Renderer Engineering

#include "prism_engineering/asset_pipeline.hpp"
#include <fstream>
#include <iostream>
#include <locale>
#include <stdexcept>
using namespace prism_engineering;
int main(int argc, char** argv) {
  try {
    if (argc > 2) throw std::runtime_error{"usage: prism-gallery [image.ppm]"};
    auto created = AssetPipeline::create();
    if (!created) throw std::runtime_error{"could not create bounded workers"};
    auto pipeline = std::move(*created);
    Gallery gallery;
    auto gate = std::make_shared<WorkGate>();
    if (!gallery.request(*pipeline,{1,32,32,40,gate}) || !gate->wait_for_arrivals(1))
      throw std::runtime_error{"could not begin A"};
    if (pipeline->try_take()) throw std::runtime_error{"closed gate unexpectedly completed"};
    std::cout << "A is still preparing; the application thread can handle another request.\n";
    if (!gallery.request(*pipeline,{2,32,32,180,{},false})) throw std::runtime_error{"could not begin B"};
    // Blocking terminal driver. A real UI calls try_take on each ordinary tick.
    auto b = pipeline->wait_take();
    if (!b || !gallery.apply(std::move(*b))) throw std::runtime_error{"B did not publish"};
    gate->open();
    auto a = pipeline->wait_take();
    if (!a || gallery.apply(std::move(*a))) throw std::runtime_error{"stale A replaced B"};
    if (!gallery.request(*pipeline,{3,32,32,0,{},true})) throw std::runtime_error{"failure request rejected"};
    auto failed = pipeline->wait_take();
    if (!failed || gallery.apply(std::move(*failed)) || gallery.latest_status()!=Status::failed)
      throw std::runtime_error{"failure publication contract"};
    pipeline->shutdown();
    if (pipeline->runtime_failed()) throw std::runtime_error{"unexpected worker runtime failure"};
    std::cout << "Published generation 2; stale generation 1 and failed generation 3 preserved it.\n";
    if (argc == 2) {
      std::ofstream output{argv[1],std::ios::binary};
      output.imbue(std::locale::classic());
      const auto& image=gallery.image();
      output << "P6\n" << image.width << ' ' << image.height << "\n255\n";
      for (const auto pixel : image.pixels) {
        const char bytes[]{static_cast<char>(pixel.r),static_cast<char>(pixel.g),static_cast<char>(pixel.b)};
        output.write(bytes,3);
      }
      output.flush();
      output.close();
      if (!output) throw std::runtime_error{"image write failed"};
    }
    return 0;
  } catch(const std::exception& error) { std::cerr << error.what() << '\n'; return 1; }
}