RPG dialogue engine / structure

user_87336 0
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I've always been interested in the data structures involved in an RPG (Role-Playing Game). In particular, I'm curious about dialogue and events based actions.

For example: If I approach an NPC at point x in the game, with items y and quests z, how would I work out what the NPC needs to say? Branching dialogue and responding to player input seems as trivial as having a defined script, and user input causes the script reader to jump to a particular line in the script, which has a corresponding set of response lines (much like a choose your own adventure)

However, tying in logic to work out if the player has certain items, and completed certain quests seems to really ruin this script based model.

I'm looking for ideas (not necessarily programming language examples) of how to approach all of this dialogue and logic, and separate it out so that it's very easy to add new branching content, without delving into too much code.

This is really an open question. I don't believe there's a single solution, but it'd be good to get the ball rolling with some ideas. As more of a designer than a programmer, I'm always interested in ways to separate content and code.

data-structures
8 Answers

It's interesting, there's seems to be a core idea being missed here. We're having a discussion that relates to a programmer performing the task. Indeed, the code examples above are coupled to code, not content.

In game development, it's the content developers that we programmers want to empower. They will not (this is very important) look at code. Period. Now and again you get a technical artist or technical designer, and they're wonderful and don't mind it; but, the majority of content authors are not technically inclined.

I understand the question is for your own edification; but, it should be pointed out that, in industry, when we solve these types of problems our end users (the people utilizing the technology we're developing) are not engineers.

A system like this (branching dialogue) requires a representation in a tool that is relatively intuitive to use. For example, Unreal's Kismet visual scripting system could be utilized.

Essentially, the data structures (more than likely a branching tree as it's easy to represent/debug/etc.) would be crafted by a programmer, as would the nodes that represent the object in script. The system with its ability to link to world objects (more than likely also represented by nodes in visual scripting), etc. would then be crafted and the whole kitten caboodle linked together in some glorious bit of elegant code.

After all of that, a designer would actually be able to build a visual representation of the dialogue branching in the visual scripting language. This would be map-encounter specific, more than likely. Of course, you could procedurally generate these; but, that's more of a programmer desire than a designer's.

Just thought I'd add that bit of knowledge and insight.

EDIT: Noticed there's an XML example. I'm not sure what other designers/artists/etc. feel about it; but, the ones I've worked with cringe at the idea of touching a text file.

user_2039360

I recently had to develop something for this, and opted for a very basic text file structure. You can see the resulting code and text format at:

https://github.com/scottbw/dialoguejs

There is a tradeoff between sophistication of scripting and ease of editing for non-programmers.

I've opted for a very simple solution for the dialogue, and handle triggering of related game events separately in a secondary scripting language.

Eventually I might add some way of adding "stage directions" to the text dialogue format that are used to trigger events in the secondary scripting engine, but again without needing to put anything that looks like code in the dialogue file itself.

user_20809000
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