cmake_minimum_required(VERSION 3.1) include(ExternalProject) add_library(uPNG STATIC) target_include_directories(uPNG PUBLIC external/upng) set(UPNG_SOURCES external/upng/upng.c) set(UPNG_HEADERS external/upng/upng.h) target_sources(uPNG PRIVATE ${UPNG_SOURCES} ${UPNG_HEADERS})