47 lines
1.5 KiB
Rust
47 lines
1.5 KiB
Rust
// pathfinder/geometry/src/unit_vector.rs
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//
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// Copyright © 2019 The Pathfinder Project Developers.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! A utility module that allows unit vectors to be treated like angles.
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use crate::basic::point::Point2DF32;
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use pathfinder_simd::default::F32x4;
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#[derive(Clone, Copy, Debug)]
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pub struct UnitVector(pub Point2DF32);
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impl UnitVector {
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#[inline]
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pub fn from_angle(theta: f32) -> UnitVector {
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UnitVector(Point2DF32::new(theta.cos(), theta.sin()))
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}
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/// Angle addition formula.
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#[inline]
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pub fn rotate_by(&self, other: UnitVector) -> UnitVector {
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let products = (self.0).0.xyyx() * (other.0).0.xyxy();
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UnitVector(Point2DF32::new(products[0] - products[1], products[2] + products[3]))
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}
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/// Angle subtraction formula.
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#[inline]
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pub fn rev_rotate_by(&self, other: UnitVector) -> UnitVector {
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let products = (self.0).0.xyyx() * (other.0).0.xyxy();
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UnitVector(Point2DF32::new(products[0] + products[1], products[2] - products[3]))
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}
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/// Half angle formula.
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#[inline]
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pub fn halve_angle(&self) -> UnitVector {
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let x = self.0.x();
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let term = F32x4::new(x, -x, 0.0, 0.0);
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UnitVector(Point2DF32((F32x4::splat(0.5) * (F32x4::splat(1.0) + term)).sqrt()))
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}
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}
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