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use super::{BoundingBox, ClipBehavior, Point, Voronoi};
use super::utils::calculate_approximated_cetroid;
/// Provides a convenient way to construct a Voronoi diagram.
#[derive(Default)]
pub struct VoronoiBuilder {
sites: Option<Vec<Point>>,
lloyd_iterations: usize,
bounding_box: BoundingBox,
clip_behavior: ClipBehavior,
}
impl VoronoiBuilder {
/// Sets the [BoundingBox] that will be used to enclose the graph.
///
/// Default value is [BoundingBox::default()].
pub fn set_bounding_box(mut self, bounding_box: BoundingBox) -> Self {
self.bounding_box = bounding_box;
self
}
/// Sets the [ClipBehavior] to be used when building the graph.
///
/// Default value is [ClipBehavior::default()].
pub fn set_clip_behavior(mut self, clip_behavior: ClipBehavior) -> Self {
self.clip_behavior = clip_behavior;
self
}
/// Sets a vector of [Point]s representing the sites of each Voronoi cell that should be constructed.
///
/// By convention, the Y-axis points downwards.
pub fn set_sites(mut self, sites: Vec<Point>) -> Self {
self.sites.replace(sites);
self
}
/// Sets the number of [LLoyd relaxation](https://en.wikipedia.org/wiki/Lloyd%27s_algorithm) iterations that should be run as part of the graph generation.
///
/// Default is 0.
pub fn set_lloyd_relaxation_iterations(mut self, iterations: usize) -> Self {
self.lloyd_iterations = iterations;
self
}
/// Consumes this builder and generates a Voronoi diagram/graph.
/// An ```Option<Voronoi>``` is returned. None may be a valid return value if the set of sites do not generate a valid graph.
///
/// # Examples
///
///```
/// use voronoice::*;
/// // creates a voronoi graph from generated square sites, within a square bounding box of side 5.0
/// // and runs 4 lloyd relaxation iterations to spread sites in the region
/// let v: Voronoi = VoronoiBuilder::default()
/// .generate_square_sites(10)
/// .set_bounding_box(BoundingBox::new_centered_square(5.0))
/// .set_lloyd_relaxation_iterations(4)
/// .build()
/// .unwrap();
///```
///
/// # Panics
///
/// Panics if no sites have been provided through [Self::set_sites] or one of the generate_*_sites methods.
pub fn build(mut self) -> Option<Voronoi> {
let v = Voronoi::new(
self.sites.take().expect("Cannot build voronoi without sites. Call set_sites() first."),
self.bounding_box.clone(),
self.clip_behavior,
);
self.perform_lloyd_relaxation(v)
}
fn perform_lloyd_relaxation(&mut self, mut v: Option<Voronoi>) -> Option<Voronoi> {
for _ in 0..self.lloyd_iterations {
if let Some(voronoi) = v {
// get vertices for each cell and approximate centroid
let new_sites = voronoi.iter_cells().map(|c| calculate_approximated_cetroid(c.iter_vertices()))
.collect::<Vec<Point>>();
// recompute new voronoi with sites after relaxation
v = Self::create_builder_from_voronoi_without_sites(&voronoi)
.set_sites(new_sites)
.build();
} else {
break;
}
}
v
}
/// Generates sites in the format of a circle centered at the origin with ```size``` points and radius ```radius```.
/// Internally calls [Self::set_sites] with the generated value.
pub fn generate_circle_sites(self, size: usize, radius: f64) -> Self {
let len = size;
let r = radius;
let mut sites = vec![];
sites.push(Point { x: 0.0, y: 0.0 });
for i in 0..len {
let a = (i as f64 * 360.0 / len as f64).to_radians();
sites.push(Point {
x: r * a.sin(),
y: r * a.cos()
});
}
self.set_sites(sites)
}
/// Generates sites in the format of a rectangle centered at the origin with ```width``` and ```height``` and ```width``` times ```height``` points.
/// Internally calls [Self::set_sites] with the generated value.
pub fn generate_rect_sites(self, width: usize, height: usize) -> Self {
let mut sites = vec![];
let fwidth = width as f64;
let fheight = height as f64;
for i in 0..width {
for j in 0..height {
sites.push(Point {
x: i as f64 / fwidth - 0.5,
y: j as f64/ fheight - 0.5
});
}
}
self.set_sites(sites)
}
/// Generates sites in the format of a square centered at the origin with ```width``` and ```width``` square points.
/// Internally calls [Self::set_sites] with the generated value.
pub fn generate_square_sites(self, width: usize) -> Self {
self.generate_rect_sites(width, width)
}
fn create_builder_from_voronoi_without_sites(v: &Voronoi) -> Self {
Self {
bounding_box: v.bounding_box.clone(),
clip_behavior: v.clip_behavior,
lloyd_iterations: 0,
sites: None,
}
}
}
impl From<&Voronoi> for VoronoiBuilder {
/// Creates a builder with same configurations that produced the original voronoi.
/// Useful for performing Lloyd relaxation or storing the configuration to generate a identical diagram.
fn from(v: &Voronoi) -> Self {
let mut builder = Self::create_builder_from_voronoi_without_sites(v);
builder.sites = Some(v.sites.clone());
builder
}
}
impl From<Voronoi> for VoronoiBuilder {
/// Creates a builder with same configurations that produced the original voronoi, consuming it.
/// Useful for performing Lloyd relaxation or storing the configuration to generate a identical diagram.
fn from(v: Voronoi) -> Self {
let mut builder = Self::create_builder_from_voronoi_without_sites(&v);
builder.sites = Some(v.sites);
builder
}
}