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