fyrox_impl/scene/dim2/

physics.rs

// Copyright (c) 2019-present Dmitry Stepanov and Fyrox Engine contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

//! Scene physics module.

use super::collider::GeometrySource;
use crate::{
    core::{
        algebra::{
            Isometry2, Isometry3, Matrix4, Point2, Rotation3, Translation2, Translation3,
            UnitComplex, UnitQuaternion, UnitVector2, Vector2, Vector3,
        },
        arrayvec::ArrayVec,
        instant,
        log::{Log, MessageKind},
        math::Matrix4Ext,
        parking_lot::Mutex,
        pool::Handle,
        reflect::prelude::*,
        variable::{InheritableVariable, VariableFlags},
        visitor::prelude::*,
        BiDirHashMap, ImmutableString, SafeLock,
    },
    graph::{SceneGraph, SceneGraphNode},
    scene::{
        self,
        collider::{self},
        debug::SceneDrawingContext,
        dim2::{
            self,
            collider::{ColliderShape, TileMapShape},
            joint::{JointLocalFrames, JointMotorParams, JointParams},
            rigidbody::ApplyAction,
        },
        graph::{
            isometric_global_transform,
            physics::{FeatureId, IntegrationParameters, PhysicsPerformanceStatistics},
            Graph, NodePool,
        },
        node::{Node, NodeTrait},
        tilemap::TileMap,
    },
};
pub use rapier2d::geometry::shape::*;
use rapier2d::parry::query::DefaultQueryDispatcher;
use rapier2d::{
    dynamics::{
        CCDSolver, GenericJoint, GenericJointBuilder, ImpulseJointHandle, ImpulseJointSet,
        IslandManager, JointAxesMask, JointAxis, MultibodyJointHandle, MultibodyJointSet,
        RigidBody, RigidBodyActivation, RigidBodyBuilder, RigidBodyHandle, RigidBodySet,
        RigidBodyType,
    },
    geometry::{
        Collider, ColliderBuilder, ColliderHandle, ColliderSet, Cuboid, DefaultBroadPhase,
        InteractionGroups, NarrowPhase, Ray, SharedShape,
    },
    parry::query::ShapeCastOptions,
    pipeline::{DebugRenderPipeline, EventHandler, PhysicsPipeline},
};
use std::{
    cmp::Ordering,
    fmt::{Debug, Formatter},
    hash::Hash,
    sync::Arc,
};

/// A trait for ray cast results storage. It has two implementations: Vec and ArrayVec.
/// Latter is needed for the cases where you need to avoid runtime memory allocations
/// and do everything on stack.
pub trait QueryResultsStorage {
    /// Pushes new intersection in the storage. Returns true if intersection was
    /// successfully inserted, false otherwise.
    fn push(&mut self, intersection: Intersection) -> bool;

    /// Clears the storage.
    fn clear(&mut self);

    /// Sorts intersections by given compare function.
    fn sort_intersections_by<C: FnMut(&Intersection, &Intersection) -> Ordering>(&mut self, cmp: C);
}

impl QueryResultsStorage for Vec<Intersection> {
    fn push(&mut self, intersection: Intersection) -> bool {
        self.push(intersection);
        true
    }

    fn clear(&mut self) {
        self.clear()
    }

    fn sort_intersections_by<C>(&mut self, cmp: C)
    where
        C: FnMut(&Intersection, &Intersection) -> Ordering,
    {
        self.sort_by(cmp);
    }
}

impl<const CAP: usize> QueryResultsStorage for ArrayVec<Intersection, CAP> {
    fn push(&mut self, intersection: Intersection) -> bool {
        self.try_push(intersection).is_ok()
    }

    fn clear(&mut self) {
        self.clear()
    }

    fn sort_intersections_by<C>(&mut self, cmp: C)
    where
        C: FnMut(&Intersection, &Intersection) -> Ordering,
    {
        self.sort_by(cmp);
    }
}

/// A ray intersection result.
#[derive(Debug, Clone, PartialEq)]
pub struct Intersection {
    /// A handle of the collider with which intersection was detected.
    pub collider: Handle<dim2::collider::Collider>,

    /// A normal at the intersection position.
    pub normal: Vector2<f32>,

    /// A position of the intersection in world coordinates.
    pub position: Point2<f32>,

    /// Additional data that contains a kind of the feature with which
    /// intersection was detected as well as its index.
    ///
    /// # Important notes.
    ///
    /// FeatureId::Face might have index that is greater than amount of triangles in
    /// a triangle mesh, this means that intersection was detected from "back" side of
    /// a face. To "fix" that index, simply subtract amount of triangles of a triangle
    /// mesh from the value.
    pub feature: FeatureId,

    /// Distance from the ray origin.
    pub toi: f32,
}

/// A set of options for the ray cast.
pub struct RayCastOptions {
    /// A ray origin.
    pub ray_origin: Point2<f32>,

    /// A ray direction. Can be non-normalized.
    pub ray_direction: Vector2<f32>,

    /// Maximum distance of cast.
    pub max_len: f32,

    /// Groups to check.
    pub groups: collider::InteractionGroups,

    /// Whether to sort intersections from closest to farthest.
    pub sort_results: bool,
}

/// Data of the contact.
#[derive(Debug, Clone, PartialEq)]
pub struct ContactData {
    /// The contact point in the local-space of the first shape.
    pub local_p1: Vector2<f32>,
    /// The contact point in the local-space of the second shape.
    pub local_p2: Vector2<f32>,
    /// The distance between the two contact points.
    pub dist: f32,
    /// The impulse, along the contact normal, applied by this contact to the first collider's rigid-body.
    /// The impulse applied to the second collider's rigid-body is given by `-impulse`.
    pub impulse: f32,
    /// The friction impulses along the basis orthonormal to the contact normal, applied to the first
    /// collider's rigid-body.
    pub tangent_impulse: f32,
}

