Module rigidmodel 

RigidModel file format support for Total War games.

Overview

RigidModel files (.rigid_model_v2) are the primary 3D model format used by Total War games to store mesh geometry, materials, skeletal animation data, and visual effects. These files contain everything needed to render game assets including characters, buildings, terrain, vegetation, and props.

File Structure

A RigidModel file contains:

1. Header: File signature (RMV2), version number, skeleton ID
2. LOD (Level of Detail) structures: Multiple quality levels for distance-based rendering
3. Mesh blocks: Individual mesh units, each with geometry and material data
4. Vertex data: 3D positions, normals, UVs, bone weights (often compressed)
5. Material definitions: Textures, shaders, attachment points, rendering parameters

Supported Versions

Version	Support	Notes
6	✅ Full	Older format
7	✅ Full	Intermediate format
8	✅ Full	Current/newest format

Material System

RigidModels support 40+ material types for different rendering needs:

• Standard rendering: DefaultMaterial, Decal, Tree, Grass, Water
• Skeletal animation: WeightedSkin, WeightedCloth
• Terrain: RsTerrain, WeightedTextureBlend, TiledDirtmap
• Special effects: Collision, DebugGeometry, PointLight

Each material type determines:

• Which vertex format is used (affects vertex compression and available data)
• What textures and parameters are stored
• How the material is rendered in-game

Vertex Formats

Different vertex formats optimize storage for specific use cases:

• Static (0): Standard geometry without animation
• Weighted (3): Skeletal animation with bone indices and weights
• Cinematic (4): High-quality vertices for cutscenes (supports 4 bones)
• Grass (5): Vegetation-specific format
• ClothSim (25): Cloth physics simulation vertices
• Collision (1): Simplified collision mesh vertices

Vertices use various compression techniques:

• Half-precision floats (f16) for positions and UVs
• Normalized u8 vectors for normals, tangents, bitangents
• Percentage encoding for bone weights

Usage

use rpfm_lib::files::rigidmodel::RigidModel;
use rpfm_lib::files::{Decodeable, Encodeable};

// Decode a RigidModel file
let model = RigidModel::decode(&mut reader, &None)?;

// Access LODs and meshes
for lod in model.lods() {
    println!("LOD distance: {}", lod.visibility_distance());
    for mesh_block in lod.mesh_blocks() {
        println!("Mesh: {}", mesh_block.mesh().name());
        println!("Vertices: {}", mesh_block.mesh().vertices().len());
    }
}

// Encode back to bytes
model.encode(&mut writer, &None)?;

Credits

Most of the reverse-engineering work for this module was done by Victimized, Phazer, and Ole. Their research enabled the implementation of this format decoder/encoder.

Modules

materials

Material system for RigidModel files.

vertices

Vertex format definitions and I/O for RigidModel files.

Structs

Lod

Level of Detail structure containing meshes at a specific quality level.

Mesh

Mesh geometry container with vertices, indices, and metadata.

MeshBlock

A single mesh unit with geometry and material data.

RigidModel

Root structure representing a complete RigidModel file.

ShaderParams

Raw shader parameter data (not fully decoded).

Constants

EXTENSION

File extension for RigidModel files.