terrain_forge/noise/
modifiers.rs

1use super::NoiseSource;
2
3/// Scale noise output by a factor
4pub struct Scale<S: NoiseSource> {
5    pub(crate) source: S,
6    pub(crate) factor: f64,
7}
8
9impl<S: NoiseSource> NoiseSource for Scale<S> {
10    fn sample(&self, x: f64, y: f64) -> f64 {
11        self.source.sample(x, y) * self.factor
12    }
13}
14
15/// Add offset to noise output
16pub struct Offset<S: NoiseSource> {
17    pub(crate) source: S,
18    pub(crate) amount: f64,
19}
20
21impl<S: NoiseSource> NoiseSource for Offset<S> {
22    fn sample(&self, x: f64, y: f64) -> f64 {
23        self.source.sample(x, y) + self.amount
24    }
25}
26
27/// Clamp noise output to range
28pub struct Clamp<S: NoiseSource> {
29    pub(crate) source: S,
30    pub(crate) min: f64,
31    pub(crate) max: f64,
32}
33
34impl<S: NoiseSource> NoiseSource for Clamp<S> {
35    fn sample(&self, x: f64, y: f64) -> f64 {
36        self.source.sample(x, y).clamp(self.min, self.max)
37    }
38}
39
40/// Absolute value of noise output
41pub struct Abs<S: NoiseSource> {
42    pub(crate) source: S,
43}
44
45impl<S: NoiseSource> NoiseSource for Abs<S> {
46    fn sample(&self, x: f64, y: f64) -> f64 {
47        self.source.sample(x, y).abs()
48    }
49}
50
51/// Blend two noise sources
52pub struct Blend<A: NoiseSource, B: NoiseSource, C: NoiseSource> {
53    pub source_a: A,
54    pub source_b: B,
55    pub control: C,
56}
57
58impl<A: NoiseSource, B: NoiseSource, C: NoiseSource> Blend<A, B, C> {
59    pub fn new(source_a: A, source_b: B, control: C) -> Self {
60        Self { source_a, source_b, control }
61    }
62}
63
64impl<A: NoiseSource, B: NoiseSource, C: NoiseSource> NoiseSource for Blend<A, B, C> {
65    fn sample(&self, x: f64, y: f64) -> f64 {
66        let a = self.source_a.sample(x, y);
67        let b = self.source_b.sample(x, y);
68        let t = (self.control.sample(x, y) + 1.0) * 0.5; // Map [-1,1] to [0,1]
69        a + t * (b - a)
70    }
71}
72
73#[cfg(test)]
74mod tests {
75    use super::*;
76    use crate::noise::{Perlin, NoiseExt};
77
78    #[test]
79    fn scale_modifier() {
80        let noise = Perlin::new(42).scale(2.0);
81        let base = Perlin::new(42);
82        let v1 = noise.sample(1.0, 1.0);
83        let v2 = base.sample(1.0, 1.0) * 2.0;
84        assert!((v1 - v2).abs() < 1e-10);
85    }
86
87    #[test]
88    fn offset_modifier() {
89        let noise = Perlin::new(42).offset(0.5);
90        let base = Perlin::new(42);
91        let v1 = noise.sample(1.0, 1.0);
92        let v2 = base.sample(1.0, 1.0) + 0.5;
93        assert!((v1 - v2).abs() < 1e-10);
94    }
95
96    #[test]
97    fn clamp_modifier() {
98        let noise = Perlin::new(42).clamp(-0.5, 0.5);
99        for i in 0..50 {
100            for j in 0..50 {
101                let v = noise.sample(i as f64 * 0.1, j as f64 * 0.1);
102                assert!(v >= -0.5 && v <= 0.5);
103            }
104        }
105    }
106
107    #[test]
108    fn abs_modifier() {
109        let noise = Perlin::new(42).abs();
110        for i in 0..50 {
111            for j in 0..50 {
112                let v = noise.sample(i as f64 * 0.1, j as f64 * 0.1);
113                assert!(v >= 0.0);
114            }
115        }
116    }
117
118    #[test]
119    fn chained_modifiers() {
120        let noise = Perlin::new(42)
121            .scale(0.5)
122            .offset(0.5)
123            .clamp(0.0, 1.0);
124        
125        for i in 0..50 {
126            for j in 0..50 {
127                let v = noise.sample(i as f64 * 0.1, j as f64 * 0.1);
128                assert!(v >= 0.0 && v <= 1.0);
129            }
130        }
131    }
132}
terrain_forge/noise/modifiers.rs

terrain_forge/noise/
modifiers.rs
