More Dirty Coding Tricks from Game Developers (2010)

http://www.gamasutra.com/view/news/249475/More_dirty_coding_tricks_from_game_developers.php

by maccard • 11 years ago

241 132 11 years ago

gamasutra.com

busterarm2• 11 years ago

Pretty sure Nicholas Vining was referring to the LithTech engine and the game would be Die Hard: Nakatomi Plaza

avesanen• 11 years ago

Yep, this is the comic he was referring to: http://www.penny-arcade.com/comic/2002/02/11

Sniffnoy• 11 years ago

This is actually not the first mention of that character -- that would be this comic[0] -- but seeing as that comic doesn't mention an engine and the rest doesn't really fit either, presumably the one you link is the one he actually meant.

[0] http://www.penny-arcade.com/comic/2001/07/11

busterarm2• 11 years ago

I also find it amusing that my favorite multiplayer PC FPS ever was released using the next iteration of that engine... (AvP 2, btw).

golergka12• 11 years ago

I want to do something very violent to that person who "hates const with a passion". No wonder he didn't provide his name.

krapp2• 11 years ago

Casey Muratori considers const a complete waste of time, so apparently that's a thing with some C/C++ programmers.

cautious_int• 11 years ago

That is why you should never learn from one exclusive source, especially if they don't provide valid arguments, and imply "trust me".

I saw a couple of his introductory videos and I think he is great to teach specifics about game programming, but should definitely not teach how to write C.

hibikir• 11 years ago

If you want to go by authority, instead of by the fact that const just makes sense, there's this guy who claims to be a complete const nazi who you might have heard of. His name is John Carmack.

http://www.phoronix.com/scan.php?page=news_item&px=MTI3NDQ

Patient0• 11 years ago

where did it mention that in the article? I don't see it

bluehawk• 11 years ago

The article is in four pages. I missed it at first too.

bitwize3• 11 years ago

'const' in C and C++ is broken. Not only is it like a Chinese word that varies wildly in meaning depending on where you use it and how it is inflected, but in C-family languages, 'const' modifies type, making objects that benefit from the compiler hints 'const' implies type-incompatible with objects that do not. This results in the problem of some know-it-all deciding that a core API needs to be const-correct, and checks in changes making it so, only to find that the entire fucking code base is now broken.

Note that I'm not saying "don't use 'const'" with the above (and I'm CERTAINLY not saying "using '#define const' in your code base is a good idea"); only that 'const' in C-family languages has significant drawbacks which may affect the engineering tradeoffs you make when you decide whether to use it.

By contrast, languages such as Ada have explicit and implicit constantness restrictions ('in' parameters, for instance, cannot be modified), but these do not modify the type of the object, allowing objects with these restrictions to be type-compatible with objects without them.

chimeracoder• 11 years ago

only that 'const' in C-family languages has significant drawbacks

AFAIK this is pretty much limited to C and C++. Many (and I am willing to venture most, or at least the most-used) C-family languages that aren't C/C++ don't suffer this issue. Go and Javascript, for example, both use "const" in a way that doesn't modify the type of the underlying object.

golergka12• 11 years ago

Can you please provide some examples where this really becomes a problem, so I can better understand what you mean?

CountSessine6• 11 years ago

I don't really understand what you're saying.

They're not type-incompatible in any way that doesn't violate those compiler hints in the first place - C and C++ fully support sensible coercion between const and non-const types. What more do you want?

This results in the problem of some know-it-all deciding that a core API needs to be const-correct, and checks in changes making it so, only to find that the entire fucking code base is now broken

Would you rather it compiled and silently broke? If some dingus breaks the build by changing an API without checking in the corresponding code using the API, how is that C/C++'s fault?

This is bizarre. Can you take that 'in' parameter and then pass it on to another function as an 'in/out' parameter? If so, then either

1. Ada just made you a copy silently (bad)

2. Ada is broken and 'in' means nothing (worse).

If neither of those are true and an 'in' can't be transitively passed on as an 'in/out', then that's a type - however you want to refer to it, 'in' is then a type with all of the 'broken' type restrictions you're railing against in C/C++.

lisivka• 11 years ago

but in C-family languages, 'const' modifies type, making objects that benefit from the compiler hints 'const' implies type-incompatible with objects that do not.

It was fixed years ago. Now const behaves properly in modern C compilers.

