display.launch.py

import launch
from launch.substitutions import Command, LaunchConfiguration
import launch_ros
from launch.conditions import IfCondition
import os
from launch_ros.descriptions import ParameterValue

def generate_launch_description():
    pkg_share = launch_ros.substitutions.FindPackageShare(package='acrux_description').find('acrux_description')
    gazebo_pkg_share = launch_ros.substitutions.FindPackageShare(package='acrux_gazebo').find('acrux_gazebo')
    default_model_path = os.path.join(pkg_share, 'urdf/acrux.xacro')
    default_rviz_config_path = os.path.join(pkg_share, 'rviz/sensors.rviz')
    world_path=os.path.join(gazebo_pkg_share, 'worlds/room2.sdf'),
    use_sim_time = LaunchConfiguration('use_sim_time')
    robot_state_publisher_node = launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'use_sim_time': use_sim_time},{'robot_description': ParameterValue(Command(['xacro ', LaunchConfiguration('model')]),value_type=str)}]
    )
    joint_state_publisher_node = launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher',
        name='joint_state_publisher',
        parameters= [{'use_sim_time': use_sim_time}],
    )
    rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        name='rviz2',
        output='screen',
        arguments=['-d', LaunchConfiguration('rvizconfig')],
        parameters= [{'use_sim_time': use_sim_time}],

    )
    spawn_entity = launch_ros.actions.Node(
    condition= IfCondition(use_sim_time),
    package='gazebo_ros',
    executable='spawn_entity.py',
    arguments=['-entity', 'acrux', '-topic', 'robot_description'],
    parameters= [{'use_sim_time': use_sim_time}],
    output='screen'
    )

    return launch.LaunchDescription([
        launch.actions.DeclareLaunchArgument(name='use_sim_time', default_value='True',
                                    description='Flag to enable use_sim_time'),
        launch.actions.DeclareLaunchArgument(name='model', default_value=default_model_path,
                                            description='Absolute path to robot urdf file'),
        launch.actions.DeclareLaunchArgument(name='rvizconfig', default_value=default_rviz_config_path,
                                            description='Absolute path to rviz config file'),
        launch.actions.ExecuteProcess(condition= IfCondition(use_sim_time),cmd=['gazebo', '--verbose', '-s', 
                                            'libgazebo_ros_init.so', '-s', 'libgazebo_ros_factory.so',world_path], 
                                            output='screen'),


        joint_state_publisher_node,
        robot_state_publisher_node,
        spawn_entity,
        rviz_node,
    ])