Difference between revisions of "Introduction to Arma Scripting"

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Revision as of 02:06, 22 December 2006

During mission editing and addon editing you will often come into the situation, where your imaginations can't be implemented using the native methods of the editors (f.i. cutscenes in missions, special animations in addons). The solution is either to learn more about the editor (f.i. advanced features and methods) or scripting.

Armed Assault's scripting language gives you the possibility of influencing the game engine. With any combination of so-called scripting commands you can create custom processes, that handle any specific needs and problems in a mission.

Terms

Before getting started, you should know the meaning of some terms.

Script
When speaking about a script, the same accounts for functions, since functions are a kind of script.
Game Engine
The running program of the game which reads and executes your scripting commands.

When Do I Need Scripting?

Scripting is primarily needed in user missions by the mission creator. The goal is to create processes that can't be done with the native features of the mission editor. So this is the first important check before you start scripting. Often the mission editor wants tiny features in a mission that arent't worth a script. Ask yourself, whether the user will notice and/or use the outcome of your script.

Be careful: Scripting isn't a solution to everything. The third step is to make sure whether your needs can be implemented with the scripting language. This can be hard for a beginner, but if you made sure the two above steps, it will be possible in most of the cases. If you aren't sure - just ask in the official forums or at OFPEC.

Checklist

Here is a short summed up checklist of the above mentioned points:

  1. Can I do it with the native features? (mission editor, addon config files, ...)
  2. Will the player notice and/or use it?
  3. Is it possible?

If all of the three points are answered with "Yes", go on and script it! But be warned: It won't always be easy. ;-)

Scripting Code

The core of scripting is scripting code. The code consists of scripting commands that tell the game engine what to do. These commands are executed one after another.

The code is written into special fields of the mission editor (see below) or into seperate files that are executed at some defined point (f.i. through triggers) during the running mission.

Syntax

Every code has to follow a syntax. The syntax makes sure that the game engine can read and understand the code.

The primary syntax used in Armed Assault is SQF syntax. Read the corresponding article to inform yourself about it.

At some point you may also find scripts written in the deprecated SQS syntax. This syntax was the primary syntax in Operation Flashpoint, but is considered deprecated since Armed Assault.

All scripting pages about Armed Assault will focus on SQF syntax.

Layout

Code should be written in a specific layout. Complementary to the syntax, the layout assures that you and other coders can easily read the code. This is especially important when you haven't looked at your code for a long time and want to improve or change this code.

  • There should be only one statement per line in scripts. This doesn't concern script lines in the mission editor, since there all the code has to be written within a single line.
  • Use spaces or tabs to indent code in blocks. This way you can easily tell to which block some code belongs.

Example:

Statement 1;

Block
{
    Statement 2;

    Nested block
    {
        Statement 3;
        Statement 4;
    };
};

Comments

You can and should write comments into your scripts that describe the purpose of your code. These comments are written in free text and completely ignored by the game engine.

Check out SQF syntax for information about the notation of comments.

Important: Don't write down what the code does, but rather what you want to do with the code. This is not as easy, but maybe the following example explains it a bit better:

Bad comment:

// the variable i gets the value 1
i = 1;

Good comment:

// reset the counter to start with 1 again
i = 1;

Code Execution

how can I execute code? (external files vs. mission editor)

Mission Editor

how to execute code in the editor, listing of mission editor fields to start scripts

External Files

how to execute code in external files, scripts & functions

Developing a Script

script in this case: code in external files (scripts/functions). how to develop a script?

  • Requirements
  • Concept
  • Implementation
  • Test

usually in your head, for complex scripts on paper and drafts

Requirements

what shall the script do?

Concept

How shall the script do it?

Implementation

Writing the code

Test

Testing the code

Further Reading

If you want to learn more about ArmA: Scripting, read the following articles:

See also