Struct SpringSystem 

pub struct SpringSystem {
    pub rest_positions: Vec<[f32; 3]>,
    pub positions: Vec<[f32; 3]>,
    pub velocities: Vec<[f32; 3]>,
    pub springs: Vec<(usize, usize, f32)>,
    pub fixed: Vec<bool>,
    pub params: SpringParams,
}

A spring-mass system attached to mesh vertices for soft-body simulation.

Fields

rest_positions: Vec<[f32; 3]>

Rest positions (used to reset).

positions: Vec<[f32; 3]>

Current positions.

velocities: Vec<[f32; 3]>

Current velocities.

springs: Vec<(usize, usize, f32)>

Springs: (vertex_a, vertex_b, rest_length).

fixed: Vec<bool>

Fixed (pinned) vertices that do not move.

params: SpringParams

Simulation parameters.

Implementations

impl SpringSystem

pub fn from_mesh(mesh: &MeshBuffers, params: SpringParams) -> Self

Construct from a mesh and simulation parameters.

pub fn vertex_count(&self) -> usize

Number of vertices in the system.

pub fn spring_count(&self) -> usize

Number of springs in the system.

pub fn kinetic_energy(&self) -> f32

Total kinetic energy: sum of 0.5 * mass * |v|^2 over all vertices.

pub fn is_settled(&self, threshold: f32) -> bool

Returns true when the kinetic energy is below threshold.

pub fn set_fixed(&mut self, vertex: usize, fixed: bool)

Pin or unpin a single vertex.

pub fn apply_impulse(&mut self, vertex: usize, force: [f32; 3])

Apply an instantaneous velocity impulse to a vertex.

pub fn apply_gravity_impulse(&mut self, dt: f32)

Accumulate gravity into all non-fixed vertex velocities.

pub fn step(&mut self, dt: f32)

Advance the simulation by dt seconds (uses params.substeps substeps).

pub fn step_n(&mut self, dt: f32, n: usize)

Advance the simulation by n steps of dt seconds each.

pub fn reset(&mut self)

Return all vertices to their rest positions and zero all velocities.

pub fn to_mesh(&self, template: &MeshBuffers) -> MeshBuffers

Build a new MeshBuffers from the template, with positions replaced by the current simulated positions, and normals recomputed.