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use core::ops::{AddAssign, Mul, MulAssign, Sub}; use cast_trait::Cast; use num_traits::{FromPrimitive, One, Zero}; use vec2; use cubic::cubic; use linear::linear; use quadratic::quadratic; #[inline] pub fn n<'out, T, F>(out: &'out mut [T; 2], points: &[[T; 2]], t: &F) -> &'out mut [T; 2] where T: Clone + Cast<F> + Zero, for<'a> T: AddAssign<&'a T>, for<'a, 'b> &'a T: Sub<&'b T, Output = T>, F: Clone + One + Zero + FromPrimitive + PartialOrd + Cast<T> + Sub<F, Output = F> + Mul<F, Output = F>, for<'a> F: MulAssign<&'a F>, for<'a, 'b> &'a F: Sub<&'b F, Output = F> + Mul<&'b F, Output = F>, { if t <= &F::zero() { match points.len() { 0 => vec2::set_zero(out), _ => { *out = points[0].clone(); out } } } else if t >= &F::one() { match points.len() { 0 => vec2::set_zero(out), n => { *out = points[n - 1].clone(); out } } } else { match points.len() { 0 => vec2::set_zero(out), 1 => { *out = points[0].clone(); out } 2 => linear(out, &points[0], &points[1], t), 3 => cubic(out, &points[0], &points[1], &points[2], t), 4 => quadratic(out, &points[0], &points[1], &points[2], &points[3], t), n => { *out = casteljau(points, n - 1, 0, t); out } } } } #[inline] fn casteljau<T, F>(points: &[[T; 2]], i: usize, j: usize, t: &F) -> [T; 2] where T: Clone + Cast<F>, F: Clone + One + Zero + PartialOrd + Cast<T> + Sub<F, Output = F> + Mul<F, Output = F>, for<'a, 'b> &'a F: Sub<&'b F, Output = F> + Mul<&'b F, Output = F>, { if i == 0_usize { points[j].clone() } else { let p0 = casteljau(points, i - 1, j, t); let p1 = casteljau(points, i - 1, j + 1, t); let p0x = p0[0].clone().cast(); let p0y = p0[1].clone().cast(); let p1x = p1[0].clone().cast(); let p1y = p1[1].clone().cast(); vec2::new( ((F::one() - t.clone()) * p0x + t.clone() * p1x).cast(), ((F::one() - t.clone()) * p0y + t.clone() * p1y).cast(), ) } } #[test] fn test_n() { assert_eq!(n(&mut [0, 0], &[], &0), &[0, 0]); assert_eq!(n(&mut [0, 0], &[], &0.5), &[0, 0]); assert_eq!(n(&mut [0, 0], &[], &1), &[0, 0]); assert_eq!( n( &mut [0, 0], &[[0, 0], [0, 200], [200, 200], [200, 0]], &0.25 ), &[31, 112] ); assert_eq!( n(&mut [0, 0], &[[0, 0], [0, 200], [200, 200], [200, 0]], &0.5), &[100, 150] ); assert_eq!( n( &mut [0, 0], &[[0, 0], [0, 200], [200, 200], [200, 0]], &0.75 ), &[168, 112] ); assert_eq!( n( &mut [0, 0], &[[0, 0], [0, 200], [200, 200], [200, 0], [100, 0]], &0.25 ), &[50, 126] ); assert_eq!( n( &mut [0, 0], &[[0, 0], [0, 200], [200, 200], [200, 0], [100, 0]], &0.5 ), &[131, 125] ); assert_eq!( n( &mut [0, 0], &[[0, 0], [0, 200], [200, 200], [200, 0], [100, 0]], &0.75 ), &[157, 50] ); }