Cockpit Tutorial

This document describes canonically how to create a cockpit resource file. Hopefully it'll be easy to read, too.

'At this time, the material presented here is only partially implemented, if at all'

A Cockpit - The Concept

The cockpit is where you're sitting when you play the game. There is the concept of a virtual cockpit which is implemented in the internal camera view, but we'll ignore that, for the most part. Otherwise, the cockpit is where you're sitting and what you're using.

A cockpit resource file provides the layout of some of the visual items you see while you're playing. Traditionally, these were referred to as the HUD, and the HUD is still the main information that's carried in a cockpit file.

In the resource file, gauges and other things have been abstracted to a Widget. Each Widget is capable of displaying all of the information you're used to seeing, and is likely capable of displaying the same information in different formats...thanks to the cockpit resource file.

Overview of the Cockpit file

The cockpit file consists of two sections. Technically they're just one, but you don't really have to worry about that. The two sections are pretty simple. The first just hooks it into the resource system for the whole game, using tags and stuff you may already know from the map files. The second section contains all the beautful cockpit stuff.

In the Cockpit section you'll find a series of widget tags that contain data tags to hook the widget into some game data. There's a caption, some position and size parameters, and so forth. You can also specify background and foreground colors, with gradiants, and with graphics, to provide a really custom gauge. Additionally, widgets can be associated with a camera, or made for all cameras, with the option of excluding specific cameras, offering the possibility to give a completely custom view for each camera you use. All of this gets mixed together and rendered to screen as your cockpit.

A complete gauge, in concept, isn't necessary a single widget in the cockpit file. As an example, you might want to build a "Performance" gauge that includes ping, frames per second, cpu usage, overall system load, and bandwidth usage. That would require placing several widgets together, stacked on top of each other or on each other's sides, to build the conceptual Performance gauge you intend. Here, we'll use "gauge" to refer to a specific gauge and "widget" to refer to the larger conceptual gauge. Most widgets that you'll build will just be gauges, so it's not a big deal. (Note: At the time of writing, all of the data in the hypothetical Performance gauge isn't available to the cockpit, but the system is easily extensible and there's no reason to think it will never be available)

Within each gauge there are a series of tags that are used to define what it looks like, what data it uses, and so forth. The tags that are available vary from gauge to gauge, but the meaning of each tag never varies. Two gauges that are diametrically opposite to each other might interpret the tag differently, but it will still mean the same thing for both gauges. That's an important subtlety that you should keep in mind.

Construction of a Gauge

Each gauge is a layered affair. In technical terms, first the back of the gauge is painted. Then the middle is painted on top of the back, and finally the front is painted on top of the middle. This is intended to allow for complete configurability for each gauge. The middle layer is always the representation of the data, whatever it is. The back and front are equivalent in size and shape and are intended for window-dressing. By painting a texture with alpha-blended pixels it should be possible to reshape parts of the gauge and give it a unique appearance. Two gauges can be identical in all ways except which texture is used for the front and have very different appearances to the user.

Gauges that are text-driven are generally constructed on a table. While you don't have to use a table to build the gauge, the table allows you to organize it in rows and columns, which is the most useful way to organize data that you expect to read only in glances.