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rapier/src/geometry/contact_pair.rs
2025-10-17 12:59:19 +02:00

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#[cfg(doc)]
use super::Collider;
use super::CollisionEvent;
use crate::dynamics::{RigidBodyHandle, RigidBodySet};
use crate::geometry::{ColliderHandle, ColliderSet, Contact, ContactManifold};
use crate::math::{Point, Real, TangentImpulse, Vector};
use crate::pipeline::EventHandler;
use crate::prelude::CollisionEventFlags;
use crate::utils::SimdRealCopy;
use parry::math::{SIMD_WIDTH, SimdReal};
use parry::query::ContactManifoldsWorkspace;
bitflags::bitflags! {
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
/// Flags affecting the behavior of the constraints solver for a given contact manifold.
pub struct SolverFlags: u32 {
/// The constraint solver will take this contact manifold into
/// account for force computation.
const COMPUTE_IMPULSES = 0b001;
}
}
impl Default for SolverFlags {
fn default() -> Self {
SolverFlags::COMPUTE_IMPULSES
}
}
#[derive(Copy, Clone, Debug)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
/// A single contact between two collider.
pub struct ContactData {
/// 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: Real,
/// The friction impulse along the vector orthonormal to the contact normal, applied to the first
/// collider's rigid-body.
pub tangent_impulse: TangentImpulse<Real>,
/// The impulse retained for warmstarting the next simulation step.
pub warmstart_impulse: Real,
/// The friction impulse retained for warmstarting the next simulation step.
pub warmstart_tangent_impulse: TangentImpulse<Real>,
/// The twist impulse retained for warmstarting the next simulation step.
#[cfg(feature = "dim3")]
pub warmstart_twist_impulse: Real,
}
impl Default for ContactData {
fn default() -> Self {
Self {
impulse: 0.0,
tangent_impulse: na::zero(),
warmstart_impulse: 0.0,
warmstart_tangent_impulse: na::zero(),
#[cfg(feature = "dim3")]
warmstart_twist_impulse: 0.0,
}
}
}
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
#[derive(Copy, Clone, Debug)]
/// The description of all the contacts between a pair of colliders.
pub struct IntersectionPair {
/// Are the colliders intersecting?
pub intersecting: bool,
/// Was a `CollisionEvent::Started` emitted for this collider?
pub(crate) start_event_emitted: bool,
}
impl IntersectionPair {
pub(crate) fn new() -> Self {
Self {
intersecting: false,
start_event_emitted: false,
}
}
pub(crate) fn emit_start_event(
&mut self,
bodies: &RigidBodySet,
colliders: &ColliderSet,
collider1: ColliderHandle,
collider2: ColliderHandle,
events: &dyn EventHandler,
) {
self.start_event_emitted = true;
events.handle_collision_event(
bodies,
colliders,
CollisionEvent::Started(collider1, collider2, CollisionEventFlags::SENSOR),
None,
);
}
pub(crate) fn emit_stop_event(
&mut self,
bodies: &RigidBodySet,
colliders: &ColliderSet,
collider1: ColliderHandle,
collider2: ColliderHandle,
events: &dyn EventHandler,
) {
self.start_event_emitted = false;
events.handle_collision_event(
bodies,
colliders,
CollisionEvent::Stopped(collider1, collider2, CollisionEventFlags::SENSOR),
None,
);
}
}
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
#[derive(Clone)]
/// All contact information between two colliding colliders.
///
/// When two colliders are touching, a ContactPair stores all the contact points, normals,
/// and forces between them. You can access this through the narrow phase or in event handlers.
///
/// ## Contact manifolds
///
/// The contacts are organized into "manifolds" - groups of contact points that share similar
/// properties (like being on the same face). Most collider pairs have 1 manifold, but complex
/// shapes may have multiple.
///
/// ## Use cases
///
/// - Reading contact normals for custom physics
/// - Checking penetration depth
/// - Analyzing impact forces
/// - Implementing custom contact responses
///
/// # Example
/// ```
/// # use rapier3d::prelude::*;
/// # use rapier3d::geometry::ContactPair;
/// # let contact_pair = ContactPair::default();
/// if let Some((manifold, contact)) = contact_pair.find_deepest_contact() {
/// println!("Deepest penetration: {}", -contact.dist);
/// println!("Contact normal: {:?}", manifold.data.normal);
/// }
/// ```
pub struct ContactPair {
/// The first collider involved in the contact pair.
pub collider1: ColliderHandle,
/// The second collider involved in the contact pair.
pub collider2: ColliderHandle,
/// The set of contact manifolds between the two colliders.
