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First public release of Rapier.

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Sébastien Crozet
2020-08-25 22:10:25 +02:00
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src/dynamics/integration_parameters.rs Normal file
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/// Parameters for a time-step of the physics engine.
#[derive(Clone)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
pub struct IntegrationParameters {
/// The timestep (default: `1.0 / 60.0`)
dt: f32,
/// The inverse of `dt`.
inv_dt: f32,
// /// If `true` and if rapier is compiled with the `parallel` feature, this will enable rayon-based multithreading (default: `true`).
// ///
// /// This parameter is ignored if rapier is not compiled with is `parallel` feature.
// /// Refer to rayon's documentation regarding how to configure the number of threads with either
// /// `rayon::ThreadPoolBuilder::new().num_threads(4).build_global().unwrap()` or `ThreadPool::install`.
// /// Note that using only one thread with `multithreading_enabled` set to `true` will result on a slower
// /// simulation than setting `multithreading_enabled` to `false`.
// pub multithreading_enabled: bool,
/// If `true`, the world's `step` method will stop right after resolving exactly one CCD event (default: `false`).
/// This allows the user to take action during a timestep, in-between two CCD events.
pub return_after_ccd_substep: bool,
/// The Error Reduction Parameter in `[0, 1]` is the proportion of
/// the positional error to be corrected at each time step (default: `0.2`).
pub erp: f32,
/// The Error Reduction Parameter for joints in `[0, 1]` is the proportion of
/// the positional error to be corrected at each time step (default: `0.2`).
pub joint_erp: f32,
/// Each cached impulse are multiplied by this coefficient in `[0, 1]`
/// when they are re-used to initialize the solver (default `1.0`).
pub warmstart_coeff: f32,
/// Contacts at points where the involved bodies have a relative
/// velocity smaller than this threshold wont be affected by the restitution force (default: `1.0`).
pub restitution_velocity_threshold: f32,
/// Amount of penetration the engine wont attempt to correct (default: `0.001m`).
pub allowed_linear_error: f32,
/// The maximal distance separating two objects that will generate predictive contacts (default: `0.002`).
pub prediction_distance: f32,
/// Amount of angular drift of joint limits the engine wont
/// attempt to correct (default: `0.001rad`).
pub allowed_angular_error: f32,
/// Maximum linear correction during one step of the non-linear position solver (default: `0.2`).
pub max_linear_correction: f32,
/// Maximum angular correction during one step of the non-linear position solver (default: `0.2`).
pub max_angular_correction: f32,
/// Maximum nonlinear SOR-prox scaling parameter when the constraint
/// correction direction is close to the kernel of the involved multibody's
/// jacobian (default: `0.2`).
pub max_stabilization_multiplier: f32,
/// Maximum number of iterations performed by the velocity constraints solver (default: `4`).
pub max_velocity_iterations: usize,
/// Maximum number of iterations performed by the position-based constraints solver (default: `1`).
pub max_position_iterations: usize,
/// Minimum number of dynamic bodies in each active island (default: `128`).
pub min_island_size: usize,
/// Maximum number of iterations performed by the position-based constraints solver for CCD steps (default: `10`).
///
/// This should be sufficiently high so all penetration get resolved. For example, if CCD cause your
/// objects to stutter, that may be because the number of CCD position iterations is too low, causing
/// them to remain stuck in a penetration configuration for a few frames.
///
/// The highest this number, the highest its computational cost.
pub max_ccd_position_iterations: usize,
/// Maximum number of substeps performed by the solver (default: `1`).
pub max_ccd_substeps: usize,
/// Controls the number of Proximity::Intersecting events generated by a trigger during CCD resolution (default: `false`).
///
/// If false, triggers will only generate one Proximity::Intersecting event during a step, even
/// if another colliders repeatedly enters and leaves the triggers during multiple CCD substeps.
///
/// If true, triggers will generate as many Proximity::Intersecting and Proximity::Disjoint/Proximity::WithinMargin
/// events as the number of times a collider repeatedly enters and leaves the triggers during multiple CCD substeps.
