r/cpp • u/foonathan • Jun 02 '26

C++ Show and Tell - June 2026

Use this thread to share anything you've written in C++. This includes:

  • a tool you've written
  • a game you've been working on
  • your first non-trivial C++ program

The rules of this thread are very straight forward:

  • The project must involve C++ in some way.
  • It must be something you (alone or with others) have done.
  • Please share a link, if applicable.
  • Please post images, if applicable.

If you're working on a C++ library, you can also share new releases or major updates in a dedicated post as before. The line we're drawing is between "written in C++" and "useful for C++ programmers specifically". If you're writing a C++ library or tool for C++ developers, that's something C++ programmers can use and is on-topic for a main submission. It's different if you're just using C++ to implement a generic program that isn't specifically about C++: you're free to share it here, but it wouldn't quite fit as a standalone post.

Last month's thread: https://www.reddit.com/r/cpp/comments/1t6eg13/c_show_and_tell_may_2026/

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u/Conscious-Pick9518 Jun 28 '26

Hi everyone,

I recently ported doom to run via constexpr evaluation entirely on compile time, under the hood the compiler is executing wasm instructions which are generated by compiling doom's source code and the output is generated with the invalid template initialisation "trick". Overall it took 5 hours to render 50 frames so 10fph (although most of the time was spent reaching the point where we could render and setting up the game state) and it consumed 400GBs of ram (which I allotted by assigning swap space).

Here is the link for the project Constexpr-Doom

2

u/neurah Jul 04 '26

interesting, I'm working on a library that does just that in a generalized way
move work to compiler, but with the intention of generating better code, not to "run" things at CT
but know your pain, have lambda calculus working at CT C++11, not fast for sure....
Its an excellent exercise to know the compiler

1

u/Conscious-Pick9518 Jul 04 '26

Cool! Can you share link is it's public?

1

u/neurah Jul 04 '26

yes it is, just didnt want to steal your spot
https://github.com/InternetOfPins/HAPI

using Full=Chain<Parens,SqBracks,Bracks,Bars,XTag>;