DeerithEngine/deerith_engine_client/src/window.cpp

#include "deerith/graphics/window.h"
#include "primitive_internals.h"

#include <glad/gl.h>
#include <GLFW/glfw3.h>

#include <imgui.h>
#include <backends/imgui_impl_glfw.h>
#include <backends/imgui_impl_opengl3.h>

#include <chrono>
#include <thread>

#include <iostream>

namespace deerith
{
    GLFWwindow *window;
    int frame_id = 0;

    constexpr double TARGET_FRAME_TIME = 1.0 / 60.0;
    std::chrono::steady_clock::time_point last_frame_time;
    std::chrono::steady_clock::time_point frame_start;

    void init_imgui();
}

int deerith::init_window()
{

    if (!glfwInit())
    {
        std::cerr << "Failed to initialize GLFW\n";
        return -1;
    }

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    window = glfwCreateWindow(
        1280,
        720,
        "Deerith",
        nullptr,
        nullptr);

    if (!window)
    {
        std::cerr << "Failed to create GLFW window\n";
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);

    int version = gladLoadGL(glfwGetProcAddress);
    if (version == 0)
    {
        std::cerr << "Failed to initialize GLAD\n";
        glfwDestroyWindow(window);
        glfwTerminate();
        return -1;
    }

    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    glDisable(GL_DEPTH_TEST);
    glDisable(GL_CULL_FACE);

    init_primitives();
    init_imgui();

    return 0;
}

bool deerith::begin_window_display()
{
    glfwPollEvents();
    if (glfwWindowShouldClose(window))
    {
        return false;
    }

    ImGui_ImplOpenGL3_NewFrame();
    ImGui_ImplGlfw_NewFrame();
    ImGui::NewFrame();

    return true;
}

void deerith::finish_window_display()
{

    ImGui::Render();
    int display_w, display_h;
    glfwGetFramebufferSize(window, &display_w, &display_h);
    glViewport(0, 0, display_w, display_h);
    ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

    using clock = std::chrono::steady_clock;

    const auto now = clock::now();
    const std::chrono::duration<double> elapsed = now - last_frame_time;

    using clock = std::chrono::steady_clock;

    while (std::chrono::duration<double>(
               clock::now() - frame_start)
               .count() < TARGET_FRAME_TIME)
    {
        std::this_thread::sleep_for(std::chrono::milliseconds(5));
    }

    frame_id++;
    glfwSwapBuffers(window);

    glClearColor(0.1f, 0.1f, 0.15f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
}

void deerith::shutdown_window()
{

    ImGui_ImplOpenGL3_Shutdown();
    ImGui_ImplGlfw_Shutdown();
    ImGui::DestroyContext();

    shutdown_primitives();

    glfwDestroyWindow(window);
    glfwTerminate();
}

int deerith::get_current_frame_id()
{
    return frame_id;
}

glm::ivec2 deerith::get_window_size()
{

    glm::ivec2 size;
    glfwGetWindowSize(window, &size.x, &size.y);

    return size;
}

float deerith::get_window_aspect_ratio()
{
    glm::ivec2 size;
    glfwGetWindowSize(window, &size.x, &size.y);

    return (float)size.x / (float)size.y;
}

void deerith::init_imgui()
{
    float main_scale = ImGui_ImplGlfw_GetContentScaleForMonitor(glfwGetPrimaryMonitor());

    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO &io = ImGui::GetIO();
    (void)io;
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;  // Enable Gamepad Controls

    ImGui::StyleColorsDark();

    ImGuiStyle &style = ImGui::GetStyle();
    style.ScaleAllSizes(main_scale);
    style.FontScaleDpi = main_scale;

    const char *glsl_version = nullptr;
    ImGui_ImplGlfw_InitForOpenGL(window, true);
    ImGui_ImplOpenGL3_Init(glsl_version);
}