Crate use_rigidbody 

use-rigidbody

Rigid-body mass properties and scalar mechanics helpers for RustUse.

Install

[dependencies]
use-rigidbody = "0.0.1"

Foundation

use-rigidbody provides small f64-first helpers for scalar rigid-body mechanics primitives: mass properties, center of mass, moments of inertia, kinetic energy, angular momentum, simple impulse response, and small rigid-body state helpers.

Inputs are expected to be SI-style numeric values:

• kilograms for mass
• meters for position, radius, length, and distance
• meters per second for velocity
• radians for angle
• radians per second for angular velocity
• kilogram square meters for moment of inertia
• kilogram meters per second for linear momentum
• kilogram square meters per second for angular momentum
• joules for kinetic energy
• newton-seconds for impulse

Vector mechanics should compose with use-vector.

Simulation loops belong in top-level use-simulation.

Collision-specific helpers belong in use-collision.

Rotation-specific helpers belong in use-rotation.

Torque-specific helpers belong in use-torque.

Example

use use_rigidbody::{MassProperties, RigidBody1D, total_kinetic_energy};

let props = MassProperties::solid_sphere(5.0, 2.0).unwrap();
let body = RigidBody1D::new(props, 10.0, 3.0, 1.0, 5.0).unwrap();

assert_eq!(body.linear_momentum(), Some(15.0));
assert_eq!(body.rotational_kinetic_energy(), Some(100.0));
assert_eq!(total_kinetic_energy(5.0, 3.0, 8.0, 5.0), Some(122.5));

When to use directly

Choose use-rigidbody when you need small, reusable scalar helpers for rigid-body mass properties, inertia, momentum, kinetic energy, and simple kinematic state updates.

Scope

• APIs stay f64-first and focus on scalar rigid-body mechanics primitives.
• This crate is not a physics engine, collision detector, contact solver, constraint solver, game physics package, or simulation framework.
• Vector rigid-body dynamics, joints, broad phase, narrow phase, and simulation loops are out of scope.

Status

use-rigidbody is a pre-1.0 crate with a deliberately small API. Scalar rigid-body mechanics helpers.

Modules

prelude

Convenient re-exports for the public rigid-body helpers.

Structs

MassProperties

Mass and rotational inertia for a scalar rigid body.

RigidBody1D

A one-dimensional rigid body with scalar translational and rotational state.

Functions

angular_impulse_from_angular_velocity_change

Computes angular impulse from an angular velocity change using J = I(ω_final - ω_initial).

angular_momentum

Computes angular momentum using L = Iω.

angular_velocity_after_angular_impulse

Computes final angular velocity after an angular impulse using ω_final = ω_initial + J / I.

center_moment_from_parallel_axis

Computes the center moment from a shifted moment using I_cm = I - md².

center_of_mass_1d

Computes the one-dimensional center of mass using x_cm = Σ(m_i * x_i) / Σm_i.

combined_mass

Computes the sum of non-negative masses.

hollow_sphere_moment_of_inertia

Computes hollow-sphere moment of inertia using I = (2 / 3)mr².

impulse_from_velocity_change

Computes impulse from a velocity change using J = m(v_final - v_initial).

linear_kinetic_energy

Computes translational kinetic energy using KE = 0.5mv².

linear_momentum

Computes linear momentum using p = mv.

parallel_axis_moment_of_inertia

Applies the parallel-axis theorem using I = I_cm + md².

point_mass_moment_of_inertia

Computes point-mass moment of inertia using I = mr².

reduced_mass

Computes reduced mass using μ = (m1 * m2) / (m1 + m2).

rod_moment_of_inertia_about_center

Computes rod moment of inertia about its center using I = (1 / 12)mL².

rod_moment_of_inertia_about_end

Computes rod moment of inertia about one end using I = (1 / 3)mL².

rotational_kinetic_energy

Computes rotational kinetic energy using KE_rot = 0.5Iω².

solid_disk_moment_of_inertia

Computes solid-disk moment of inertia using I = 0.5mr².

solid_sphere_moment_of_inertia

Computes solid-sphere moment of inertia using I = (2 / 5)mr².

thin_ring_moment_of_inertia

Computes thin-ring moment of inertia using I = mr².

total_kinetic_energy

Computes total kinetic energy using KE_total = 0.5mv² + 0.5Iω².

velocity_after_impulse

Computes final velocity after an impulse using v_final = v_initial + J / m.