noise-functions 0.8.4

A collection of fast and lightweight noise functions.
Documentation 
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use core::{cell::Cell, f32};
use std::{boxed::Box, thread_local};

use crate::{Constant, Noise, NoiseFn, OpenSimplex2, Perlin, Sample};

#[test]
fn translate() {
    const OFFSET: f32 = 10.0;

    thread_local! {
        static X: Cell<f32> = const { Cell::new(f32::NAN) };
        static Y: Cell<f32> = const { Cell::new(f32::NAN) };
        static Z: Cell<f32> = const { Cell::new(f32::NAN) };
        static W: Cell<f32> = const { Cell::new(f32::NAN) };
    }

    fn reset() {
        X.set(f32::NAN);
        Y.set(f32::NAN);
        Z.set(f32::NAN);
        W.set(f32::NAN);
    }

    fn assert(dim: usize) {
        for (i, value) in [&X, &Y, &Z, &W].into_iter().enumerate().take(dim) {
            assert_eq!(value.get(), OFFSET + (i + 1) as f32);
        }
    }

    fn noise2([x, y]: [f32; 2]) -> f32 {
        X.set(x);
        Y.set(y);
        x + y
    }

    fn noise3([x, y, z]: [f32; 3]) -> f32 {
        X.set(x);
        Y.set(y);
        Z.set(z);
        x + y + z
    }

    fn noise4([x, y, z, w]: [f32; 4]) -> f32 {
        X.set(x);
        Y.set(y);
        Z.set(z);
        W.set(w);
        x + y + z + w
    }

    reset();
    NoiseFn(noise2).translate_xy(1.0, 2.0).sample2([OFFSET; 2]);
    assert(2);

    reset();
    NoiseFn(noise3).translate_xyz(1.0, 2.0, 3.0).sample3([OFFSET; 3]);
    assert(3);

    reset();
    NoiseFn(noise4).translate_xyzw(1.0, 2.0, 3.0, 4.0).sample4([OFFSET; 4]);
    assert(4);
}

#[test]
fn translate_doesnt_crash() {
    Sample::<0>::sample_with_seed(&Constant(0.0).translate_x(0.0), [0.0; 0], 0);
    Sample::<0>::sample_with_seed(&Constant(0.0).translate_xy(0.0, 0.0), [0.0; 0], 0);
    Sample::<0>::sample_with_seed(&Constant(0.0).translate_xyz(0.0, 0.0, 0.0), [0.0; 0], 0);
    Sample::<0>::sample_with_seed(&Constant(0.0).translate_xyzw(0.0, 0.0, 0.0, 0.0), [0.0; 0], 0);

    Sample::<1>::sample_with_seed(&Constant(0.0).translate_x(0.0), [0.0; 1], 0);
    Sample::<1>::sample_with_seed(&Constant(0.0).translate_xy(0.0, 0.0), [0.0; 1], 0);
    Sample::<1>::sample_with_seed(&Constant(0.0).translate_xyz(0.0, 0.0, 0.0), [0.0; 1], 0);
    Sample::<1>::sample_with_seed(&Constant(0.0).translate_xyzw(0.0, 0.0, 0.0, 0.0), [0.0; 1], 0);

    Sample::<2>::sample_with_seed(&Constant(0.0).translate_x(0.0), [0.0; 2], 0);
    Sample::<2>::sample_with_seed(&Constant(0.0).translate_xy(0.0, 0.0), [0.0; 2], 0);
    Sample::<2>::sample_with_seed(&Constant(0.0).translate_xyz(0.0, 0.0, 0.0), [0.0; 2], 0);
    Sample::<2>::sample_with_seed(&Constant(0.0).translate_xyzw(0.0, 0.0, 0.0, 0.0), [0.0; 2], 0);

    Sample::<3>::sample_with_seed(&Constant(0.0).translate_x(0.0), [0.0; 3], 0);
    Sample::<3>::sample_with_seed(&Constant(0.0).translate_xy(0.0, 0.0), [0.0; 3], 0);
    Sample::<3>::sample_with_seed(&Constant(0.0).translate_xyz(0.0, 0.0, 0.0), [0.0; 3], 0);
    Sample::<3>::sample_with_seed(&Constant(0.0).translate_xyzw(0.0, 0.0, 0.0, 0.0), [0.0; 3], 0);

    Sample::<4>::sample_with_seed(&Constant(0.0).translate_x(0.0), [0.0; 4], 0);
    Sample::<4>::sample_with_seed(&Constant(0.0).translate_xy(0.0, 0.0), [0.0; 4], 0);
    Sample::<4>::sample_with_seed(&Constant(0.0).translate_xyz(0.0, 0.0, 0.0), [0.0; 4], 0);
    Sample::<4>::sample_with_seed(&Constant(0.0).translate_xyzw(0.0, 0.0, 0.0, 0.0), [0.0; 4], 0);
}

#[test]
fn clamp() {
    assert_eq!(Constant(0.0).clamp(1.0, 2.0).sample2([0.0; 2]), 1.0);
    assert_eq!(Constant(1.5).clamp(1.0, 2.0).sample2([0.0; 2]), 1.5);
    assert_eq!(Constant(3.0).clamp(1.0, 2.0).sample2([0.0; 2]), 2.0);
    assert!(Constant(f32::NAN).clamp(1.0, 2.0).sample2([0.0; 2]).is_nan());

    // these would panic if we used `f32::clamp`, but our clamp must not panic
    Constant(0.0).clamp(2.0, 1.0).sample2([0.0; 2]);
    assert_eq!(Constant(0.0).clamp(f32::NAN, f32::NAN).sample2([0.0; 2]), 0.0);
}

#[test]
fn modifiers_manual_ridged() {
    let base = OpenSimplex2;
    let a = base.ridged();
    let b = base.abs().mul(-2.0).add(1.0);
    assert_eq(a, b);
}

fn assert_eq<A, B>(a: A, b: B)
where
    A: Sample<2>,
    B: Sample<2>,
{
    assert_approx_eq(0.0, a, b);
}

fn assert_approx_eq<A, B>(epsilon: f32, a: A, b: B)
where
    A: Sample<2>,
    B: Sample<2>,
{
    let mut max_error = 0.0f32;

    for x in 0..100 {
        for y in 0..100 {
            let x = x as f32 * 1.34900342;
            let y = y as f32 * 0.93124235;
            let p = [x, y];
            let av = a.sample2(p);
            let bv = b.sample2(p);
            max_error = max_error.max((av - bv).abs());
        }
    }

    std::println!("max error: {max_error}");

    if max_error > epsilon {
        panic!("error too big!");
    }
}

#[test]
fn test_trait_object_noise() {
    let perlin_dyn: &dyn Sample<2> = &Perlin;
    let _value = (&perlin_dyn).sample2([1.0, 2.0]);

    let perlin_box_dyn: Box<dyn Sample<2>> = Box::new(Perlin);
    let _value = perlin_box_dyn.sample2([1.0, 2.0]);
}