How to compile and use this library if I clone it into a subdirectory?

I have this simple SDL application, with snippets of example2.cpp thrown in:

#include "SDL.h"
#include <SDL_opengl.h>
#include <nanogui/screen.h>
#include <nanogui/window.h>
#include <nanogui/layout.h>
#include <nanogui/label.h>
#include <nanogui/checkbox.h>
#include <nanogui/button.h>
#include <nanogui/toolbutton.h>
#include <nanogui/popupbutton.h>
#include <nanogui/combobox.h>
#include <nanogui/progressbar.h>
#include <nanogui/entypo.h>
#include <nanogui/messagedialog.h>
#include <nanogui/textbox.h>
#include <nanogui/slider.h>
#include <nanogui/imagepanel.h>
#include <nanogui/imageview.h>
#include <nanogui/vscrollpanel.h>
#include <nanogui/colorwheel.h>
#include <nanogui/graph.h>
#include <nanogui/formhelper.h>
#include <iostream>

using namespace nanogui;

enum test_enum {
    Item1 = 0,
    Item2,
    Item3
};

int main(int, char**)
{
    SDL_Window* window = SDL_CreateWindow("test",  SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN);
   SDL_Renderer* render = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    SDL_Event* event = new SDL_Event();
    bool quit = false;

    bool bvar = true;
    int ivar = 12345678;
    double dvar = 3.1415926;
    float fvar = (float)dvar;
    std::string strval = "A string";
    test_enum enumval = Item2;
    Color colval(0.5f, 0.5f, 0.7f, 1.f);
    int winWidth = 1024;
    int winHeight = 768;

    Screen *screen = new Screen( window, Vector2i(winWidth, winHeight), "NanoGUI test");

    bool enabled = true;
    FormHelper *gui = new FormHelper(screen);
    ref<Window> rwindow = gui->addWindow(Eigen::Vector2i(10, 10), "Form helper example");
    gui->addGroup("Basic types");
    gui->addVariable("bool", bvar);
    gui->addVariable("string", strval);
    gui->addGroup("Validating fields");
    gui->addVariable("int", ivar);
    gui->addVariable("float", fvar);
    gui->addVariable("double", dvar);
    gui->addGroup("Complex types");
    gui->addVariable("Enumeration", enumval, enabled)
       ->setItems({"Item 1", "Item 2", "Item 3"});
    gui->addVariable("Color", colval);
    gui->addGroup("Other widgets");
    gui->addButton("A button", [](){ std::cout << "Button pressed." << std::endl; });
    screen->setVisible(true);
    screen->performLayout();
    rwindow->center();

    while(!quit && event->type != SDL_QUIT) {
        SDL_PollEvent(event);
        SDL_RenderClear(render);

        if (event->type == SDL_KEYDOWN) {
            switch(event->key.keysym.sym) {
                case SDLK_ESCAPE:
                    quit = true;
                    break;
                default:
                    break;
            }
        }

        SDL_RenderPresent(render);
    }

    return 0;
}

My folder structure is:

app/
    test2.cpp
    libs/
        nanogui-sdl/

What's the correct g++ command to compile and run test2.cpp? I tried many things but they all error.

dalerank / nanogui-sdl

How to compile and use this library if I clone it into a subdirectory? #16