/// A contact manifold between two colliders.
#[derive(Debug, Clone, PartialEq)]
pub struct ContactManifold {
    /// The contacts points.
    pub points: Vec<ContactData>,
    /// The contact normal of all the contacts of this manifold, expressed in the local space of the first shape.
    pub local_n1: Vector2<f32>,
    /// The contact normal of all the contacts of this manifold, expressed in the local space of the second shape.
    pub local_n2: Vector2<f32>,
    /// The first rigid-body involved in this contact manifold.
    pub rigid_body1: Handle<dim2::rigidbody::RigidBody>,
    /// The second rigid-body involved in this contact manifold.
    pub rigid_body2: Handle<dim2::rigidbody::RigidBody>,
    /// The world-space contact normal shared by all the contact in this contact manifold.
    pub normal: Vector2<f32>,
}

/// Contact info for pair of colliders.
#[derive(Debug, Clone, PartialEq)]
pub struct ContactPair {
    /// The first collider involved in the contact pair.
    pub collider1: Handle<dim2::collider::Collider>,
    /// The second collider involved in the contact pair.
    pub collider2: Handle<dim2::collider::Collider>,
    /// The set of contact manifolds between the two colliders.
    /// All contact manifold contain themselves contact points between the colliders.
    pub manifolds: Vec<ContactManifold>,
    /// Is there any active contact in this contact pair?
    /// When false, this pair may just mean that bounding boxes are touching.
    pub has_any_active_contact: bool,
}

impl ContactPair {
    /// Given the handle of a collider that is expected to be part of the collision,
    /// return the other node involved in the collision.
    /// Often one will have a list of contact pairs for some collider, but that collider
    /// may be the first member of some pairs and the second member of other pairs.
    /// This method simplifies determining which objects a collider has collided with.
    #[inline]
    pub fn other(
        &self,
        subject: Handle<dim2::collider::Collider>,
    ) -> Handle<dim2::collider::Collider> {
        if subject == self.collider1 {
            self.collider2
        } else {
            self.collider1
        }
    }

    fn from_native(c: &rapier2d::geometry::ContactPair, physics: &PhysicsWorld) -> Option<Self> {
        Some(ContactPair {
            collider1: Handle::decode_from_u128(physics.colliders.get(c.collider1)?.user_data),
            collider2: Handle::decode_from_u128(physics.colliders.get(c.collider2)?.user_data),
            manifolds: c
                .manifolds
                .iter()
                .filter_map(|m| {
                    Some(ContactManifold {
                        points: m
                            .points
                            .iter()
                            .map(|p| ContactData {
                                local_p1: p.local_p1.coords,
                                local_p2: p.local_p2.coords,
                                dist: p.dist,
                                impulse: p.data.impulse,
                                tangent_impulse: p.data.tangent_impulse.x,
                            })
                            .collect(),
                        local_n1: m.local_n1,
                        local_n2: m.local_n2,
                        rigid_body1: m.data.rigid_body1.and_then(|h| {
                            physics
                                .bodies
                                .get(h)
                                .map(|b| Handle::decode_from_u128(b.user_data))
                        })?,
                        rigid_body2: m.data.rigid_body2.and_then(|h| {
                            physics
                                .bodies
                                .get(h)
                                .map(|b| Handle::decode_from_u128(b.user_data))
                        })?,
                        normal: m.data.normal,
                    })
                })
                .collect(),
            has_any_active_contact: c.has_any_active_contact,
        })
    }
}

/// Intersection info for pair of colliders.
#[derive(Debug, Clone, PartialEq)]
pub struct IntersectionPair {
    /// The first collider involved in the contact pair.
    pub collider1: Handle<dim2::collider::Collider>,
    /// The second collider involved in the contact pair.
    pub collider2: Handle<dim2::collider::Collider>,
    /// Is there any active contact in this contact pair?
    /// When false, this pair may just mean that bounding boxes are touching.
    pub has_any_active_contact: bool,
}

impl IntersectionPair {
    /// Given the handle of a collider that is expected to be part of the collision,
    /// return the other node involved in the collision.
    /// Often one will have a list of contact pairs for some collider, but that collider
    /// may be the first member of some pairs and the second member of other pairs.
    /// This method simplifies determining which objects a collider has collided with.
    #[inline]
    pub fn other(
        &self,
        subject: Handle<dim2::collider::Collider>,
    ) -> Handle<dim2::collider::Collider> {
        if subject == self.collider1 {
            self.collider2
        } else {
            self.collider1
        }
    }
}

pub(super) struct Container<S, A>
where
    A: Hash + Eq + Clone,
{
    set: S,
    map: BiDirHashMap<A, Handle<Node>>,
}

fn convert_joint_params(
    params: scene::dim2::joint::JointParams,
    local_frame1: Isometry2<f32>,
    local_frame2: Isometry2<f32>,
) -> GenericJoint {
    let locked_axis = match params {
        JointParams::BallJoint(_) => JointAxesMask::LOCKED_REVOLUTE_AXES,
        JointParams::FixedJoint(_) => JointAxesMask::LOCKED_FIXED_AXES,
        JointParams::PrismaticJoint(_) => JointAxesMask::LOCKED_PRISMATIC_AXES,
    };

    let mut joint = GenericJointBuilder::new(locked_axis)
        .local_frame1(local_frame1)
        .local_frame2(local_frame2)
        .build();

    match params {
        scene::dim2::joint::JointParams::BallJoint(v) => {
            if v.limits_enabled {
                joint.set_limits(
                    JointAxis::AngX,
                    [v.limits_angles.start, v.limits_angles.end],
                );
            }
        }
        scene::dim2::joint::JointParams::FixedJoint(_) => {}
        scene::dim2::joint::JointParams::PrismaticJoint(v) => {
            if v.limits_enabled {
                joint.set_limits(JointAxis::LinX, [v.limits.start, v.limits.end]);
            }
        }
    }

    joint
}

fn tile_map_to_collider_shape(
    tile_map: &GeometrySource,
    owner_inv_transform: Matrix4<f32>,
    nodes: &NodePool,
    collider_name: &ImmutableString,
) -> Option<SharedShape> {
    let tile_map = nodes
        .try_borrow(tile_map.0)
        .ok()?
        .component_ref::<TileMap>()?;

    let tile_set_resource = tile_map.tile_set()?.data_ref();
    let tile_set = tile_set_resource.as_loaded_ref()?;

    let tile_scale = tile_map.tile_scale();
    let global_transform = owner_inv_transform
        * tile_map.global_transform()
        * Matrix4::new_nonuniform_scaling(&Vector3::new(-tile_scale.x, tile_scale.y, 1.0));

    let mut vertices = Vec::new();
    let mut triangles = Vec::new();

    let collider_uuid = tile_set.collider_name_to_uuid(collider_name)?;
    let tile_data = tile_map.tiles()?.data_ref();
    let tile_data = tile_data.as_loaded_ref()?;
    for (position, handle) in tile_data.iter() {
        let Some(tile_definition) = tile_set.get_tile_data(handle.into()) else {
            continue;
        };

        if let Some(collider) = tile_definition.colliders.get(&collider_uuid) {
            let position = position.cast::<f32>().to_homogeneous();
            collider.build_collider_shape(
                &global_transform,
                position,
                &mut vertices,
                &mut triangles,
            );
        }
    }

