::string SingleMeshCollisionUrdf(std::string_view packageMeshUri) {
+    return std::string(R"(<?xml version="1.0"?>
+<robot name="test_robot">
+  <link name="base_link">
+    <collision>
+      <geometry>
+        <mesh filename=")") +
+        std::string(packageMeshUri) + R"("/>
+      </geometry>
+    </collision>
+  </link>
+</robot>
+)";
+  }
+
+  // Primitive-only collision geometry (no mesh).
+  static std::string SinglePrimitiveCollisionUrdf() {
+    return std::string(R"(<?xml version="1.0"?>
+<robot name="test_robot">
+  <link name="base_link">
+    <collision>
+      <geometry>
+        <cylinder length="0.1" radius="0.02"/>
+      </geometry>
+    </collision>
+  </link>
+</robot>
+)");
+  }
+
   mochi::TempDirCleanup _tempDirCleanup =
       mochi::CreateTempDirectory("urdf_mesh_resolution_test", ExpectOK{});
   fs::path _tempDir = _tempDirCleanup.Path();
@@ -164,3 +195,39 @@ TEST_F(UrdfMeshResolutionTest, UnresolvableMeshPreservesRawReference) {
       std::string(meshRefs.links[0].visual.c_str()), "package://ur_description/meshes/base.dae");
   EXPECT_TRUE(meshRefs.links[0].collision.empty());
 }
+
+// A mesh-bearing <collision> must enable the collider: ColliderType::None is the
+// prefab default, which left imported robots contactless (contact queries and
+// contact forces unavailable).
+TEST_F(UrdfMeshResolutionTest, MeshCollisionEnablesColliderType) {
+  auto const packageDir = _tempDir / "ur_description";
+  auto const urdfPath = packageDir / "urdf" / "robot.urdf";
+  auto const meshPath = packageDir / "meshes" / "base.dae";
+
+  WriteFileText(meshPath, "dummy");
+  WriteFileText(
+      urdfPath, SingleMeshCollisionUrdf("package://ur_description/meshes/base.dae"));
+
+  BotPrefab const prefab = LoadBotPrefabFromUrdfFile(urdfPath.string(), ExpectOK{});
+
+  ASSERT_FALSE(prefab.links.empty());
+  EXPECT_FALSE(prefab.links[0].shapeFile.empty());
+  EXPECT_EQ(static_cast<int>(prefab.links[0].colliderType),
+              static_cast<int>(ColliderType::Auto));
+}
+
+// Primitive-only <collision> geometry keeps the prefab default: the field is not
+// touched and the bot stays contactless.
+TEST_F(UrdfMeshResolutionTest, PrimitiveCollisionKeepsDefaultColliderType) {
+  auto const packageDir = _tempDir / "some_other_dir";
+  auto const urdfPath = packageDir / "urdf" / "robot.urdf";
+
+  WriteFileText(urdfPath, SinglePrimitiveCollisionUrdf());
+
+  BotPrefab const prefab = LoadBotPrefabFromUrdfFile(urdfPath.string(), ExpectOK{});
+
+  ASSERT_FALSE(prefab.links.empty());
+  EXPECT_TRUE(prefab.links[0].shapeFile.empty());
+  EXPECT_EQ(static_cast<int>(prefab.links[0].colliderType),
+              static_cast<int>(ColliderType::None));
+}