Decode.cpp NanoGUI Sample code

/*
    src/example3.cpp -- C++ version of an example application that shows
    how to use nanogui in an application with an already created and managed
    glfw context.

    NanoGUI was developed by Wenzel Jakob <[email protected]>.
    The widget drawing code is based on the NanoVG demo application
    by Mikko Mononen.

    All rights reserved. Use of this source code is governed by a
    BSD-style license that can be found in the LICENSE.txt file.
*/

// GLFW
//
#if defined(NANOGUI_GLAD)
#if defined(NANOGUI_SHARED) && !defined(GLAD_GLAPI_EXPORT)
#define GLAD_GLAPI_EXPORT
#endif

#include <glad/glad.h>
#else
#if defined(__APPLE__)
#define GLFW_INCLUDE_GLCOREARB
#else
#define GL_GLEXT_PROTOTYPES
#endif
#endif

#include <GLFW/glfw3.h>
#include <nanogui/nanogui.h>
#include <iostream>

using namespace nanogui;

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

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);

Screen *screen = nullptr;

int main(int /* argc */, char ** /* argv */) {

    glfwInit();

    glfwSetTime(0);

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    glfwWindowHint(GLFW_SAMPLES, 0);
    glfwWindowHint(GLFW_RED_BITS, 8);
    glfwWindowHint(GLFW_GREEN_BITS, 8);
    glfwWindowHint(GLFW_BLUE_BITS, 8);
    glfwWindowHint(GLFW_ALPHA_BITS, 8);
    glfwWindowHint(GLFW_STENCIL_BITS, 8);
    glfwWindowHint(GLFW_DEPTH_BITS, 24);
    glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);

    // Create a GLFWwindow object
    GLFWwindow* window = glfwCreateWindow(800, 800, "example3", nullptr, nullptr);
    if (window == nullptr) {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

#if defined(NANOGUI_GLAD)
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
        throw std::runtime_error("Could not initialize GLAD!");
    glGetError(); // pull and ignore unhandled errors like GL_INVALID_ENUM
#endif

    glClearColor(0.2f, 0.25f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // Create a nanogui screen and pass the glfw pointer to initialize
    screen = new Screen();
    screen->initialize(window, true);

    int width, height;
    glfwGetFramebufferSize(window, &width, &height);
    glViewport(0, 0, width, height);
    glfwSwapInterval(0);
    glfwSwapBuffers(window);

    // Create nanogui gui
    bool enabled = true;
    FormHelper *gui = new FormHelper(screen);
    ref<Window> nanoguiWindow = gui->addWindow(Eigen::Vector2i(10, 10), "Form helper example");
    gui->addGroup("Basic types");
    gui->addVariable("bool", bvar)->setTooltip("Test tooltip.");
    gui->addVariable("string", strval);

    gui->addGroup("Validating fields");
    gui->addVariable("int", ivar)->setSpinnable(true);
    gui->addVariable("float", fvar)->setTooltip("Test.");
    gui->addVariable("double", dvar)->setSpinnable(true);

    gui->addGroup("Complex types");
    gui->addVariable("Enumeration", enumval, enabled)->setItems({ "Item 1", "Item 2", "Item 3" });
    gui->addVariable("Color", colval)
        ->setFinalCallback([](const Color &c) {
        std::cout << "ColorPicker Final Callback: ["
            << c.r() << ", "
            << c.g() << ", "
            << c.b() << ", "
            << c.w() << "]" << std::endl;
    });

    gui->addGroup("Other widgets");
    gui->addButton("A button", []() { std::cout << "Button pressed." << std::endl; })->setTooltip("Testing a much longer tooltip, that will wrap around to new lines multiple times.");;

    screen->setVisible(true);
    screen->performLayout();
    nanoguiWindow->center();

    glfwSetCursorPosCallback(window,
        [](GLFWwindow *, double x, double y) {
        screen->cursorPosCallbackEvent(x, y);
    }
    );

    glfwSetMouseButtonCallback(window,
        [](GLFWwindow *, int button, int action, int modifiers) {
        screen->mouseButtonCallbackEvent(button, action, modifiers);
    }
    );

    glfwSetKeyCallback(window,
        [](GLFWwindow *, int key, int scancode, int action, int mods) {
        screen->keyCallbackEvent(key, scancode, action, mods);
    }
    );

    glfwSetCharCallback(window,
        [](GLFWwindow *, unsigned int codepoint) {
        screen->charCallbackEvent(codepoint);
    }
    );

    glfwSetDropCallback(window,
        [](GLFWwindow *, int count, const char **filenames) {
        screen->dropCallbackEvent(count, filenames);
    }
    );

    glfwSetScrollCallback(window,
        [](GLFWwindow *, double x, double y) {
        screen->scrollCallbackEvent(x, y);
    }
    );

    glfwSetFramebufferSizeCallback(window,
        [](GLFWwindow *, int width, int height) {
        screen->resizeCallbackEvent(width, height);
    }
    );

    // Game loop
    while (!glfwWindowShouldClose(window)) {
        // Check if any events have been activated (key pressed, mouse moved etc.) and call corresponding response functions
        glfwPollEvents();

        glClearColor(0.2f, 0.25f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        // Draw nanogui
        screen->drawContents();
        screen->drawWidgets();

        glfwSwapBuffers(window);
    }

    // Terminate GLFW, clearing any resources allocated by GLFW.
    glfwTerminate();

    return 0;
}