///
/// All contact manifold contain themselves contact points between the colliders.
/// Note that contact points in the contact manifold do not take into account the
/// [`Collider::contact_skin`] which only affects the constraint solver and the
/// [`SolverContact`].
pub manifolds: Vec<ContactManifold>,
/// Is there any active contact in this contact pair?
pub has_any_active_contact: bool,
/// Was a `CollisionEvent::Started` emitted for this collider?
pub(crate) start_event_emitted: bool,
pub(crate) workspace: Option<ContactManifoldsWorkspace>,
}
impl Default for ContactPair {
fn default() -> Self {
Self::new(ColliderHandle::invalid(), ColliderHandle::invalid())
}
}
impl ContactPair {
pub(crate) fn new(collider1: ColliderHandle, collider2: ColliderHandle) -> Self {
Self {
collider1,
collider2,
has_any_active_contact: false,
manifolds: Vec::new(),
start_event_emitted: false,
workspace: None,
}
}
/// Clears all the contacts of this contact pair.
pub fn clear(&mut self) {
self.manifolds.clear();
self.has_any_active_contact = false;
self.workspace = None;
}
/// The total impulse (force × time) applied by all contacts.
///
/// This is the accumulated force that pushed the colliders apart.
/// Useful for determining impact strength.
pub fn total_impulse(&self) -> Vector<Real> {
self.manifolds
.iter()
.map(|m| m.total_impulse() * m.data.normal)
.sum()
}
/// The total magnitude of all contact impulses (sum of lengths, not length of sum).
///
/// This is what's compared against `contact_force_event_threshold`.
pub fn total_impulse_magnitude(&self) -> Real {
self.manifolds
.iter()
.fold(0.0, |a, m| a + m.total_impulse())
}
/// Finds the strongest contact impulse and its direction.
///
/// Returns `(magnitude, normal_direction)` of the strongest individual contact.
pub fn max_impulse(&self) -> (Real, Vector<Real>) {
let mut result = (0.0, Vector::zeros());
for m in &self.manifolds {
let impulse = m.total_impulse();
if impulse > result.0 {
result = (impulse, m.data.normal);
}
}
result
}
/// Finds the contact point with the deepest penetration.
///
/// When objects overlap, this returns the contact point that's penetrating the most.
/// Useful for:
/// - Finding the "worst" overlap
/// - Determining primary contact direction
/// - Custom penetration resolution
///
/// Returns both the contact point and its parent manifold.
///
/// # Example
/// ```
/// # use rapier3d::prelude::*;
/// # use rapier3d::geometry::ContactPair;
/// # let pair = ContactPair::default();
/// if let Some((manifold, contact)) = pair.find_deepest_contact() {
/// let penetration_depth = -contact.dist; // Negative dist = penetration
/// println!("Deepest penetration: {} units", penetration_depth);
/// }
/// ```
#[profiling::function]
pub fn find_deepest_contact(&self) -> Option<(&ContactManifold, &Contact)> {
let mut deepest = None;
for m2 in &self.manifolds {
let deepest_candidate = m2.find_deepest_contact();
deepest = match (deepest, deepest_candidate) {
(_, None) => deepest,
(None, Some(c2)) => Some((m2, c2)),
(Some((m1, c1)), Some(c2)) => {
if c1.dist <= c2.dist {
Some((m1, c1))
} else {
Some((m2, c2))
}
}
}
}
deepest
}
pub(crate) fn emit_start_event(
&mut self,
bodies: &RigidBodySet,
colliders: &ColliderSet,
events: &dyn EventHandler,
) {
self.start_event_emitted = true;
events.handle_collision_event(
bodies,
colliders,
CollisionEvent::Started(self.collider1, self.collider2, CollisionEventFlags::empty()),
Some(self),
);
}
pub(crate) fn emit_stop_event(
&mut self,
bodies: &RigidBodySet,
colliders: &ColliderSet,
events: &dyn EventHandler,
) {
self.start_event_emitted = false;
events.handle_collision_event(
bodies,
colliders,
CollisionEvent::Stopped(self.collider1, self.collider2, CollisionEventFlags::empty()),
Some(self),
);
}
}
#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
/// A contact manifold between two colliders.
///
/// A contact manifold describes a set of contacts between two colliders. All the contact
/// part of the same contact manifold share the same contact normal and contact kinematics.
pub struct ContactManifoldData {
// The following are set by the narrow-phase.
