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use crate::dynamics::MassProperties;
#[cfg(feature = "dim3")]
use crate::math::{Point, Rotation};
use crate::math::{PrincipalAngularInertia, Vector};
impl MassProperties {
pub(crate) fn cylinder_y_volume_unit_inertia(
half_height: f32,
radius: f32,
) -> (f32, PrincipalAngularInertia<f32>) {
#[cfg(feature = "dim2")]
{
Self::cuboid_volume_unit_inertia(Vector::new(radius, half_height))
}
#[cfg(feature = "dim3")]
{
let volume = half_height * radius * radius * std::f32::consts::PI * 2.0;
let sq_radius = radius * radius;
let sq_height = half_height * half_height * 4.0;
let off_principal = (sq_radius * 3.0 + sq_height) / 12.0;
let inertia = Vector::new(off_principal, sq_radius / 2.0, off_principal);
(volume, inertia)
}
}
#[cfg(feature = "dim3")]
pub(crate) fn from_cylinder(density: f32, half_height: f32, radius: f32) -> Self {
let (cyl_vol, cyl_unit_i) = Self::cylinder_y_volume_unit_inertia(half_height, radius);
let cyl_mass = cyl_vol * density;
Self::with_principal_inertia_frame(
Point::origin(),
cyl_mass,
cyl_unit_i * cyl_mass,
Rotation::identity(),
)
}
}
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