use core::convert::From;
use std::cmp::Reverse;
use std::collections::{BTreeSet, BinaryHeap};
use std::ops::Bound::{Excluded, Unbounded};
use crate::operations::{to_sorted_pair, IntersectCrossingSegments, Orient};
use crate::oriented::Orientation;
use crate::sweeping::traits::{EventsQueue, SweepLine};
use crate::traits::{Segmental, Sequence};
use super::event::{
is_event_left, segment_id_to_left_event, segment_id_to_right_event, Event,
};
use super::events_queue_key::EventsQueueKey;
use super::sweep_line_key::SweepLineKey;
pub(crate) struct EventsRegistry<Point, const UNIQUE: bool> {
#[allow(clippy::box_collection)]
endpoints: Box<Vec<Point>>,
events_queue_data: BinaryHeap<Reverse<EventsQueueKey<Point>>>,
min_collinear_segments_ids: Vec<usize>,
#[allow(clippy::box_collection)]
opposites: Box<Vec<Event>>,
segments_ids: Vec<usize>,
sweep_line_data: BTreeSet<SweepLineKey<Point>>,
}
impl<Point: Clone + PartialOrd, const UNIQUE: bool> Iterator
for EventsRegistry<Point, UNIQUE>
where
Self: EventsQueue<Event = Event> + SweepLine<Event = Event>,
for<'a> &'a Point: IntersectCrossingSegments<Output = Point> + Orient,
{
type Item = Event;
fn next(&mut self) -> Option<Self::Item> {
if let Some(event) = self.pop() {
if is_event_left(event) {
if let Some(equal_segment_event) =
<Self as SweepLine>::find(self, event)
{
self.merge_equal_segment_events(
equal_segment_event,
event,
);
if UNIQUE {
self.next()
} else {
Some(event)
}
} else {
self.insert(event);
if let Some(below_event) = self.below(event) {
self.detect_intersection(below_event, event);
}
if let Some(above_event) = self.above(event) {
self.detect_intersection(event, above_event);
}
Some(event)
}
} else {
let event_opposite = self.to_opposite_event(event);
debug_assert!(is_event_left(event_opposite));
if let Some(equal_segment_event) =
<Self as SweepLine>::find(self, event_opposite)
{
let (maybe_above_event, maybe_below_event) = (
self.above(equal_segment_event),
self.below(equal_segment_event),
);
self.remove(equal_segment_event);
if let (Some(above_event), Some(below_event)) =
(maybe_above_event, maybe_below_event)
{
self.detect_intersection(below_event, above_event);
}
if equal_segment_event != event_opposite {
self.merge_equal_segment_events(
event_opposite,
equal_segment_event,
);
}
Some(event)
} else if UNIQUE {
self.next()
} else {
Some(event)
}
}
} else {
None
}
}
}
impl<Point, const UNIQUE: bool> EventsRegistry<Point, UNIQUE> {
pub(super) fn are_collinear(
&self,
segment_id: usize,
other_segment_id: usize,
) -> bool {
self.to_min_collinear_segment_id(segment_id)
== self.to_min_collinear_segment_id(other_segment_id)
}
pub(super) fn get_event_end(&self, event: Event) -> &Point {
&self.endpoints[self.to_opposite_event(event)]
}
pub(super) fn get_event_start(&self, event: Event) -> &Point {
&self.endpoints[event]
}
pub(super) fn get_segment_end(&self, segment_id: usize) -> &Point {
&self.endpoints[segment_id_to_right_event(segment_id)]
}
pub(super) fn get_segment_start(&self, segment_id: usize) -> &Point {
&self.endpoints[segment_id_to_left_event(segment_id)]
}
pub(super) fn to_event_segment_id(&self, event: Event) -> usize {
self.to_left_event_segment_id(if is_event_left(event) {
event
} else {
self.to_opposite_event(event)
})
}
fn to_left_event_segment_id(&self, event: Event) -> usize {
debug_assert!(is_event_left(event));
self.segments_ids[event / 2]
}
fn to_min_collinear_segment_id(&self, segment_id: usize) -> usize {
let mut candidate = segment_id;
let mut iterations_count = 0;
while self.min_collinear_segments_ids[candidate] != candidate {
candidate = self.min_collinear_segments_ids[candidate];
iterations_count += 1;
