Crate phyz 

phyz — Multi-physics differentiable simulation engine.

This crate is a thin umbrella over the rigid-body stack: every type and function below lives in one of the focused phyz-* crates and is re-exported here, so cargo add phyz gives you that stack behind a single dependency. The re-exported modules are aliases, not copies, so a fix in phyz-collision is a fix for phyz::collision by construction. sim is the one module with code of its own: the time loop, which none of the focused crates own.

It does not cover the whole workspace. phyz-gpu, phyz-particle, phyz-lbm, phyz-em, phyz-md and the rest are separate crates you add explicitly.

Features

• collision (default) — GJK/EPA narrow phase and broad-phase spatial hashing.
• contact (default) — soft/penalty contact dynamics; implies collision.
• diff (default) — per-step Jacobians and the trajectory adjoint. Only the adjoint (diff::adjoint_rollout_gradient) and the symbolic path are derivative-exact; see phyz_diff for which is which.

math, model, and rigid are always present.

Re-exports

pub use sim::Rk4Solver;

pub use sim::SemiImplicitEulerSolver;

pub use sim::Simulator;

pub use sim::Solver;

pub use phyz_math;

pub use phyz_model;

pub use phyz_rigid;

pub use phyz_math as math;

pub use phyz_model as model;

pub use phyz_rigid as rigid;

pub use phyz_collision;

pub use phyz_collision as collision;

pub use phyz_contact;

pub use phyz_contact as contact;

pub use phyz_diff;

Modules

aba

Articulated Body Algorithm (ABA) – O(n) forward dynamics.

crba

Composite Rigid Body Algorithm (CRBA) – mass matrix computation.

determinism

Tools for checking that a rollout reproduces, and for telling chaos from bugs when it does not.

diff

Differentiation: Jacobians of the dynamics and the trajectory adjoint.

rnea

Recursive Newton-Euler Algorithm (RNEA) — inverse dynamics.

sim

Integrated time stepping: the Simulator driver and its solvers.

Structs

AABB

Axis-aligned bounding box.

Actuator

An actuator attached to a joint.

Body

A rigid body in the kinematic tree.

BodyKinematics

Body transforms, velocities, and accelerations from a full kinematics pass.

Collision

Result of a collision query between two geometries.

ContactMaterial

Material properties for contact interactions.

ContactProblem

The assembled convex contact problem.

ContactSolverConfig

Tuning for the contact solve.

GeomInstance

A geometry placed at an offset within a body frame.

IkConfig

Solver settings. IkConfig::default is tuned for robot-arm-sized problems: metres and radians, goals within reach, a seed that is not exactly at a singularity.

IkGoal

A single kinematic goal.

IkSolution

What solve_ik found.

Joint

A joint connecting two bodies.

Model

Static model describing the topology and parameters of a physical system.

ModelBuilder

Builder for constructing models.

Ray

A ray with a normalized direction.

RayHit

A ray/shape intersection.

State

Mutable simulation state.

Enums

Geometry

Collision geometry types (mirrors phyz-collision’s shapes for convenience).

IkGoalKind

The two things a goal can ask for.

JointType

Joint type enumeration.

Constants

GRAVITY

Functions

aba

Run the Articulated Body Algorithm.

aba_with_external_forces

Run ABA with optional external spatial forces applied to each body.

body_wrenches

Net spatial wrench transmitted through each body’s joint.

crba

Compute the joint-space mass matrix M(q) using CRBA.

epa_penetration

Compute penetration depth and contact normal using EPA.

epa_penetration_rot

EPA with rotation matrices. Runs GJK to obtain a valid seed simplex.

find_contacts

Find all body-body contacts in the current state.

find_ground_contacts

Find contacts against a horizontal ground plane at z = ground_height.

forward_kinematics

Compute forward kinematics: body transforms and spatial velocities.

forward_kinematics_acc

Forward kinematics extended with accelerations, for a given qdd.

gjk_distance

Compute signed distance between two geometries.

gjk_distance_rot

Signed distance with rotation matrices: +separation when disjoint, -depth when overlapping.

ray_cast

Cast a ray against many placed geometries, returning the nearest hit within max_distance along with the index of the geometry that was hit.

ray_intersect

Intersect a ray with a geometry placed at pos with orientation rot.

rnea

Run RNEA: compute inverse dynamics torques.

skew

Cross-product matrix [v]× such that [v]× w = v × w

solve_contacts

Solve the convex contact problem from a cold start (zero impulses).

solve_ik

Solve for a configuration satisfying goals, starting from seed.

sweep_and_prune

Sweep-and-prune broad phase collision detection.

Type Aliases

DMat

Dynamic matrix.

DVec

Dynamic vector.

Mat3

3x3 matrix alias.

Mat4

4x4 matrix alias.

Quat

Unit quaternion for 3D rotations (scalar w, vector v).

SpatialInertia

Spatial inertia of a rigid body about its center of mass.

SpatialMat

6x6 spatial matrix stored as four 3x3 blocks.

SpatialTransform

Plucker transform: rigid body transformation acting on spatial vectors.

SpatialVec

6D spatial vector – either a motion vector (twist) or force vector (wrench).

Vec3

3D vector alias.