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|
use crate::{BackendCoord, BackendStyle, DrawingBackend, DrawingErrorKind};
use std::cmp::{Ord, Ordering, PartialOrd};
#[derive(Clone, Debug)]
struct Edge {
epoch: u32,
total_epoch: u32,
slave_begin: i32,
slave_end: i32,
}
impl Edge {
fn horizontal_sweep(mut from: BackendCoord, mut to: BackendCoord) -> Option<Edge> {
if from.0 == to.0 {
return None;
}
if from.0 > to.0 {
std::mem::swap(&mut from, &mut to);
}
Some(Edge {
epoch: 0,
total_epoch: (to.0 - from.0) as u32,
slave_begin: from.1,
slave_end: to.1,
})
}
fn vertical_sweep(from: BackendCoord, to: BackendCoord) -> Option<Edge> {
Edge::horizontal_sweep((from.1, from.0), (to.1, to.0))
}
fn get_master_pos(&self) -> i32 {
(self.total_epoch - self.epoch) as i32
}
fn inc_epoch(&mut self) {
self.epoch += 1;
}
fn get_slave_pos(&self) -> f64 {
f64::from(self.slave_begin)
+ (i64::from(self.slave_end - self.slave_begin) * i64::from(self.epoch)) as f64
/ f64::from(self.total_epoch)
}
}
impl PartialOrd for Edge {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
self.get_slave_pos().partial_cmp(&other.get_slave_pos())
}
}
impl PartialEq for Edge {
fn eq(&self, other: &Self) -> bool {
self.get_slave_pos() == other.get_slave_pos()
}
}
impl Eq for Edge {}
impl Ord for Edge {
fn cmp(&self, other: &Self) -> Ordering {
self.get_slave_pos()
.partial_cmp(&other.get_slave_pos())
.unwrap()
}
}
pub fn fill_polygon<DB: DrawingBackend, S: BackendStyle>(
back: &mut DB,
vertices: &[BackendCoord],
style: &S,
) -> Result<(), DrawingErrorKind<DB::ErrorType>> {
if let Some((x_span, y_span)) =
vertices
.iter()
.fold(None, |res: Option<((i32, i32), (i32, i32))>, (x, y)| {
Some(
res.map(|((min_x, max_x), (min_y, max_y))| {
(
(min_x.min(*x), max_x.max(*x)),
(min_y.min(*y), max_y.max(*y)),
)
})
.unwrap_or(((*x, *x), (*y, *y))),
)
})
{
// First of all, let's handle the case that all the points is in a same vertical or
// horizontal line
if x_span.0 == x_span.1 || y_span.0 == y_span.1 {
return back.draw_line((x_span.0, y_span.0), (x_span.1, y_span.1), style);
}
let horizontal_sweep = x_span.1 - x_span.0 > y_span.1 - y_span.0;
let mut edges: Vec<_> = vertices
.iter()
.zip(vertices.iter().skip(1))
.map(|(a, b)| (*a, *b))
.collect();
edges.push((vertices[vertices.len() - 1], vertices[0]));
edges.sort_by_key(|((x1, y1), (x2, y2))| {
if horizontal_sweep {
*x1.min(x2)
} else {
*y1.min(y2)
}
});
for edge in &mut edges.iter_mut() {
if horizontal_sweep {
if (edge.0).0 > (edge.1).0 {
std::mem::swap(&mut edge.0, &mut edge.1);
}
} else if (edge.0).1 > (edge.1).1 {
std::mem::swap(&mut edge.0, &mut edge.1);
}
}
let (low, high) = if horizontal_sweep { x_span } else { y_span };
let mut idx = 0;
let mut active_edge: Vec<Edge> = vec![];
for sweep_line in low..=high {
let mut new_vec = vec![];
for mut e in active_edge {
if e.get_master_pos() > 0 {
e.inc_epoch();
new_vec.push(e);
}
}
active_edge = new_vec;
loop {
if idx >= edges.len() {
break;
}
let line = if horizontal_sweep {
(edges[idx].0).0
} else {
(edges[idx].0).1
};
if line > sweep_line {
break;
}
let edge_obj = if horizontal_sweep {
Edge::horizontal_sweep(edges[idx].0, edges[idx].1)
} else {
Edge::vertical_sweep(edges[idx].0, edges[idx].1)
};
if let Some(edge_obj) = edge_obj {
active_edge.push(edge_obj);
}
idx += 1;
}
active_edge.sort();
let mut first = None;
let mut second = None;
for edge in active_edge.iter() {
if first.is_none() {
first = Some(edge.clone())
} else if second.is_none() {
second = Some(edge.clone())
}
if let Some(a) = first.clone() {
if let Some(b) = second.clone() {
if a.get_master_pos() == 0 && b.get_master_pos() != 0 {
first = Some(b);
second = None;
continue;
}
if a.get_master_pos() != 0 && b.get_master_pos() == 0 {
first = Some(a);
second = None;
continue;
}
let from = a.get_slave_pos();
let to = b.get_slave_pos();
if a.get_master_pos() == 0 && b.get_master_pos() == 0 && to - from > 1.0 {
first = None;
second = None;
continue;
}
if horizontal_sweep {
check_result!(back.draw_line(
(sweep_line, from.ceil() as i32),
(sweep_line, to.floor() as i32),
&style.color(),
));
check_result!(back.draw_pixel(
(sweep_line, from.floor() as i32),
style.color().mix(from.ceil() - from),
));
check_result!(back.draw_pixel(
(sweep_line, to.ceil() as i32),
style.color().mix(to - to.floor()),
));
} else {
check_result!(back.draw_line(
(from.ceil() as i32, sweep_line),
(to.floor() as i32, sweep_line),
&style.color(),
));
check_result!(back.draw_pixel(
(from.floor() as i32, sweep_line),
style.color().mix(from.ceil() - from),
));
check_result!(back.draw_pixel(
(to.ceil() as i32, sweep_line),
style.color().mix(to.floor() - to),
));
}
first = None;
second = None;
}
}
}
}
}
Ok(())
}
|
