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use crate::dynamics::SpringModel;
use crate::math::{Point, Real, Rotation, Vector};
#[derive(Copy, Clone)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
/// A joint that removes all relative linear motion between a pair of points on two bodies.
pub struct BallJoint {
/// Where the ball joint is attached on the first body, expressed in the first body local frame.
pub local_anchor1: Point<Real>,
/// Where the ball joint is attached on the first body, expressed in the first body local frame.
pub local_anchor2: Point<Real>,
/// The impulse applied by this joint on the first body.
///
/// The impulse applied to the second body is given by `-impulse`.
pub impulse: Vector<Real>,
/// The target relative angular velocity the motor will attempt to reach.
#[cfg(feature = "dim2")]
pub motor_target_vel: Real,
/// The target relative angular velocity the motor will attempt to reach.
#[cfg(feature = "dim3")]
pub motor_target_vel: Vector<Real>,
/// The target angular position of this joint, expressed as an axis-angle.
pub motor_target_pos: Rotation<Real>,
/// The motor's stiffness.
/// See the documentation of `SpringModel` for more information on this parameter.
pub motor_stiffness: Real,
/// The motor's damping.
/// See the documentation of `SpringModel` for more information on this parameter.
pub motor_damping: Real,
/// The maximal impulse the motor is able to deliver.
pub motor_max_impulse: Real,
/// The angular impulse applied by the motor.
#[cfg(feature = "dim2")]
pub motor_impulse: Real,
/// The angular impulse applied by the motor.
#[cfg(feature = "dim3")]
pub motor_impulse: Vector<Real>,
/// The spring-like model used by the motor to reach the target velocity and .
pub motor_model: SpringModel,
// Used to handle cases where the position target ends up being more than pi radians away.
pub(crate) motor_last_angle: Real,
}
impl BallJoint {
/// Creates a new Ball joint from two anchors given on the local spaces of the respective bodies.
pub fn new(local_anchor1: Point<Real>, local_anchor2: Point<Real>) -> Self {
Self::with_impulse(local_anchor1, local_anchor2, Vector::zeros())
}
pub(crate) fn with_impulse(
local_anchor1: Point<Real>,
local_anchor2: Point<Real>,
impulse: Vector<Real>,
) -> Self {
Self {
local_anchor1,
local_anchor2,
impulse,
motor_target_vel: na::zero(),
motor_target_pos: Rotation::identity(),
motor_stiffness: 0.0,
motor_damping: 0.0,
motor_impulse: na::zero(),
motor_max_impulse: Real::MAX,
motor_model: SpringModel::default(),
motor_last_angle: 0.0,
}
}
/// Can a SIMD constraint be used for resolving this joint?
pub fn supports_simd_constraints(&self) -> bool {
// SIMD ball constraints don't support motors right now.
self.motor_max_impulse == 0.0 || (self.motor_stiffness == 0.0 && self.motor_damping == 0.0)
}
pub fn configure_motor_model(&mut self, model: SpringModel) {
self.motor_model = model;
}
#[cfg(feature = "dim2")]
pub fn configure_motor_velocity(&mut self, target_vel: Real, factor: Real) {
self.configure_motor(self.motor_target_pos, target_vel, 0.0, factor)
}
#[cfg(feature = "dim3")]
pub fn configure_motor_velocity(&mut self, target_vel: Vector<Real>, factor: Real) {
self.configure_motor(self.motor_target_pos, target_vel, 0.0, factor)
}
pub fn configure_motor_position(
&mut self,
target_pos: Rotation<Real>,
stiffness: Real,
damping: Real,
) {
self.configure_motor(target_pos, na::zero(), stiffness, damping)
}
#[cfg(feature = "dim2")]
pub fn configure_motor(
&mut self,
target_pos: Rotation<Real>,
target_vel: Real,
stiffness: Real,
damping: Real,
) {
self.motor_target_vel = target_vel;
self.motor_target_pos = target_pos;
self.motor_stiffness = stiffness;
self.motor_damping = damping;
}
#[cfg(feature = "dim3")]
pub fn configure_motor(
&mut self,
target_pos: Rotation<Real>,
target_vel: Vector<Real>,
stiffness: Real,
damping: Real,
) {
self.motor_target_vel = target_vel;
self.motor_target_pos = target_pos;
self.motor_stiffness = stiffness;
self.motor_damping = damping;
}
}
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