    SharedShape::trimesh(vertices, triangles).ok()
}

// Converts descriptor in a shared shape.
fn collider_shape_into_native_shape(
    shape: &ColliderShape,
    owner_inv_transform: Matrix4<f32>,
    nodes: &NodePool,
) -> Option<SharedShape> {
    match shape {
        ColliderShape::Ball(ball) => Some(SharedShape::ball(ball.radius)),
        ColliderShape::Cuboid(cuboid) => {
            Some(SharedShape(Arc::new(Cuboid::new(cuboid.half_extents))))
        }
        ColliderShape::Capsule(capsule) => Some(SharedShape::capsule(
            Point2::from(capsule.begin),
            Point2::from(capsule.end),
            capsule.radius,
        )),
        ColliderShape::Segment(segment) => Some(SharedShape::segment(
            Point2::from(segment.begin),
            Point2::from(segment.end),
        )),
        ColliderShape::Triangle(triangle) => Some(SharedShape::triangle(
            Point2::from(triangle.a),
            Point2::from(triangle.b),
            Point2::from(triangle.c),
        )),
        ColliderShape::Trimesh(_) => {
            None // TODO
        }
        ColliderShape::Heightfield(_) => {
            None // TODO
        }
        ColliderShape::TileMap(TileMapShape {
            tile_map,
            layer_name: collider_layer_name,
        }) => tile_map_to_collider_shape(tile_map, owner_inv_transform, nodes, collider_layer_name),
    }
}

fn isometry2_to_mat4(isometry: &Isometry2<f32>) -> Matrix4<f32> {
    Isometry3 {
        rotation: UnitQuaternion::from_euler_angles(0.0, 0.0, isometry.rotation.angle()),
        translation: Translation3 {
            vector: Vector3::new(isometry.translation.x, isometry.translation.y, 0.0),
        },
    }
    .to_homogeneous()
}

/// Physics world is responsible for physics simulation in the engine. There is a very few public
/// methods, mostly for ray casting. You should add physical entities using scene graph nodes, such
/// as RigidBody, Collider, Joint.
#[derive(Visit, Reflect)]
pub struct PhysicsWorld {
    /// A flag that defines whether physics simulation is enabled or not.
    pub enabled: InheritableVariable<bool>,

    /// A set of parameters that define behavior of every rigid body.
    pub integration_parameters: InheritableVariable<IntegrationParameters>,

    /// Current gravity vector. Default is (0.0, -9.81)
    pub gravity: InheritableVariable<Vector2<f32>>,

    /// Performance statistics of a single simulation step.
    #[visit(skip)]
    #[reflect(hidden)]
    pub performance_statistics: PhysicsPerformanceStatistics,

    // Current physics pipeline.
    #[visit(skip)]
    #[reflect(hidden)]
    pipeline: PhysicsPipeline,
    // Broad phase performs rough intersection checks.
    #[visit(skip)]
    #[reflect(hidden)]
    broad_phase: DefaultBroadPhase,
    // Narrow phase is responsible for precise contact generation.
    #[visit(skip)]
    #[reflect(hidden)]
    narrow_phase: NarrowPhase,
    // A continuous collision detection solver.
    #[visit(skip)]
    #[reflect(hidden)]
    ccd_solver: CCDSolver,
    // Structure responsible for maintaining the set of active rigid-bodies, and putting non-moving
    // rigid-bodies to sleep to save computation times.
    #[visit(skip)]
    #[reflect(hidden)]
    islands: IslandManager,
    // A container of rigid bodies.
    #[visit(skip)]
    #[reflect(hidden)]
    bodies: RigidBodySet,
    // A container of colliders.
    #[visit(skip)]
    #[reflect(hidden)]
    pub(crate) colliders: ColliderSet,
    // A container of impulse joints.
    #[visit(skip)]
    #[reflect(hidden)]
    joints: Container<ImpulseJointSet, ImpulseJointHandle>,
    // A container of multibody joints.
    #[visit(skip)]
    #[reflect(hidden)]
    multibody_joints: Container<MultibodyJointSet, MultibodyJointHandle>,
    // Event handler collects info about contacts and proximity events.
    #[visit(skip)]
    #[reflect(hidden)]
    event_handler: Box<dyn EventHandler>,
    #[visit(skip)]
    #[reflect(hidden)]
    debug_render_pipeline: Mutex<DebugRenderPipeline>,
}

impl Clone for PhysicsWorld {
    fn clone(&self) -> Self {
        PhysicsWorld {
            enabled: self.enabled.clone(),
            integration_parameters: self.integration_parameters.clone(),
            gravity: self.gravity.clone(),
            ..Default::default()
        }
    }
}

fn isometry_from_global_transform(transform: &Matrix4<f32>) -> Isometry2<f32> {
    Isometry2 {
        translation: Translation2::new(transform[12], transform[13]),
        rotation: UnitComplex::from_angle(
            Rotation3::from_matrix_eps(&transform.basis(), f32::EPSILON, 16, Rotation3::identity())
                .euler_angles()
                .2,
        ),
    }
}

fn calculate_local_frames(
    joint: &dyn NodeTrait,
    body1: &dyn NodeTrait,
    body2: &dyn NodeTrait,
) -> (Isometry2<f32>, Isometry2<f32>) {
    let joint_isometry = isometry_from_global_transform(&joint.global_transform());

