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use math;
use math::{Point2, Point3, Point4};
use modules::NoiseModule;
use num_traits::Float;
pub const DEFAULT_CHECKERBOARD_SIZE: usize = 0;
#[derive(Clone, Copy, Debug)]
pub struct Checkerboard {
pub size: usize,
_dummy: (),
}
impl Checkerboard {
pub fn new() -> Checkerboard {
Checkerboard {
size: 1 << DEFAULT_CHECKERBOARD_SIZE,
_dummy: (),
}
}
pub fn set_size(self, size: usize) -> Checkerboard {
Checkerboard { size: 1 << size, ..self }
}
}
fn fast_floor<T: Float>(x: T) -> usize {
if x > T::zero() {
math::cast(x)
} else {
math::cast(x - T::one())
}
}
impl<T: Float> NoiseModule<Point2<T>> for Checkerboard {
type Output = T;
fn get(&self, point: Point2<T>) -> Self::Output {
calculate_checkerboard(&point, self.size)
}
}
impl<T: Float> NoiseModule<Point3<T>> for Checkerboard {
type Output = T;
fn get(&self, point: Point3<T>) -> Self::Output {
calculate_checkerboard(&point, self.size)
}
}
impl<T: Float> NoiseModule<Point4<T>> for Checkerboard {
type Output = T;
fn get(&self, point: Point4<T>) -> Self::Output {
calculate_checkerboard(&point, self.size)
}
}
fn calculate_checkerboard<T: Float>(point: &[T], size: usize) -> T {
let result = point.iter()
.map(|&a| fast_floor(a))
.fold(0, |a, b| (a & size) ^ (b & size));
if result > 0 { -T::one() } else { T::one() }
}