glfw linking by cmake undefined reference error - cmake

Question

I tried to link staticly glfw lib but it's not working (idk why),so basically when i complie and run the compile throw many error mostly "undefined reference" so it's the linking error I have encounter
here's my cmake code:
cmake_minimum_required(VERSION 3.1)
project(nerd)
add_executable(${PROJECT_NAME} main.cpp)
target_link_directories(${PROJECT_NAME} PUBLIC ${CMAKE_SOURCE_DIR}/../external/glfw/include)
target_link_libraries(${PROJECT_NAME} ${CMAKE_SOURCE_DIR}/../external/glfw/lib/libglfw3.a)
and here's my c++ code :
#include "../external/glfw/include/glfw3.h"
int main(void)
{
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit())
return -1;
window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
if (!window)
{
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
while (!glfwWindowShouldClose(window))
{
/* Render here */
glClear(GL_COLOR_BUFFER_BIT);
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glfwTerminate();
return 0;
}
you can check file structre on my github : https://github.com/Solirous/glfw-help
I tried to read many document,many problem but it doesnt help
trying to link glfw:
and the error is
CMakeFiles\nerd.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x17): undefined reference to `glfwInit'
CMakeFiles\nerd.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x56): undefined reference to `glfwCreateWindow'
CMakeFiles\nerd.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x64): undefined reference to `glfwTerminate'
CMakeFiles\nerd.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x76): undefined reference to `glfwMakeContextCurrent'
CMakeFiles\nerd.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x81): undefined reference to `glfwWindowShouldClose'
CMakeFiles\nerd.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x96): undefined reference to `_imp__glClear#4'
CMakeFiles\nerd.dir/objects.a(main.cpp.obj):main.cpp:(.text+0xa6): undefined reference to `glfwSwapBuffers'
CMakeFiles\nerd.dir/objects.a(main.cpp.obj):main.cpp:(.text+0xab): undefined reference to `glfwPollEvents'
CMakeFiles\nerd.dir/objects.a(main.cpp.obj):main.cpp:(.text+0xb2): undefined reference to `glfwTerminate'
collect2.exe: error: ld returned 1 exit status