Struct Scratch 

pub struct Scratch {
    pub grid: NeighborGrid,
    /* private fields */
}

Reusable scratch buffers for the crowd models.

Every step_* path in this crate needs exactly one Vec<Vec2> of length peds.len() (for next-tick accelerations, velocities, or positions) and one NeighborGrid rebuilt against the current pedestrian slice. Scratch bundles both so a caller can allocate once per simulation instead of twice per tick.

let mut scratch = Scratch::with_capacity(peds.len(), 1.0);
for _ in 0..num_steps {
    social_force::step_scratch(&mut peds, &walls, &params, dt, &mut scratch);
}

Scratch is not tied to a specific model: the same instance can drive social_force, collision_free_speed, anticipation_velocity, generalized_centrifugal_force, or optimal_steps step-by-step, provided the grid’s cell_size is a sensible cap on the largest neighbor_cutoff in play.

Fields

grid: NeighborGrid

Neighbour grid rebuilt against the pedestrian slice each tick.

Implementations

impl Scratch

pub fn new(cell_size: f64) -> Self

Empty scratch with a grid of the given cell size (metres).

Panics

Panics if cell_size is not strictly positive.

pub fn with_capacity(n: usize, cell_size: f64) -> Self

Scratch pre-sized for n pedestrians and a grid of cell_size.

pub fn clear(&mut self)

Clear the buffers without releasing their capacity.

Trait Implementations

impl Clone for Scratch

fn clone(&self) -> Scratch

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Scratch

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

Formats the value using the given formatter.