    (
        joint_isometry * isometry_from_global_transform(&body1.global_transform()).inverse(),
        joint_isometry * isometry_from_global_transform(&body2.global_transform()).inverse(),
    )
}

fn u32_to_group(v: u32) -> rapier2d::geometry::Group {
    rapier2d::geometry::Group::from_bits(v).unwrap_or_else(rapier2d::geometry::Group::all)
}

/// A filter tha describes what collider should be included or excluded from a scene query.
#[derive(Copy, Clone, Default)]
#[allow(clippy::type_complexity)]
pub struct QueryFilter<'a> {
    /// Flags indicating what particular type of colliders should be excluded from the scene query.
    pub flags: collider::QueryFilterFlags,
    /// If set, only colliders with collision groups compatible with this one will
    /// be included in the scene query.
    pub groups: Option<collider::InteractionGroups>,
    /// If set, this collider will be excluded from the scene query.
    pub exclude_collider: Option<Handle<Node>>,
    /// If set, any collider attached to this rigid-body will be excluded from the scene query.
    pub exclude_rigid_body: Option<Handle<Node>>,
    /// If set, any collider for which this closure returns false will be excluded from the scene query.
    pub predicate: Option<&'a dyn Fn(Handle<Node>, &collider::Collider) -> bool>,
}

/// The result of a time-of-impact (TOI) computation.
#[derive(Copy, Clone, Debug)]
pub struct TOI {
    /// The time at which the objects touch.
    pub toi: f32,
    /// The local-space closest point on the first shape at the time of impact.
    ///
    /// Undefined if `status` is `Penetrating`.
    pub witness1: Point2<f32>,
    /// The local-space closest point on the second shape at the time of impact.
    ///
    /// Undefined if `status` is `Penetrating`.
    pub witness2: Point2<f32>,
    /// The local-space outward normal on the first shape at the time of impact.
    ///
    /// Undefined if `status` is `Penetrating`.
    pub normal1: UnitVector2<f32>,
    /// The local-space outward normal on the second shape at the time of impact.
    ///
    /// Undefined if `status` is `Penetrating`.
    pub normal2: UnitVector2<f32>,
    /// The way the time-of-impact computation algorithm terminated.
    pub status: collider::TOIStatus,
}

impl PhysicsWorld {
    /// Creates a new instance of the physics world.
    pub(crate) fn new() -> Self {
        Self {
            enabled: true.into(),
            pipeline: PhysicsPipeline::new(),
            gravity: Vector2::new(0.0, -9.81).into(),
            integration_parameters: IntegrationParameters::default().into(),
            broad_phase: DefaultBroadPhase::new(),
            narrow_phase: NarrowPhase::new(),
            ccd_solver: CCDSolver::new(),
            islands: IslandManager::new(),
            bodies: RigidBodySet::new(),
            colliders: ColliderSet::new(),
            joints: Container {
                set: ImpulseJointSet::new(),
                map: Default::default(),
            },
            multibody_joints: Container {
                set: MultibodyJointSet::new(),
                map: Default::default(),
            },
            event_handler: Box::new(()),
            performance_statistics: Default::default(),
            debug_render_pipeline: Default::default(),
        }
    }

    /// Update the physics pipeline with a timestep of the given length.
    ///
    /// * `dt`: The amount of time that has passed since the previous update.
    ///   This may be overriden by [`PhysicsWorld::integration_parameters`] if
    ///   `integration_parameters.dt` is `Some`, in which case that value is used
    ///   instead of this argument.
    /// * `dt_enabled`: If this is true then `dt` is used as usual, but if this is false
    ///   then both the `dt` argument and `integration_parameters.dt` are ignored and
    ///   a `dt` of zero is used instead, freezing all physics. This corresponds to the
    ///   [`GraphUpdateSwitches::physics_dt`](crate::scene::graph::GraphUpdateSwitches::physics_dt).
    pub(crate) fn update(&mut self, dt: f32, dt_enabled: bool) {
        let time = instant::Instant::now();
        let parameter_dt = self.integration_parameters.dt;
        let parameter_dt = if parameter_dt == Some(0.0) {
            None
        } else {
            parameter_dt
        };
        let dt = if dt_enabled {
            parameter_dt.unwrap_or(dt)
        } else {
            0.0
        };

        if *self.enabled {
            let integration_parameters = rapier2d::dynamics::IntegrationParameters {
                dt,
                min_ccd_dt: self.integration_parameters.min_ccd_dt,
                contact_damping_ratio: self.integration_parameters.contact_damping_ratio,
                contact_natural_frequency: self.integration_parameters.contact_natural_frequency,
                joint_natural_frequency: self.integration_parameters.joint_natural_frequency,
                joint_damping_ratio: self.integration_parameters.joint_damping_ratio,
                warmstart_coefficient: self.integration_parameters.warmstart_coefficient,
                length_unit: self.integration_parameters.length_unit,
                normalized_allowed_linear_error: self.integration_parameters.allowed_linear_error,
                normalized_max_corrective_velocity: self
                    .integration_parameters
                    .normalized_max_corrective_velocity,
                normalized_prediction_distance: self.integration_parameters.prediction_distance,
                num_solver_iterations: self.integration_parameters.num_solver_iterations,
                num_internal_pgs_iterations: self
                    .integration_parameters
                    .num_internal_pgs_iterations,
                num_internal_stabilization_iterations: self
                    .integration_parameters
                    .num_internal_stabilization_iterations,
                min_island_size: self.integration_parameters.min_island_size as usize,
                max_ccd_substeps: self.integration_parameters.max_ccd_substeps as usize,
            };

            self.pipeline.step(
                &self.gravity,
                &integration_parameters,
                &mut self.islands,
                &mut self.broad_phase,
                &mut self.narrow_phase,
                &mut self.bodies,
                &mut self.colliders,
                &mut self.joints.set,
                &mut self.multibody_joints.set,
                &mut self.ccd_solver,
                &(),
                &*self.event_handler,
            );
        }

        self.performance_statistics.step_time += instant::Instant::now() - time;
    }

    pub(crate) fn add_body(&mut self, owner: Handle<Node>, mut body: RigidBody) -> RigidBodyHandle {
        body.user_data = owner.encode_to_u128();
        self.bodies.insert(body)
    }

    pub(crate) fn remove_body(&mut self, handle: RigidBodyHandle) {
        self.bodies.remove(
            handle,
            &mut self.islands,
            &mut self.colliders,
            &mut self.joints.set,
            &mut self.multibody_joints.set,
            true,
        );
    }