}
debug_assert!(iterations_count < 3);
candidate
}
fn to_opposite_event(&self, event: Event) -> Event {
self.opposites[event]
}
fn to_sweep_line_key(&self, event: Event) -> SweepLineKey<Point> {
debug_assert!(is_event_left(event));
SweepLineKey::new(event, &self.endpoints, &self.opposites)
}
}
impl<
Point: Ord,
Segment: Clone + Segmental<Endpoint = Point>,
Segments: Sequence<IndexItem = Segment>,
const UNIQUE: bool,
> From<&Segments> for EventsRegistry<Point, UNIQUE>
{
fn from(segments: &Segments) -> Self {
let mut result = Self::with_capacity(segments.len());
result.extend(segments.iter().cloned());
result
}
}
impl<Point: Clone + PartialOrd, const UNIQUE: bool>
EventsRegistry<Point, UNIQUE>
where
Self: EventsQueue<Event = Event> + SweepLine<Event = Event>,
for<'a> &'a Point: IntersectCrossingSegments<Output = Point> + Orient,
{
pub(super) fn detect_intersection(
&mut self,
below_event: Event,
event: Event,
) {
debug_assert_ne!(below_event, event);
let event_start = self.get_event_start(event);
let event_end = self.get_event_end(event);
let below_event_start = self.get_event_start(below_event);
let below_event_end = self.get_event_end(below_event);
let event_start_orientation =
below_event_end.orient(below_event_start, event_start);
let event_end_orientation =
below_event_end.orient(below_event_start, event_end);
if event_start_orientation == event_end_orientation {
if event_start_orientation == Orientation::Collinear {
if event_start == below_event_start {
debug_assert!(event_end != below_event_end);
let (max_end_event, min_end_event) =
if event_end < below_event_end {
(below_event, event)
} else {
(event, below_event)
};
self.remove(max_end_event);
let min_end = self.get_event_end(min_end_event).clone();
let (_, min_end_to_max_end_event) =
self.divide(max_end_event, min_end);
self.push(min_end_to_max_end_event);
self.merge_equal_segment_events(event, below_event);
} else if event_end == below_event_end {
let (max_start_event, min_start_event) =
if event_start < below_event_start {
(below_event, event)
} else {
(event, below_event)
};
let max_start =
self.get_event_start(max_start_event).clone();
let (max_start_to_min_start_event, max_start_to_end_event) =
self.divide(min_start_event, max_start);
self.push(max_start_to_min_start_event);
self.merge_equal_segment_events(
max_start_event,
max_start_to_end_event,
);
} else if below_event_start < event_start
&& event_start < below_event_end
{
if event_end < below_event_end {
let event_start = event_start.clone();
let event_end = event_end.clone();
self.divide_event_by_mid_segment_event_endpoints(
below_event,
event,
event_start,
event_end,
);
} else {
let (max_start, min_end) =
(event_start.clone(), below_event_end.clone());
self.divide_overlapping_events(
below_event,
event,
max_start,
min_end,
);
}
} else if event_start < below_event_start
&& below_event_start < event_end
{
if below_event_end < event_end {
let below_event_start = below_event_start.clone();
let below_event_end = below_event_end.clone();
self.divide_event_by_mid_segment_event_endpoints(
event,
below_event,
below_event_start,
below_event_end,
);
} else {
let (max_start, min_end) =
(below_event_start.clone(), event_end.clone());
self.divide_overlapping_events(
event,
below_event,
max_start,
min_end,
);
}
}
}
} else if event_start_orientation == Orientation::Collinear {
if below_event_start < event_start && event_start < below_event_end
{
let point = event_start.clone();
self.divide_event_by_midpoint(below_event, point);
}
} else if event_end_orientation == Orientation::Collinear {
if below_event_start < event_end && event_end < below_event_end {