/// This is more computationally intensive.
pub multiple_ccd_substep_sensor_events_enabled: bool,
/// Whether penetration are taken into account in CCD resolution (default: `false`).
///
/// If this is set to `false` two penetrating colliders will not be considered to have any time of impact
/// while they are penetrating. This may end up allowing some tunelling, but will avoid stuttering effect
/// when the constraints solver fails to completely separate two colliders after a CCD contact.
///
/// If this is set to `true`, two penetrating colliders will be considered to have a time of impact
/// equal to 0 until the constraints solver manages to separate them. This will prevent tunnelling
/// almost completely, but may introduce stuttering effects when the constraints solver fails to completely
/// separate two colliders after a CCD contact.
// FIXME: this is a very binary way of handling penetration.
// We should provide a more flexible solution by letting the user choose some
// minimal amount of movement applied to an object that get stuck.
pub ccd_on_penetration_enabled: bool,
}
impl IntegrationParameters {
/// Creates a set of integration parameters with the given values.
pub fn new(
dt: f32,
// multithreading_enabled: bool,
erp: f32,
joint_erp: f32,
warmstart_coeff: f32,
restitution_velocity_threshold: f32,
allowed_linear_error: f32,
allowed_angular_error: f32,
max_linear_correction: f32,
max_angular_correction: f32,
prediction_distance: f32,
max_stabilization_multiplier: f32,
max_velocity_iterations: usize,
max_position_iterations: usize,
max_ccd_position_iterations: usize,
max_ccd_substeps: usize,
return_after_ccd_substep: bool,
multiple_ccd_substep_sensor_events_enabled: bool,
ccd_on_penetration_enabled: bool,
) -> Self {
IntegrationParameters {
dt,
inv_dt: if dt == 0.0 { 0.0 } else { 1.0 / dt },
// multithreading_enabled,
erp,
joint_erp,
warmstart_coeff,
restitution_velocity_threshold,
allowed_linear_error,
allowed_angular_error,
max_linear_correction,
max_angular_correction,
prediction_distance,
max_stabilization_multiplier,
max_velocity_iterations,
max_position_iterations,
// FIXME: what is the optimal value for min_island_size?
// It should not be too big so that we don't end up with
// huge islands that don't fit in cache.
// However we don't want it to be too small and end up with
// tons of islands, reducing SIMD parallelism opportunities.
min_island_size: 128,
max_ccd_position_iterations,
max_ccd_substeps,
return_after_ccd_substep,
multiple_ccd_substep_sensor_events_enabled,
ccd_on_penetration_enabled,
}
}
/// The current time-stepping length.
#[inline(always)]
pub fn dt(&self) -> f32 {
self.dt
}
/// The inverse of the time-stepping length.
///
/// This is zero if `self.dt` is zero.
#[inline(always)]
pub fn inv_dt(&self) -> f32 {
self.inv_dt
}
/// Sets the time-stepping length.
///
/// This automatically recompute `self.inv_dt`.
#[inline]
pub fn set_dt(&mut self, dt: f32) {
assert!(dt >= 0.0, "The time-stepping length cannot be negative.");
self.dt = dt;
if dt == 0.0 {
self.inv_dt = 0.0
} else {
self.inv_dt = 1.0 / dt
}
}
/// Sets the inverse time-stepping length (i.e. the frequency).
///
/// This automatically recompute `self.dt`.
#[inline]
pub fn set_inv_dt(&mut self, inv_dt: f32) {
self.inv_dt = inv_dt;
if inv_dt == 0.0 {
self.dt = 0.0
} else {
self.dt = 1.0 / inv_dt
}
}
}
impl Default for IntegrationParameters {
fn default() -> Self {
Self::new(
1.0 / 60.0,
// true,
0.2,
0.2,
1.0,
1.0,
0.005,
0.001,
0.2,
0.2,
0.002,
0.2,
4,
1,
10,
1,
false,
false,
false,
)
}
}