Ionic Release Notes and Highlights

highlights.md

@@ -2,9 +2,178 @@
 
 ## New Features
 
+- [Add new console logging functionality based on `spdlog`](https://github.com/gazebosim/gz-common/pull/615).
+  Also see [gz-utils#134](https://github.com/gazebosim/gz-utils/pull/134)
+
+  - Console logging has been reimplemented using `spdlog`. While the existing
+    macros such as `gzerr`, `gzwarn`, and `gzmsg` continue to work as before,
+    you can now get access to the raw `spdlog` logger, which provides greater
+    control and flexibility. A new macro, `gztrace` is also provided, which can
+    be useful in debugging or data collection scenarios. With `spdlog`, you also
+    get the ability to use format strings. Here's a quick example:
+
+    ```c++
+    auto logger = gz::common::Console::Root().RawLoggerPtr();
+    logger->trace("π to 5th decimal = {:.5f}\n", M_PI);
+    ```
+
+- Improvements to the bullet-featherstone physics plugin
+
+  - Many new features and bugfixes were made to the bullet-featherstone plugin
+    in gz-physics, which include support for nested models,
+    off-diagonal inertia, enforcing joint velocity and effort limits,
+    configuring solver iterations, and more. There are also features for
+    performance improvements and physics stability such as auto-deactivation,
+    static object collision optimization, and use of convex hull shapes for
+    convex decomposed meshes.
+
+- [Support for mesh optimization](https://github.com/gazebosim/gz-sim/pull/2417),
+[gzsim#2352](https://github.com/gazebosim/gz-sim/pull/2352),
+[gz-common#585](https://github.com/gazebosim/gz-common/pull/585),
+[sdformat#1382](https://github.com/gazebosim/gz-common/pull/585), and
+[gz-physics#606](https://github.com/gazebosim/gz-physics/pull/606)
+
+  - Added support for mesh optimization on the collision mesh. Users can now
+    specify whether or not to perform mesh optimization on a
+    collision mesh in SDF (requires SDF spec version >= 1.11). Two optimization
+    methods are currently supported: `convex_decomposition` and `convex_hull`.
+    Gazebo uses the open source
+    [V-HACD](https://github.com/kmammou/v-hacd) library to perform
+    convex decomposition to split the mesh into multiple submeshes.
+    Example SDF usage:
+
+    ```xml
+    <collision>
+      <mesh optimization="convex_decomposition">
+        <convex_decomposition>
+          <max_convex_hulls>16</max_convex_hulls>
+          <voxel_resolution>400000</voxel_resolution>
+        </convex_decomposition>
+        <uri>/path/to/mesh.dae</uri>
+      </mesh>
+    </collision>
+    ```
+
+- [Support specifying plugins in SDF files without overriding default
+  plugins](https://github.com/gazebosim/gz-sim/pull/2497) and [gz-gui#631](https://github.com/gazebosim/gz-gui/pull/631)
+
+  - In prior Gazebo versions, if a user specified a server plugin at the
+    world level, it would override all default plugins. This required
+    users to have in-depth knowledge and specify every plugin necessary
+    for a simulation to run correctly. Omitting critical plugins would
+    lead to unexpected simulation behavior, causing confusion,
+    particularly for new Gazebo users.
+
+  - Gazebo Ionic addresses this issue by loading default plugins even when
+    users specify additional plugins. Gazebo Ionic also introduces
+    `<gz:policy>` settings to revert this behavior to how it functioned in
+    previous Gazebo versions, if desired.  For example, the
+    `contact_sensor.sdf` example can now include just the additional Contact
+    system:
+
+    ```xml
+    <world name="contact_sensor">
+      <plugin filename="gz-sim-contact-system" name="gz::sim::systems::Contact"/>
+      ...
+    </world>
+
+    ```
+
+    whereas previously, the SDF file has all the default plugins:
+
+    ```xml
+    <world name="contact_sensor">
+      <plugin
+        filename="gz-sim-physics-system"
+        name="gz::sim::systems::Physics">
+      </plugin>
+      <plugin
+        filename="gz-sim-contact-system"
+        name="gz::sim::systems::Contact">
+      </plugin>
+      <plugin
