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//! Simulation settings shared by every soft body of a world, grouped on
//! [`IntegrationParameters::soft_bodies`](crate::dynamics::IntegrationParameters::soft_bodies).
use super::SoftRecoverySettings;
use crate::math::Real;
/// Simulation settings shared by every soft body of a world.
///
/// Lives on [`IntegrationParameters::soft_bodies`], so it can be changed between steps.
///
/// [`IntegrationParameters::soft_bodies`]: crate::dynamics::IntegrationParameters::soft_bodies
#[derive(Copy, Clone, Debug, PartialEq)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde-serialize", serde(default))]
pub struct SoftBodiesSettings {
/// Runtime toggles and tuning for the soft-body tangle detection and recovery stack
/// (see [`SoftRecoverySettings`]). Every mechanism can be switched off individually.
pub recovery: SoftRecoverySettings,
/// Strain beyond which a soft-body constraint (an elastic cell's strain component, a distance
/// constraint's relative error) is re-solved after the contacts inside every substep, so a
/// light body buried under heavier ones is not torn (default: `0.75`; `Real::MAX` to disable).
pub resweep_strain: Real,
/// Maximum number of extra substeps a soft body requests for its island component while it
/// is hit fast (default: `4`; `0` disables the impact-adaptive substeps): enough substeps to
/// bound the per-substep travel of its particles and approaching rigid bodies by one radius.
pub max_extra_substeps: usize,
/// Factor applied to the [`IntegrationParameters`](crate::dynamics::IntegrationParameters)
/// contact softness natural frequencies for the soft-body contacts (default: `4.0`); they run
/// stiffer because a contact's effective mass is a few particles' worth, not the whole body's.
pub contact_stiffening: Real,
/// Tuning of the FEM soft-body solver (see
/// [`SoftBodySolver::Fem`](crate::dynamics::SoftBodySolver::Fem)); only read by the soft
/// bodies that select it.
#[cfg(feature = "fem")]
pub fem: SoftFemParameters,
}
impl Default for SoftBodiesSettings {
fn default() -> Self {
Self {
recovery: SoftRecoverySettings::default(),
resweep_strain: 0.75,
max_extra_substeps: 4,
contact_stiffening: 4.0,
#[cfg(feature = "fem")]
fem: SoftFemParameters::default(),
}
}
}
/// Tuning of the FEM soft-body solver (see
/// [`SoftBodySolver::Fem`](crate::dynamics::SoftBodySolver::Fem)), which solves a linear system
/// per substep by conjugate gradient and factorizes it once per step (see `max_dense_dofs`).
#[cfg(feature = "fem")]
#[derive(Copy, Clone, Debug, PartialEq)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
pub struct SoftFemParameters {
/// Relative residual at which the conjugate gradient stops (default: `1.0e-5`).
pub linear_tolerance: Real,
/// Hard cap on the conjugate-gradient iterations, whatever the residual (default: `20`).
///
/// A very stiff, finely meshed body can need several hundred iterations to converge; the
/// truncated step it gets instead is under-relaxed (safe), only slower to settle.
pub max_linear_iterations: usize,
/// Largest number of degrees of freedom (`DIM` per particle) for which the step-start
/// matrix `A` of a body is factorized directly (default: `600`). Each constraint on a FEM body
/// needs one solve against `A` per step; larger bodies fall back to a conjugate gradient.
pub max_dense_dofs: usize,
}
#[cfg(feature = "fem")]
impl Default for SoftFemParameters {
fn default() -> Self {
Self {
linear_tolerance: 1.0e-5,
max_linear_iterations: 20,
max_dense_dofs: 600,
}
}
}