Struct ContactManifold 

pub struct ContactManifold {
    pub entity_a: Entity,
    pub entity_b: Entity,
    pub contacts: Vec<ContactPoint>,
    pub friction: f32,
    pub static_friction: f32,
    pub restitution: f32,
    pub lifetime: u32,
}

Up to four contact points between a pair of bodies, along with the combined material properties needed by the constraint solver.

Contact limit & point selection

Physics engines conventionally cap manifolds at 4 points because that is the minimum required to fully constrain a convex face-face contact. When a 5th point would be added we keep the configuration that maximises the contact area while retaining the deepest point:

1. Always keep the deepest point (most important for penetration resolution).
2. Fill the remaining 3 slots by greedily maximising the minimum distance to any already-selected point (farthest-point heuristic — O(n) per slot).

This gives a good approximation of the convex hull of the contact patch without an expensive full hull computation.

Fields

entity_a: Entity

entity_b: Entity

contacts: Vec<ContactPoint>

At most 4 contact points.

friction: f32

Combined dynamic friction coefficient (geometric mean of both materials).

static_friction: f32

Combined static friction coefficient.

restitution: f32

Combined coefficient of restitution (max of both materials).

lifetime: u32

Number of consecutive physics frames this manifold has been alive. Incremented by the pipeline each frame; reset when the collision ends.

Implementations

impl ContactManifold

pub fn new(entity_a: Entity, entity_b: Entity) -> ContactManifold

Create a new manifold. Entity order is normalised (lower id → entity_a) so that cache lookups with either ordering always hit.

pub fn add_contact(&mut self, contact: ContactPoint)

Add contact to the manifold, warm-starting from any existing point that is within MERGE_RADIUS in world space.

If the manifold is already at capacity (4 points) and no merge occurs, the 5-point set is reduced back to 4 using the area-maximisation heuristic described in the type-level docs.

pub fn clear(&mut self)

Remove all contact points (does not reset lifetime).

pub fn is_stale(&self, max_lifetime: u32) -> bool

Returns true if the manifold has not been refreshed within max_lifetime frames — i.e. the collision pair has separated.

Trait Implementations

impl Clone for ContactManifold

fn clone(&self) -> ContactManifold

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ContactManifold

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

Formats the value using the given formatter.