[CMake] Separating build from source

[motes motes]

I am trying to build an application which use the itk library based on
the following structure:

code/
code/src
code/src/MyItkProject
code/build
code/build/release
code/build/debug
CMakeLists.txt

I have located my CMakeLists.txt file in the 'code' dir where I
specify the necessary includes. I have my main.cpp file in:

code/src/MyItkProject/main.cpp


I have extracted and build the itk library in another location and set
up the above CMakeLists.txt file to ask the user to specify the build
dir with:

cmake_minimum_required(VERSION 2.6)
PROJECT(MyItkProject)

FIND_PATH(PROJECT_HOME REQUIRED)

FIND_PATH(ITK_DIR REQUIRED)

# Find ITK.
FIND_PACKAGE(ITK REQUIRED)
IF( ITK_FOUND )
  INCLUDE( ${ITK_USE_FILE} )
ELSE( ITK_FOUND )
  MESSAGE( FATAL_ERROR "Cannot build without ITK.  Please set ITK_DIR." )
ENDIF( ITK_FOUND )

I then run ccmake from the code/build/release dir like:

code/build/release$ ccmake ../../

After specifying the necessary paths (and Release as build type) I run
'configure' followed by 'generate' but get the error:

CMake Error in CMakeLists.txt
  Cannot find source file "main.cpp". Tried extensions ....

Do I need to add another CMakeLists.txt file in the dir
code/src/MyItkProject which specifies the main.cpp file?