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use na::Real;
use na;
use ncollide::shape::Ball;
use crate::volumetric::Volumetric;
use crate::math::{AngularInertia, Point, DIM};
#[inline]
pub fn ball_volume<N: Real>(radius: N) -> N {
if DIM == 2 {
let _pi = N::pi();
_pi * radius * radius
} else {
let _pi = N::pi();
_pi * radius * radius * radius * na::convert(4.0f64 / 3.0)
}
}
#[inline]
pub fn ball_area<N: Real>(radius: N) -> N {
if DIM == 2 {
let _pi = N::pi();
_pi * radius * na::convert(2.0f64)
} else {
let _pi = N::pi();
_pi * radius * radius * na::convert(4.0f64)
}
}
#[inline]
pub fn ball_center_of_mass<N: Real>() -> Point<N> {
Point::origin()
}
#[inline]
pub fn ball_unit_angular_inertia<N: Real>(radius: N) -> AngularInertia<N> {
let diag = if DIM == 2 {
radius * radius / na::convert(2.0f64)
} else {
radius * radius * na::convert(2.0f64 / 5.0)
};
AngularInertia::from_diagonal_element(diag)
}
impl<N: Real> Volumetric<N> for Ball<N> {
fn area(&self) -> N {
ball_area(self.radius())
}
fn volume(&self) -> N {
ball_volume(self.radius())
}
fn center_of_mass(&self) -> Point<N> {
ball_center_of_mass()
}
fn unit_angular_inertia(&self) -> AngularInertia<N> {
ball_unit_angular_inertia(self.radius())
}
}