Roblox Mesh Parser

rbx_mesh is a collection of deserializers for the different mesh versions in Roblox, and a function to detect the version and invoke the correct deserializer. The meshes are decoded into a structure that reflects the on-disk format of the particular mesh version, rather than being translated into a catch-all structure.

Mesh Example

Print the mesh vertices for any mesh version / vertex size

use rbx_mesh::{read_versioned,mesh::{Mesh,SizeOfVertex2}};

let file=std::fs::read("torso.mesh")?;
let versioned_mesh=read_versioned(std::io::Cursor::new(file))?;
match versioned_mesh{
	Mesh::V1(mesh)=>println!("{:?}",mesh.vertices),
	Mesh::V2(mesh)=>{
		match mesh.header.sizeof_vertex{
			SizeOfVertex2::Full=>println!("{:?}",mesh.vertices),
			SizeOfVertex2::Truncated=>println!("{:?}",mesh.vertices_truncated),
		}
	},
	Mesh::V3(mesh)=>{
		match mesh.header.sizeof_vertex{
			SizeOfVertex2::Full=>println!("{:?}",mesh.vertices),
			SizeOfVertex2::Truncated=>println!("{:?}",mesh.vertices_truncated),
		}
	},
	Mesh::V4(mesh)=>println!("{:?}",mesh.vertices),
	Mesh::V5(mesh)=>println!("{:?}",mesh.vertices),
}

Union Example

// PART 1: MeshData
use rbx_mesh::read_mesh_data_versioned;
use rbx_mesh::mesh_data::{MeshData,CSGMDL};

// this data is extracted from the "MeshData" property of UnionOperation
// the data is not usually contained in the roblox file itself
// but is sourced from the associated "AssetId" of the UnionOperation
let mesh_file=std::fs::read("4500696697_4.meshdata")?;
let mesh_data=read_mesh_data_versioned(std::io::Cursor::new(mesh_file))?;

// print mesh vertices
match mesh_data{
	MeshData::CSGK(_)=>(),
	MeshData::CSGMDL(CSGMDL::V2(mesh_data2))=>println!("{:?}",mesh_data2.mesh.vertices),
	MeshData::CSGMDL(CSGMDL::V4(mesh_data4))=>println!("{:?}",mesh_data4.mesh.vertices),
	MeshData::CSGMDL(CSGMDL::V5(mesh_data5))=>{
		// CSGMDL::V5
		let vertices:Vec<_>=mesh_data5
			.faces
			.indices
			.chunks_exact(3)
			.map(|face_vertex_indices|{
				// construct face triangle from indices
				[
					mesh_data5.positions[face_vertex_indices[0] as usize],
					mesh_data5.positions[face_vertex_indices[1] as usize],
					mesh_data5.positions[face_vertex_indices[2] as usize],
				]
			})
			.collect();
		println!("{:?}",vertices);
	},
}


// PART 2: PhysicsData
use rbx_mesh::read_physics_data_versioned;
use rbx_mesh::physics_data::{PhysicsData,CSGPHS};

// this data is extracted from the "PhysicsData" property of UnionOperation
let phys_file=std::fs::read("CSGPHS_3.data")?;
let physics_data=read_physics_data_versioned(std::io::Cursor::new(phys_file))?;

match physics_data{
	// the most common format (99% of the 100000 unions in my testing)
	PhysicsData::CSGPHS(CSGPHS::V3(meshes)),
	|PhysicsData::CSGPHS(CSGPHS::V5(meshes))=>println!("CSGPHS V3 or V5"),
	// new mesh format (2025)
	PhysicsData::CSGPHS(CSGPHS::V7(meshes))=>println!("CSGPHS V7"),
	// Only one occurence in my data set.
	// Who writes a uuid as ascii hex in a binary format!?
	PhysicsData::CSGK(csgk)=>println!("CSGK"),
	// These formats have zero occurences in my dataset
	// But they are documented at
	// https://devforum.roblox.com/t/some-info-on-sharedstrings-for-custom-collision-data-meshparts-unions-etc/294588
	PhysicsData::CSGPHS(CSGPHS::Block)=>println!("CSGPHS Block"),
	PhysicsData::CSGPHS(CSGPHS::V6(csgphs))=>println!("CSGPHS V6"),
}

License