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use std;
use std::ops::Mul;
use cgmath::{BaseFloat, Basis2, Matrix, Matrix3, Quaternion, SquareMatrix, Zero};
use super::{Material, Volume};
#[derive(Debug, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Mass<S, I> {
mass: S,
inverse_mass: S,
inertia: I,
inverse_inertia: I,
}
pub trait Inertia: Mul<Self, Output = Self> + Copy {
type Orientation;
fn infinite() -> Self;
fn invert(&self) -> Self;
fn tensor(&self, orientation: &Self::Orientation) -> Self;
}
impl Inertia for f32 {
type Orientation = Basis2<f32>;
fn infinite() -> Self {
std::f32::INFINITY
}
fn invert(&self) -> Self {
if *self == 0. || self.is_infinite() {
0.
} else {
1. / *self
}
}
fn tensor(&self, _: &Basis2<f32>) -> Self {
*self
}
}
impl Inertia for f64 {
type Orientation = Basis2<f64>;
fn invert(&self) -> Self {
if *self == 0. || self.is_infinite() {
0.
} else {
1. / *self
}
}
fn tensor(&self, _: &Basis2<f64>) -> Self {
*self
}
fn infinite() -> Self {
std::f64::INFINITY
}
}
impl<S> Inertia for Matrix3<S>
where
S: BaseFloat,
{
type Orientation = Quaternion<S>;
fn invert(&self) -> Self {
if self.x.x.is_infinite() {
Matrix3::zero()
} else {
SquareMatrix::invert(self).unwrap_or_else(Matrix3::zero)
}
}
fn tensor(&self, orientation: &Quaternion<S>) -> Self {
let mat3 = Matrix3::from(*orientation);
mat3 * (*self * mat3.transpose())
}
fn infinite() -> Self {
Matrix3::from_value(S::infinity())
}
}
impl<S, I> Mass<S, I>
where
S: BaseFloat,
I: Inertia,
{
pub fn new(mass: S) -> Self {
Self::new_with_inertia(mass, I::infinite())
}
pub fn infinite() -> Self {
Self::new_with_inertia(S::infinity(), I::infinite())
}
pub fn new_with_inertia(mass: S, inertia: I) -> Self {
let inverse_mass = if mass.is_infinite() {
S::zero()
} else {
S::one() / mass
};
let inverse_inertia = inertia.invert();
Mass {
mass,
inverse_mass,
inertia,
inverse_inertia,
}
}
pub fn from_volume_and_material<V>(volume: &V, material: &Material) -> Self
where
V: Volume<S, I>,
{
volume.get_mass(material)
}
pub fn mass(&self) -> S {
self.mass
}
pub fn inverse_mass(&self) -> S {
self.inverse_mass
}
pub fn local_inertia(&self) -> I {
self.inertia
}
pub fn world_inertia(&self, orientation: &I::Orientation) -> I {
self.inertia.tensor(orientation)
}
pub fn local_inverse_inertia(&self) -> I {
self.inverse_inertia
}
pub fn world_inverse_inertia(&self, orientation: &I::Orientation) -> I {
self.inverse_inertia.tensor(orientation)
}
}