+        filename="gz-sim-user-commands-system"
+        name="gz::sim::systems::UserCommands">
+      </plugin>
+      <plugin
+        filename="gz-sim-scene-broadcaster-system"
+        name="gz::sim::systems::SceneBroadcaster">
+      </plugin>
+
+      ...
+    </world>
+
+    ```
+
+- Gazebo Transport improvements.
+See [gz-transport#477](https://github.com/gazebosim/gz-transport/pull/477), [gz-transport#486](https://github.com/gazebosim/gz-transport/pull/486), [gz-transport#487](https://github.com/gazebosim/gz-transport/pull/487) and [gz-transport#506](https://github.com/gazebosim/gz-transport/pull/506/).
+
+  - An extra option has been added to the `SubscriberOptions` class allowing the ability to ignore messages when publisher
+  and subscriber share the same node. This feature was particularly interesting to avoid loops in the `ros_gz` bridge.
+  See more context [here](https://github.com/gazebosim/ros_gz/issues/555).
+
+  - Most of the gz-transport functionality can be exercised via command line with the `gz topic` or `gz service` subcommands.
+  We've reduced the amount of typing needed to request certain services from CLI. Here's a summary:
+    - Gazebo Ionic allows to request one-way service requests directly from the command line. In prior Gazebo versions, users
+    had to specify `--reptype gz.msgs.Empty ` to simulate one-way service requests.
+    - The synchronous service requests have now a default timeout, reducing the amount of typing from the CLI.
+    - Gazebo Ionic allows to request no-input service requests directly from the command line. In prior Gazebo versions, users
+    had to specify `--reqtype gz.msgs.Empty ` to simulate no-input service requests.
+
+
+- Gazebo/ROS Vendor Packages
+
+Gazebo libraries and simulator are now available directly from
+packages.ros.org via vendor packages. The packages are built in the ROS
+buildfarm and as part of their build process, fetch the sources of the
+underlying Gazebo library and build it. In addition, the vendor packages
+provide CMake shims that make it possible to use CMake targets without
+version numbers. See the documentation for full details.
+
+- Improved ros_gz Launch Files
+
+ROS launch files used to start Gazebo, spawn models in simulation, and
+start the ros_gz bridge are now much simpler and more idiomatic. New XML
+and YAML elements are available to simplify the creation of launch files.
+As an example, here's how you can start gzserver and the bridge from an
+XML file:
+
+```xml
+<launch>
+  <gz_server world_sdf_file="$(find-pkg-share my_package)/worlds/my_world.sdf" />
+  <ros_gz_bridge config_file="$(find-pkg-share my_package)/config/bridge_config.yaml" />
+</launch>
+```
+
+- Improved ros_gz_bridge performance
+
+A new parameter use_composition is also available all the new  launch
+files to leverage the ability to launch composable nodes. This feature
+allows us to run Gazebo, the ros_gz_bridge, and other potential ROS
+composable nodes within the same process. This improves performance by
+avoiding message serialization and network transport between Gazebo and
+ROS.
+
+
 ## Bug Fixes
 
 ## Breaking Changes
 
 ## Documentation
 
+- [Improved Gazebo Documentation Website](https://github.com/gazebosim/docs/pull/441)
+  - The main documentation [website](https://gazebosim.org/docs) has been
+    migrated to a statically generated site built with
+    [Sphinx](https://sphinx-doc.org/). This adds a number of features and solves
+    a number of problems with the previous website, namely:
+    - Documentation authors can easily preview their changes by downloading the
+      generated website instead of having to set up a local development
+      environment
+    - The website is updated automatically instead of being manually triggered
+      after each PR.
+    - Search functionality is now available
+    - Improved layout and UX on mobile devices
+    - Dark and light modes
+    - Improved SEO as the content is now more easily accessible to search
+      engines.
+    - Use of Sphinx as a common documentation tool for both Gazebo and ROS.