Coding for CoH

Does anyone know how many lines of code CoH is made of? Just wondering, I'm learning C++ and was thinking about how many lines of code it must take to run CoH.

No idea for CoH, but another MMO is apparently about 5.5 million lines of code

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5.5 million lines!? lol and I thought my little phone book project was long...

At a guess it'll be done across several languages aswell which means building a method of interacting with an 'engine frontend scripty thing' aswell as interface shite... God only knows. More than i'd care to imagine :/

I used to be a volunteer developer for a text-based game. I don't know know how many lines of code the game had, but it had to be several thousands.

FYI the old Diku MUD codebases are still around and can be downloaded. if you obtain a server it is actually possible to build your own text based game. By complete coincidence, one of the codebases now widely available is "The Forest's Edge," which happens to be the MUD I played back in 1997 or 98.

I don't know what City of Heroes looks like under the hood. I can tell you that the game I worked for had a custom codebase. It was a very nice setup how they had it. The overarching engine was in C++ but the company had invented their own scripting language that compiled in real time without having to take the servers down. When we developed things, we would program it on a live development server and test it in real time, then "roll" the code over to live servers once everything was QAed and ready. The game rarely had downtime at all.

However, text based games have some huge advantages over graphical ones. For one thing, its probably obvious that you can make on the fly changes much faster in a text based game. But the other major advantage is that your code is not reliant on a game client. That means that while you may crash the server, you won't independantly crash the player's game client. Have you ever noticed that everytime CoH makes major changes under the server hood, they make us all update to a new client? That's part of why. They're making sure if they start getting tons of reports about us crashing that we're all on the same version.

In any case, the number of lines of code would be hard to guess because most games break code down into segments. Generally speaking, you have:
- an interface layer that governs loading and saving player data, and logins and logouts
- seperate server code that governs actual gameplay (e.g. resolves combat rolls)
- the player game client, which plays animations and sounds in accordance with what the server tells it is happening, and accepts user commands to pass to the server*
- lists of things: items, spells, etc. sometimes in scripting languages, sometimes xml, sometimes other formats. FYI it is rare for these things to be literally coded in C++ these days. in the old DIKU MUDs I believe they were however. I would have to go back and look.
- instance code, usually in a custom script language, that governs missions/instances

[*Have you ever wondered why when the game starts lagging you start "rubber banding?" It's because a portion of the movement code is faked. The client doesn't literally check up with the server every millisecond to see if you can move to a new location on the map, it just lets you move around based on what it knows about on your local computer. When you start lagging, the client is still letting you move around, but the server isn't getting the information fast enough to check up and make sure you can actually move you to where you're instructing it to go. When it finally does send information back to the client, the client is like "Oops, okay I got THAT one wrong" and warps you to where your character is standing on the server. One way to tell for sure you're lagging is to try clicking a power that should normally fire; powers always require a server okay before activating (in this and any game coded by anyone half competent). Movement, however, is different, because if it asked for a server okay literally the whole time you were pressing the keys, the game would stutter constantly.]

In City of Heroes specifically we can see how the AE code works by going into the CoH folders and reading the script language there. In fact I often edit this code directly because it is faster than using the interface (tho I do use the interface to generate the basic script first). You can also see what I suspect is similar to the script the server feeds the game client during the live game by reading demorecord files.

One thing to keep in mind about all this is that there are also probably code libraries being used by the client or servers our developers did not actually write. For example, mechanics that handle capes and ragdoll effects.

My understanding is that much of CoH is actually a giant Excel spreadsheet of all the powers' effects.

Not a joke.