TwoBit• 11 years ago

Dude you are clueless. I hope you aren't in the position of making technical decisions for any major C/C++ projects.

andresmanz• 11 years ago

What people like him don't get is that const is not only about security. It also documents the intents behind the code and thus makes writing new code around it easier. Const really helped me thinking about better designs when I started coding in C++.

daodedickinson3• 11 years ago

What about final for Java function parameters? A professor was requiring that and I'm not sure whether its something I should continue doing or not.

golergka12• 11 years ago

Make everything you can as immutable as possible. The less possibilities exist for data to change, the more you know about it during runtime, the easier it is to reason about it. I love the trend that new languages, like Swift and Rust, make it really easy to make variables immutable and even disallow using "null" values unless a variable is explicitly nullable.

shoo4• 11 years ago

Curious. I haven't written anything in Java for a long time so I wasn't aware that you could mark parameters as `final`, or what that would mean.

If you are working with code where you know that functions never modify their parameters then it is simpler to reason about what it does. I prefer to write code this way myself if there is no language mechanism to enforce it.

Other possible uses of `final` (to tag methods or classes) have the downside of reducing the flexibility of code by removing interfaces / "seams" that can be overridden. This reduction of flexibility will generally make things harder to test, which may or may not matter. Michael Feathers has a short article discussing this [1].

[1] Michael Feathers' "Testable Java" : http://www.objectmentor.com/resources/articles/TestableJava....

AdieuToLogic2• 11 years ago

What about final for Java function parameters?

For built-ins, such as numeric types and "char" (String is obviously disallowed from this definition), final will prevent changes to instances of those types similar to what "const int" does for C++.

For pointers, however, the final keyword in Java limits the ability to change the variable holding the pointer, not to what it references. The equivalent in C++ would be:

  SomeClass * const foo = &instanceOfSomeClass;

Here, the pointer "foo" could not change, but operations changing foo would be allowed.

Java (the language) does not possess the semantics to express "the pointer given to a method cannot allow changes to what it points."

mahyarm• 11 years ago

const is an awkward poorly thought out keyword syntax that is too ambiguous. Const is a good idea, how it was implemented in C++ was not. One of my old managers used it as his C++ interview question to 'really see if they know C++ well'.

See http://duramecho.com/ComputerInformation/WhyHowCppConst.html

danielweber• 11 years ago

Absolutely nothing there was surprising. The worst thing is that if a library uses const, you have to use it too.

golergka12• 11 years ago

I don't think I saw anything strange or ambiguous in this article, and the only thing I didn't know before. And I'm a beginner C++ programmer.

CountSessine6• 11 years ago

So, to summarize the article in the link,

1. I don't like the syntax for const [fair enough]

2. I want to have an object that obeys someone's const'ing of it but still be able to mess around with its internal state (like for logging, data caching, or intermediate calculations), and there's no way of doing that...

3. ...except that there is - it's the mutable keyword, but that's bad because other programmers other than me who are using it to modify 'const'ed classes (for logging, data caching, or intermediate calculations) can't be trusted.

Seriously - that's what he says:

One in particular annoys me because my programs often needed to be optimized for speed. [because I'm 'leet] This is that a method which is declared ‘const’ cannot even make changes to the hidden parts of its object that would not make any changes that would be apparent from the outside

...

In later versions of C++, the ‘mutable’ keyword was added which enables ‘const’ to be overridden for this purpose but it totally relies on trusting the programmer to only use it for that purpose so

!!!

Turbo_hedgehog• 11 years ago

What happened to altdevblogaday.com anyway? It had content similar to this.

tylorr• 11 years ago

I've been wondering the same thing for a while. I don't know why it just disappeared out of nowhere.

daodedickinson3• 11 years ago

Isn't it awful when such resources vanish?

When Megaupload was destroyed, it was like losing the Library of Alexandria to me. The ATF can't just destroy the entire nation's set of self-storage units because they found drugs or pirate DVDs in some of the units. But that's what happened with Megaupload. Some people lost family photos, some people lost backups of theses... Why couldn't the authorities have taken it over, eliminated illegal content, and turned it over to some sort of Vichy CEO? There need to be protections for data storage customers in a FDIC sort of way, I feel.

ivanca2• 11 years ago

Police (and the like) are paid for capturing criminals, not for doing what is morally right (some hope they are the same thing, but many times it isn't)

Keyframe• 11 years ago

It's dead. I remember Mike Acton said something like site had serious technical issues or whatever and since then it's dead.

barbs2• 11 years ago

First I've heard of it (thanks for mentioning it), but the Wayback Machine seems to have it reasonably intact:

https://web.archive.org/web/20140328003222/http://www.altdev...

