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use super::AnyPositionConstraint;
use crate::dynamics::{IntegrationParameters, RigidBodySet};
use crate::geometry::{ContactManifold, KinematicsCategory};
use crate::math::{
AngularInertia, Isometry, Point, Rotation, Translation, Vector, MAX_MANIFOLD_POINTS,
};
use crate::utils::{WAngularInertia, WCross, WDot};
pub(crate) struct PositionGroundConstraint {
pub rb2: usize,
// NOTE: the points are relative to the center of masses.
pub p1: [Point<f32>; MAX_MANIFOLD_POINTS],
pub local_p2: [Point<f32>; MAX_MANIFOLD_POINTS],
pub n1: Vector<f32>,
pub num_contacts: u8,
pub radius: f32,
pub im2: f32,
pub ii2: AngularInertia<f32>,
pub erp: f32,
pub max_linear_correction: f32,
}
impl PositionGroundConstraint {
pub fn generate(
params: &IntegrationParameters,
manifold: &ContactManifold,
bodies: &RigidBodySet,
out_constraints: &mut Vec<AnyPositionConstraint>,
push: bool,
) {
let mut rb1 = &bodies[manifold.body_pair.body1];
let mut rb2 = &bodies[manifold.body_pair.body2];
let flip = !rb2.is_dynamic();
let local_n1;
let local_n2;
let delta1;
let delta2;
if flip {
std::mem::swap(&mut rb1, &mut rb2);
local_n1 = manifold.local_n2;
local_n2 = manifold.local_n1;
delta1 = &manifold.delta2;
delta2 = &manifold.delta1;
} else {
local_n1 = manifold.local_n1;
local_n2 = manifold.local_n2;
delta1 = &manifold.delta1;
delta2 = &manifold.delta2;
};
let coll_pos1 = rb1.position * delta1;
let shift1 = local_n1 * -manifold.kinematics.radius1;
let shift2 = local_n2 * -manifold.kinematics.radius2;
let n1 = coll_pos1 * local_n1;
let radius =
manifold.kinematics.radius1 + manifold.kinematics.radius2 /* - params.allowed_linear_error */;
for (l, manifold_contacts) in manifold
.active_contacts()
.chunks(MAX_MANIFOLD_POINTS)
.enumerate()
{
let mut p1 = [Point::origin(); MAX_MANIFOLD_POINTS];
let mut local_p2 = [Point::origin(); MAX_MANIFOLD_POINTS];
if flip {
// Don't forget that we already swapped rb1 and rb2 above.
// So if we flip, only manifold_contacts[k].{local_p1,local_p2} have to
// be swapped.
for k in 0..manifold_contacts.len() {
p1[k] = coll_pos1 * (manifold_contacts[k].local_p2 + shift1);
local_p2[k] = delta2 * (manifold_contacts[k].local_p1 + shift2);
}
} else {
for k in 0..manifold_contacts.len() {
p1[k] = coll_pos1 * (manifold_contacts[k].local_p1 + shift1);
local_p2[k] = delta2 * (manifold_contacts[k].local_p2 + shift2);
}
}
let constraint = PositionGroundConstraint {
rb2: rb2.active_set_offset,
p1,
local_p2,
n1,
radius,
im2: rb2.mass_properties.inv_mass,
ii2: rb2.world_inv_inertia_sqrt.squared(),
num_contacts: manifold_contacts.len() as u8,
erp: params.erp,
max_linear_correction: params.max_linear_correction,
};
if push {
if manifold.kinematics.category == KinematicsCategory::PointPoint {
out_constraints.push(AnyPositionConstraint::NongroupedPointPointGround(
constraint,
));
} else {
out_constraints.push(AnyPositionConstraint::NongroupedPlanePointGround(
constraint,
));
}
} else {
if manifold.kinematics.category == KinematicsCategory::PointPoint {
out_constraints[manifold.constraint_index + l] =
AnyPositionConstraint::NongroupedPointPointGround(constraint);
} else {
out_constraints[manifold.constraint_index + l] =
AnyPositionConstraint::NongroupedPlanePointGround(constraint);
}
}
}
}
pub fn solve_point_point(
&self,
params: &IntegrationParameters,
positions: &mut [Isometry<f32>],
) {
// FIXME: can we avoid most of the multiplications by pos1/pos2?
// Compute jacobians.
let mut pos2 = positions[self.rb2];
let allowed_err = params.allowed_linear_error;
let target_dist = self.radius - allowed_err;
for k in 0..self.num_contacts as usize {
let p1 = self.p1[k];
let p2 = pos2 * self.local_p2[k];
let dpos = p2 - p1;
let sqdist = dpos.norm_squared();
// NOTE: only works for the point-point case.
if sqdist < target_dist * target_dist {
let dist = sqdist.sqrt();
let n = dpos / dist;
let err = ((dist - target_dist) * self.erp).max(-self.max_linear_correction);
let dp2 = p2.coords - pos2.translation.vector;
let gcross2 = -dp2.gcross(n);
let ii_gcross2 = self.ii2.transform_vector(gcross2);
// Compute impulse.
let inv_r = self.im2 + gcross2.gdot(ii_gcross2);
let impulse = err / inv_r;
// Apply impulse.
let tra2 = Translation::from(n * (-impulse * self.im2));
let rot2 = Rotation::new(ii_gcross2 * impulse);
pos2 = Isometry::from_parts(tra2 * pos2.translation, rot2 * pos2.rotation);
}
}
positions[self.rb2] = pos2;
}
pub fn solve_plane_point(
&self,
params: &IntegrationParameters,
positions: &mut [Isometry<f32>],
) {
// FIXME: can we avoid most of the multiplications by pos1/pos2?
// Compute jacobians.
let mut pos2 = positions[self.rb2];
let allowed_err = params.allowed_linear_error;
let target_dist = self.radius - allowed_err;
for k in 0..self.num_contacts as usize {
let n1 = self.n1;
let p1 = self.p1[k];
let p2 = pos2 * self.local_p2[k];
let dpos = p2 - p1;
let dist = dpos.dot(&n1);
if dist < target_dist {
let err = ((dist - target_dist) * self.erp).max(-self.max_linear_correction);
let dp2 = p2.coords - pos2.translation.vector;
let gcross2 = -dp2.gcross(n1);
let ii_gcross2 = self.ii2.transform_vector(gcross2);
// Compute impulse.
let inv_r = self.im2 + gcross2.gdot(ii_gcross2);
let impulse = err / inv_r;
// Apply impulse.
let tra2 = Translation::from(n1 * (-impulse * self.im2));
let rot2 = Rotation::new(ii_gcross2 * impulse);
pos2 = Isometry::from_parts(tra2 * pos2.translation, rot2 * pos2.rotation);
}
}
positions[self.rb2] = pos2;
}
}
|
