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use crate::math::{Isometry, Point, Real, Vector, DIM};
use crate::utils::WBasis;
use na::Unit;
#[cfg(feature = "dim2")]
use na::Vector2;
#[cfg(feature = "dim3")]
use na::Vector5;
#[derive(Copy, Clone)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
/// A joint that removes all relative motion between two bodies, except for the translations along one axis.
pub struct PrismaticJoint {
/// Where the prismatic joint is attached on the first body, expressed in the local space of the first attached body.
pub local_anchor1: Point<Real>,
/// Where the prismatic joint is attached on the second body, expressed in the local space of the second attached body.
pub local_anchor2: Point<Real>,
pub(crate) local_axis1: Unit<Vector<Real>>,
pub(crate) local_axis2: Unit<Vector<Real>>,
pub(crate) basis1: [Vector<Real>; DIM - 1],
pub(crate) basis2: [Vector<Real>; DIM - 1],
/// The impulse applied by this joint on the first body.
///
/// The impulse applied to the second body is given by `-impulse`.
#[cfg(feature = "dim3")]
pub impulse: Vector5<Real>,
/// The impulse applied by this joint on the first body.
///
/// The impulse applied to the second body is given by `-impulse`.
#[cfg(feature = "dim2")]
pub impulse: Vector2<Real>,
/// Whether or not this joint should enforce translational limits along its axis.
pub limits_enabled: bool,
/// The min an max relative position of the attached bodies along this joint's axis.
pub limits: [Real; 2],
/// The impulse applied by this joint on the first body to enforce the position limit along this joint's axis.
///
/// The impulse applied to the second body is given by `-impulse`.
pub limits_impulse: Real,
// pub motor_enabled: bool,
// pub target_motor_vel: Real,
// pub max_motor_impulse: Real,
// pub motor_impulse: Real,
}
impl PrismaticJoint {
/// Creates a new prismatic joint with the given point of applications and axis, all expressed
/// in the local-space of the affected bodies.
#[cfg(feature = "dim2")]
pub fn new(
local_anchor1: Point<Real>,
local_axis1: Unit<Vector<Real>>,
local_anchor2: Point<Real>,
local_axis2: Unit<Vector<Real>>,
) -> Self {
Self {
local_anchor1,
local_anchor2,
local_axis1,
local_axis2,
basis1: local_axis1.orthonormal_basis(),
basis2: local_axis2.orthonormal_basis(),
impulse: na::zero(),
limits_enabled: false,
limits: [-Real::MAX, Real::MAX],
limits_impulse: 0.0,
// motor_enabled: false,
// target_motor_vel: 0.0,
// max_motor_impulse: Real::MAX,
// motor_impulse: 0.0,
}
}
/// Creates a new prismatic joint with the given point of applications and axis, all expressed
/// in the local-space of the affected bodies.
///
/// The local tangent are vector orthogonal to the local axis. It is used to compute a basis orthonormal
/// to the joint's axis. If this tangent is set to zero, te orthonormal basis will be automatically
/// computed arbitrarily.
#[cfg(feature = "dim3")]
pub fn new(
local_anchor1: Point<Real>,
local_axis1: Unit<Vector<Real>>,
local_tangent1: Vector<Real>,
local_anchor2: Point<Real>,
local_axis2: Unit<Vector<Real>>,
local_tangent2: Vector<Real>,
) -> Self {
let basis1 = if let Some(local_bitangent1) =
Unit::try_new(local_axis1.cross(&local_tangent1), 1.0e-3)
{
[
local_bitangent1.into_inner(),
local_bitangent1.cross(&local_axis1),
]
} else {
local_axis1.orthonormal_basis()
};
let basis2 = if let Some(local_bitangent2) =
Unit::try_new(local_axis2.cross(&local_tangent2), 2.0e-3)
{
[
local_bitangent2.into_inner(),
local_bitangent2.cross(&local_axis2),
]
} else {
local_axis2.orthonormal_basis()
};
Self {
local_anchor1,
local_anchor2,
local_axis1,
local_axis2,
basis1,
basis2,
impulse: na::zero(),
limits_enabled: false,
limits: [-Real::MAX, Real::MAX],
limits_impulse: 0.0,
// motor_enabled: false,
// target_motor_vel: 0.0,
// max_motor_impulse: Real::MAX,
// motor_impulse: 0.0,
}
}
/// The local axis of this joint, expressed in the local-space of the first attached body.
pub fn local_axis1(&self) -> Unit<Vector<Real>> {
self.local_axis1
}
/// The local axis of this joint, expressed in the local-space of the second attached body.
pub fn local_axis2(&self) -> Unit<Vector<Real>> {
self.local_axis2
}
// FIXME: precompute this?
#[cfg(feature = "dim2")]
pub(crate) fn local_frame1(&self) -> Isometry<Real> {
use na::{Matrix2, Rotation2, UnitComplex};
let mat = Matrix2::from_columns(&[self.local_axis1.into_inner(), self.basis1[0]]);
let rotmat = Rotation2::from_matrix_unchecked(mat);
let rotation = UnitComplex::from_rotation_matrix(&rotmat);
let translation = self.local_anchor1.coords.into();
Isometry::from_parts(translation, rotation)
}
// FIXME: precompute this?
#[cfg(feature = "dim2")]
pub(crate) fn local_frame2(&self) -> Isometry<Real> {
use na::{Matrix2, Rotation2, UnitComplex};
let mat = Matrix2::from_columns(&[self.local_axis2.into_inner(), self.basis2[0]]);
let rotmat = Rotation2::from_matrix_unchecked(mat);
let rotation = UnitComplex::from_rotation_matrix(&rotmat);
let translation = self.local_anchor2.coords.into();
Isometry::from_parts(translation, rotation)
}
// FIXME: precompute this?
#[cfg(feature = "dim3")]
pub(crate) fn local_frame1(&self) -> Isometry<Real> {
use na::{Matrix3, Rotation3, UnitQuaternion};
let mat = Matrix3::from_columns(&[
self.local_axis1.into_inner(),
self.basis1[0],
self.basis1[1],
]);
let rotmat = Rotation3::from_matrix_unchecked(mat);
let rotation = UnitQuaternion::from_rotation_matrix(&rotmat);
let translation = self.local_anchor1.coords.into();
Isometry::from_parts(translation, rotation)
}
// FIXME: precompute this?
#[cfg(feature = "dim3")]
pub(crate) fn local_frame2(&self) -> Isometry<Real> {
use na::{Matrix3, Rotation3, UnitQuaternion};
let mat = Matrix3::from_columns(&[
self.local_axis2.into_inner(),
self.basis2[0],
self.basis2[1],
]);
let rotmat = Rotation3::from_matrix_unchecked(mat);
let rotation = UnitQuaternion::from_rotation_matrix(&rotmat);
let translation = self.local_anchor2.coords.into();
Isometry::from_parts(translation, rotation)
}
}