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use crate::dynamics::{IntegrationParameters, PrismaticJoint, RigidBody};
use crate::math::{AngularInertia, Isometry, Point, Real, Rotation, Vector};
use crate::utils::WAngularInertia;
use na::Unit;
#[derive(Debug)]
pub(crate) struct PrismaticPositionConstraint {
position1: usize,
position2: usize,
im1: Real,
im2: Real,
ii1: AngularInertia<Real>,
ii2: AngularInertia<Real>,
lin_inv_lhs: Real,
ang_inv_lhs: AngularInertia<Real>,
limits: [Real; 2],
local_frame1: Isometry<Real>,
local_frame2: Isometry<Real>,
local_axis1: Unit<Vector<Real>>,
local_axis2: Unit<Vector<Real>>,
}
impl PrismaticPositionConstraint {
pub fn from_params(rb1: &RigidBody, rb2: &RigidBody, cparams: &PrismaticJoint) -> Self {
let ii1 = rb1.effective_world_inv_inertia_sqrt.squared();
let ii2 = rb2.effective_world_inv_inertia_sqrt.squared();
let im1 = rb1.effective_inv_mass;
let im2 = rb2.effective_inv_mass;
let lin_inv_lhs = 1.0 / (im1 + im2);
let ang_inv_lhs = (ii1 + ii2).inverse();
Self {
im1,
im2,
ii1,
ii2,
lin_inv_lhs,
ang_inv_lhs,
local_frame1: cparams.local_frame1(),
local_frame2: cparams.local_frame2(),
local_axis1: cparams.local_axis1,
local_axis2: cparams.local_axis2,
position1: rb1.active_set_offset,
position2: rb2.active_set_offset,
limits: cparams.limits,
}
}
pub fn solve(&self, params: &IntegrationParameters, positions: &mut [Isometry<Real>]) {
let mut position1 = positions[self.position1 as usize];
let mut position2 = positions[self.position2 as usize];
let frame1 = position1 * self.local_frame1;
let frame2 = position2 * self.local_frame2;
let ang_err = frame2.rotation * frame1.rotation.inverse();
#[cfg(feature = "dim2")]
let ang_impulse = self
.ang_inv_lhs
.transform_vector(ang_err.angle() * params.joint_erp);
#[cfg(feature = "dim3")]
let ang_impulse = self
.ang_inv_lhs
.transform_vector(ang_err.scaled_axis() * params.joint_erp);
position1.rotation =
Rotation::new(self.ii1.transform_vector(ang_impulse)) * position1.rotation;
position2.rotation =
Rotation::new(self.ii2.transform_vector(-ang_impulse)) * position2.rotation;
let anchor1 = position1 * Point::from(self.local_frame1.translation.vector);
let anchor2 = position2 * Point::from(self.local_frame2.translation.vector);
let axis1 = position1 * self.local_axis1;
let dpos = anchor2 - anchor1;
let limit_err = dpos.dot(&axis1);
let mut err = dpos - *axis1 * limit_err;
if limit_err < self.limits[0] {
err += *axis1 * (limit_err - self.limits[0]);
} else if limit_err > self.limits[1] {
err += *axis1 * (limit_err - self.limits[1]);
}
let impulse = err * (self.lin_inv_lhs * params.joint_erp);
position1.translation.vector += self.im1 * impulse;
position2.translation.vector -= self.im2 * impulse;
positions[self.position1 as usize] = position1;
positions[self.position2 as usize] = position2;
}
}
#[derive(Debug)]
pub(crate) struct PrismaticPositionGroundConstraint {
position2: usize,
frame1: Isometry<Real>,
local_frame2: Isometry<Real>,
axis1: Unit<Vector<Real>>,
local_axis2: Unit<Vector<Real>>,
limits: [Real; 2],
}
impl PrismaticPositionGroundConstraint {
pub fn from_params(
rb1: &RigidBody,
rb2: &RigidBody,
cparams: &PrismaticJoint,
flipped: bool,
) -> Self {
let frame1;
let local_frame2;
let axis1;
let local_axis2;
if flipped {
frame1 = rb1.predicted_position * cparams.local_frame2();
local_frame2 = cparams.local_frame1();
axis1 = rb1.predicted_position * cparams.local_axis2;
local_axis2 = cparams.local_axis1;
} else {
frame1 = rb1.predicted_position * cparams.local_frame1();
local_frame2 = cparams.local_frame2();
axis1 = rb1.predicted_position * cparams.local_axis1;
local_axis2 = cparams.local_axis2;
};
Self {
frame1,
local_frame2,
axis1,
local_axis2,
position2: rb2.active_set_offset,
limits: cparams.limits,
}
}
pub fn solve(&self, params: &IntegrationParameters, positions: &mut [Isometry<Real>]) {
let mut position2 = positions[self.position2 as usize];
let frame2 = position2 * self.local_frame2;
let ang_err = frame2.rotation * self.frame1.rotation.inverse();
position2.rotation = ang_err.powf(-params.joint_erp) * position2.rotation;
let anchor1 = Point::from(self.frame1.translation.vector);
let anchor2 = position2 * Point::from(self.local_frame2.translation.vector);
let dpos = anchor2 - anchor1;
let limit_err = dpos.dot(&self.axis1);
let mut err = dpos - *self.axis1 * limit_err;
if limit_err < self.limits[0] {
err += *self.axis1 * (limit_err - self.limits[0]);
} else if limit_err > self.limits[1] {
err += *self.axis1 * (limit_err - self.limits[1]);
}
let impulse = err * params.joint_erp;
position2.translation.vector -= impulse;
positions[self.position2 as usize] = position2;
}
}