Negitivefrags2• 11 years ago

I have a story kind of similar to the one called "...Or is it over here!?"

A friend of mine was having crashes with a program. When debugging it he found that a bunch of his local variables had weird values. He suspected that there might be a buffer overflow elsewhere that was trampling over the memory.

The fix? Just add "char buffer[ 1000 ];" to the function to absorb the damage. It fixed the crash and it shipped like that.

shoo4• 11 years ago

This reminds me of an older "dirty trick" where a buffer was sacrificed, instead of added, at the end of the project in order to ship.

See "The Programming Antihero"[1].

[1]. http://www.gamasutra.com/view/feature/132500/dirty_coding_tr...

tfigment• 11 years ago

I've done something like this on a production data base server before. Maybe not the same thing but I allocated a really big file because mysql would occasionally grow its ibdata file to full the disk before we could handle the alert. Deleting this file allowed room to maneuver after restarting the database and dealing with this run away journal file.

The other similar urban legend is the enterprise teams which have for(int i=0;i<10000000;++i); loops in code which they can remove a zero when performance boost is needed and they can quickly provide a fix.

bananaboy7• 11 years ago

Now this is a dirty coding trick!

ygra• 11 years ago

There's even a compat shim in Windows for that kind of thing where the memory manager would allocate a few bytes more than requested so that subsequent code (that ran fine in Win 95, for example) could overrun the allocated buffer without crashing. Back in Vista there were around 5000 applications that had shims applied by Windows to make them run correctly. I wonder how the count would look like today ...

bnastic• 11 years ago

Ah, debugging games... It screams desperation when you see code that is sprinkled with "int 3" 'cos no one knows where or why it's crashing.

CountSessine6• 11 years ago

There's a whole lot of desperation in the air when you're final-ing and your development director is standing over your shoulder at 1 in the morning. :-)

wh-uws• 11 years ago

The battery backup initialization hack from NBA JAM TE is random and hilarious

http://www.ign.com/cheats/games/nba-jam-tournament-edition-g...

daodedickinson3• 11 years ago

Is there an explanation for this somewhere?

barbs2• 11 years ago

I was also looking for more info on this. Sounds like a good idea for a blog post if anyone can shed light on how/why this works.

Natsu• 11 years ago

My best guess would be some kind of anti-piracy measure failing.

michaelx386• 11 years ago

That one's included in the article, bottom of page 1 called "Flash forward"[0]

someone figured out if you played the games in an odd, and very specific order, the flash memory would sort of work. So an extra leaflet was added to every box explaining how to use this "feature."

[0] http://www.gamasutra.com/view/news/249475/More_dirty_coding_...

ketralnis2• 11 years ago

A couple of those are cited like this:

- Anonymous (sourced from Reddit replies to the original 2009 Dirty Coding Tricks article)

So not anonymous at all then. reddit comments have usernames attached to them, URLs that can be linked to, and even an on-site messaging system that can can be used to ask the author for permission to use the content. Heck, every comment has an "embed" link below it to conveniently embed the properly cited comment right on your page.

Is this a thing that's okay to do? Take someone else's content from someone else's website, copy-paste it into your article, and claim it was "anonymous"?

Would this author be okay with it if I copy-pasted their articles to my blog? What about if I stole all of the comments posted to their articles to make my site look more active?

rjbwork• 11 years ago

No, it's not okay. The media, especially gaming publications, have been doing this stuff for years now, and it's ridiculous. Some publications have wised up, but many haven't.

It's greatly amusing when someone just gives up all pretense and just scrapes a subreddit, then SEO blog spams every single post - because then the members will upvote stories about how terrible the website is. I unfortunately can't find anything specific at the moment, but 2 of the big ones I remember was /r/makeupaddiction and /r/gaming.

