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use crate::dynamics::{IntegrationParameters, RevoluteJoint, RigidBody};
use crate::math::{AngularInertia, Isometry, Point, Rotation, Vector};
use crate::utils::WAngularInertia;
use na::Unit;
#[derive(Debug)]
pub(crate) struct RevolutePositionConstraint {
position1: usize,
position2: usize,
im1: f32,
im2: f32,
ii1: AngularInertia<f32>,
ii2: AngularInertia<f32>,
lin_inv_lhs: f32,
ang_inv_lhs: AngularInertia<f32>,
local_anchor1: Point<f32>,
local_anchor2: Point<f32>,
local_axis1: Unit<Vector<f32>>,
local_axis2: Unit<Vector<f32>>,
}
impl RevolutePositionConstraint {
pub fn from_params(rb1: &RigidBody, rb2: &RigidBody, cparams: &RevoluteJoint) -> Self {
let ii1 = rb1.world_inv_inertia_sqrt.squared();
let ii2 = rb2.world_inv_inertia_sqrt.squared();
let im1 = rb1.mass_properties.inv_mass;
let im2 = rb2.mass_properties.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_anchor1: cparams.local_anchor1,
local_anchor2: cparams.local_anchor2,
local_axis1: cparams.local_axis1,
local_axis2: cparams.local_axis2,
position1: rb1.active_set_offset,
position2: rb2.active_set_offset,
}
}
pub fn solve(&self, params: &IntegrationParameters, positions: &mut [Isometry<f32>]) {
let mut position1 = positions[self.position1 as usize];
let mut position2 = positions[self.position2 as usize];
let axis1 = position1 * self.local_axis1;
let axis2 = position2 * self.local_axis2;
let delta_rot =
Rotation::rotation_between_axis(&axis1, &axis2).unwrap_or(Rotation::identity());
let ang_error = delta_rot.scaled_axis() * params.joint_erp;
let ang_impulse = self.ang_inv_lhs.transform_vector(ang_error);
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 * self.local_anchor1;
let anchor2 = position2 * self.local_anchor2;
let delta_tra = anchor2 - anchor1;
let lin_error = delta_tra * params.joint_erp;
let lin_impulse = self.lin_inv_lhs * lin_error;
position1.translation.vector += self.im1 * lin_impulse;
position2.translation.vector -= self.im2 * lin_impulse;
positions[self.position1 as usize] = position1;
positions[self.position2 as usize] = position2;
}
}
#[derive(Debug)]
pub(crate) struct RevolutePositionGroundConstraint {
position2: usize,
anchor1: Point<f32>,
local_anchor2: Point<f32>,
axis1: Unit<Vector<f32>>,
local_axis2: Unit<Vector<f32>>,
}
impl RevolutePositionGroundConstraint {
pub fn from_params(
rb1: &RigidBody,
rb2: &RigidBody,
cparams: &RevoluteJoint,
flipped: bool,
) -> Self {
let anchor1;
let local_anchor2;
let axis1;
let local_axis2;
if flipped {
anchor1 = rb1.predicted_position * cparams.local_anchor2;
local_anchor2 = cparams.local_anchor1;
axis1 = rb1.predicted_position * cparams.local_axis2;
local_axis2 = cparams.local_axis1;
} else {
anchor1 = rb1.predicted_position * cparams.local_anchor1;
local_anchor2 = cparams.local_anchor2;
axis1 = rb1.predicted_position * cparams.local_axis1;
local_axis2 = cparams.local_axis2;
};
Self {
anchor1,
local_anchor2,
axis1,
local_axis2,
position2: rb2.active_set_offset,
}
}
pub fn solve(&self, params: &IntegrationParameters, positions: &mut [Isometry<f32>]) {
let mut position2 = positions[self.position2 as usize];
let axis2 = position2 * self.local_axis2;
let delta_rot =
Rotation::scaled_rotation_between_axis(&axis2, &self.axis1, params.joint_erp)
.unwrap_or(Rotation::identity());
position2.rotation = delta_rot * position2.rotation;
let anchor2 = position2 * self.local_anchor2;
let delta_tra = anchor2 - self.anchor1;
let lin_error = delta_tra * params.joint_erp;
position2.translation.vector -= lin_error;
positions[self.position2 as usize] = position2;
}
}
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