robocomp_rapier3d

robocomp_rapier3d

Rapier 3D physics integration for robocomp — the physics-agnostic core crate for robot/rigid-body composition in Bevy.

This crate re-exports robocomp, rc, and rd, so you typically depend on robocomp_rapier3d only and get the full robocomp API alongside the Rapier backend.

Plugins

Plugin	Purpose
RobocompRapierPlugin	Bundles RobocompPlugin with the Rapier pre-processor that spawns colliders and joints from Rc* scene markers.
RobocompRapierControllerPlugin	Optional keyboard motor control for revolute and prismatic joints (used by the *_ctrl_* examples).

The Rapier physics plugin must be added alongside the robocomp backend — this crate does not bundle bevy_rapier3d.

Quick Start

[dependencies]
robocomp_rapier3d = "0.1"

use bevy::prelude::*;
use bevy_rapier3d::prelude::*;
use robocomp_rapier3d::{RobocompRapierPlugin, rc::RcSceneRoot};

app.add_plugins((
    RapierPhysicsPlugin::<NoUserData>::default(),
    RobocompRapierPlugin,
));

Controller-driven examples also require RobocompRapierControllerPlugin:

use robocomp_rapier3d::{RobocompRapierControllerPlugin, RobocompRapierPlugin};

app.add_plugins((
    RapierPhysicsPlugin::<NoUserData>::default(),
    RobocompRapierPlugin,
    RobocompRapierControllerPlugin,
));

From the workspace root (assets live at the repo root):

cargo run -p robocomp_rapier3d --example simple_rigid_bodies_rapier3d

Examples

Example	Description	Run
simple_rigid_bodies_rapier3d	A simple rigid bodies example with a fixed table and cube(s) that fall onto it.	cargo run -p robocomp_rapier3d --example simple_rigid_bodies_rapier3d
revolute_rapier3d	Example demonstrating a simple robot with a revolute joint between two cubes.	cargo run -p robocomp_rapier3d --example revolute_rapier3d
revolute_skein_rapier3d	Example demonstrating a scene imported from Blender using Skein, with a revolute joint between two cubes.	cargo run -p robocomp_rapier3d --example revolute_skein_rapier3d
prismatic_ctrl_rapier3d	Example demonstrating a robot with a prismatic joint (w/ limits) between two cubes; control via W/S + ShiftLeft.	cargo run -p robocomp_rapier3d --example prismatic_ctrl_rapier3d
multi_joints_ctrl_rapier3d	Robot chain with interleaved revolute and prismatic joints (5 links); W/S + Shift to drive, Arrow Up/Down to cycle active joint.	cargo run -p robocomp_rapier3d --example multi_joints_ctrl_rapier3d

Backend Specifics and Caveats

Robocomp is physics-agnostic — switching backends requires minimal code and scene changes, but motor tuning and simulation feel are not guaranteed to match out of the box. The same Rd* / Rc* components are mapped differently per backend. If porting from another physics backend, consider the differences below.

Topic	Behavior
RdMotorModel::SpringDamper	No native Rapier equivalent. Mapped to MotorModel::AccelerationBased with converted stiffness/damping: stiffness = (2π·f)², damping = 2·ζ·(2π·f). Behavior differs from Avian's implicit spring-damper integrator.
RdMotorModel::AccelerationBased	Maps to Rapier AccelerationBased.
RdMotorModel::ForceBased	Maps to Rapier ForceBased.
Velocity motor damping	Rapier set_motor_velocity(target, factor) uses the model's damping coefficient as the velocity factor. Not the same semantics as Avian velocity motors.
Recommended motor models	Examples use AccelerationBased { stiffness, damping } for position-controlled prismatic joints. The Avian prismatic example's SpringDamper is roughly equivalent to { stiffness: 5000., damping: 650. } on Rapier.
RcRigidBody::Fixed	Maps to Rapier RigidBody::Fixed.
RcCcd	Supported — inserts Rapier Ccd::enabled().
RcDisableSleep	Supported — inserts Sleeping::disabled().
Spherical joint motors	Spawned in the pre-processor, but controller motor control for spherical joints is not implemented yet.
Controller timing	Motor control runs in FixedUpdate, before PhysicsSet::SyncBackend.

Bevy Compatibility

Bevy	bevy_rapier3d	robocomp_rapier3d
0.18	0.34	0.1