A time-travelling door bug in Half Life 2

(mastodon.gamedev.place)

95 points | by AshleysBrain 1 day ago

6 comments

  • g7r 6 hours ago
    Ah, nice story!

    This reminds me of another story with FPU involved. I was a game developer once. We were making a game that consistently triggered assertion failures related to FPU calculations, but only on a single PC in the whole office. The game was explicitly setting FPU precision to 32 bits at the start to make all calculations more consistent. However, on that particular PC, there was a fancy hand writing input software that injected its DLL into every process. As you've probably already guessed, that DLL did FPU mode reset to the default in the event handling loop (i.e., main thread). I had to shift FPU mode setting code from process initialization to the event handling loop to be able to deal with the damage that third party DLLs could inflict.

  • HelloUsername 19 hours ago
  • Wowfunhappy 1 day ago
    Wait, so is that "beta" of Half Life 2 VR a thing I can play? If it is, how did I not know about this, and if not... why not?

    I'd also love to play Portal, actually. They say it makes you sick, but to my knowledge I'm immune from VR motion sickness, so worth a try...

    • davepdotorg 17 hours ago
      There’s a great VR mod for Portal 2. Played it all the way through. Surprisingly comfortable to play too.
    • aranelsurion 1 day ago
      I don’t know about the beta, but there’s an excellent HL2 VR conversion mod you can play today. It feels just right and got me to play HL2 again after all these years.
  • Panzerschrek 1 day ago
    It seems to be typical - some calculations break while switching from x87 to SSE. The same happened with TF2 too - it's ammo calculation code worked slightly differently on GNU/Linux build of the game, because it was built with SSE instructions (Windows version still used x87).
    • arcfour 1 day ago
      I think the only visible effect from that was the Engineer's metal, giving +40 or +41 from a small box, depending on the server platform (all classes technically do have metal, but the others can't use it).

      It was always fun to play on a new server and check what OS it was running that way, too. :-)

      • stoltzmann 23 hours ago
        And IIRC ammo for heavy and health for soldier!
  • nasretdinov 22 hours ago
    I wonder how on earth stuff like x86->ARM translation works so well if games break even after switching from x87 registers to SSE preserving all the logic otherwise...
    • toast0 13 hours ago
      I think x87 fpu is the only 'weird' floating point units left. I think if you stick with 64-bit double precision floats or 32-bit single precision floats, where the registers are also 64 or 32 bits, all the modern stuff behaves the same. x87 is just weird because registers are 80-bits ... the idea was to have more accurate results from more precision, but it ends up weird because if you run out of registers and have to spill to memory, you typically lose precision.
  • netsharc 1 day ago
    Meta: I'm going to make a Twitter clone that bans you if you use it as a multi-paragraph blogging platform... god damn !#@#%!!!.
    • bathtub365 20 hours ago
      Here’s a link with the thread unrolled onto a single page: https://mastoreader.io/?url=https%3A%2F%2Fmastodon.gamedev.p...
    • viraptor 1 day ago
      Do you actively want the linked thread to not exist? Because not having this posting option does not mean it would appear anywhere else.
    • fragmede 1 day ago
      I'll make one that's the opposite (your post must be at least two paragraphs and an LLM is going to judge your text to make sure it's not lorum Ipsum) if you'll help me get users.