Files
rapier/src/pipeline/physics_pipeline.rs
2021-03-30 17:11:52 +02:00

560 lines
20 KiB
Rust

//! Physics pipeline structures.
use crate::counters::Counters;
#[cfg(not(feature = "parallel"))]
use crate::dynamics::IslandSolver;
use crate::dynamics::{CCDSolver, IntegrationParameters, JointSet, RigidBodySet};
#[cfg(feature = "parallel")]
use crate::dynamics::{JointGraphEdge, ParallelIslandSolver as IslandSolver};
use crate::geometry::{
BroadPhase, BroadPhasePairEvent, ColliderPair, ColliderSet, ContactManifoldIndex, NarrowPhase,
};
use crate::math::{Real, Vector};
use crate::pipeline::{EventHandler, PhysicsHooks};
/// The physics pipeline, responsible for stepping the whole physics simulation.
///
/// This structure only contains temporary data buffers. It can be dropped and replaced by a fresh
/// copy at any time. For performance reasons it is recommended to reuse the same physics pipeline
/// instance to benefit from the cached data.
///
/// Rapier relies on a time-stepping scheme. Its force computations
/// uses two solvers:
/// - A velocity based solver based on PGS which computes forces for contact and joint constraints.
/// - A position based solver based on non-linear PGS which performs constraint stabilization (i.e. correction of errors like penetrations).
// NOTE: this contains only workspace data, so there is no point in making this serializable.
pub struct PhysicsPipeline {
/// Counters used for benchmarking only.
pub counters: Counters,
manifold_indices: Vec<Vec<ContactManifoldIndex>>,
joint_constraint_indices: Vec<Vec<ContactManifoldIndex>>,
broadphase_collider_pairs: Vec<ColliderPair>,
broad_phase_events: Vec<BroadPhasePairEvent>,
solvers: Vec<IslandSolver>,
}
impl Default for PhysicsPipeline {
fn default() -> Self {
PhysicsPipeline::new()
}
}
#[allow(dead_code)]
fn check_pipeline_send_sync() {
fn do_test<T: Sync>() {}
do_test::<PhysicsPipeline>();
}
impl PhysicsPipeline {
/// Initializes a new physics pipeline.
pub fn new() -> PhysicsPipeline {
PhysicsPipeline {
counters: Counters::new(false),
solvers: Vec::new(),
manifold_indices: Vec::new(),
joint_constraint_indices: Vec::new(),
broadphase_collider_pairs: Vec::new(),
broad_phase_events: Vec::new(),
}
}
fn detect_collisions(
&mut self,
integration_parameters: &IntegrationParameters,
broad_phase: &mut BroadPhase,
narrow_phase: &mut NarrowPhase,
bodies: &mut RigidBodySet,
colliders: &mut ColliderSet,
hooks: &dyn PhysicsHooks,
events: &dyn EventHandler,
handle_user_changes: bool,
) {
self.counters.stages.collision_detection_time.resume();
self.counters.cd.broad_phase_time.resume();
// Update broad-phase.
self.broad_phase_events.clear();
self.broadphase_collider_pairs.clear();
broad_phase.update(
integration_parameters.prediction_distance,
colliders,
&mut self.broad_phase_events,
);
self.counters.cd.broad_phase_time.pause();
self.counters.cd.narrow_phase_time.resume();
// Update narrow-phase.
if handle_user_changes {
narrow_phase.handle_user_changes(colliders, bodies, events);
}
narrow_phase.register_pairs(colliders, bodies, &self.broad_phase_events, events);
narrow_phase.compute_contacts(
integration_parameters.prediction_distance,
bodies,
colliders,
hooks,
events,
);
narrow_phase.compute_intersections(bodies, colliders, hooks, events);
// Clear colliders modification flags.
