psychopath/src/lerp.rs

380 lines
8.3 KiB
Rust

#![allow(dead_code)]
use float4;
use math3d::{Matrix4x4, Normal, Point, Vector};
/// Trait for allowing a type to be linearly interpolated.
pub trait Lerp {
fn lerp(self, other: Self, alpha: f32) -> Self;
}
/// Interpolates between two instances of a Lerp types.
pub fn lerp<T: Lerp>(a: T, b: T, alpha: f32) -> T {
debug_assert!(alpha >= 0.0);
debug_assert!(alpha <= 1.0);
a.lerp(b, alpha)
}
/// Interpolates a slice of data as if each adjecent pair of elements
/// represent a linear segment.
pub fn lerp_slice<T: Lerp + Copy>(s: &[T], alpha: f32) -> T {
debug_assert!(!s.is_empty());
debug_assert!(alpha >= 0.0);
debug_assert!(alpha <= 1.0);
if s.len() == 1 || alpha == 1.0 {
*s.last().unwrap()
} else {
let tmp = alpha * ((s.len() - 1) as f32);
let i1 = tmp as usize;
let i2 = i1 + 1;
let alpha2 = tmp - (i1 as f32);
lerp(s[i1], s[i2], alpha2)
}
}
pub fn lerp_slice_with<T, F>(s: &[T], alpha: f32, f: F) -> T
where
T: Copy,
F: Fn(T, T, f32) -> T,
{
debug_assert!(!s.is_empty());
debug_assert!(alpha >= 0.0);
debug_assert!(alpha <= 1.0);
if s.len() == 1 || alpha == 1.0 {
*s.last().unwrap()
} else {
let tmp = alpha * ((s.len() - 1) as f32);
let i1 = tmp as usize;
let i2 = i1 + 1;
let alpha2 = tmp - (i1 as f32);
f(s[i1], s[i2], alpha2)
}
}
impl Lerp for f32 {
fn lerp(self, other: f32, alpha: f32) -> f32 {
(self * (1.0 - alpha)) + (other * alpha)
}
}
impl Lerp for f64 {
fn lerp(self, other: f64, alpha: f32) -> f64 {
(self * (1.0 - alpha as f64)) + (other * alpha as f64)
}
}
impl<T: Lerp> Lerp for (T, T) {
fn lerp(self, other: (T, T), alpha: f32) -> (T, T) {
(self.0.lerp(other.0, alpha), self.1.lerp(other.1, alpha))
}
}
impl Lerp for float4::Float4 {
fn lerp(self, other: float4::Float4, alpha: f32) -> float4::Float4 {
(self * (1.0 - alpha)) + (other * alpha)
}
}
impl Lerp for Matrix4x4 {
fn lerp(self, other: Matrix4x4, alpha: f32) -> Matrix4x4 {
let alpha_minus = 1.0 - alpha;
Matrix4x4 {
values: [
(self[0] * alpha_minus) + (other[0] * alpha),
(self[1] * alpha_minus) + (other[1] * alpha),
(self[2] * alpha_minus) + (other[2] * alpha),
(self[3] * alpha_minus) + (other[3] * alpha),
],
}
}
}
impl Lerp for Normal {
fn lerp(self, other: Normal, alpha: f32) -> Normal {
(self * (1.0 - alpha)) + (other * alpha)
}
}
impl Lerp for Point {
fn lerp(self, other: Point, alpha: f32) -> Point {
let s = self.norm();
let o = other.norm();
Point {
co: (s.co * (1.0 - alpha)) + (o.co * alpha),
}
}
}
impl Lerp for Vector {
fn lerp(self, other: Vector, alpha: f32) -> Vector {
(self * (1.0 - alpha)) + (other * alpha)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn lerp1() {
let a = 1.0f32;
let b = 2.0f32;
let alpha = 0.0f32;
assert_eq!(1.0, lerp(a, b, alpha));
}
#[test]
fn lerp2() {
let a = 1.0f32;
let b = 2.0f32;
let alpha = 1.0f32;
assert_eq!(2.0, lerp(a, b, alpha));
}
#[test]
fn lerp3() {
let a = 1.0f32;
let b = 2.0f32;
let alpha = 0.5f32;
assert_eq!(1.5, lerp(a, b, alpha));
}
#[test]
fn lerp_slice1() {
let s = [0.0f32, 1.0, 2.0, 3.0, 4.0];
let alpha = 0.0f32;
assert_eq!(0.0, lerp_slice(&s[..], alpha));
}
#[test]
fn lerp_slice2() {
