Sunday, October 23, 2011

How could I do scripting?

Yes, this milestone is pretty far ahead, but I still wonder how I could do scripting.

Do I even need scripting? You usually add a scripting engine to a game engine so that you have a simpler work environment for team members which are less skilled at programming. But I am working alone. So why not just create a simple framework to define quests in Java and leave it as that? Could be much less work because I wouldn't have to worry about script bindings and could interact with the server engine directly.

A drawback would be that I would not be able to change quest coding at runtime. I would have to rebuild the server for every single script change (Although Manaserv has the same problem even though it uses Lua as a scripting backend). Also when I ever do hire people to help me with content or I would like to license the server to someone without revealing the sourcecode, I would need to give them a way to do stuff without any hardcoding.

An alternative to implementing a full scripting backend with a real scripting language would be to use some kind of markup language like JSON or XML to describe NPC dialog trees and other frequent use-cases for scripting. That way I could move the trivial stuff to external files and not clutter the servers codebase with hundreds of trivial NPC dialogs.

This is an example how I could do a simple dialog with JSON:
{"dialog": [
    {   message: "Hello" },
    {   message: "How can I help you?" },
    {   choice: [
            {   option: "Where is the castle?",
                dialog: [
                        {   message: "Just down the road, you can't miss it." }
                    ],
                next: "back"
            },
            {   only_when_equal { "quest_slay_dragon", false },
                option: "I need a job",
                dialog: [
                    {   message: "I got a quest for you." }
                    {   message: "slay the dragon in the mountains." }
                    {   choice: [
                            {   option: "No, that's too dangerous!" ,
                                next: "back"
                            },
                            {   option: "Sure, let's go!",
                                dialog: [
                                    {   setvar: { "quest_slay_dragon", true } },
                                    {   message: "good luck, then" }
                                ],
                                next: "quit"
                            }
                        ]
                    }
                ],
                next: "back"
            },
            {   only_when_equal { "quest_slay_dragon", true },
                option: "I need a job",
                dialog: [ 
                    {    message: "I already told you to slay the dragon!" }
                ],
                next: "back"
            }
            {   option: "Nothing, goodbye",
                next: "continue"
            },
        ]},
    {   message: "It was a pleasure to meet you." },
    {   only_when_equal: { "quest_slay_dragon", true },
        message: "And good luck with the dragon!" }
]}

Explanation:
dialog: Process the following elements as dialog.
dialog->setvar: Set the variable as key to the value
choice: present the elements of this array to the user as dialog options:
choice->option: dialog option text the user can select
choice->dialog: (optional) process the following dialog when the user clicks this option
choice->next: what to do after processing the dialog. "back": go back to choice. "continue": continue after the choice. "quit": leave the dialog.
*->only_when_equal: ignore this element, when the variable is unequal to the value

No comments:

Post a Comment

Post a Comment