31 lines
819 B
Rust
31 lines
819 B
Rust
extern crate nalgebra as na;
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use na::{Unit, Vector3};
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fn length_on_direction_with_unit(v: &Vector3<f32>, dir: &Unit<Vector3<f32>>) -> f32 {
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// No need to normalize `dir`: we know that it is non-zero and normalized.
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v.dot(dir.as_ref())
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}
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fn length_on_direction_without_unit(v: &Vector3<f32>, dir: &Vector3<f32>) -> f32 {
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// Obligatory normalization of the direction vector (and test, for robustness).
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if let Some(unit_dir) = dir.try_normalize(1.0e-6) {
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v.dot(&unit_dir)
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}
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else {
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// Normalization failed because the norm was too small.
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panic!("Invalid input direction.")
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}
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}
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fn main() {
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let v = Vector3::new(1.0, 2.0, 3.0);
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let l1 = length_on_direction_with_unit(&v, &Vector3::y_axis());
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let l2 = length_on_direction_without_unit(&v, &Vector3::y());
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assert_eq!(l1, l2)
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}
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