attempt to reflect integration parameters 🤔

Author: ThierryBerger

src/lib.rs

@@ -57,6 +57,9 @@ pub mod pipeline;
 /// The physics plugin and systems.
 pub mod plugin;
 
+/// Reflection utilities.
+pub mod reflect;
+
 #[cfg(feature = "picking-backend")]
 pub mod picking_backend;
 

src/plugin/plugin.rs

@@ -8,6 +8,7 @@ use bevy::ecs::{
 use bevy::utils::HashSet;
 use bevy::{prelude::*, transform::TransformSystem};
 use rapier::dynamics::IntegrationParameters;
+use reflect::IntegrationParametersWrapper;
 use std::marker::PhantomData;
 
 use super::context::DefaultRapierContext;
@@ -52,8 +53,12 @@ where
     /// likely always be 1.0 in 3D. In 2D, this is useful to specify a "pixels-per-meter"
     /// conversion ratio.
     pub fn with_length_unit(mut self, length_unit: f32) -> Self {
-        self.default_world_setup =
-            RapierContextInitialization::InitializeDefaultRapierContext { length_unit };
+        self.default_world_setup = RapierContextInitialization::InitializeDefaultRapierContext {
+            integration_parameters: IntegrationParameters {
+                length_unit,
+                ..default()
+            },
+        };
         self
     }
 
@@ -85,7 +90,10 @@ where
         Self {
             default_system_setup: true,
             default_world_setup: RapierContextInitialization::InitializeDefaultRapierContext {
-                length_unit: pixels_per_meter,
+                integration_parameters: IntegrationParameters {
+                    length_unit: pixels_per_meter,
+                    ..default()
+                },
             },
             ..default()
         }
@@ -370,14 +378,17 @@ pub enum RapierContextInitialization {
     /// [`RapierPhysicsPlugin`] will spawn an entity containing a [`RapierContextSimulation`]
     /// automatically during [`PreStartup`], with the [`DefaultRapierContext`] marker component.
     InitializeDefaultRapierContext {
-        /// See [`IntegrationParameters::length_unit`]
-        length_unit: f32,
+        /// Integration
+        #[reflect(remote = IntegrationParametersWrapper)]
+        integration_parameters: IntegrationParameters,
     },
 }
 
 impl Default for RapierContextInitialization {
     fn default() -> Self {
-        RapierContextInitialization::InitializeDefaultRapierContext { length_unit: 1f32 }
+        RapierContextInitialization::InitializeDefaultRapierContext {
+            integration_parameters: IntegrationParameters::default(),
+        }
     }
 }
 
@@ -387,14 +398,13 @@ pub fn insert_default_context(
 ) {
     match initialization_data.as_ref() {
         RapierContextInitialization::NoAutomaticRapierContext => {}
-        RapierContextInitialization::InitializeDefaultRapierContext { length_unit } => {
+        RapierContextInitialization::InitializeDefaultRapierContext {
+            integration_parameters,
+        } => {
             commands.spawn((
                 Name::new("Rapier Context"),
                 RapierContextSimulation {
-                    integration_parameters: IntegrationParameters {
-                        length_unit: *length_unit,
-                        ..default()
-                    },
+                    integration_parameters: *integration_parameters,
                     ..RapierContextSimulation::default()
                 },
                 DefaultRapierContext,