colliders.clear_modified_colliders();
self.counters.cd.narrow_phase_time.pause();
self.counters.stages.collision_detection_time.pause();
}
fn solve_position_constraints(
&mut self,
integration_parameters: &IntegrationParameters,
bodies: &mut RigidBodySet,
) {
#[cfg(not(feature = "parallel"))]
{
enable_flush_to_zero!();
for island_id in 0..bodies.num_islands() {
self.solvers[island_id].solve_position_constraints(
island_id,
&mut self.counters,
integration_parameters,
bodies,
)
}
}
}
fn build_islands_and_solve_velocity_constraints(
&mut self,
gravity: &Vector<Real>,
integration_parameters: &IntegrationParameters,
narrow_phase: &mut NarrowPhase,
bodies: &mut RigidBodySet,
colliders: &mut ColliderSet,
joints: &mut JointSet,
) {
self.counters.stages.island_construction_time.resume();
bodies.update_active_set_with_contacts(
colliders,
narrow_phase,
joints.joint_graph(),
integration_parameters.min_island_size,
);
self.counters.stages.island_construction_time.pause();
if self.manifold_indices.len() < bodies.num_islands() {
self.manifold_indices
.resize(bodies.num_islands(), Vec::new());
}
if self.joint_constraint_indices.len() < bodies.num_islands() {
self.joint_constraint_indices
.resize(bodies.num_islands(), Vec::new());
}
let mut manifolds = Vec::new();
narrow_phase.select_active_contacts(bodies, &mut manifolds, &mut self.manifold_indices);
joints.select_active_interactions(bodies, &mut self.joint_constraint_indices);
self.counters.stages.update_time.resume();
bodies.foreach_active_dynamic_body_mut_internal(|_, b| {
b.update_world_mass_properties();
b.add_gravity(*gravity)
});
self.counters.stages.update_time.pause();
self.counters.stages.solver_time.resume();
if self.solvers.len() < bodies.num_islands() {
self.solvers
.resize_with(bodies.num_islands(), IslandSolver::new);
}
#[cfg(not(feature = "parallel"))]
{
enable_flush_to_zero!();
for island_id in 0..bodies.num_islands() {
self.solvers[island_id].init_constraints_and_solve_velocity_constraints(
island_id,
&mut self.counters,
integration_parameters,
bodies,
&mut manifolds[..],
&self.manifold_indices[island_id],
joints.joints_mut(),
&self.joint_constraint_indices[island_id],
)
}
}
#[cfg(feature = "parallel")]
{
use crate::geometry::ContactManifold;
use rayon::prelude::*;
use std::sync::atomic::Ordering;
let num_islands = bodies.num_islands();
let solvers = &mut self.solvers[..num_islands];
let bodies = &std::sync::atomic::AtomicPtr::new(bodies as *mut _);
let manifolds = &std::sync::atomic::AtomicPtr::new(&mut manifolds as *mut _);
let joints = &std::sync::atomic::AtomicPtr::new(joints.joints_vec_mut() as *mut _);
let manifold_indices = &self.manifold_indices[..];
let joint_constraint_indices = &self.joint_constraint_indices[..];
rayon::scope(|scope| {
enable_flush_to_zero!();
solvers
.par_iter_mut()
.enumerate()
.for_each(|(island_id, solver)| {
let bodies: &mut RigidBodySet =
unsafe { std::mem::transmute(bodies.load(Ordering::Relaxed)) };
let manifolds: &mut Vec<&mut ContactManifold> =
unsafe { std::mem::transmute(manifolds.load(Ordering::Relaxed)) };
let joints: &mut Vec<JointGraphEdge> =
unsafe { std::mem::transmute(joints.load(Ordering::Relaxed)) };
solver.solve_island(
scope,
island_id,
integration_parameters,
bodies,
manifolds,
&manifold_indices[island_id],
joints,
&joint_constraint_indices[island_id],
is_last_substep,
)
});
});
}
self.counters.stages.solver_time.pause();
}
fn run_ccd_motion_clamping(
&mut self,
integration_parameters: &IntegrationParameters,
bodies: &mut RigidBodySet,
colliders: &mut ColliderSet,
narrow_phase: &NarrowPhase,
ccd_solver: &mut CCDSolver,
events: &dyn EventHandler,
) {
self.counters.ccd.toi_computation_time.start();
// Handle CCD
let impacts = ccd_solver.predict_impacts_at_next_positions(
integration_parameters.dt,
bodies,
colliders,
narrow_phase,
events,
);
ccd_solver.clamp_motions(integration_parameters.dt, bodies, &impacts);
self.counters.ccd.toi_computation_time.pause();
}
fn advance_to_final_positions(
&mut self,
bodies: &mut RigidBodySet,
colliders: &mut ColliderSet,
clear_forces: bool,
) {
// Set the rigid-bodies and kinematic bodies to their final position.
bodies.foreach_active_body_mut_internal(|_, rb| {
if rb.is_kinematic() {
rb.linvel = na::zero();
rb.angvel = na::zero();
}
if clear_forces {
rb.force = na::zero();
rb.torque = na::zero();
}
rb.position = rb.next_position;
rb.update_colliders_positions(colliders);
});
}
fn interpolate_kinematic_velocities(
&mut self,
integration_parameters: &IntegrationParameters,
bodies: &mut RigidBodySet,
) {
// Update kinematic bodies velocities.
