Added get_materials to URDFParser

Author: ft-lab

tests/data/verifying_elements.urdf

@@ -59,7 +59,9 @@
       <geometry>
         <cylinder radius="0.5" length="1"/>
       </geometry>
-      <material name="blue"/>
+      <material name="yellow"> <!-- New materials that do not exist in the global materials -->
+        <color rgba="1.0 1.0 0.0 1"/>
+      </material>
     </visual>
     <collision>
       <origin xyz="2 0 0.5"/>  <!-- Omit rpy -->

tests/test_parser.py

@@ -237,7 +237,7 @@ def test_get_basic_information(self):
         self.assertEqual(root_robot_name, "verifying_elements")
         self.assertEqual(root_element.get_with_default("version"), "1.0")
 
-    def test_get_materials(self):
+    def test_find_materials(self):
         # Get the root element.
         root_element = self.parser.get_root_element()
 
@@ -373,7 +373,7 @@ def test_get_links(self):
         self.assertEqual(geometry.geometry.get_with_default("length"), 1.0)
         material = visual.material
         self.assertTrue(material)
-        self.assertEqual(material.get_with_default("name"), "blue")
+        self.assertEqual(material.get_with_default("name"), "yellow")
 
         collision = link.collision
         self.assertTrue(collision)
@@ -453,6 +453,41 @@ def test_get_meshes(self):
         self.assertEqual(mesh[0], "assets/box.stl")
         self.assertEqual(mesh[1], (0.5, 0.6, 1.0))
 
+    def test_get_materials(self):
+        materials = self.parser.get_materials()
+
+        self.assertEqual(len(materials), 6)
+
+        material = materials[0]
+        self.assertEqual(material[0], "red")
+        self.assertEqual(material[1], (1.0, 0.0, 0.0, 1.0))
+        self.assertEqual(material[2], None)
+
+        material = materials[1]
+        self.assertEqual(material[0], "green")
+        self.assertEqual(material[1], (0.0, 1.0, 0.0, 1.0))
+        self.assertEqual(material[2], None)
+
+        material = materials[2]
+        self.assertEqual(material[0], "blue")
+        self.assertEqual(material[1], (0.0, 0.0, 1.0, 1.0))
+        self.assertEqual(material[2], None)
+
+        material = materials[3]
+        self.assertEqual(material[0], "black")
+        self.assertEqual(material[1], (0.0, 0.0, 0.0, 0.0))
+        self.assertEqual(material[2], None)
+
+        material = materials[4]
+        self.assertEqual(material[0], "texture")
+        self.assertEqual(material[1], (0.0, 0.0, 0.0, 0.0))
+        self.assertEqual(material[2], "assets/grid.png")
+
+        material = materials[5]
+        self.assertEqual(material[0], "yellow")
+        self.assertEqual(material[1], (1.0, 1.0, 0.0, 1.0))
+        self.assertEqual(material[2], None)
+
     def test_get_transmissions(self):
         # Get the root element.
         root_element = self.parser.get_root_element()

urdf_usd_converter/_impl/urdf_parser/parser.py

@@ -54,6 +54,10 @@ def __init__(self, input_file: Path):
         # A list of mesh file paths and scales.
         self.meshes: list[tuple[str, tuple[float, float, float]]] = []
 
+        # A list of material colors and file paths.
+        # However, this does not include materials used in mesh(dae, obj).
+        self.materials: list[tuple[str, tuple[float, float, float, float], str]] = []
+
         self.texture_paths: list[str] = []
 
     def parse(self):
@@ -75,6 +79,9 @@ def parse(self):
             # Store the meshes data.
             self._store_meshes()
 
+            # Store the materials data.
+            self._store_materials()
+
         except Exception as e:
             raise RuntimeError(f"Error parsing XML: {e}")
 
@@ -120,6 +127,15 @@ def get_meshes(self) -> list[tuple[str, tuple[float, float, float]]]:
         """
         return self.meshes
 
+    def get_materials(self) -> list[tuple[str, tuple[float, float, float, float], str]]:
+        """
+        Get the materials.
+
+        Returns:
+            A list of tuples containing the material name, color, and file path.
+        """
+        return self.materials
+
     def get_undefined_elements(self) -> list[UndefinedData]:
         """
         Get undefined elements.
@@ -225,6 +241,7 @@ def _parse_xml_elements(self, node: ET.Element, prev_element: ElementBase = None
                 element,
                 ElementRobot
                 | ElementMaterialGlobal
+                | ElementMaterial
                 | ElementLink
                 | ElementJoint
                 | ElementTransmission
@@ -568,6 +585,29 @@ def _store_meshes(self):
             else:
                 self.meshes.append((geometry.filename, scale))
 
+    def _store_materials(self):
+        """
+        Store the materials.
+        A material has a name, color, and file path.
+        """
+        # Global material names are unique, so they are stored as is.
+        for material in self.root_element.materials:
+            color = material.color.get_with_default("rgba") if material.color else (0.0, 0.0, 0.0, 0.0)
+            texture = material.texture.get_with_default("filename") if material.texture else None
+            self.materials.append((material.name, color, texture))
+
+        for link in self.root_element.links:
+            if link.visual and link.visual.material:
+                visual_material = link.visual.material
+
+                # If the material name is already stored, skip it.
+                if visual_material.name in [material[0] for material in self.materials]:
+                    continue
+
+                color = visual_material.color.get_with_default("rgba") if visual_material.color else (0.0, 0.0, 0.0, 0.0)
+                texture = visual_material.texture.get_with_default("filename") if visual_material.texture else None
+                self.materials.append((visual_material.name, color, texture))
+
     def _get_undefined_elements_nested(self, element: ElementBase, undefined_elements: list[UndefinedData]):
         """
         Get undefined elements nested in an element.