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use na::{Real, Unit};
use ncollide::query::ContactKinematic;
use math::Vector;
use object::{BodyHandle, BodySet};
use solver::IntegrationParameters;
/// A generic non-linear position constraint.
pub struct GenericNonlinearConstraint<N: Real> {
/// The first body affected by the constraint.
pub body1: BodyHandle,
/// The second body affected by the constraint.
pub body2: BodyHandle,
/// Whether this constraint affects the bodies translation or orientation.
pub is_angular: bool,
// FIXME: rename ndofs1?
/// Number of degree of freedom of the first body.
pub dim1: usize,
/// Number of degree of freedom of the second body.
pub dim2: usize,
/// Index of the first entry of the constraint jacobian multiplied by the inverse mass of the first body.
pub wj_id1: usize,
/// Index of the first entry of the constraint jacobian multiplied by the inverse mass of the second body.
pub wj_id2: usize,
/// The target position change this constraint must apply.
pub rhs: N,
/// The scaling parameter of the SOR-prox method.
pub r: N,
}
impl<N: Real> GenericNonlinearConstraint<N> {
/// Initialize a new nonlinear constraint.
pub fn new(
body1: BodyHandle,
body2: BodyHandle,
is_angular: bool,
dim1: usize,
dim2: usize,
wj_id1: usize,
wj_id2: usize,
rhs: N,
r: N,
) -> Self {
GenericNonlinearConstraint {
body1,
body2,
is_angular,
dim1,
dim2,
wj_id1,
wj_id2,
rhs,
r,
}
}
}
/// Implemented by structures that generate non-linear constraints.
pub trait NonlinearConstraintGenerator<N: Real> {
/// Maximum of non-linear position constraint this generater needs to output.
fn num_position_constraints(&self, bodies: &BodySet<N>) -> usize;
/// Generate the `i`-th position constraint of this generator.
fn position_constraint(
&self,
params: &IntegrationParameters<N>,
i: usize,
bodies: &mut BodySet<N>,
jacobians: &mut [N],
) -> Option<GenericNonlinearConstraint<N>>;
}
/// A non-linear position-based non-penetration constraint.
pub struct NonlinearUnilateralConstraint<N: Real> {
/// The scaling parameter of the SOR-prox method.
pub r: N,
/// The target position change this constraint must apply.
pub rhs: N,
/// Number of degree of freedom of the first body.
pub ndofs1: usize,
/// The first body affected by the constraint.
pub body1: BodyHandle,
/// Number of degree of freedom of the second body.
pub ndofs2: usize,
/// The second body affected by the constraint.
pub body2: BodyHandle,
/// The kinematic information used to update the contact location.
pub kinematic: ContactKinematic<N>,
/// The contact normal on the local space of `self.body1`.
pub normal1: Unit<Vector<N>>,
/// The contact normal on the local space of `self.body1`.
pub normal2: Unit<Vector<N>>,
}
impl<N: Real> NonlinearUnilateralConstraint<N> {
/// Create a new nonlinear position-based non-penetration constraint.
pub fn new(
body1: BodyHandle,
ndofs1: usize,
body2: BodyHandle,
ndofs2: usize,
normal1: Unit<Vector<N>>,
normal2: Unit<Vector<N>>,
kinematic: ContactKinematic<N>,
) -> Self {
let r = N::zero();
let rhs = N::zero();
NonlinearUnilateralConstraint {
r,
rhs,
ndofs1,
body1,
ndofs2,
body2,
kinematic,
normal1,
normal2,
}
}
}
/// A non-linear position constraint generator to enforce multibody joint limits.
pub struct MultibodyJointLimitsNonlinearConstraintGenerator {
link: BodyHandle,
}
impl MultibodyJointLimitsNonlinearConstraintGenerator {
/// Creates the constraint generator from the given multibody link.
pub fn new(link: BodyHandle) -> Self {
MultibodyJointLimitsNonlinearConstraintGenerator { link }
}
}
impl<N: Real> NonlinearConstraintGenerator<N> for MultibodyJointLimitsNonlinearConstraintGenerator {
fn num_position_constraints(&self, bodies: &BodySet<N>) -> usize {
if let Some(link) = bodies.multibody_link(self.link) {
link.joint().num_position_constraints()
} else {
0
}
}
fn position_constraint(
&self,
_: &IntegrationParameters<N>,
i: usize,
bodies: &mut BodySet<N>,
jacobians: &mut [N],
) -> Option<GenericNonlinearConstraint<N>> {
if let Some(link) = bodies.multibody_link(self.link) {
link.joint().position_constraint(i, &link, 0, jacobians)
} else {
None
}
}
}