fix: refine indoor mailbox collision

src/nav2_turtlebot_simulator/launch/simulator.launch.py

@@ -54,6 +54,38 @@ def replace_house_visual_meshes_with_boxes(house_model):
                 visual_pose = ET.SubElement(visual, 'pose')
             visual_pose.text = pose
 
+    # The house references Gazebo's external mailbox asset, which is not shipped
+    # with the module image. Replace both its visual and collision with the same
+    # local box so it remains visible and navigable in the flat indoor world.
+    mailbox = next(
+        (model for model in house_model.findall('.//model') if model.attrib.get('name') == 'Mailbox'),
+        None,
+    )
+    if mailbox is None:
+        return
+
+    mailbox_link = mailbox.find('link')
+    if mailbox_link is None:
+        return
+
+    for element in list(mailbox_link):
+        if element.tag in {'visual', 'collision'}:
+            mailbox_link.remove(element)
+
+    # The laser is roughly 17 cm above the ground. Keep the mailbox body above
+    # that plane and retain the single thin support from mailbox.dae.
+    mailbox_parts = (
+        ('body', '0.133 0.355 0.29', '0.002 0.017 0.922 0 0 0'),
+        ('leg', '0.043 0.044 0.803', '0.000 0.012 0.401 0 0 0'),
+    )
+    for element_type in ('collision', 'visual'):
+        for name, size, pose in mailbox_parts:
+            element = ET.SubElement(mailbox_link, element_type, name=f'mailbox_{element_type}_{name}')
+            ET.SubElement(element, 'pose').text = pose
+            geometry = ET.SubElement(element, 'geometry')
+            box = ET.SubElement(geometry, 'box')
+            ET.SubElement(box, 'size').text = size
+
 
 def create_flat_house_world(gazebo_dir):
     """Create a texture-free house copy with box-rendered furniture."""