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use na::{self, RealField}; /// Parameters for a time-step of the physics engine. #[derive(Clone)] pub struct IntegrationParameters<N: RealField> { /// The timestep (default: `1.0 / 60.0`) dt: N, /// The inverse of `dt`. inv_dt: N, /// 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 total elapsed time in the physics world. /// /// This is the accumulation of the `dt` of all the calls to `world.step()`. pub t: N, /// 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: N, /// 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: N, /// 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: N, /// Ammount of penetration the engine wont attempt to correct (default: `0.001m`). pub allowed_linear_error: N, /// Ammount of angular drift of joint limits the engine wont /// attempt to correct (default: `0.001rad`). pub allowed_angular_error: N, /// Maximum linear correction during one step of the non-linear position solver (default: `0.2`). pub max_linear_correction: N, /// Maximum angular correction during one step of the non-linear position solver (default: `0.2`). pub max_angular_correction: N, /// 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: N, /// Maximum number of iterations performed by the velocity constraints solver (default: `8`). pub max_velocity_iterations: usize, /// Maximum number of iterations performed by the position-based constraints solver (default: `3`). pub max_position_iterations: 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 /// seperate 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<N: RealField> IntegrationParameters<N> { /// Creates a set of integration parameters with the given values. pub fn new( dt: N, erp: N, warmstart_coeff: N, restitution_velocity_threshold: N, allowed_linear_error: N, allowed_angular_error: N, max_linear_correction: N, max_angular_correction: N, max_stabilization_multiplier: N, 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 { t: N::zero(), dt, inv_dt: if dt == N::zero() { N::zero() } else { N::one() / dt }, erp, warmstart_coeff, restitution_velocity_threshold, allowed_linear_error, allowed_angular_error, max_linear_correction, max_angular_correction, max_stabilization_multiplier, max_velocity_iterations, max_position_iterations, 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) -> N { self.dt } /// The inverse of the time-stepping length. /// /// This is zero if `self.dt` is zero. #[inline(always)] pub fn inv_dt(&self) -> N { self.inv_dt } /// Sets the time-stepping length. /// /// This automatically recompute `self.inv_dt`. #[inline] pub fn set_dt(&mut self, dt: N) { assert!( dt >= N::zero(), "The time-stepping length cannot be negative." ); self.dt = dt; if dt == N::zero() { self.inv_dt = N::zero() } else { self.inv_dt = N::one() / 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: N) { self.inv_dt = inv_dt; if inv_dt == N::zero() { self.dt = N::zero() } else { self.dt = N::one() / inv_dt } } } impl<N: RealField> Default for IntegrationParameters<N> { fn default() -> Self { Self::new( na::convert(1.0 / 60.0), na::convert(0.2), na::convert(1.0), na::convert(1.0), na::convert(0.001), na::convert(0.001), na::convert(0.2), na::convert(0.2), na::convert(0.2), 8, 3, 10, 1, false, false, false, ) } }