centerFace+ncnn编译（linux）

1. 安装opencv
   在官网下载最新的opencv，按照如下教程安装
   https://blog.csdn.net/AQRSXIAO/article/details/81458912
2. 安装protobuf
   https://github.com/protocolbuffers/protobuf/blob/master/src/README.md
3. 编译ncnn
   https://github.com/Tencent/ncnn/wiki/how-to-build#build-for-linux-x86
4. 编译centerFace的prj-ncc
   我在这一步卡住了，主要是因为CMakeLists文件书写有问题，可能作者的ncnn安装后的目录结构与我的不一样。更改CMakeLists之后，就ok了。

#1.cmake verson
cmake_minimum_required(VERSION 2.8)

set (DIR  "/your_dir/ncnn")


#2.project name
project(demo C CXX)

#opencv
find_package(OpenCV REQUIRED)

#3.set environment variable
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")

#4. include
include_directories(${DIR}/src
                    ${DIR}/build/src
                    ${CMAKE_CURRENT_LIST_DIR}/cpp)

# ncnn lib
add_library( libncnn STATIC IMPORTED )
set_target_properties(
        libncnn
        PROPERTIES IMPORTED_LOCATION
        ${DIR}/build/src/libncnn.a
)

# add OPENMP support 
FIND_PACKAGE( OpenMP REQUIRED)
if(OPENMP_FOUND)
message("OPENMP FOUND")
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}")
endif()

#6.source directory
file(GLOB TEST_SRC ${CMAKE_CURRENT_LIST_DIR}/cpp/*.cpp
                   ${CMAKE_CURRENT_LIST_DIR}/demo.cpp)
set(TEST_COMPILE_CODE ${TEST_SRC})


add_executable(demo ${TEST_COMPILE_CODE})

target_link_libraries(demo 
                      libncnn
                      ${OpenCV_LIBS}
                      )