/// The first rigid-body involved in this contact manifold.
pub rigid_body1: Option<RigidBodyHandle>,
/// The second rigid-body involved in this contact manifold.
pub rigid_body2: Option<RigidBodyHandle>,
// We put the following fields here to avoids reading the colliders inside of the
// contact preparation method.
/// Flags used to control some aspects of the constraints solver for this contact manifold.
pub solver_flags: SolverFlags,
/// The world-space contact normal shared by all the contact in this contact manifold.
// NOTE: read the comment of `solver_contacts` regarding serialization. It applies
// to this field as well.
pub normal: Vector<Real>,
/// The contacts that will be seen by the constraints solver for computing forces.
// NOTE: unfortunately, we can't ignore this field when serialize
// the contact manifold data. The reason is that the solver contacts
// won't be updated for sleeping bodies. So it means that for one
// frame, we won't have any solver contacts when waking up an island
// after a deserialization. Not only does this break post-snapshot
// determinism, but it will also skip constraint resolution for these
// contacts during one frame.
//
// An alternative would be to skip the serialization of `solver_contacts` and
// find a way to recompute them right after the deserialization process completes.
// However, this would be an expensive operation. And doing this efficiently as part
// of the narrow-phase update or the contact manifold collect will likely lead to tricky
// bugs too.
//
// So right now it is best to just serialize this field and keep it that way until it
// is proven to be actually problematic in real applications (in terms of snapshot size for example).
pub solver_contacts: Vec<SolverContact>,
/// The relative dominance of the bodies involved in this contact manifold.
pub relative_dominance: i16,
/// A user-defined piece of data.
pub user_data: u32,
}
/// A single solver contact.
pub type SolverContact = SolverContactGeneric<Real, 1>;
/// A group of `SIMD_WIDTH` solver contacts stored in SoA fashion for SIMD optimizations.
pub type SimdSolverContact = SolverContactGeneric<SimdReal, SIMD_WIDTH>;
/// A contact seen by the constraints solver for computing forces.
#[derive(Copy, Clone, Debug)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
#[cfg_attr(
feature = "serde-serialize",
serde(bound(serialize = "N: serde::Serialize, [u32; LANES]: serde::Serialize"))
)]
#[cfg_attr(
feature = "serde-serialize",
serde(bound(
deserialize = "N: serde::Deserialize<'de>, [u32; LANES]: serde::Deserialize<'de>"
))
)]
#[repr(C)]
#[repr(align(16))]
pub struct SolverContactGeneric<N: SimdRealCopy, const LANES: usize> {
// IMPORTANT: dont change the fields unless `SimdSolverContactRepr` is also changed.
//
// TOTAL: 11/14 = 3*4/4*4-1
/// The contact point in world-space.
pub point: Point<N>, // 2/3
/// The distance between the two original contacts points along the contact normal.
/// If negative, this is measures the penetration depth.
pub dist: N, // 1/1
/// The effective friction coefficient at this contact point.
pub friction: N, // 1/1
/// The effective restitution coefficient at this contact point.
pub restitution: N, // 1/1
/// The desired tangent relative velocity at the contact point.
///
/// This is set to zero by default. Set to a non-zero value to
/// simulate, e.g., conveyor belts.
pub tangent_velocity: Vector<N>, // 2/3
/// Impulse used to warmstart the solve for the normal constraint.
pub warmstart_impulse: N, // 1/1
/// Impulse used to warmstart the solve for the friction constraints.
pub warmstart_tangent_impulse: TangentImpulse<N>, // 1/2
/// Impulse used to warmstart the solve for the twist friction constraints.
pub warmstart_twist_impulse: N, // 1/1
/// Whether this contact existed during the last timestep.
///
/// A value of 0.0 means `false` and `1.0` means `true`.
/// This isnt a bool for optimizations purpose with SIMD.
pub is_new: N, // 1/1
/// The index of the manifold contact used to generate this solver contact.
pub(crate) contact_id: [u32; LANES], // 1/1
#[cfg(feature = "dim3")]
pub(crate) padding: [N; 1],
}
#[repr(C)]
#[repr(align(16))]
pub struct SimdSolverContactRepr {
data0: SimdReal,
data1: SimdReal,
data2: SimdReal,
#[cfg(feature = "dim3")]
data3: SimdReal,
}
// NOTE: if these assertion fail with a weird "0 - 1 would overflow" error, it means the equality doesnt hold.
