Scripting

About This Guide

Intro

This guide will get you started with the basic aspects of EDuke32's commands -- those which set it apart from vanilla DN3D. This guide makes no assumptions regarding the programming experience of the reader, other than that the reader comprehends and understands the basic CON system as was seen in Duke Nukem 3D 1.3d-1.5.

Con Basics

As stated, this guide assume that you are familiar with the original CON code from Duke3D. If you are not already familiar with the default commands, the authors of this guide recommend the following guide to the basics, imported into the EDukeWiki for your convenience:

• Con FAQ 4.2 by Jonah Bishop
  • Download stand-alone zipped version

Another good source of basic information is the following FAQ:

• Con Editing Information v1.3 by James Ferry

Custom Variables

About

Variables were introduced in EDuke 2.0 and remain the most important aspect of the new commandset. Variables allow you to store, manipulate, and execute code based on defined values. Prior to custom variables, the only usable alternatives were manipulations of inventory item counters and were, as you can imagine, very limited.

Types

There are three types of custom variables, each type storing a signed, 32-bit fixed-point integer.

• Global variable: A global variable will be the same for any actor it is used in. Changing a global variable changes it for all actors in the game.
• Per-player variable: A per-player variable may be set independently for each player in the game. If a player performs an action that triggers a per-player variable change within an event or the APLAYER actor code, it will only change for the player that initiated that action. If an actor changes a per-player variable, it will change for the closest player to the actor that changed it.
• Per-actor variable: A per-actor variable may be independently assigned to each copy of an actor in the game.

Use and manipulation

Manipulation of gamevars is accomplished by using a variety of commands that range in functionality from simple mathematical functions to grabbing internal values for manipulation in the CONs. Here are a few of the more common variable manipulation primitives:

• addvar
• addvarvar
• divvar
• divvarvar
• mulvar
• mulvarvar
• randvar
• randvarvar
• subvar
• subvarvar
• setvar
• setvarvar

And some of the more rarely used ones:

• andvar
• andvarvar
• orvar
• orvarvar
• shiftvarl
• shiftvarr
• xorvar
• xorvarvar

Note that a complete list of primitives is, of course, available here. The importance of manipulating variables will become clear when we get to talking about getting and setting the members of the various structures in the game.

Events

EDuke32 provides both an object-oriented and an event-oriented interface to the game's internal workings. As you already know, the object-oriented part of Duke is the actor system -- in contrast to that, we'll be talking about the event-oriented portion in this section. As the name suggests, an event is a block of code that is triggered when a certain event in the game happens. Events in the game are triggered internally whenever a certain point in the code is reached.

Events are a key component in the manipulation of the game. Using events, we can do a variety of things such as intercept keypresses, draw to the screen (more on this later), redefine what a player does when certain actions are executed, et cetera.