Bevy Silk

CPU driven Cloth engine for Bevy using Verlet integration.

by Félix Lescaudey de Maneville

Get started

Dependency

Add bevy_silk as a dependency in the Cargo.toml

bevy_silk = "0.1"

Or follow the main git branch

bevy_silk = { git = "https://github.com/ManevilleF/bevy_silk" }

Plugin

Add the ClothPlugin to your bevy app

use bevy::prelude::*;
use bevy_silk::prelude::*;

fn main() {
  App::new()
    .add_plugins(DefaultPlugins)
    .add_plugin(ClothPlugin)
    // ... Add your resources and systems
    .run();
}

Add cloth to a mesh

For a mesh to be used as cloth, add the ClothBuilder component to any entity with a Handle<Mesh> component.

Note: Transform and GlobalTransform are also required

cloth data which will be populated automatically from the associated Handle<Mesh>.

use bevy::prelude::*;
use bevy_silk::prelude::*;

fn spawn(mut commands: Commands) {
    commands.spawn_bundle(PbrBundle {
        // Add your mesh, material and your custom PBR data   
        ..Default::default()
    }).insert(ClothBuilder::new()
        // Define fixed vertices using an Iterator
        .with_fixed_points(0..9)
        // Define the stick generation mode
        .with_stick_generation(StickGeneration::Quads)
        // Defines the sticks target length option
        .with_stick_length(StickLen::Auto)
        // The cloth will compute flat mesh normals
        .with_flat_normal_computation()
        // ...
    );
}

Configuration

You can customize the global cloth physics by inserting the ClothConfig resource to your app:

use bevy::prelude::*;
use bevy_silk::prelude::*;

fn main() {
  App::new()
    .add_plugins(DefaultPlugins)
    .insert_resource(ClothConfig {
        gravity: Vec3::new(0.0, -9.81, 0.0),
        friction: 0.02,
        sticks_computation_depth: 5
    })
    .add_plugin(ClothPlugin)
    // ... Add your resources and systems
    .run();
}

ClothConfig can also be used as a component to override the global configuration.

Wind

You may add wind forces to the simulation for a more dynamic clothing effect, for each force you may choose from:

Wind::Constant for constant wind force
Wind::SinWave for a sinwave following wind intensity with custom force and frequency.

Wind forces can be added as a resource to your app through the Winds container:

use bevy::prelude::*;
use bevy_silk::prelude::*;

fn main() {
  App::new()
    .add_plugins(DefaultPlugins)
    .insert_resource(Winds {
        wind_forces: vec![Wind::SinWave {
            max_velocity: Vec3::new(10.0, 15.0, -5.0),
            frequency: 3.0,
            normalize: false,
            abs: false
        }]
    })
    .add_plugin(ClothPlugin)
    // ... Add your resources and systems
    .run();
}

Check the flag example for simple wind effect.

Mesh utils

bevy_silk provides a plane mesh generation function rectangle_mesh useful for classic cloth uses like flags or capes

Q&A

My mesh falls immediately and infinitely when I add a Cloth component, how to fix it?

You probably didn't specify any fixed points, meaning there are no vertices anchored to your entity's GlobalTransform.

TODO list

Wind
Custom stick target length options
Different stick behaviors (spring, stick, etc)
dynamic flat normal mapping
dynamic smooth normal mapping
Collision support
Cloth cutting maybe?

Examples

Flag example

run cargo run --example flag_example --features debug

Balloon example

run cargo run --example balloon_example --features debug

Moving example

run cargo run --example moving_example --features debug

bevy_silk 0.1.0