static_assertions::const_assert_eq!(
align_of::<SimdSolverContactRepr>(),
align_of::<SolverContact>()
);
#[cfg(feature = "simd-is-enabled")]
static_assertions::assert_eq_size!(SimdSolverContactRepr, SolverContact);
static_assertions::const_assert_eq!(
align_of::<SimdSolverContact>(),
align_of::<[SolverContact; SIMD_WIDTH]>()
);
#[cfg(feature = "simd-is-enabled")]
static_assertions::assert_eq_size!(SimdSolverContact, [SolverContact; SIMD_WIDTH]);
impl SimdSolverContact {
#[cfg(not(feature = "simd-is-enabled"))]
pub unsafe fn gather_unchecked(contacts: &[&[SolverContact]; SIMD_WIDTH], k: usize) -> Self {
contacts[0][k]
}
#[cfg(feature = "simd-is-enabled")]
pub unsafe fn gather_unchecked(contacts: &[&[SolverContact]; SIMD_WIDTH], k: usize) -> Self {
// TODO PERF: double-check that the compiler is using simd loads and
// isnt generating useless copies.
let data_repr: &[&[SimdSolverContactRepr]; SIMD_WIDTH] =
unsafe { std::mem::transmute(contacts) };
/* NOTE: this is a manual NEON implementation. To compare with what the compiler generates with `wide`.
unsafe {
use std::arch::aarch64::*;
assert!(k < SIMD_WIDTH);
// Fetch.
let aos0_0 = vld1q_f32(&data_repr[0][k].data0.0 as *const _ as *const f32);
let aos0_1 = vld1q_f32(&data_repr[1][k].data0.0 as *const _ as *const f32);
let aos0_2 = vld1q_f32(&data_repr[2][k].data0.0 as *const _ as *const f32);
let aos0_3 = vld1q_f32(&data_repr[3][k].data0.0 as *const _ as *const f32);
let aos1_0 = vld1q_f32(&data_repr[0][k].data1.0 as *const _ as *const f32);
let aos1_1 = vld1q_f32(&data_repr[1][k].data1.0 as *const _ as *const f32);
let aos1_2 = vld1q_f32(&data_repr[2][k].data1.0 as *const _ as *const f32);
let aos1_3 = vld1q_f32(&data_repr[3][k].data1.0 as *const _ as *const f32);
let aos2_0 = vld1q_f32(&data_repr[0][k].data2.0 as *const _ as *const f32);
let aos2_1 = vld1q_f32(&data_repr[1][k].data2.0 as *const _ as *const f32);
let aos2_2 = vld1q_f32(&data_repr[2][k].data2.0 as *const _ as *const f32);
let aos2_3 = vld1q_f32(&data_repr[3][k].data2.0 as *const _ as *const f32);
// Transpose.
let a = vzip1q_f32(aos0_0, aos0_2);
let b = vzip1q_f32(aos0_1, aos0_3);
let c = vzip2q_f32(aos0_0, aos0_2);
let d = vzip2q_f32(aos0_1, aos0_3);
let soa0_0 = vzip1q_f32(a, b);
let soa0_1 = vzip2q_f32(a, b);
let soa0_2 = vzip1q_f32(c, d);
let soa0_3 = vzip2q_f32(c, d);
let a = vzip1q_f32(aos1_0, aos1_2);
let b = vzip1q_f32(aos1_1, aos1_3);
let c = vzip2q_f32(aos1_0, aos1_2);
let d = vzip2q_f32(aos1_1, aos1_3);
let soa1_0 = vzip1q_f32(a, b);
let soa1_1 = vzip2q_f32(a, b);
let soa1_2 = vzip1q_f32(c, d);
let soa1_3 = vzip2q_f32(c, d);
let a = vzip1q_f32(aos2_0, aos2_2);
let b = vzip1q_f32(aos2_1, aos2_3);
let c = vzip2q_f32(aos2_0, aos2_2);
let d = vzip2q_f32(aos2_1, aos2_3);
let soa2_0 = vzip1q_f32(a, b);
let soa2_1 = vzip2q_f32(a, b);
let soa2_2 = vzip1q_f32(c, d);
let soa2_3 = vzip2q_f32(c, d);
// Return.
