add dependency to pigpio library in CMake build

use CMake's [`ExternalProject`] functionality to pull in the [`pigpio`]
library.

we explicitly check out the latest release tag (instead of just the
default branch) to ensure that we always have the same version.
the installation directory is explicitly specified as otherwise it tries
to install the library globally, which would require root access. as we
only need it for our build we don't want to interfer with the rest of
the system and don't need root.

in the best case this would've been mostly provided by the library
directly, but so far this isn't the case. two issues,
joan2937/pigpio#572 and joan2937/pigpio#573 have been raised by me while
implementing this to hopefully make this better in the future.

[`ExternalProject`]: https://cmake.org/cmake/help/latest/module/ExternalProject.html
[`pigpio`]: https://github.com/joan2937/pigpio

smt_movement_controller/CMakeLists.txt

@@ -1,6 +1,9 @@
 cmake_minimum_required(VERSION 3.0.2)
 project(smt_movement_controller)
 
+## Additional CMake Modules
+list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR}/cmake)
+
 ## Compile as C++11, supported in ROS Kinetic and newer
 # add_compile_options(-std=c++11)
 
@@ -14,6 +17,7 @@ find_package(catkin REQUIRED COMPONENTS
 
 ## System dependencies are found with CMake's conventions
 # find_package(Boost REQUIRED COMPONENTS system)
+find_package(pigpio REQUIRED)
 
 
 ## Uncomment this if the package has a setup.py. This macro ensures
@@ -115,9 +119,9 @@ catkin_package(
 ## Specify additional locations of header files
 ## Your package locations should be listed before other locations
 include_directories(
-# include
-  ${catkin_INCLUDE_DIRS}
   ${PROJECT_SOURCE_DIR}/include
+  ${catkin_INCLUDE_DIRS}
+  ${pigpio_INCLUDE_DIR}
 )
 
 # Declare a C++ executable
@@ -136,6 +140,7 @@ add_executable(
 ## as an example, code may need to be generated before libraries
 ## either from message generation or dynamic reconfigure
 # add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})
+add_dependencies(${PROJECT_NAME} pigpio)
 
 ## Declare a C++ executable
 ## With catkin_make all packages are built within a single CMake context
@@ -156,7 +161,7 @@ add_executable(
 target_link_libraries(
   ${PROJECT_NAME} 
   ${catkin_LIBRARIES}
-  pigpio
+  ${pigpio_LIBRARIES}
 )
 
 #############

smt_movement_controller/cmake/Findpigpio.cmake

@@ -0,0 +1,13 @@
+include(ExternalProject)
+ExternalProject_Add(pigpio
+  GIT_REPOSITORY    https://github.com/joan2937/pigpio.git
+  GIT_TAG           v79
+  CMAKE_ARGS        -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
+)
+
+ExternalProject_Get_Property(pigpio INSTALL_DIR)
+
+set(pigpio_INCLUDE_DIR ${INSTALL_DIR}/include)
+set(pigpio_LIBRARIES ${INSTALL_DIR}/lib/libpigpio.so)
+
+mark_as_advanced(pigpio_INCLUDE_DIR pigpio_LIBRARIES)