src/reflect/mod.rs

@@ -0,0 +1,99 @@
+use crate::math::Real;
+use bevy::reflect::reflect_remote;
+use rapier::dynamics::IntegrationParameters;
+
+#[reflect_remote(IntegrationParameter)]
+#[derive(Copy, Clone, Debug, PartialEq)]
+/// Parameters affecting the physical behavior of a wheel.
+pub struct IntegrationParameterWrapper {
+    /// The timestep length (default: `1.0 / 60.0`).
+    pub dt: Real,
+    /// Minimum timestep size when using CCD with multiple substeps (default: `1.0 / 60.0 / 100.0`).
+    ///
+    /// When CCD with multiple substeps is enabled, the timestep is subdivided
+    /// into smaller pieces. This timestep subdivision won't generate timestep
+    /// lengths smaller than `min_ccd_dt`.
+    ///
+    /// Setting this to a large value will reduce the opportunity to performing
+    /// CCD substepping, resulting in potentially more time dropped by the
+    /// motion-clamping mechanism. Setting this to an very small value may lead
+    /// to numerical instabilities.
+    pub min_ccd_dt: Real,
+
+    /// > 0: the damping ratio used by the springs for contact constraint stabilization.
+    ///
+    /// Larger values make the constraints more compliant (allowing more visible
+    /// penetrations before stabilization).
+    /// (default `5.0`).
+    pub contact_damping_ratio: Real,
+
+    /// > 0: the natural frequency used by the springs for contact constraint regularization.
+    ///
+    /// Increasing this value will make it so that penetrations get fixed more quickly at the
+    /// expense of potential jitter effects due to overshooting. In order to make the simulation
+    /// look stiffer, it is recommended to increase the [`Self::contact_damping_ratio`] instead of this
+    /// value.
+    /// (default: `30.0`).
+    pub contact_natural_frequency: Real,
+
+    /// > 0: the natural frequency used by the springs for joint constraint regularization.
+    ///
+    /// Increasing this value will make it so that penetrations get fixed more quickly.
+    /// (default: `1.0e6`).
+    pub joint_natural_frequency: Real,
+
+    /// The fraction of critical damping applied to the joint for constraints regularization.
+    ///
+    /// Larger values make the constraints more compliant (allowing more joint
+    /// drift before stabilization).
+    /// (default `1.0`).
+    pub joint_damping_ratio: Real,
+
+    /// The coefficient in `[0, 1]` applied to warmstart impulses, i.e., impulses that are used as the
+    /// initial solution (instead of 0) at the next simulation step.
+    ///
+    /// This should generally be set to 1.
+    ///
+    /// (default `1.0`).
+    pub warmstart_coefficient: Real,
+
+    /// The approximate size of most dynamic objects in the scene.
+    ///
+    /// This value is used internally to estimate some length-based tolerance. In particular, the
+    /// values [`IntegrationParameters::allowed_linear_error`],
+    /// [`IntegrationParameters::max_corrective_velocity`],
+    /// [`IntegrationParameters::prediction_distance`], [`RigidBodyActivation::normalized_linear_threshold`]
+    /// are scaled by this value implicitly.
+    ///
+    /// This value can be understood as the number of units-per-meter in your physical world compared
+    /// to a human-sized world in meter. For example, in a 2d game, if your typical object size is 100
+    /// pixels, set the [`Self::length_unit`] parameter to 100.0. The physics engine will interpret
+    /// it as if 100 pixels is equivalent to 1 meter in its various internal threshold.
+    /// (default `1.0`).
+    pub length_unit: Real,
+
+    /// Amount of penetration the engine won’t attempt to correct (default: `0.001m`).
+    ///
+    /// This value is implicitly scaled by [`IntegrationParameters::length_unit`].
+    pub normalized_allowed_linear_error: Real,
+    /// Maximum amount of penetration the solver will attempt to resolve in one timestep (default: `10.0`).
+    ///
+    /// This value is implicitly scaled by [`IntegrationParameters::length_unit`].
+    pub normalized_max_corrective_velocity: Real,
+    /// The maximal distance separating two objects that will generate predictive contacts (default: `0.002m`).
+    ///
+    /// This value is implicitly scaled by [`IntegrationParameters::length_unit`].
+    pub normalized_prediction_distance: Real,
+    /// The number of solver iterations run by the constraints solver for calculating forces (default: `4`).
+    pub num_solver_iterations: NonZeroUsize,
+    /// Number of addition friction resolution iteration run during the last solver sub-step (default: `0`).
+    pub num_additional_friction_iterations: usize,
+    /// Number of internal Project Gauss Seidel (PGS) iterations run at each solver iteration (default: `1`).
+    pub num_internal_pgs_iterations: usize,
+    /// The number of stabilization iterations run at each solver iterations (default: `2`).
+    pub num_internal_stabilization_iterations: usize,
+    /// Minimum number of dynamic bodies in each active island (default: `128`).
+    pub min_island_size: usize,
+    /// Maximum number of substeps performed by the  solver (default: `1`).
+    pub max_ccd_substeps: usize,
+}