EDIT: For the curious, here's the mod post about the /r/makeupaddiction incident https://www.reddit.com/r/MakeupAddiction/comments/39o74y/mod... I'm unable to find the others at the moment, though there is a list under the top comment on the thread I've linked.

ivanca2• 11 years ago

Just to be fair the original reddit entry [0] no longer has that comment in it (it was probably deleted) so maybe they just went with "anonymous" after being unable to find the actual source.

[0]http://www.reddit.com/comments/9ch0s/dirty_coding_tricks_nin...

ketralnis2• 11 years ago

There are two cited that way, and neither appears in that link. I don't think both were coincidentally deleted, I think that's just the wrong comments page

Besides, he has to have fetched them at some point and he should have taken the cites at the same time. "I found it somewhere on reddit" just isn't enough. It makes me wonder where he stole the other ones labelled "anonymous"

benihana• 11 years ago

For anyone who loves a good rant, Maddox talks about this topic: http://www.thebestpageintheuniverse.net/c.cgi?u=buzzfeed

TeMPOraL2• 11 years ago

His rants are excellent. Under the coating of expletives hides a goldmine of no-bullshit common sense.

airza• 11 years ago

we'd inexplicably get a crash in printf [..] The client in debug would print out the hashes of every content package the server told it to load, and apparently one of them (on this build) had a % in the hash. We couldn't figure out a reasonable fix for it, but #ifndef PS3 worked just fine until the next data build

Friends don't let friends printf(str).

Kenji• 11 years ago

I didn't really understand that problem. They couldn't fix this?? Like, they didn't know how to escape/replace percent signs or print differently? Maybe I am missing something but it does not look like a particularly elusive problem.

bananaboy7• 11 years ago

Yeah I thought that one was weird too. Also I wouldn't really call it much of a dirty coding trick if it was just something that was hacked in during development! Many times I've #ifndef <someplatform> because something or other didn't work on that platform. Then later before shipping you fix/implement it!

pandaman• 11 years ago

How I understand is that they had printf(x) somewhere and some values of x included the '%' character. If this has been inside the UE and the x itself was a hash value then both replacing with printf("%s",x) and changing the x's value could be problematic.

curryhoward• 11 years ago

Here is a horror story from the good old days when men were men and used DirectX 7.

Ugh.

Personally, I hate CONST with a passion, so I like this trick.

Ugh.

PhysicalObjects could take damage. The air strikes did enough damage in a large enough radius that they were quite literally "killing" the camera. I did fix the bug by ensuring that cameras couldn't take damage, but just to be sure, I boosted their armor and hit points to ridiculous levels. I believe I can safely say we had the toughest camera in any game.

Awesome.

shoo4• 11 years ago

Regarding the camera with hitpoints, is there a name for that class of bug? Poorly thought out code reuse? Overly specific inheritance?

A similar seeming bug is the old "kangaroos with rocket launchers" story (from military simulations, not games) [1].

[1] http://www.petting-zoo.net/~deadbeef/archive/4488.html

tinco• 11 years ago

It's inherent to common game architecture. Far out the most flexible way of dealing with the multitude of complex entities in a game is to not work with inheritance but rather with 'components'. Ideally this means that an entity is nothing more than a UUID for which data is stored in component tables (a la relational databases).

Unfortunately that approach is rather cumbersome to reason about and brings with it unhandy syntax requisites. Given an entity UUID, how do you get a value for some property? It would be component_table_get(health_components, entity_id)->hitpoints. Or something similar. (note: what happens if you accidentily call that function on a entity_id for which no health_components entry exists?)

The alternative which is really fine for smaller games and which often leaks into the codebase of larger games, sometimes for performance reasons is to make the entity a struct which has some members common to all entities. Now you can do entity->hitpoints, but the downside is that every entity, including abstract game components such as the camera also have hitpoints.

If you're curious why games don't do inheritance (anymore) look up articles about Component Entity Systems, they usually do a good idea of explaining why games are too complex for inheritance.

kilotaras• 11 years ago

I can't recall the source, but the story goes as follow.

In some game, menu was written on stone tablets. Due to the bug tablets received guard AI and would randomly walk away to patrol the island.

okasaki• 11 years ago

There used to be a bug in Kerbal Space Program where solar panels would be occluded by the UI windows.

TeMPOraL2• 11 years ago

That's what you get when you keep your UI and game objects mixed together in a some sort of "scene". I suppose Unity that encourages this style.

SamReidHughes4• 11 years ago

> Personally, I hate CONST with a passion, so I like this trick.
Ugh.

