How to include a library in CMakeLists

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What's the proper way to include external libraries in a C++ ROS package?

I've written a C++ program that reads data from an I2C device using the I2Cdevlib, and now I'm trying to re-package it as a ROS node and build it via catkin.

I'm building the non-catkin code via:

gcc -o mpu6050_reader ${PATH_I2CDEVLIB}RaspberryPi_bcm2835/MPU6050/examples/MPU6050_example_1.cpp \
 -I ${PATH_I2CDEVLIB}RaspberryPi_bcm2835/I2Cdev ${PATH_I2CDEVLIB}RaspberryPi_bcm2835/I2Cdev/I2Cdev.cpp \
 -I ${PATH_I2CDEVLIB}Arduino/MPU6050/ ${PATH_I2CDEVLIB}Arduino/MPU6050/MPU6050.cpp -l bcm2835 -l m

I've initialized a C++ ROS package, and refactored MPU6050_example_1.cpp into the ROS-equivalent mpu6050_node.cpp, and now I'm trying to translate the above call to CMakeLists.txt so it compiles with catkin_make. What's the best way to do this?

Should I include the i2cdevlib and bcm2835 libraries in my package, or require the user to download and install them separately?

I've read through the documentation on CMakeLists.txt, but it's unclear to me which parameters I should use. Should I use add_library() or include_directories() or add_dependencies() or target_link_libraries()?