gui.cpp

// SPDX-License-Identifier: MIT
// Author:  Giovanni Santini
// Mail:    giovanni.santini@proton.me
// Github:  @San7o
 
#include <brenta/gl.hpp>
#include <brenta/gui.hpp>
#include <brenta/window.hpp>
#include <brenta/texture.hpp>
#include <brenta/logger.hpp>
 
#ifdef BRENTA_USE_IMGUI
 
using namespace brenta;
using namespace brenta::types;
 
//
// Static variables
//
 
const std::string gui::subsystem_name = "gui";
bool gui::initialized = false;
 
//
// Subsystem interface
//
 
std::expected<void, subsystem::error> gui::initialize()
{
  if (this->is_initialized()) return {};
  
  IMGUI_CHECKVERSION();
  ImGui::CreateContext();
  ImGuiIO &io = ImGui::GetIO();
  
  // Enable Keyboard and Gamepad Controls
  io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
  io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;
  io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
 
  // Setup Platform/Renderer backends
  ImGui_ImplGlfw_InitForOpenGL(window::get_window(), true);
  ImGui_ImplOpenGL3_Init();
  ImGui::SetNextWindowPos(ImVec2(0, 0));
 
  gui::initialized = true;
  INFO("{} initialized", gui::subsystem_name);
  return {};
}
 
std::expected<void, subsystem::error> gui::terminate()
{
  if (!this->is_initialized()) return {};
  
  ImGui_ImplOpenGL3_Shutdown();
  ImGui_ImplGlfw_Shutdown();
  ImGui::DestroyContext();
 
  gui::initialized = false;
  INFO("{}: terminated", gui::subsystem_name);
  return {};
}
 
std::string gui::name()
{
  return gui::subsystem_name;
}
 
bool gui::is_initialized()
{
  return gui::initialized;
}
 
//
// Member functions
//
 
gui &gui::instance()
{
  static gui _gui;
  return _gui;
}
 
void gui::new_frame(framebuffer *fb, std::string name)
{
  ImGui_ImplOpenGL3_NewFrame();
  ImGui_ImplGlfw_NewFrame();
  ImGui::NewFrame();
 
  ImGui::DockSpaceOverViewport(0, ImGui::GetMainViewport());
 
  //
  // Game window
  //
 
  ImGui::SetNextWindowSize(ImVec2(window::get_width() * 0.8,
                                  window::get_width() * 0.8),
                           ImGuiCond_FirstUseEver);
  ImGui::Begin(name.c_str());
 
  float window_width = ImGui::GetContentRegionAvail().x;
  float window_height = ImGui::GetContentRegionAvail().y;
 
  fb->rescale(window_width, window_height);
  gl::set_viewport(0, 0, window_width, window_height);
 
  ImGui::Image((void *) (intptr_t) fb->texture_id,
               ImGui::GetContentRegionAvail(), ImVec2(0, 1), ImVec2(1, 0));
 
  ImGui::End();
}
 
void gui::render()
{
  ImGui::Render();
  ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
}
 
//
// Builder
//
 
subsystem &gui::builder::build()
{
  return gui::instance();
}
 
#endif