std::mem::transmute([
soa0_0, soa0_1, soa0_2, soa0_3, soa1_0, soa1_1, soa1_2, soa1_3, soa2_0, soa2_1,
soa2_2, soa2_3,
])
}
*/
let aos0 = [
unsafe { data_repr[0].get_unchecked(k).data0.0 },
unsafe { data_repr[1].get_unchecked(k).data0.0 },
unsafe { data_repr[2].get_unchecked(k).data0.0 },
unsafe { data_repr[3].get_unchecked(k).data0.0 },
];
let aos1 = [
unsafe { data_repr[0].get_unchecked(k).data1.0 },
unsafe { data_repr[1].get_unchecked(k).data1.0 },
unsafe { data_repr[2].get_unchecked(k).data1.0 },
unsafe { data_repr[3].get_unchecked(k).data1.0 },
];
let aos2 = [
unsafe { data_repr[0].get_unchecked(k).data2.0 },
unsafe { data_repr[1].get_unchecked(k).data2.0 },
unsafe { data_repr[2].get_unchecked(k).data2.0 },
unsafe { data_repr[3].get_unchecked(k).data2.0 },
];
#[cfg(feature = "dim3")]
let aos3 = [
unsafe { data_repr[0].get_unchecked(k).data3.0 },
unsafe { data_repr[1].get_unchecked(k).data3.0 },
unsafe { data_repr[2].get_unchecked(k).data3.0 },
unsafe { data_repr[3].get_unchecked(k).data3.0 },
];
use crate::utils::transmute_to_wide;
let soa0 = wide::f32x4::transpose(transmute_to_wide(aos0));
let soa1 = wide::f32x4::transpose(transmute_to_wide(aos1));
let soa2 = wide::f32x4::transpose(transmute_to_wide(aos2));
#[cfg(feature = "dim3")]
let soa3 = wide::f32x4::transpose(transmute_to_wide(aos3));
#[cfg(feature = "dim2")]
return unsafe {
std::mem::transmute::<[[wide::f32x4; 4]; 3], SolverContactGeneric<SimdReal, 4>>([
soa0, soa1, soa2,
])
};
#[cfg(feature = "dim3")]
return unsafe {
std::mem::transmute::<[[wide::f32x4; 4]; 4], SolverContactGeneric<SimdReal, 4>>([
soa0, soa1, soa2, soa3,
])
};
}
}
#[cfg(feature = "simd-is-enabled")]
impl SimdSolverContact {
/// Should we treat this contact as a bouncy contact?
/// If `true`, use [`Self::restitution`].
pub fn is_bouncy(&self) -> SimdReal {
use na::{SimdPartialOrd, SimdValue};
let one = SimdReal::splat(1.0);
let zero = SimdReal::splat(0.0);
// Treat new collisions as bouncing at first, unless we have zero restitution.
let if_new = one.select(self.restitution.simd_gt(zero), zero);
// If the contact is still here one step later, it is now a resting contact.
// The exception is very high restitutions, which can never rest
let if_not_new = one.select(self.restitution.simd_ge(one), zero);
if_new.select(self.is_new.simd_ne(zero), if_not_new)
}
}
impl SolverContact {
/// Should we treat this contact as a bouncy contact?
/// If `true`, use [`Self::restitution`].
pub fn is_bouncy(&self) -> Real {
if self.is_new != 0.0 {
// Treat new collisions as bouncing at first, unless we have zero restitution.
(self.restitution > 0.0) as u32 as Real
} else {
// If the contact is still here one step later, it is now a resting contact.
// The exception is very high restitutions, which can never rest
(self.restitution >= 1.0) as u32 as Real
}
}
}
impl Default for ContactManifoldData {
fn default() -> Self {
Self::new(None, None, SolverFlags::empty())
}
}
impl ContactManifoldData {
pub(crate) fn new(
rigid_body1: Option<RigidBodyHandle>,
rigid_body2: Option<RigidBodyHandle>,
solver_flags: SolverFlags,
) -> ContactManifoldData {
Self {
rigid_body1,
rigid_body2,
solver_flags,
normal: Vector::zeros(),
solver_contacts: Vec::new(),
relative_dominance: 0,
user_data: 0,
}
}
/// Number of actives contacts, i.e., contacts that will be seen by
/// the constraints solver.
#[inline]
pub fn num_active_contacts(&self) -> usize {
self.solver_contacts.len()
}
}
/// Additional methods for the contact manifold.
pub trait ContactManifoldExt {
/// Computes the sum of all the impulses applied by contacts from this contact manifold.
fn total_impulse(&self) -> Real;
}
impl ContactManifoldExt for ContactManifold {
fn total_impulse(&self) -> Real {
self.points.iter().map(|pt| pt.data.impulse).sum()
}
}