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use crate::dynamics::MassProperties;
use crate::math::{Point, PrincipalAngularInertia, Rotation, Vector};
impl MassProperties {
pub(crate) fn cone_y_volume_unit_inertia(
half_height: f32,
radius: f32,
) -> (f32, PrincipalAngularInertia<f32>) {
let volume = radius * radius * std::f32::consts::PI * half_height * 2.0 / 3.0;
let sq_radius = radius * radius;
let sq_height = half_height * half_height * 4.0;
let off_principal = sq_radius * 3.0 / 20.0 + sq_height * 3.0 / 5.0;
let principal = sq_radius * 3.0 / 10.0;
(volume, Vector::new(off_principal, principal, off_principal))
}
pub(crate) fn from_cone(density: f32, half_height: f32, radius: f32) -> Self {
let (cyl_vol, cyl_unit_i) = Self::cone_y_volume_unit_inertia(half_height, radius);
let cyl_mass = cyl_vol * density;
Self::with_principal_inertia_frame(
Point::new(0.0, -half_height / 2.0, 0.0),
cyl_mass,
cyl_unit_i * cyl_mass,
Rotation::identity(),
)
}
}
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