    pub(crate) fn add_collider(
        &mut self,
        owner: Handle<Node>,
        parent_body: RigidBodyHandle,
        mut collider: Collider,
    ) -> ColliderHandle {
        collider.user_data = owner.encode_to_u128();
        self.colliders
            .insert_with_parent(collider, parent_body, &mut self.bodies)
    }

    pub(crate) fn remove_collider(&mut self, handle: ColliderHandle) -> bool {
        self.colliders
            .remove(handle, &mut self.islands, &mut self.bodies, false)
            .is_some()
    }

    pub(crate) fn add_joint(
        &mut self,
        owner: Handle<Node>,
        body1: RigidBodyHandle,
        body2: RigidBodyHandle,
        params: GenericJoint,
    ) -> ImpulseJointHandle {
        let handle = self.joints.set.insert(body1, body2, params, false);
        self.joints.map.insert(handle, owner);
        handle
    }

    pub(crate) fn remove_joint(&mut self, handle: ImpulseJointHandle) {
        if self.joints.set.remove(handle, false).is_some() {
            assert!(self.joints.map.remove_by_key(&handle).is_some());
        }
    }

    /// Draws physics world. Very useful for debugging, it allows you to see where are
    /// rigid bodies, which colliders they have and so on.
    pub fn draw(&self, context: &mut SceneDrawingContext) {
        self.debug_render_pipeline.safe_lock().render(
            context,
            &self.bodies,
            &self.colliders,
            &self.joints.set,
            &self.multibody_joints.set,
            &self.narrow_phase,
        );
    }

    /// Casts a ray with given options.
    pub fn cast_ray<S: QueryResultsStorage>(&self, opts: RayCastOptions, query_buffer: &mut S) {
        let time = instant::Instant::now();

        let query = self.broad_phase.as_query_pipeline(
            &DefaultQueryDispatcher,
            &self.bodies,
            &self.colliders,
            rapier2d::pipeline::QueryFilter::new().groups(InteractionGroups::new(
                u32_to_group(opts.groups.memberships.0),
                u32_to_group(opts.groups.filter.0),
            )),
        );

        query_buffer.clear();
        let ray = Ray::new(
            opts.ray_origin,
            opts.ray_direction
                .try_normalize(f32::EPSILON)
                .unwrap_or_default(),
        );
        for (_, collider, intersection) in query.intersect_ray(ray, opts.max_len, true) {
            query_buffer.push(Intersection {
                collider: Handle::decode_from_u128(collider.user_data),
                normal: intersection.normal,
                position: ray.point_at(intersection.time_of_impact),
                feature: intersection.feature.into(),
                toi: intersection.time_of_impact,
            });
        }
        if opts.sort_results {
            query_buffer.sort_intersections_by(|a, b| {
                if a.toi > b.toi {
                    Ordering::Greater
                } else if a.toi < b.toi {
                    Ordering::Less
                } else {
                    Ordering::Equal
                }
            })
        }

        self.performance_statistics.total_ray_cast_time.set(
            self.performance_statistics.total_ray_cast_time.get()
                + (instant::Instant::now() - time),
        );
    }

    /// Casts a shape at a constant linear velocity and retrieve the first collider it hits.
    ///
    /// This is similar to ray-casting except that we are casting a whole shape instead of just a
    /// point (the ray origin). In the resulting `TOI`, witness and normal 1 refer to the world
    /// collider, and are in world space.
    ///
    /// # Parameters
    ///
    /// * `graph` - a reference to the scene graph.
    /// * `shape` - The shape to cast.
    /// * `shape_pos` - The initial position of the shape to cast.
    /// * `shape_vel` - The constant velocity of the shape to cast (i.e. the cast direction).
    /// * `max_toi` - The maximum time-of-impact that can be reported by this cast. This effectively
    ///   limits the distance traveled by the shape to `shapeVel.norm() * maxToi`.
    /// * `stop_at_penetration` - If set to `false`, the linear shape-cast won’t immediately stop if
    ///   the shape is penetrating another shape at its starting point **and** its trajectory is such
    ///   that it’s on a path to exist that penetration state.
    /// * `filter`: set of rules used to determine which collider is taken into account by this scene
    ///   query.
    pub fn cast_shape(
        &self,
        graph: &Graph,
        shape: &dyn Shape,
        shape_pos: &Isometry2<f32>,
        shape_vel: &Vector2<f32>,
        max_toi: f32,
        stop_at_penetration: bool,
        filter: QueryFilter,
    ) -> Option<(Handle<Node>, TOI)> {
        let predicate = |handle: ColliderHandle, _: &Collider| -> bool {
            if let Some(pred) = filter.predicate {
                let h = Handle::decode_from_u128(self.colliders.get(handle).unwrap().user_data);
                pred(
                    h,
                    graph.node(h).component_ref::<collider::Collider>().unwrap(),
                )
            } else {
                true
            }
        };

        let filter = rapier2d::pipeline::QueryFilter {
            flags: rapier2d::pipeline::QueryFilterFlags::from_bits(filter.flags.bits()).unwrap(),
            groups: filter.groups.map(|g| {
                InteractionGroups::new(u32_to_group(g.memberships.0), u32_to_group(g.filter.0))
            }),
            exclude_collider: filter
                .exclude_collider
                .and_then(|h| graph.try_get_of_type::<dim2::collider::Collider>(h).ok())
                .map(|c| c.native.get()),
            exclude_rigid_body: filter
                .exclude_collider
                .and_then(|h| graph.try_get_of_type::<dim2::rigidbody::RigidBody>(h).ok())
                .map(|c| c.native.get()),
            predicate: Some(&predicate),
        };

        let query = self.broad_phase.as_query_pipeline(
            &DefaultQueryDispatcher,
            &self.bodies,
            &self.colliders,
            filter,
        );

        let opts = ShapeCastOptions {
            max_time_of_impact: max_toi,
            target_distance: 0.0,
            stop_at_penetration,
            compute_impact_geometry_on_penetration: true,
        };

