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Added missing parts to the CMakeLists.txt code. #400

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merged 7 commits into from
Nov 3, 2023
Merged

Added missing parts to the CMakeLists.txt code. #400

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dadd27a
Added missing lines, so copy-paste of the example leads to a working …
jrutgeer Oct 13, 2023
7bb56cd
Merge branch 'gz-msgs10' into gz-msgs10
mjcarroll Oct 13, 2023
2f9a11d
Added reference to the examples folder in the repository, and adapted…
jrutgeer Oct 16, 2023
8b77943
Merge branch 'gz-msgs10' into gz-msgs10
mjcarroll Oct 23, 2023
c37e2ba
Merge branch 'gz-msgs10' into gz-msgs10
mjcarroll Oct 30, 2023
8d2a795
Removed illegal </br> tag.
jrutgeer Nov 3, 2023
a546ff2
Remove a few more <br>
mjcarroll Nov 3, 2023
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7 changes: 5 additions & 2 deletions examples/generating_custom_msgs/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -11,15 +11,17 @@ project(generating_custom_messages VERSION 1.0.0)
find_package(gz-cmake3 REQUIRED)

find_package(gz-msgs10 REQUIRED)
# Define a variable 'GZ_MSGS_VER' holding the version number
set(GZ_MSGS_VER ${gz-msgs10_VERSION_MAJOR})

# Example of custom messages that depend on gz.msgs
# Define a variable 'MSGS_PROTOS' listing the .proto files
set(MSGS_PROTOS
${CMAKE_CURRENT_SOURCE_DIR}/proto/gz/custom_msgs/foo.proto
${CMAKE_CURRENT_SOURCE_DIR}/proto/gz/custom_msgs/bar.proto
${CMAKE_CURRENT_SOURCE_DIR}/proto/gz/custom_msgs/baz.proto
)

# Call 'gz_msgs_generate_messages()' to process the .proto files
gz_msgs_generate_messages(
# The cmake target to be generated for libraries/executables to link
TARGET msgs
Expand All @@ -28,8 +30,9 @@ gz_msgs_generate_messages(
# The path to the base directory of the proto files
# All import paths should be relative to this (eg gz/custom_msgs/vector3d.proto)
MSGS_PATH ${CMAKE_CURRENT_SOURCE_DIR}/proto
# List of proto files to generate
# List of proto files to process
MSGS_PROTOS ${MSGS_PROTOS}
# Depenency on gz-msgs
DEPENDENCIES gz-msgs${GZ_MSGS_VER}::gz-msgs${GZ_MSGS_VER}
)

Expand Down
34 changes: 30 additions & 4 deletions tutorials/message_generation.md
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Original file line number Diff line number Diff line change
Expand Up @@ -119,6 +119,10 @@ For the collection, `gz_msgs_factory` generates:
Now that we understand the components of the message generation pipeline,
we can use them in our own custom package.

The code for this example can be found in the `gz-msgs` [repository](https://github.com/gazebosim/gz-msgs/tree/gz-msgs10), in the [`examples/generating_custom_msgs`](https://github.com/gazebosim/gz-msgs/tree/gz-msgs10/examples/generating_custom_msgs) folder.



The `cmake` functionality is exported from the `gz-msgs` library, via the `gz-cmake` [`extras` functionality](https://github.com/gazebosim/gz-cmake/pull/345).
To make the functions available, simply `find_package(gz-msgs10)` in your `CMakeLists.txt`:

Expand All @@ -129,6 +133,7 @@ find_package(gz-cmake3 REQUIRED)
find_package(gz-msgs10 REQUIRED)
```


Next, create a directory for your custom message definitions:

```sh
Expand Down Expand Up @@ -189,9 +194,17 @@ message BazStamped
```


Then, back in the `CMakeLists.txt` file, generate the message library.
Then, back in the `CMakeLists.txt` file, add following lines to generate the message library:

```cmake
# Define a variable 'MSGS_PROTOS' listing the .proto files
set(MSGS_PROTOS
${CMAKE_CURRENT_SOURCE_DIR}/proto/gz/custom_msgs/foo.proto
${CMAKE_CURRENT_SOURCE_DIR}/proto/gz/custom_msgs/bar.proto
${CMAKE_CURRENT_SOURCE_DIR}/proto/gz/custom_msgs/baz.proto
)

# Call 'gz_msgs_generate_messages()' to process the .proto files
gz_msgs_generate_messages(
# The cmake target to be generated for libraries/executables to link
TARGET msgs
Expand All @@ -200,12 +213,25 @@ gz_msgs_generate_messages(
# The path to the base directory of the proto files
# All import paths should be relative to this (eg gz/custom_msgs/vector3d.proto)
MSGS_PATH ${CMAKE_CURRENT_SOURCE_DIR}/proto
# List of proto files to generate
# List of proto files to process
MSGS_PROTOS ${MSGS_PROTOS}
DEPENDENCIES gz-msgs${GZ_MSGS_VER}::gz-msgs${GZ_MSGS_VER}
# Depenency on gz-msgs
DEPENDENCIES gz-msgs10::gz-msgs10
)
```

In order to reduce the amount of edits needed upon a version change of `gz-msgs`, it is common to:

- Define a variable `GZ_MSGS_VER`, holding the version number:
```cmake
find_package(gz-msgs10 REQUIRED)
set(GZ_MSGS_VER ${gz-msgs10_VERSION_MAJOR})
```
- And change the dependency line in above code block to:
```cmake
DEPENDENCIES gz-msgs${GZ_MSGS_VER}::gz-msgs${GZ_MSGS_VER}
```

### Using Custom messages

There are two primary ways that Gazebo messages are used as part of an application.
Expand Down Expand Up @@ -270,7 +296,7 @@ $ cd build/
$ export GZ_DESCRIPTOR_PATH=`pwd`

$ gz msg -l | grep "custom_msgs" | wc -l
6
4

$ gz msg --info gz.custom_msgs.Foo
Name: gz.custom_msgs.Foo
Expand Down