let point = event_end.clone();
self.divide_event_by_midpoint(below_event, point);
}
} else {
let below_event_start_orientation =
event_start.orient(event_end, below_event_start);
let below_event_end_orientation =
event_start.orient(event_end, below_event_end);
if below_event_start_orientation == Orientation::Collinear {
if event_start < below_event_start
&& below_event_start < event_end
{
let point = below_event_start.clone();
self.divide_event_by_midpoint_checking_above(event, point);
}
} else if below_event_end_orientation == Orientation::Collinear {
if event_start < below_event_end && below_event_end < event_end
{
let point = below_event_end.clone();
self.divide_event_by_midpoint_checking_above(event, point);
}
} else if below_event_start_orientation
!= below_event_end_orientation
{
let cross_point =
IntersectCrossingSegments::intersect_crossing_segments(
event_start,
event_end,
below_event_start,
below_event_end,
);
self.divide_event_by_midpoint(
below_event,
cross_point.clone(),
);
self.divide_event_by_midpoint_checking_above(
event,
cross_point,
);
}
}
}
pub(super) fn merge_equal_segment_events(
&mut self,
first: Event,
second: Event,
) {
debug_assert_ne!(first, second);
debug_assert!(is_event_left(first));
debug_assert!(is_event_left(second));
debug_assert_ne!(
self.to_left_event_segment_id(first),
self.to_left_event_segment_id(second)
);
debug_assert!(
self.get_event_start(first) == self.get_event_start(second)
);
debug_assert!(self.get_event_end(first) == self.get_event_end(second));
let first_segment_id = self.to_left_event_segment_id(first);
let second_segment_id = self.to_left_event_segment_id(second);
let first_min_collinear_segment_id =
self.min_collinear_segments_ids[first_segment_id];
let second_min_collinear_segment_id =
self.min_collinear_segments_ids[second_segment_id];
let min_collinear_segment_id = first_min_collinear_segment_id
.min(second_min_collinear_segment_id);
self.min_collinear_segments_ids[first_segment_id] =
min_collinear_segment_id;
self.min_collinear_segments_ids[second_segment_id] =
min_collinear_segment_id;
self.min_collinear_segments_ids[first_min_collinear_segment_id] =
min_collinear_segment_id;
self.min_collinear_segments_ids[second_min_collinear_segment_id] =
min_collinear_segment_id;
}
fn divide_overlapping_events(
&mut self,
min_start_event: Event,
max_start_event: Event,
max_start: Point,
min_end: Point,
) {
self.divide_event_by_midpoint(max_start_event, min_end);
let (max_start_to_min_start_event, max_start_to_min_end_event) =
self.divide(min_start_event, max_start);
self.push(max_start_to_min_start_event);
self.merge_equal_segment_events(
max_start_event,
max_start_to_min_end_event,
);
}
fn divide_event_by_mid_segment_event_endpoints(
&mut self,
event: Event,
mid_segment_event: Event,
mid_segment_event_start: Point,
mid_segment_event_end: Point,
) where
Point: PartialEq,
{
debug_assert!(mid_segment_event_start
.eq(self.get_event_start(mid_segment_event)));
debug_assert!(
mid_segment_event_end.eq(self.get_event_end(mid_segment_event))
);
debug_assert!(mid_segment_event_start.ne(self.get_event_start(event)));
debug_assert!(mid_segment_event_end.ne(self.get_event_end(event)));
self.divide_event_by_midpoint(event, mid_segment_event_end);
let (
mid_segment_event_start_to_event_start_event,
mid_segment_event_start_to_mid_segment_event_end_event,
) = self.divide(event, mid_segment_event_start);
self.push(mid_segment_event_start_to_event_start_event);
self.merge_equal_segment_events(
mid_segment_event,
mid_segment_event_start_to_mid_segment_event_end_event,
);
}
fn divide_event_by_midpoint(&mut self, event: Event, point: Point) {
