Patch drake-extras.cmake with comments in #7

Signed-off-by: Jose Luis Rivero <[email protected]>

drake-extras.cmake

@@ -1 +1,21 @@
-find_package(drake REQUIRED)
+# The code will search for the upstream drake-config.cmake file
+# installed under the root of the ROS installation + /opt/drake
+# (i.e /opt/ros/rolling/opt/drake ).
+#
+# Long explanation of how this file works can be found in:
+# https://github.com/RobotLocomotion/ros-drake-vendor/issues/7#issuecomment-1979757703
+
+# drake_DIR will return the absolute path to the ROS package
+# of drake (share/drake/cmake under the ROS root installation)
+# The relative path should drive us to the root of the drake
+# upstream installation done under ROS.
+set(_drake_path "${drake_DIR}/../../../opt/drake")
+
+# Since the upstream installation has the same CMake module name
+# than the ROS package we need to unset the cache variable
+# that points to the ROS package to be sure to force the
+# find_package to find the drake config module under the
+# paths
+unset(drake_DIR CACHE)
+
+find_package(drake PATHS ${_drake_path} NO_DEFAULT_PATH)