        query
            .cast_shape(shape_pos, shape_vel, shape, opts)
            .map(|(handle, toi)| {
                (
                    Handle::decode_from_u128(self.colliders.get(handle).unwrap().user_data),
                    TOI {
                        toi: toi.time_of_impact,
                        witness1: toi.witness1,
                        witness2: toi.witness2,
                        normal1: toi.normal1,
                        normal2: toi.normal2,
                        status: toi.status.into(),
                    },
                )
            })
    }

    pub(crate) fn set_rigid_body_position(
        &mut self,
        rigid_body: &scene::dim2::rigidbody::RigidBody,
        new_global_transform: &Matrix4<f32>,
    ) {
        if let Some(native) = self.bodies.get_mut(rigid_body.native.get()) {
            native.set_position(
                isometry_from_global_transform(new_global_transform),
                // Do not wake up body, it is too expensive and must be done **only** by explicit
                // `wake_up` call!
                false,
            );
        }
    }

    pub(crate) fn sync_rigid_body_node(
        &mut self,
        rigid_body: &mut scene::dim2::rigidbody::RigidBody,
        parent_transform: Matrix4<f32>,
    ) {
        if *self.enabled {
            if let Some(native) = self.bodies.get(rigid_body.native.get()) {
                if native.body_type() != RigidBodyType::Fixed {
                    let local_transform: Matrix4<f32> = parent_transform
                        .try_inverse()
                        .unwrap_or_else(Matrix4::identity)
                        * isometry2_to_mat4(native.position());

                    let new_local_rotation = UnitQuaternion::from_matrix_eps(
                        &local_transform.basis(),
                        f32::EPSILON,
                        16,
                        UnitQuaternion::identity(),
                    );
                    let new_x = local_transform[12];
                    let new_y = local_transform[13];

                    // Do not touch local transform if position/rotation is not changing. This will
                    // prevent redundant update of its global transform, which in its turn save some
                    // CPU cycles.
                    let local_transform = rigid_body.local_transform();
                    let current_position = **local_transform.position();
                    if current_position.x != new_x
                        || current_position.y != new_y
                        || **local_transform.rotation() != new_local_rotation
                    {
                        rigid_body
                            .local_transform_mut()
                            // Keep the Z, since it can be used for layers in 2D.
                            .set_position(Vector3::new(new_x, new_y, current_position.z))
                            .set_rotation(new_local_rotation);
                    }

                    rigid_body
                        .lin_vel
                        .set_value_with_flags(*native.linvel(), VariableFlags::MODIFIED);
                    rigid_body
                        .ang_vel
                        .set_value_with_flags(native.angvel(), VariableFlags::MODIFIED);
                    rigid_body.sleeping = native.is_sleeping();
                }
            }
        }
    }

    pub(crate) fn sync_to_rigid_body_node(
        &mut self,
        handle: Handle<Node>,
        rigid_body_node: &scene::dim2::rigidbody::RigidBody,
    ) {
        if !rigid_body_node.is_globally_enabled() {
            self.remove_body(rigid_body_node.native.get());
            rigid_body_node.native.set(Default::default());
            return;
        }

        // Important notes!
        // 1) `get_mut` is **very** expensive because it forces physics engine to recalculate contacts
        //    and a lot of other stuff, this is why we need `anything_changed` flag.
        if rigid_body_node.native.get() != RigidBodyHandle::invalid() {
            let mut actions = rigid_body_node.actions.safe_lock();
            if rigid_body_node.need_sync_model() || !actions.is_empty() {
                if let Some(native) = self.bodies.get_mut(rigid_body_node.native.get()) {
                    // Sync native rigid body's properties with scene node's in case if they
                    // were changed by user.
                    rigid_body_node
                        .body_type
                        .try_sync_model(|v| native.set_body_type(v.into(), false));
                    rigid_body_node
                        .lin_vel
                        .try_sync_model(|v| native.set_linvel(v, true));
                    rigid_body_node
                        .ang_vel
                        .try_sync_model(|v| native.set_angvel(v, true));
                    rigid_body_node.mass.try_sync_model(|v| {
                        native.set_additional_mass(v, true);
                    });
                    rigid_body_node
                        .lin_damping
                        .try_sync_model(|v| native.set_linear_damping(v));
                    rigid_body_node
                        .ang_damping
                        .try_sync_model(|v| native.set_angular_damping(v));
                    rigid_body_node
                        .ccd_enabled
                        .try_sync_model(|v| native.enable_ccd(v));
                    rigid_body_node.can_sleep.try_sync_model(|v| {
                        if v {
                            *native.activation_mut() = RigidBodyActivation::active();
                        } else {
                            *native.activation_mut() = RigidBodyActivation::cannot_sleep();
                        };
                    });
                    rigid_body_node
                        .translation_locked
                        .try_sync_model(|v| native.lock_translations(v, false));
                    rigid_body_node.rotation_locked.try_sync_model(|v| {
                        native.set_enabled_rotations(!v, !v, !v, false);
                    });
                    rigid_body_node
                        .dominance
                        .try_sync_model(|v| native.set_dominance_group(v));
                    rigid_body_node
                        .gravity_scale
                        .try_sync_model(|v| native.set_gravity_scale(v, false));

                    // We must reset any forces applied at previous update step, otherwise physics engine
                    // will keep pushing the rigid body infinitely.
                    if rigid_body_node.reset_forces.replace(false) {
                        native.reset_forces(false);
                        native.reset_torques(false);
                    }