// TODO: what is the best place for this? It should at least be
// located before the island computation because we test the velocity
// there to determine if this kinematic body should wake-up dynamic
// bodies it is touching.
bodies.foreach_active_kinematic_body_mut_internal(|_, body| {
body.compute_velocity_from_next_position(integration_parameters.inv_dt());
});
}
/// Executes one timestep of the physics simulation.
pub fn step(
&mut self,
gravity: &Vector<Real>,
integration_parameters: &IntegrationParameters,
broad_phase: &mut BroadPhase,
narrow_phase: &mut NarrowPhase,
bodies: &mut RigidBodySet,
colliders: &mut ColliderSet,
joints: &mut JointSet,
ccd_solver: &mut CCDSolver,
hooks: &dyn PhysicsHooks,
events: &dyn EventHandler,
) {
self.counters.reset();
self.counters.step_started();
colliders.handle_user_changes(bodies);
bodies.handle_user_changes(colliders);
self.detect_collisions(
integration_parameters,
broad_phase,
narrow_phase,
bodies,
colliders,
hooks,
events,
true,
);
let mut remaining_time = integration_parameters.dt;
let mut integration_parameters = *integration_parameters;
let (ccd_is_enabled, mut remaining_substeps) =
if integration_parameters.max_ccd_substeps == 0 {
(false, 1)
} else {
(true, integration_parameters.max_ccd_substeps)
};
while remaining_substeps > 0 {
// If there are more than one CCD substep, we need to split
// the timestep into multiple intervals. First, estimate the
// size of the time slice we will integrate for this substep.
//
// Note that we must do this now, before the constrains resolution
// because we need to use the correct timestep length for the
// integration of external forces.
//
// If there is only one or zero CCD substep, there is no need
// to split the timetsep interval. So we can just skip this part.
if ccd_is_enabled && remaining_substeps > 1 {
// NOTE: Take forces into account when updating the bodies CCD activation flags
// these forces have not been integrated to the body's velocity yet.
let ccd_active = ccd_solver.update_ccd_active_flags(bodies, remaining_time, true);
let first_impact = if ccd_active {
ccd_solver.find_first_impact(remaining_time, bodies, colliders, narrow_phase)
} else {
None
};
if let Some(toi) = first_impact {
let original_interval = remaining_time / (remaining_substeps as Real);
if toi < original_interval {
integration_parameters.dt = original_interval;
} else {
integration_parameters.dt =
toi + (remaining_time - toi) / (remaining_substeps as Real);
}
remaining_substeps -= 1;
} else {
// No impact, don't do any other substep after this one.
integration_parameters.dt = remaining_time;
remaining_substeps = 0;
}
remaining_time -= integration_parameters.dt;
// Avoid substep length that are too small.
if remaining_time <= integration_parameters.min_ccd_dt {
integration_parameters.dt += remaining_time;
remaining_substeps = 0;
}
} else {
integration_parameters.dt = remaining_time;
remaining_time = 0.0;
remaining_substeps = 0;
}
self.counters.ccd.num_substeps += 1;
self.interpolate_kinematic_velocities(&integration_parameters, bodies);
self.build_islands_and_solve_velocity_constraints(
gravity,
&integration_parameters,
narrow_phase,
bodies,
colliders,
joints,
);
// If CCD is enabled, execute the CCD motion clamping.
if ccd_is_enabled {
// NOTE: don't the forces into account when updating the CCD active flags because
// they have already been integrated into the velocities by the solver.
let ccd_active =
ccd_solver.update_ccd_active_flags(bodies, integration_parameters.dt, false);
if ccd_active {
self.run_ccd_motion_clamping(
&integration_parameters,
bodies,
colliders,
narrow_phase,
ccd_solver,
events,
);
}
}
// NOTE: we need to run the position solver **after** the
// CCD motion clamping because otherwise the clamping
// would undo the depenetration done by the position
// solver.