let (point_to_event_start_event, point_to_event_end_event) =
self.divide(event, point);
self.push(point_to_event_start_event);
self.push(point_to_event_end_event);
}
fn divide_event_by_midpoint_checking_above(
&mut self,
event: Event,
point: Point,
) {
if let Some(above_event) = self.above(event) {
if self
.get_event_start(above_event)
.eq(self.get_event_start(event))
&& self.get_event_end(above_event).eq(&point)
{
self.remove(above_event);
self.divide_event_by_midpoint(event, point);
self.merge_equal_segment_events(event, above_event);
return;
}
}
self.divide_event_by_midpoint(event, point);
}
}
impl<Point: Clone, const UNIQUE: bool> EventsRegistry<Point, UNIQUE> {
pub(super) fn divide(
&mut self,
event: Event,
mid_point: Point,
) -> (Event, Event) {
debug_assert!(is_event_left(event));
let opposite_event = self.to_opposite_event(event);
let mid_point_to_event_end_event = self.endpoints.len();
self.segments_ids.push(self.to_left_event_segment_id(event));
self.endpoints.push(mid_point.clone());
self.opposites.push(opposite_event);
self.opposites[opposite_event] = mid_point_to_event_end_event;
let mid_point_to_event_start_event = self.endpoints.len();
self.endpoints.push(mid_point);
self.opposites.push(event);
self.opposites[event] = mid_point_to_event_start_event;
(mid_point_to_event_start_event, mid_point_to_event_end_event)
}
}
impl<Point: Ord, const UNIQUE: bool> EventsQueue
for EventsRegistry<Point, UNIQUE>
{
type Event = Event;
fn peek(&mut self) -> Option<Self::Event> {
self.events_queue_data.peek().map(|key| key.0.event)
}
fn pop(&mut self) -> Option<Self::Event> {
self.events_queue_data.pop().map(|key| key.0.event)
}
fn push(&mut self, event: Self::Event) {
self.events_queue_data.push(Reverse(EventsQueueKey::new(
event,
&self.endpoints,
&self.opposites,
)));
}
}
impl<Point, const UNIQUE: bool> SweepLine for EventsRegistry<Point, UNIQUE>
where
SweepLineKey<Point>: Ord,
{
type Event = Event;
fn above(&self, event: Self::Event) -> Option<Self::Event> {
self.sweep_line_data
.range((Excluded(&self.to_sweep_line_key(event)), Unbounded))
.next()
.map(|key| key.event)
}
fn below(&self, event: Self::Event) -> Option<Self::Event> {
self.sweep_line_data
.range((Unbounded, Excluded(&self.to_sweep_line_key(event))))
.last()
.map(|key| key.event)
}
fn find(&self, event: Self::Event) -> Option<Self::Event> {
self.sweep_line_data
.get(&self.to_sweep_line_key(event))
.map(|key| key.event)
}
fn insert(&mut self, event: Self::Event) -> bool {
self.sweep_line_data.insert(self.to_sweep_line_key(event))
}
fn remove(&mut self, event: Self::Event) -> bool {
self.sweep_line_data.remove(&self.to_sweep_line_key(event))
}
}
impl<Point: Ord, const UNIQUE: bool> EventsRegistry<Point, UNIQUE> {
fn extend<Segment>(&mut self, segments: impl Iterator<Item = Segment>)
where
Segment: Segmental<Endpoint = Point>,
{
for (segment_id, segment) in segments.enumerate() {
let (start, end) = to_sorted_pair(segment.endpoints());
debug_assert!(start != end);
let left_event = segment_id_to_left_event(segment_id);
let right_event = segment_id_to_right_event(segment_id);
self.endpoints.push(start);
self.endpoints.push(end);
self.opposites.push(right_event);
self.opposites.push(left_event);
self.push(left_event);
self.push(right_event);
}
}
fn with_capacity(segments_count: usize) -> Self {
let capacity = 2 * segments_count;
Self {
endpoints: Box::new(Vec::with_capacity(capacity)),
events_queue_data: BinaryHeap::with_capacity(capacity),
min_collinear_segments_ids: (0..segments_count).collect(),
opposites: Box::new(Vec::with_capacity(capacity)),
segments_ids: (0..segments_count).collect(),
sweep_line_data: BTreeSet::new(),
}
}
}