                    while let Some(action) = actions.pop_front() {
                        match action {
                            ApplyAction::Force(force) => {
                                native.add_force(force, false);
                                rigid_body_node.reset_forces.set(true);
                            }
                            ApplyAction::Torque(torque) => {
                                native.add_torque(torque, false);
                                rigid_body_node.reset_forces.set(true);
                            }
                            ApplyAction::ForceAtPoint { force, point } => {
                                native.add_force_at_point(force, Point2::from(point), false);
                                rigid_body_node.reset_forces.set(true);
                            }
                            ApplyAction::Impulse(impulse) => native.apply_impulse(impulse, false),
                            ApplyAction::TorqueImpulse(impulse) => {
                                native.apply_torque_impulse(impulse, false)
                            }
                            ApplyAction::ImpulseAtPoint { impulse, point } => {
                                native.apply_impulse_at_point(impulse, Point2::from(point), false)
                            }
                            ApplyAction::WakeUp => native.wake_up(true),
                            ApplyAction::NextTranslation(position) => {
                                native.set_next_kinematic_translation(position)
                            }
                            ApplyAction::NextRotation(rotation) => {
                                native.set_next_kinematic_rotation(rotation)
                            }
                            ApplyAction::NextPosition(position) => {
                                native.set_next_kinematic_position(position)
                            }
                        }
                    }
                }
            }
        } else {
            let mut builder = RigidBodyBuilder::new(rigid_body_node.body_type().into())
                .pose(isometry_from_global_transform(
                    &rigid_body_node.global_transform(),
                ))
                .ccd_enabled(rigid_body_node.is_ccd_enabled())
                .additional_mass(rigid_body_node.mass())
                .angvel(*rigid_body_node.ang_vel)
                .linvel(*rigid_body_node.lin_vel)
                .linear_damping(*rigid_body_node.lin_damping)
                .angular_damping(*rigid_body_node.ang_damping)
                .can_sleep(rigid_body_node.is_can_sleep())
                .dominance_group(rigid_body_node.dominance())
                .gravity_scale(rigid_body_node.gravity_scale());

            if rigid_body_node.is_translation_locked() {
                builder = builder.lock_translations();
            }

            let mut body = builder.build();

            body.set_enabled_rotations(
                !rigid_body_node.is_rotation_locked(),
                !rigid_body_node.is_rotation_locked(),
                !rigid_body_node.is_rotation_locked(),
                false,
            );

            rigid_body_node.native.set(self.add_body(handle, body));

            Log::writeln(
                MessageKind::Information,
                format!(
                    "Native rigid body was created for node {}",
                    rigid_body_node.name()
                ),
            );
        }
    }

    pub(crate) fn sync_to_collider_node(
        &mut self,
        nodes: &NodePool,
        handle: Handle<Node>,
        collider_node: &scene::dim2::collider::Collider,
    ) {
        if !collider_node.is_globally_enabled() {
            self.remove_collider(collider_node.native.get());
            collider_node.native.set(Default::default());
            return;
        }

        let anything_changed = collider_node.needs_sync_model();

        // Important notes!
        // 1) The collider node may lack backing native physics collider in case if it
        //    is not attached to a rigid body.
        // 2) `get_mut` is **very** expensive because it forces physics engine to recalculate contacts
        //    and a lot of other stuff, this is why we need `anything_changed` flag.
        if collider_node.native.get() != ColliderHandle::invalid() {
            if anything_changed {
                if let Some(native) = self.colliders.get_mut(collider_node.native.get()) {
                    collider_node
                        .restitution
                        .try_sync_model(|v| native.set_restitution(v));
                    collider_node.collision_groups.try_sync_model(|v| {
                        native.set_collision_groups(InteractionGroups::new(
                            u32_to_group(v.memberships.0),
                            u32_to_group(v.filter.0),
                        ))
                    });
                    collider_node.solver_groups.try_sync_model(|v| {
                        native.set_solver_groups(InteractionGroups::new(
                            u32_to_group(v.memberships.0),
                            u32_to_group(v.filter.0),
                        ))
                    });
                    collider_node
                        .friction
                        .try_sync_model(|v| native.set_friction(v));
                    collider_node
                        .is_sensor
                        .try_sync_model(|v| native.set_sensor(v));
                    collider_node
                        .friction_combine_rule
                        .try_sync_model(|v| native.set_friction_combine_rule(v.into()));
                    collider_node
                        .restitution_combine_rule
                        .try_sync_model(|v| native.set_restitution_combine_rule(v.into()));
                    let mut remove_collider = false;
                    collider_node.shape.try_sync_model(|v| {
                        let inv_global_transform = isometric_global_transform(nodes, handle)
                            .try_inverse()
                            .unwrap_or_default();

                        if let Some(shape) =
                            collider_shape_into_native_shape(&v, inv_global_transform, nodes)
                        {
                            native.set_shape(shape);
                        } else {
                            remove_collider = true;
                        }
                    });
                    if remove_collider {
                        self.remove_collider(collider_node.native.get());
                        collider_node.native.set(ColliderHandle::invalid());
                    }
                }
            }
        } else if let Ok(parent_body) =
            nodes.try_get_component_of_type::<dim2::rigidbody::RigidBody>(collider_node.parent())
        {
            if parent_body.native.get() != RigidBodyHandle::invalid() {
                let rigid_body_native = parent_body.native.get();
                let inv_global_transform = isometric_global_transform(nodes, handle)
                    .try_inverse()
                    .unwrap();
                if let Some(shape) = collider_shape_into_native_shape(
                    collider_node.shape(),
                    inv_global_transform,
                    nodes,
                ) {
                    let mut builder = ColliderBuilder::new(shape)
                        .position(Isometry2 {
                            rotation: UnitComplex::from_angle(
                                collider_node.local_transform().rotation().euler_angles().2,
                            ),
                            translation: Translation2 {
                                vector: collider_node.local_transform().position().xy(),
                            },
                        })
                        .friction(collider_node.friction())
                        .restitution(collider_node.restitution())
                        .collision_groups(InteractionGroups::new(
                            u32_to_group(collider_node.collision_groups().memberships.0),
                            u32_to_group(collider_node.collision_groups().filter.0),
                        ))
                        .friction_combine_rule(collider_node.friction_combine_rule().into())
                        .restitution_combine_rule(collider_node.restitution_combine_rule().into())
                        .solver_groups(InteractionGroups::new(
                            u32_to_group(collider_node.solver_groups().memberships.0),
                            u32_to_group(collider_node.solver_groups().filter.0),
                        ))
                        .sensor(collider_node.is_sensor());

                    if let Some(density) = collider_node.density() {
                        builder = builder.density(density);
                    }

                    let native_handle =
                        self.add_collider(handle, rigid_body_native, builder.build());

                    collider_node.native.set(native_handle);