// This happens because our CCD use the real rigid-body
// velocities instead of just interpolating between
// isometries.
self.solve_position_constraints(&integration_parameters, bodies);
let clear_forces = remaining_substeps == 0;
self.advance_to_final_positions(bodies, colliders, clear_forces);
self.detect_collisions(
&integration_parameters,
broad_phase,
narrow_phase,
bodies,
colliders,
hooks,
events,
false,
);
bodies.modified_inactive_set.clear();
}
self.counters.step_completed();
}
}
#[cfg(test)]
mod test {
use crate::dynamics::{IntegrationParameters, JointSet, RigidBodyBuilder, RigidBodySet};
use crate::geometry::{BroadPhase, ColliderBuilder, ColliderSet, NarrowPhase};
use crate::math::Vector;
use crate::pipeline::PhysicsPipeline;
#[test]
fn kinematic_and_static_contact_crash() {
let mut colliders = ColliderSet::new();
let mut joints = JointSet::new();
let mut pipeline = PhysicsPipeline::new();
let mut bf = BroadPhase::new();
let mut nf = NarrowPhase::new();
let mut bodies = RigidBodySet::new();
let rb = RigidBodyBuilder::new_static().build();
let h1 = bodies.insert(rb.clone());
let co = ColliderBuilder::ball(10.0).build();
colliders.insert(co.clone(), h1, &mut bodies);
// The same but with a kinematic body.
let rb = RigidBodyBuilder::new_kinematic().build();
let h2 = bodies.insert(rb.clone());
colliders.insert(co, h2, &mut bodies);
pipeline.step(
&Vector::zeros(),
&IntegrationParameters::default(),
&mut bf,
&mut nf,
&mut bodies,
&mut colliders,
&mut joints,
&(),
&(),
);
}
#[test]
fn rigid_body_removal_before_step() {
let mut colliders = ColliderSet::new();
let mut joints = JointSet::new();
let mut pipeline = PhysicsPipeline::new();
let mut bf = BroadPhase::new();
let mut nf = NarrowPhase::new();
let mut bodies = RigidBodySet::new();
// Check that removing the body right after inserting it works.
// We add two dynamic bodies, one kinematic body and one static body before removing
// them. This include a non-regression test where deleting a kimenatic body crashes.
let rb = RigidBodyBuilder::new_dynamic().build();
let h1 = bodies.insert(rb.clone());
let h2 = bodies.insert(rb.clone());
// The same but with a kinematic body.
let rb = RigidBodyBuilder::new_kinematic().build();
let h3 = bodies.insert(rb.clone());
// The same but with a static body.
let rb = RigidBodyBuilder::new_static().build();
let h4 = bodies.insert(rb.clone());
let to_delete = [h1, h2, h3, h4];
for h in &to_delete {
bodies.remove(*h, &mut colliders, &mut joints);
}
pipeline.step(
&Vector::zeros(),
&IntegrationParameters::default(),
&mut bf,
&mut nf,
&mut bodies,
&mut colliders,
&mut joints,
&(),
&(),
);
}
#[cfg(feature = "serde")]
#[test]
fn rigid_body_removal_snapshot_handle_determinism() {
let mut colliders = ColliderSet::new();
let mut joints = JointSet::new();
let mut bodies = RigidBodySet::new();
let rb = RigidBodyBuilder::new_dynamic().build();
let h1 = bodies.insert(rb.clone());
let h2 = bodies.insert(rb.clone());
let h3 = bodies.insert(rb.clone());
bodies.remove(h1, &mut colliders, &mut joints);
bodies.remove(h3, &mut colliders, &mut joints);
bodies.remove(h2, &mut colliders, &mut joints);
let ser_bodies = bincode::serialize(&bodies).unwrap();
let mut bodies2: RigidBodySet = bincode::deserialize(&ser_bodies).unwrap();
let h1a = bodies.insert(rb.clone());
let h2a = bodies.insert(rb.clone());
let h3a = bodies.insert(rb.clone());
let h1b = bodies2.insert(rb.clone());
let h2b = bodies2.insert(rb.clone());
let h3b = bodies2.insert(rb.clone());
assert_eq!(h1a, h1b);
assert_eq!(h2a, h2b);
assert_eq!(h3a, h3b);
}
}