Gamedevs gonna gamedev.

bananaboy7• 11 years ago

I've read that Wing Commander anecdote before, and it still doesn't make any sense to me (also I don't remember that original message "Thank you for playing Wing Commander" message and every abandonware version I found had a different message - "You step out of the airlock and into.."). It doesn't make sense because EMM386 is the expanded memory manager that came with DOS. It's not something you ship with your game and can hex edit at will. Now if it was a 3rd party library that USED EMM386, and which they didn't have the source for, then that might make sense..

InclinedPlane2• 11 years ago

In the DOS days the operating system was mostly just a boot loader and a set of tools. Whichever program happened to be running at any given time would have complete control over the system. So a program could simply find out where any other program was in memory and modify it, which for something like changing a string was fairly easy.

bananaboy7• 11 years ago

Yeah sure, I know, so I suppose they could have modified the string in memory. But he specifically says that he "hex edited the error in the memory manager itself", which makes it sound like he modified an executable. A programmer wouldn't say he hex edited a string in memory when what he meant was he wrote some code to replace the string in memory.

IvyMike• 11 years ago

There were third party memory managers that you could use in DOS; for example, QEMM and 386max. I assume Wing Commander was licensing and shipping one of those rather than relying on the stock memory manager. In fact in 1993 MS licensed some technology for later versions of EMM386 from Helix's third party memory manager[0].

[0] https://en.wikipedia.org/wiki/Helix_Software_Company

bananaboy7• 11 years ago

Yeah I used to run QEMM. I don't think anyone would have shipped QEMM or 386max with their game, since they were commercial products for end users. It sounds like, as someone else said, the story was mangled over time.

chipsy• 11 years ago

EMM386 only became the defacto standard for games around 1993 or so. Prior to that developers would purchase or create a solution from scratch to deal with the rapidly shifting PC development environment. A decent chunk of the market was still on 286, and this was the most likely target for the first Wing Commander (1990) - later games from Origin such as Ultima 7 and Privateer continued using memory extenders branded "Voodoo" and "JEMM" that were known to run in unreal mode[0] - they were generally a nightmare for users as they were less stable than EMM386 and typically had a huge conventional memory minimum requirement, but it was tolerated as what one had to go through to play high end PC games.

[0] http://wiki.ultimacodex.com/wiki/Voodoo_Memory_Manager

bananaboy7• 11 years ago

Right, yeah that makes sense then. Since WC also ran on a 286, they must have created or licensed an EMS library.

e28eta• 11 years ago

I wonder if these anecdotes would be a good litmus test for developers. They make me cringe, but I work on business software, not games.

I really don't like the idea of papering over the bugs so that your testers can't find them anymore, I'd much rather find the underlying issue. On the other hand, the described changes were often very practical, solved a customer need, and were manageable to implement. So that sounds like a win!

gambiting• 11 years ago

Few things contribute to it. Mostly it's lack of time, and the fact that we don't really have to support code for long periods of time. If the input code works then it works, when a game is released its code it's mothballed on a server and I don't even see it again unless there's some urgent patches(and 6 months after release the chance of that happening reduces to zero), and then I have to request IT to give me access to that code again.

shoo4• 11 years ago

The earlier articles[1][2] are also pretty good.

I'm utterly horrified by the "(s)elf-exploitation" story. Ugh. Clever.

[1] http://www.gamasutra.com/view/feature/194772/dirty_game_deve...

[2] http://www.gamasutra.com/view/feature/132500/dirty_coding_tr...

plq• 11 years ago

I then remembered that when you put the window in the notification area or in the start-menu bar, Windows immediately reclaims unused/freed memory.

Wow. Is this a horrible hack or a wonder of the tight integration between the GUI and the kernel in an operating system designed to be used in a desktop? I'm torn :)

dfox• 11 years ago

I think that this is some kind of oversimplification of what actually happened.

AFAIK there is not even an operation like "put window into notification area" as part of WinAPI as the icons are mostly orthogonal to windows (and are not even intended to represent "more-minimized" windows).

The icon has to reference some window, but only because it generates window messages that have to be consumed somewhere. Fun fact: at least on 2k and XP, when the window goes away, the icon stays visible unless it is explicitly deleted by user code and is removed only when some message would be sent to now non-existent window (ie. when users mouses over the icon).

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