                    Log::writeln(
                        MessageKind::Information,
                        format!(
                            "Native collider was created for node {}",
                            collider_node.name()
                        ),
                    );
                }
            }
        }
    }

    pub(crate) fn sync_to_joint_node(
        &mut self,
        nodes: &NodePool,
        handle: Handle<Node>,
        joint: &scene::dim2::joint::Joint,
    ) {
        if !joint.is_globally_enabled() {
            self.remove_joint(joint.native.get());
            joint.native.set(ImpulseJointHandle(Default::default()));
            return;
        }

        if let Some(native) = self.joints.set.get_mut(joint.native.get(), false) {
            joint.body1.try_sync_model(|v| {
                if let Ok(rigid_body_node) = nodes.try_get(v) {
                    native.body1 = rigid_body_node.native.get();
                }
            });
            joint.body2.try_sync_model(|v| {
                if let Ok(rigid_body_node) = nodes.try_get(v) {
                    native.body2 = rigid_body_node.native.get();
                }
            });
            joint.params.try_sync_model(|v| {
                native.data =
                    // Preserve local frames.
                    convert_joint_params(v, native.data.local_frame1, native.data.local_frame2)
            });
            joint.motor_params.try_sync_model(|v|{
                // The free axis is defined to be the x axis for both prismatic and ball joints in fyrox.
                // If you want the joint to translate / rotate along a different axis, you can rotate the joint itself.
                let joint_axis = match joint.params.get_value_ref(){
                    JointParams::PrismaticJoint(_) => JointAxis::LinX,
                    JointParams::BallJoint(_) => JointAxis::AngX,
                    _ => {
                        Log::warn("Try to modify motor parameters for unsupported joint type, this operation will be ignored.");
                        return;
                    }
                };
                // Force based motor model is better in the Fyrox's context
                native.data.set_motor_model(joint_axis, rapier2d::prelude::MotorModel::ForceBased);
                let JointMotorParams {
                    target_vel,
                    target_pos,
                    stiffness,
                    damping,
                    max_force
                } = v;
                native.data.set_motor(joint_axis, target_pos, target_vel, stiffness, damping);
                native.data.set_motor_max_force(joint_axis, max_force);
                // wake up the bodies connected to the joint to ensure they respond to the motor changes immediately
                // however, the rigid bodies may fall asleep any time later unless Joint::set_motor_* functions are called periodically,
                // or the rigid bodies are set to cannot sleep
                let Some(body1) = self.bodies.get_mut(native.body1) else {
                    return;
                };
                body1.wake_up(true);
                let Some(body2) = self.bodies.get_mut(native.body2) else {
                    return;
                };
                body2.wake_up(true);
            });
            joint.contacts_enabled.try_sync_model(|v| {
                native.data.set_contacts_enabled(v);
            });
            let mut local_frames = joint.local_frames.borrow_mut();
            if local_frames.is_none() {
                if let (Ok(body1), Ok(body2)) =
                    (nodes.try_get(joint.body1()), nodes.try_get(joint.body2()))
                {
                    let (local_frame1, local_frame2) = calculate_local_frames(joint, body1, body2);
                    native.data =
                        convert_joint_params((*joint.params).clone(), local_frame1, local_frame2);
                    *local_frames = Some(JointLocalFrames::new(&local_frame1, &local_frame2));
                }
            }
        } else {
            let body1_handle = joint.body1();
            let body2_handle = joint.body2();
            let params = joint.params().clone();

            // A native joint can be created iff both rigid bodies are correctly assigned.
            if let (Ok(body1), Ok(body2)) =
                (nodes.try_get(body1_handle), nodes.try_get(body2_handle))
            {
                let native_body1 = body1.native.get();
                let native_body2 = body2.native.get();

                if self.bodies.get(native_body1).is_none()
                    || self.bodies.get(native_body2).is_none()
                {
                    // A joint may be synced before the connected bodies, this way the connected
                    // rigid bodies does not have native rigid bodies, and in this case we should
                    // simply skip the joint and initialize it on the next frame.
                    return;
                }

                // Calculate local frames first (if needed).
                let mut local_frames = joint.local_frames.borrow_mut();
                let (local_frame1, local_frame2) = local_frames
                    .clone()
                    .map(|frames| {
                        (
                            Isometry2 {
                                rotation: frames.body1.rotation,
                                translation: Translation2 {
                                    vector: frames.body1.position,
                                },
                            },
                            Isometry2 {
                                rotation: frames.body2.rotation,
                                translation: Translation2 {
                                    vector: frames.body2.position,
                                },
                            },
                        )
                    })
                    .unwrap_or_else(|| calculate_local_frames(joint, body1, body2));

                let mut native_joint = convert_joint_params(params, local_frame1, local_frame2);
                native_joint.contacts_enabled = joint.is_contacts_enabled();
                let native_handle =
                    self.add_joint(handle, native_body1, native_body2, native_joint);

                joint.native.set(native_handle);
                *local_frames = Some(JointLocalFrames::new(&local_frame1, &local_frame2));

                Log::writeln(
                    MessageKind::Information,
                    format!("Native joint was created for node {}", joint.name()),
                );
            }
        }
    }

    /// Intersections checks between regular colliders and sensor colliders
    pub(crate) fn intersections_with(
        &self,
        collider: ColliderHandle,
    ) -> impl Iterator<Item = IntersectionPair> + '_ {
        self.narrow_phase
            .intersection_pairs_with(collider)
            .filter_map(|(collider1, collider2, intersecting)| {
                Some(IntersectionPair {
                    collider1: Handle::decode_from_u128(self.colliders.get(collider1)?.user_data),
                    collider2: Handle::decode_from_u128(self.colliders.get(collider2)?.user_data),
                    has_any_active_contact: intersecting,
                })
            })
    }

    /// Contacts checks between two regular colliders
    pub(crate) fn contacts_with(
        &self,
        collider: ColliderHandle,
    ) -> impl Iterator<Item = ContactPair> + '_ {
        self.narrow_phase
            .contact_pairs_with(collider)
            .filter_map(|c| ContactPair::from_native(c, self))
    }

    /// Returns an iterator over all contact pairs generated in this frame.
    pub fn contacts(&self) -> impl Iterator<Item = ContactPair> + '_ {
        self.narrow_phase
            .contact_pairs()
            .filter_map(|c| ContactPair::from_native(c, self))
    }
}

impl Default for PhysicsWorld {
    fn default() -> Self {
        Self::new()
    }
}

impl Debug for PhysicsWorld {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(f, "PhysicsWorld")
    }
}