let s = [0.0f32, 1.0, 2.0, 3.0, 4.0];
let alpha = 1.0f32;
assert_eq!(4.0, lerp_slice(&s[..], alpha));
}
#[test]
fn lerp_slice3() {
let s = [0.0f32, 1.0, 2.0, 3.0, 4.0];
let alpha = 0.5f32;
assert_eq!(2.0, lerp_slice(&s[..], alpha));
}
#[test]
fn lerp_slice4() {
let s = [0.0f32, 1.0, 2.0, 3.0, 4.0];
let alpha = 0.25f32;
assert_eq!(1.0, lerp_slice(&s[..], alpha));
}
#[test]
fn lerp_slice5() {
let s = [0.0f32, 1.0, 2.0, 3.0, 4.0];
let alpha = 0.75f32;
assert_eq!(3.0, lerp_slice(&s[..], alpha));
}
#[test]
fn lerp_slice6() {
let s = [0.0f32, 1.0, 2.0, 3.0, 4.0];
let alpha = 0.625f32;
assert_eq!(2.5, lerp_slice(&s[..], alpha));
}
#[test]
fn lerp_matrix() {
let a = Matrix4x4::new_from_values(
0.0,
2.0,
2.0,
3.0,
4.0,
5.0,
6.0,
7.0,
8.0,
9.0,
10.0,
11.0,
12.0,
13.0,
14.0,
15.0,
);
let b = Matrix4x4::new_from_values(
-1.0,
1.0,
3.0,
4.0,
5.0,
6.0,
7.0,
8.0,
9.0,
10.0,
11.0,
12.0,
13.0,
14.0,
15.0,
16.0,
);
let c1 = Matrix4x4::new_from_values(
-0.25,
1.75,
2.25,
3.25,
4.25,
5.25,
6.25,
7.25,
8.25,
9.25,
10.25,
11.25,
12.25,
13.25,
14.25,
15.25,
);
let c2 = Matrix4x4::new_from_values(
-0.5,
1.5,
2.5,
3.5,
4.5,
5.5,
6.5,
7.5,
8.5,
9.5,
10.5,
11.5,
12.5,
13.5,
14.5,
15.5,
);
let c3 = Matrix4x4::new_from_values(
-0.75,
1.25,
2.75,
3.75,
4.75,
5.75,
6.75,
7.75,
8.75,
9.75,
10.75,
11.75,
12.75,
13.75,
14.75,
15.75,
);
assert_eq!(a.lerp(b, 0.0), a);
assert_eq!(a.lerp(b, 0.25), c1);
assert_eq!(a.lerp(b, 0.5), c2);
assert_eq!(a.lerp(b, 0.75), c3);
assert_eq!(a.lerp(b, 1.0), b);
}
#[test]
fn lerp_point_1() {
let p1 = Point::new(1.0, 2.0, 1.0);
let p2 = Point::new(-2.0, 1.0, -1.0);
let p3 = Point::new(1.0, 2.0, 1.0);
assert_eq!(p3, p1.lerp(p2, 0.0));
}
#[test]
fn lerp_point_2() {
let p1 = Point::new(1.0, 2.0, 1.0);
let p2 = Point::new(-2.0, 1.0, -1.0);
let p3 = Point::new(-2.0, 1.0, -1.0);
assert_eq!(p3, p1.lerp(p2, 1.0));
}
#[test]
fn lerp_point_3() {
let p1 = Point::new(1.0, 2.0, 1.0);
let p2 = Point::new(-2.0, 1.0, -1.0);
let p3 = Point::new(-0.5, 1.5, 0.0);
assert_eq!(p3, p1.lerp(p2, 0.5));
}
#[test]
fn lerp_normal_1() {
let n1 = Normal::new(1.0, 2.0, 1.0);
let n2 = Normal::new(-2.0, 1.0, -1.0);
let n3 = Normal::new(1.0, 2.0, 1.0);
assert_eq!(n3, n1.lerp(n2, 0.0));
}
#[test]
fn lerp_normal_2() {
let n1 = Normal::new(1.0, 2.0, 1.0);
let n2 = Normal::new(-2.0, 1.0, -1.0);
let n3 = Normal::new(-2.0, 1.0, -1.0);
assert_eq!(n3, n1.lerp(n2, 1.0));
}
#[test]
fn lerp_normal_3() {
let n1 = Normal::new(1.0, 2.0, 1.0);
let n2 = Normal::new(-2.0, 1.0, -1.0);
let n3 = Normal::new(-0.5, 1.5, 0.0);
assert_eq!(n3, n1.lerp(n2, 0.5));
}
#[test]
fn lerp_vector_1() {
let v1 = Vector::new(1.0, 2.0, 1.0);
let v2 = Vector::new(-2.0, 1.0, -1.0);
let v3 = Vector::new(1.0, 2.0, 1.0);
assert_eq!(v3, v1.lerp(v2, 0.0));
}
#[test]
fn lerp_vector_2() {
let v1 = Vector::new(1.0, 2.0, 1.0);
let v2 = Vector::new(-2.0, 1.0, -1.0);
let v3 = Vector::new(-2.0, 1.0, -1.0);
assert_eq!(v3, v1.lerp(v2, 1.0));
}
#[test]
fn lerp_vector_3() {
let v1 = Vector::new(1.0, 2.0, 1.0);
let v2 = Vector::new(-2.0, 1.0, -1.0);
let v3 = Vector::new(-0.5, 1.5, 0.0);
assert_eq!(v3, v1.lerp(v2, 0.5));
}
}