31 lines
941 B
Rust
31 lines
941 B
Rust
use crate::dynamics::MassProperties;
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#[cfg(feature = "dim3")]
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use crate::math::Vector;
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use crate::math::{Point, PrincipalAngularInertia};
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impl MassProperties {
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pub(crate) fn ball_volume_unit_angular_inertia(
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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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let volume = std::f32::consts::PI * radius * radius;
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let i = radius * radius / 2.0;
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(volume, i)
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}
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#[cfg(feature = "dim3")]
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{
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let volume = std::f32::consts::PI * radius * radius * radius * 4.0 / 3.0;
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let i = radius * radius * 2.0 / 5.0;
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(volume, Vector::repeat(i))
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}
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}
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pub(crate) fn from_ball(density: f32, radius: f32) -> Self {
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let (vol, unit_i) = Self::ball_volume_unit_angular_inertia(radius);
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let mass = vol * density;
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Self::new(Point::origin(), mass, unit_i * mass)
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}
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}
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