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use glam::Vec2;
use rand::distributions::Uniform;
use rand::Rng;
use sphere::sphere_volume;
use crate::algorithm::{Algorithm, Creator};
use crate::utils::*;
use crate::Builder;
#[derive(Debug, Clone, Copy)]
pub struct Ebeida;
impl Creator for Ebeida {
type Algo = Algo;
fn create(poisson: &Builder) -> Self::Algo {
let grid = Grid::new(poisson.radius, poisson.poisson_type);
let mut indices = Vec::with_capacity(grid.cells() * 2);
let choices = (0..grid.side()).map(|i| i as f32).collect::<Vec<_>>();
indices.extend(each_combination(&choices));
let a = 0.3;
Algo {
a,
grid,
throws: (a * indices.len() as f64).ceil() as usize,
range: Uniform::new(0, indices.len()),
indices,
level: 0,
success: 0,
outside: vec![],
mantissa_digits: f32::MANTISSA_DIGITS as usize,
}
}
}
pub struct Algo {
grid: Grid,
indices: Vec<Vec2>,
level: usize,
range: Uniform<usize>,
throws: usize,
success: usize,
outside: Vec<Vec2>,
mantissa_digits: usize,
a: f64,
}
impl Algorithm for Algo {
fn next<R>(&mut self, poisson: &mut Builder, rng: &mut R) -> Option<mint::Vector2<f32>>
where
R: Rng,
{
if self.indices.is_empty() {
return None;
}
while self.level < self.mantissa_digits {
while self.throws > 0 {
self.throws -= 1;
let index = rng.sample(self.range);
let cur = self.indices[index].clone();
let parent = get_parent(cur.clone(), self.level);
if !self
.grid
.get(parent.clone())
.expect("Indexing base grid by valid parent failed.")
.is_empty()
{
self.indices.swap_remove(index);
if self.indices.is_empty() {
return None;
}
self.range = Uniform::new(0, self.indices.len());
} else {
let sample = choose_random_sample(rng, &self.grid, cur.clone(), self.level);
if is_disk_free(
&self.grid,
poisson,
cur.clone(),
self.level,
sample.clone(),
&self.outside,
) {
self.grid
.get_mut(parent)
.expect("Indexing base grid by already indexed valid parent failed.")
.push(sample.clone());
self.indices.swap_remove(index);
if !self.indices.is_empty() {
self.range = Uniform::new(0, self.indices.len());
}
self.success += 1;
return Some(sample.into());
}
}
}
self.subdivide(&poisson);
if self.indices.is_empty() {
return None;
}
self.range = Uniform::new(0, self.indices.len());
self.throws = (self.a * self.indices.len() as f64).ceil() as usize;
self.level += 1;
}
let index = rng.sample(self.range);
let cur = self.indices.swap_remove(index);
let side = 2usize.pow(self.level as u32);
let sample = index_to_sample(&cur, side);
if is_disk_free(
&self.grid,
poisson,
cur.clone(),
self.level,
sample.clone(),
&self.outside,
) {
Some(sample.into())
} else {
None
}
}
fn size_hint(&self, poisson: &Builder) -> (usize, Option<usize>) {
let side = 2usize.pow(self.level as u32);
let spacing = self.grid.cell() / (side as f32);
let grid_volume = (self.indices.len() as f32) * spacing.powi(2);
let sphere_volume = sphere_volume(2.0 * poisson.radius, 2);
let lower = grid_volume / sphere_volume;
let mut lower = lower.floor() as usize;
if lower > 0 {
lower -= 1;
}
let upper = self.grid.cells() - self.success;
(lower, Some(upper))
}
fn restrict(&mut self, sample: mint::Vector2<f32>) {
let sample: Vec2 = sample.into();
self.success += 1;
let index = sample_to_index(&sample, self.grid.side());
if let Some(g) = self.grid.get_mut(index) {
g.push(sample);
} else {
self.outside.push(sample);
}
}
fn stays_legal(&self, poisson: &Builder, sample: mint::Vector2<f32>) -> bool {
let sample: Vec2 = sample.into();
let index = sample_to_index(&sample, self.grid.side());
is_disk_free(&self.grid, poisson, index, 0, sample.clone(), &self.outside)
}
}
impl Algo {
fn subdivide(&mut self, poisson: &Builder) {
let choices = &[0.0, 1.0];
let (grid, outside, level) = (&self.grid, &self.outside, self.level);
self.indices.flat_map_inplace(|i| {
each_combination(choices)
.map(move |n: Vec2| n + i.clone() * 2.0)
.filter(|c| !covered(grid, poisson, outside, c.clone(), level + 1))
});
}
}
fn covered(
grid: &Grid,
poisson: &Builder,
outside: &[Vec2],
index: Vec2,
level: usize,
) -> bool {
let side = 2usize.pow(level as u32);
let spacing = grid.cell() / (side as f32);
let sqradius = (2.0 * poisson.radius).powi(2);
let parent = get_parent(index.clone(), level);
each_combination(&[0.0, 1.0])
.map(|t| (index.clone() + t) * spacing)
.all(|t| {
each_combination(&[-2.0, -1.0, 0.0, 1.0, 2.0])
.filter_map(|t| grid.get(parent.clone() + t))
.flat_map(|t| t)
.any(|v| sqdist(v.clone(), t.clone(), poisson.poisson_type) < sqradius)
|| !is_valid(poisson, &outside, t)
})
}