Wartbed:Design

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War And Regimental Tactics Battle Engine Deluxe (WARTBED) High-Level Design Document

This document outlines the large-scale principles and design underlying the WARTBED tactical battles meta-engine.

⇐ WARTBED: Building Blocks for Medieval Tactical Warfare Games



Overview

For a general overview, see the WARTBED Design Document
For an overview of the WARTBED technical architecture, see the Architecture document

For in-depth view of specific topics and aspects, see

WARTBED

 0.1 "Clausewitz"
0.2 "Jomini"


WARTBED Codenames

At its highest level and end goal WARTBED is a meta-engine for tactical wargaming. More precisely, though, WARTBED is a framework to automate a number of tasks related to this:

  • 3D graphic of contemporary standards (implemented through the OGRE middleware)
  • Input bindings and input handling (where raw input hardware is accessed through the OIS middleware)
  • Flexible camera handling suitable for a wide spectrum of strategy game styles
  • A GUI system (currently implemented through the CEGUI middleware)
  • Human-readable data file parsing
  • Audio layer (as of yet unimplemented)
  • Scripting language support (as of yet unimplemented)
  • Network support (not yet implemented)

Remaining design decisions

  • How game modules (Bright Portents etc) should be implemented:
    • First option: As internal parts of WARTBED framework itself.
    • Second option: Modules are stand-alone applications using WARTBED as a library modules will use.
    • Third option: Modules will be fully implemented in script languages using the WARTBED framework.

"Regimental tactical warfare"

What being a framework for implementing tactical regimental warfare games more specifically means is providing a number of standard formats (and data converter to these formats):

  • A unit and regiment ability and statistics set capable of accurately represent most games, periods and battle types.
  • A regiment representation system capable of handling several individual units organised into formations (which can consist of other regiments), and formatted movement (manoeuvres) of these.
  • Battle arena (battlefield) description
  • Campaign definition and flow handling
  • Unit and regiment ordering system
  • Suitable and flexible AI

Design principles

WARTBED is being designed according to a set of principles and assumptions.

1. WARTBED is multi-platform and should be natively compilable on at least Win32, Linux and OSX.
2. External dependencies are to be kept to a minimum
  • For major components (3D, physics, network, audio/multimedia) third party systems are preferred over native ones
  • Otherwise, third party middleware are dissuaded and avoided to decrease dependencies.
3. The system is divided into a Model-View-Controller design layout to decouple dependencies.
  • The MVC design structure is interpreted and adhered to as strict as possible (within reason).
  • Game objects belong to the Model aspect of the MVC division, whereas their graphical and auditory representations belong to the View type. Input and unit ordering belongs to the Controller distinction.
4. The structural composition is indented to be as simple as possible. This does not mean that is must be simple, only that it shouldn't be over-complicated or over-designed, which is a common source of failure. Too great complexity means unmaintainable code, while too simple code is limiting, restrictive and incapable of representing a complex game.
5. WARTBED is written in ANSI C++ without proprietary extensions (f.i. MSVC++ extensions). STL containers are preferred for storage and data management throughout, unless for very specific reasons.
6. WARTBED is intended to be data-driven to as far en extent as possible.
  • Data files are as a rule to be written in as human-readable a format as possible (i.e. not XML). Currently (the unimaginatively named) Script V2 is used.

Dependencies

External and third party dependencies are being avoided. Nonetheless, some aspects of a modern game system are impractical or impossible to produce in-house. For such, open-source, free-licensed (Free or LGPL, but not GLP), well tested, stable and actively maintained solutions are acceptable.

To be considered for inclusion, any 3rd party library must
  • be multi-platform for at least Windows, Linux and OSX
  • be fully stand-alone (atomically portable and not introduce additional dependencies)
  • be mature and stable
  • Be under a liberal, non-viral FOSS licence (f.i. LGPL, MIT, zlib)
3rd party libraries currently in WARTBED:
Purpose Package Version Notes
3D Graphics: OGRE 3D 1.6 ("Shoggoth")
Input: OIS (Open Input System) 1.7
In-game GUI: CEGUI 0.7.1 See GUI evaluation and GUI widgets
General-purpose: Boost 1.41 See multi_index_container

Libraries considered for WARTBED:

  • Currently full-scale physics support isn't needed. The physics required consists of gravity, wind and trajectories, which can be sufficiently simulated in native code (air/liquid pressure variance, medium drag etc is unnecessary, and still there is no reason for ragdoll animation or forward kinematics). Candidates would be the Newton framework, ODE (Open Dynamics Engine) or Bullet (preferred due to licencing), all have existing OGRE integration modules.
  • For memory management nedmalloc is being evaluated. It is used internally in OGRE and is highly speed- and anti-fragmentation efficient under random usage.
  • For audio libraries being avaluated, see Audio evaluation.
  • No system has yet been chosen for networking.
  • Boost is currently not yet officially included in WARTBED. Boost ASIO may be used for networking and multi_index_container is currently experimentally implemented as the game entity repository. Possibly, the Boost filesystem may be used.
  • Though there is no immediate need for scripting as of yet, alternatives are being evaluated: see Scripting evaluation.

Strictness of MVC organisation

See Architecture/Model-View-Controller

WARTBED strictly separates the game rules and logic (the model) from the session and player management (the controller) and the visual and auditory representation of the game universe (the view). This is emphasises by the client/server architecture used where even local games are clients that connects to a local server, where the clients are strict views removed from any direct model access, and the server is the controller dispatching all communications between player input and underlying game data.

Strictly speaking, WARTBED employs a two-tier controller architecture, where client is a controller with a view module and the server is a controller with a model module, wherefore the two controllers communicate.

Coding standard

Though not religious on the topic WARTBED is coded according to a set code style which is an adaptation of the Allman style.

Strict client/server game architecture

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WARTBED intended to be strictly client server to the extent that even single player games entail the game being a front-end to a local server.

Pros:

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Cons:

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Graphics specification

Further information: Wartbed:Design/Map_format
  • The base measurement unit is 1 meter. All 3D graphics are designed with 1 unit == 1 meter.
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