Module group_formations 

This module contains the implementation of the Group Formations file format for Total War games.

Group formations define fixed formation templates that both the AI and player can use to deploy their units on the battlefield. Each formation is designed for specific tactical scenarios (attack, defend, naval, etc.) and specifies unit placement, spacing, arrangement patterns, and which unit types should be placed in each position.

File Format

The group formations file (groupformations.bin) is a binary file containing formation definitions that can be used by both AI and players to deploy armies tactically. Each formation can specify:

• AI purpose flags (attack, defend, river crossing, naval, etc.)
• Priority and unit category requirements
• Supported factions and subcultures
• Formation blocks defining unit positions (absolute, relative, or spanning)
• Entity preferences specifying which unit types go where

Game Support

This file format is not versioned in the traditional sense. Instead, different games have different implementations in the versions/ subdirectory:

• Shogun 2: Basic formation system with entity types and arrangements
• Rome 2 (and later): Extended system with entity weights, subcultures, and more AI purposes

File Location

Group formations files are typically found at:

• groupformations.bin in the root of a game’s pack

Usage Example

use rpfm_lib::files::{Decodeable, group_formations::*};

// Decode a group formations file
let mut data = std::io::Cursor::new(file_data);
let extra_data = Some(DecodeableExtraData {
    game_info: Some(game_info),
    ..Default::default()
});
let formations = GroupFormations::decode(&mut data, &extra_data)?;

// Access formation data
for formation in formations.formations() {
    println!("Formation: {}", formation.name());
    println!("Priority: {}", formation.ai_priority());
}

Modules

versions

Structs

ContainerAbsolute

A container block positioned at absolute coordinates on the battlefield.

ContainerRelative

A container block positioned relative to another block.

EntityPreference

Defines a preference for a specific type of unit to occupy a formation block.

GroupFormation

A single formation definition specifying how units should be arranged.

GroupFormationBlock

A formation block defining a specific position or region in the formation.

GroupFormations

Represents an entire Group Formations file decoded in memory.

MinUnitCategoryPercentage

Specifies a minimum percentage requirement for a unit category in a formation.

Spanning

A spanning block that encompasses multiple other blocks.

Enums

AIPurpose

AI purpose flags indicating when a formation should be used.

Block

Types of formation blocks that can be used to define unit positions.

Entity

Entity type classifications.

EntityArrangement

How units should be arranged within a formation block (line, column, crescent, etc.).

EntityWeight

Entity weight classifications (light, medium, heavy, etc.).

UnitCategory

Unit category classifications (cavalry, infantry melee, infantry ranged, naval, etc.).

Constants

PATH

Fixed path to the Group Formations file.