Struct ContactProblem 

pub struct ContactProblem {
    pub n: usize,
    pub delassus: Vec<f64>,
    pub free_velocity: Vec<f64>,
    pub rows: Vec<ContactRow>,
    pub bodies: Vec<(usize, usize)>,
}

The assembled convex contact problem.

delassus is row-major 3n x 3n, ordered [n, u, w] per contact.

Fields

n: usize

Number of contacts.

delassus: Vec<f64>

A = J M^-1 J^T, row-major 3n x 3n.

free_velocity: Vec<f64>

Free contact-space velocity b, length 3n.

rows: Vec<ContactRow>

Per-contact parameters.

bodies: Vec<(usize, usize)>

The body pair each contact acts between, (body_i, body_j), with usize::MAX for the static world — the same sentinel phyz_collision::Collision uses.

Only ContactCoupling::PerBody reads this; it is what decides whether two contacts share a body and therefore whether their off-diagonal block is one the GPU can afford.

A map whose length is not n means “body structure unknown”, and PerBody then degrades to ContactCoupling::Full rather than dropping blocks it cannot justify dropping. Failing toward more coupling is the safe direction: it costs time, where the other direction silently changes the physics. Hand-built problems in the tests take this path.

Implementations

impl ContactProblem

pub fn effective_restitution(e: f64, approach_speed: f64, v_rest: f64) -> f64

Effective restitution after the smooth low-speed ramp.

smoothstep between v_rest and 2*v_rest keeps this C^1 in the approach speed; a hard if |v_n| < eps { 0 } would not be, and a gradient through it would be wrong exactly at rest.

pub fn impact_weight(approach_speed: f64, v_rest: f64) -> f64

The restitution ramp alone: how much of an impact an approach at this speed is, 0 at and below v_rest, 1 at and above 2 * v_rest. This is what ContactRow::impact carries.

Trait Implementations

impl Clone for ContactProblem

fn clone(&self) -> ContactProblem

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ContactProblem

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.