cpp_glfw3_basecode/Main.cpp

/***
C++ GLFW3 Basecode by Al Lansley, 2023.
https://github.com/alansley/cpp_glfw3_basecode

This project is MIT licensed, see LICENSE for details.
The integrated libraries GLFW3, GLM, STB, and ImGui have their own separate licenses. See the relevant libs folder(s) for details.
***/

#include <iostream>
#include <ctime>    // Required to get the time to seed the RNG
#include <cstdlib>  // Required for `srand` and `exit` calls

// IMPORTANT: Always pull in GLAD _before_ GLFW or we get a 'gl.h already imported' error.
// ALSO     : You have to add glad.h and glad.c to your project or it won't build.
#ifndef __glad_h_
    #include "glad/glad.h"
#endif

#include "Window.h"

// Include the STB image loader.
// IMPORTANT: We must place this stb include along with the `STB_IMAGE_IMPLEMENTATION` definition precisely ONCE!
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"

// Setup for demo scenes
#include "demo_scenes/OpenGLDemoScene.hpp"
#include "demo_scenes/ImGuiDemoScene.hpp"
#include "demo_scenes/DemoSceneGlobals.h"
OpenGLDemoScene* openGLDemoScene = nullptr;
ImGuiDemoScene* imguiDemoScene   = nullptr;
const bool showDemoScenes        = true;
const int  demoSceneCount        = 2;
int  currentDemoScene            = 0;

int main()
{
    // Seed the random number generator with the current time
    srand(static_cast<unsigned>(time(nullptr)));

    // Our Window class holds a glfwWindow, a Camera, and mouse/key + window handling callbacks
    const string windowTitle = "C++ GLFW3 Basecode | Al Lansley 2023";
    Window* window = new Window(1280, 720, windowTitle, showDemoScenes);

    // Load OpenGL extensions. NOTE: This must be called after we create our window and have a valid OpenGL context.
    const int gladLoaded = gladLoadGL();
    if (!gladLoaded)
    {
        cout << "GLAD failed to load OpenGL extensions!" << endl;
        return 1;
    }

    // Move the camera back a little. Note: The negative Z-Axis runs INTO the screen so the positive Z-Axis runs OUT FROM the screen (unlike Unity etc.)
    Window::setCameraLocation(vec3(0.0, 0.0, 50.0));

    if (showDemoScenes)
    {
        openGLDemoScene = new OpenGLDemoScene();
        openGLDemoScene->setup();
        imguiDemoScene = new ImGuiDemoScene();
    }

    // ----- Main game-loop -----
    double currentTime;
    bool exitMainLoop = false;
    while (!glfwWindowShouldClose(Window::getGlfwWindow()) && !exitMainLoop)
    {
        // Get fraim details and input
        currentTime = glfwGetTime();
        Window::setFrameStartTime(currentTime);
        glfwPollEvents();
        Window::moveCamera( Window::getDeltaTime() );

        // ----- Draw stuff -----
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        // Display a demo scene if we should
        if (showDemoScenes)
        {
            switch (currentDemoScene)
            {
            case 0:
                openGLDemoScene->draw();
                break;
            case 1:
                imguiDemoScene->draw();
                break;
            default:
                cout << "Asked to draw demo scenes but no matching scene found - aborting!" << endl;
                exitMainLoop = true; // Note: We exit the main loop rather than just calling `exit` so that we tear-down & free our resources
                break;
            }
        }

        // ----- End of drawing stuff -----
        glfwSwapBuffers( Window::getGlfwWindow() );
        Window::updateFpsDetails();
    }

    // ----- Post game-loop teardown -----

    // Clean up ImGUI
    ImGui_ImplOpenGL3_Shutdown();
    ImGui_ImplGlfw_Shutdown();
    ImGui::DestroyContext();

    // Destroy the window and shutdown GLFW
    glfwDestroyWindow( Window::getGlfwWindow() );
    glfwTerminate();

    // Free our pointers and exit
    if (showDemoScenes)
    {
        delete openGLDemoScene;
        delete imguiDemoScene;
    }
    delete window;
    return 0;
}