Managing dependencies

CMake has the ability to search our dependencies and external libraries, giving us the facility to build complex projects depending on external components in our projects and by adding some requirements.

In this book, the most important dependency is, of course, OpenCV, and we will add it to all our projects:

cmake_minimum_required (VERSION 2.6)
cmake_policy(SET CMP0012 NEW)
PROJECT(Chapter2)
# Requires OpenCV
FIND_PACKAGE( OpenCV 3.0.0 REQUIRED )
# Show a message with the opencv version detected
MESSAGE("OpenCV version : ${OpenCV_VERSION}")
include_directories(${OpenCV_INCLUDE_DIRS})
link_directories(${OpenCV_LIB_DIR})
# Create a variable called SRC
SET(SRC main.cpp )
# Create our executable
ADD_EXECUTABLE( ${PROJECT_NAME} ${SRC} )
# Link our library
TARGET_LINK_LIBRARIES( ${PROJECT_NAME} ${OpenCV_LIBS} )

Now, let's understand the working of the script:

cmake_minimum_required (VERSION 2.6)
cmake_policy(SET CMP0012 NEW)
PROJECT(Chapter2)

The first line defines...