snake/game/SplashState.cxx

#include "SplashState.hxx"
#include "AssetManager.hxx"
#include "GameStateManager.hxx"

using namespace std::chrono_literals;

void SplashState::update(GameStateManager& gsm, std::chrono::milliseconds delta_time)
{
    time_in_state_ += delta_time;
    auto const key_state = SDL_GetKeyboardState(nullptr);
    if (time_in_state_>13'000ms || key_state[SDL_SCANCODE_SPACE] || key_state[SDL_SCANCODE_RETURN])
      gsm.replace_state(GameStates::MainMenu);
}

void SplashState::render(SDLRenderer& renderer)
{
  if (logo_==nullptr) {
    // right now this is required here as we need the renderer and the main thread
    logo_ = SDL_CreateTextureFromSurface(
        renderer,
        AssetManager::instance().get_image_asset("logo.jpg")
    );
    SDL_SetTextureBlendMode(logo_, SDL_BLENDMODE_BLEND);
  }

  SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);
  SDL_RenderClear(renderer);

  int w, h;
  SDL_GetRendererOutputSize(renderer, &w, &h);

  if (time_in_state_>=2'000ms && time_in_state_<4'000ms) {
    auto const progress = static_cast<float>(time_in_state_.count()-2'000)/2'000.0f;
    auto const alpha = static_cast<int>(std::lerp(SDL_ALPHA_TRANSPARENT, SDL_ALPHA_OPAQUE, progress));
    SDL_SetTextureAlphaMod(logo_, alpha);
    SDL_RenderCopy(renderer, logo_, nullptr, nullptr);
  }
  else if (time_in_state_>=4'000ms && time_in_state_<9'000ms) {
    SDL_SetTextureAlphaMod(logo_, SDL_ALPHA_OPAQUE);
    SDL_RenderCopy(renderer, logo_, nullptr, nullptr);
  }
  else if (time_in_state_>=9'000ms && time_in_state_<11'000ms) {
    auto const progress = static_cast<float>(time_in_state_.count()-11'000)/2'000.0f;
    auto const alpha = static_cast<int>(std::lerp(SDL_ALPHA_OPAQUE, SDL_ALPHA_TRANSPARENT, progress));
    SDL_SetTextureAlphaMod(logo_, alpha);
    SDL_RenderCopy(renderer, logo_, nullptr, nullptr);
  }

  SDL_RenderPresent(renderer);
}

void SplashState::on_enter()
{
  time_in_state_ = 0ms;
  logo_ = nullptr;
}

void SplashState::on_leave()
{
  SDL_DestroyTexture(logo_);
  logo_ = nullptr;
}