building sdl_image as CMake external project

gistfile1.cmake

cmake_minimum_required(VERSION 2.8)
include(ExternalProject)

project(freetype_test)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall")
set(LIBS_DIR ${PROJECT_SOURCE_DIR}/libs)

set(FREETYPE_VER "2.5.3")
set(SDL2_VER "2.0.3")



# Freetype library
ExternalProject_Add(freetype_project
    URL http://download.savannah.gnu.org/releases/freetype/freetype-${FREETYPE_VER}.tar.gz
    PREFIX ${LIBS_DIR}/freetype
    INSTALL_COMMAND ""
)

ExternalProject_Get_Property(freetype_project SOURCE_DIR)
ExternalProject_Get_Property(freetype_project BINARY_DIR)

set(FREETYPE_SRC ${SOURCE_DIR})
set(FREETYPE_BIN ${BINARY_DIR})



# SDL library
ExternalProject_Add(sdl2_project
    URL http://www.libsdl.org/release/SDL2-${SDL2_VER}.tar.gz
    PREFIX ${LIBS_DIR}/SDL2
    INSTALL_COMMAND ""
)

ExternalProject_Get_Property(sdl2_project SOURCE_DIR)
ExternalProject_Get_Property(sdl2_project BINARY_DIR)

set(SDL2_SRC ${SOURCE_DIR})
set(SDL2_BIN ${BINARY_DIR})



# SDL_image library
ExternalProject_Add(sdl2_image_project
    URL https://www.libsdl.org/projects/SDL_image/release/SDL2_image-2.0.0.tar.gz
    DEPENDS sdl2_project
    PREFIX ${LIBS_DIR}/SDL2_image
    CONFIGURE_COMMAND LDFLAGS=-L${SDL2_BIN} CFLAGS=-I${SDL2_SRC}/include SDL2_CONFIG=${SDL2_BIN}/sdl2-config <SOURCE_DIR>/configure --prefix=<INSTALL_DIR> --enable-shared=no
    BUILD_COMMAND make
    INSTALL_COMMAND ""
)

ExternalProject_Get_Property(sdl2_image_project SOURCE_DIR)
ExternalProject_Get_Property(sdl2_image_project BINARY_DIR)

set(SDL2_IMAGE_SRC ${SOURCE_DIR})
set(SDL2_IMAGE_BIN ${BINARY_DIR})


include_directories(${FREETYPE_SRC}/include)
include_directories(${SDL2_SRC}/include)
include_directories(${SDL2_IMAGE_SRC}/include)

set(SOURCE freetype_test.cpp)
add_executable(ft_test ${SOURCE})
add_dependencies(ft_test    freetype_project
                            sdl2_project
                            sdl2_image_project)


target_link_libraries(ft_test   ${FREETYPE_BIN}/libfreetype.a
                                ${SDL2_BIN}/libSDL2.a)

Would you just run this as cmake . from the same folder as the .cmake file?

@SergNikitin, I think this just doesn't work anymore. ;(