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use math;
use math::{Point2, Point3, Point4};
use modules::{MultiFractal, NoiseModule, Perlin, Seedable};
use num_traits::Float;
pub const DEFAULT_FBM_SEED: usize = 0;
pub const DEFAULT_FBM_OCTAVE_COUNT: usize = 6;
pub const DEFAULT_FBM_FREQUENCY: f32 = 1.0;
pub const DEFAULT_FBM_LACUNARITY: f32 = 2.0;
pub const DEFAULT_FBM_PERSISTENCE: f32 = 0.5;
pub const FBM_MAX_OCTAVES: usize = 32;
#[derive(Clone, Debug)]
pub struct Fbm<T> {
pub seed: usize,
pub octaves: usize,
pub frequency: T,
pub lacunarity: T,
pub persistence: T,
sources: Vec<Perlin>,
}
impl<T: Float> Fbm<T> {
pub fn new() -> Fbm<T> {
Fbm {
seed: DEFAULT_FBM_SEED,
octaves: DEFAULT_FBM_OCTAVE_COUNT,
frequency: math::cast(DEFAULT_FBM_FREQUENCY),
lacunarity: math::cast(DEFAULT_FBM_LACUNARITY),
persistence: math::cast(DEFAULT_FBM_PERSISTENCE),
sources: super::build_sources(DEFAULT_FBM_SEED, DEFAULT_FBM_OCTAVE_COUNT),
}
}
}
impl<T> MultiFractal<T> for Fbm<T> {
fn set_octaves(self, mut octaves: usize) -> Fbm<T> {
if self.octaves == octaves {
return self;
} else if octaves > FBM_MAX_OCTAVES {
octaves = FBM_MAX_OCTAVES;
} else if octaves < 1 {
octaves = 1;
}
Fbm {
octaves: octaves,
sources: super::build_sources(self.seed, octaves),
..self
}
}
fn set_frequency(self, frequency: T) -> Fbm<T> {
Fbm { frequency: frequency, ..self }
}
fn set_lacunarity(self, lacunarity: T) -> Fbm<T> {
Fbm { lacunarity: lacunarity, ..self }
}
fn set_persistence(self, persistence: T) -> Fbm<T> {
Fbm { persistence: persistence, ..self }
}
}
impl<T> Seedable for Fbm<T> {
fn set_seed(self, seed: usize) -> Fbm<T> {
if self.seed == seed {
return self;
}
Fbm {
seed: seed,
sources: super::build_sources(seed, self.octaves),
..self
}
}
}
impl<T: Float> NoiseModule<Point2<T>> for Fbm<T> {
type Output = T;
fn get(&self, mut point: Point2<T>) -> T {
let mut result = T::zero();
point = math::mul2(point, self.frequency);
for x in 0..self.octaves {
let mut signal = self.sources[x].get(point);
signal = signal * self.persistence.powi(math::cast(x));
result = result + signal;
point = math::mul2(point, self.lacunarity);
}
let scale = T::from(2.0).unwrap() - self.persistence.powi(self.octaves as i32 - 1);
result / math::cast(scale)
}
}
impl<T: Float> NoiseModule<Point3<T>> for Fbm<T> {
type Output = T;
fn get(&self, mut point: Point3<T>) -> T {
let mut result = T::zero();
point = math::mul3(point, self.frequency);
for x in 0..self.octaves {
let mut signal = self.sources[x].get(point);
signal = signal * self.persistence.powi(math::cast(x));
result = result + signal;
point = math::mul3(point, self.lacunarity);
}
let scale = T::from(2.0).unwrap() - self.persistence.powi(self.octaves as i32 - 1);
result / math::cast(scale)
}
}
impl<T: Float> NoiseModule<Point4<T>> for Fbm<T> {
type Output = T;
fn get(&self, mut point: Point4<T>) -> T {
let mut result = T::zero();
point = math::mul4(point, self.frequency);
for x in 0..self.octaves {
let mut signal = self.sources[x].get(point);
signal = signal * self.persistence.powi(math::cast(x));
result = result + signal;
point = math::mul4(point, self.lacunarity);
}
let scale = T::from(2.0).unwrap() - self.persistence.powi(self.octaves as i32 - 1);
result / math::cast(scale)
}
}