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|
use crate::*;
pub use obj;
use obj::raw::object::RawObj;
#[derive(Debug, Error)]
pub enum ObjImportError {
#[error("vertex {0} position index out of bounds")]
InvalidPositionIndex(usize),
#[error("half-edge between vertices {0} and {1} appears twice")]
SameHalfEdge(usize, usize),
#[error("half-edge between vertices {0} and {1} does not have a twin")]
UnclaimedHalfEdge(usize, usize),
#[error("empty face")]
EmptyFace,
#[error("vertex {0} is not connected to any edges")]
StandaloneVertex(usize),
}
use ObjImportError::*;
pub struct ObjImport<'tok, 'brand, 'arena, V> {
dcel: &'tok mut Dcel<'brand, 'arena, V>,
obj: &'tok RawObj,
shell: ptr!(Shell),
half_edges: HashMap<(usize, usize), Option<ptr!(HalfEdge)>>,
vertices: Vec<ptr!(Vertex)>,
}
struct CyclicWindows<T, I> {
first: Option<T>,
last: Option<T>,
iter: I,
}
fn cyclic_windows<T, I>(iter: I) -> CyclicWindows<T, I> {
CyclicWindows {
first: None,
last: None,
iter,
}
}
impl<T, I> Iterator for CyclicWindows<T, I>
where
T: Clone,
I: Iterator<Item = T>,
{
type Item = (T, T);
fn next(&mut self) -> Option<Self::Item> {
let Some(item) = self.iter.next() else {
let first = self.first.take()?;
let last = self.last.take()?;
return Some((last, first));
};
self.first.get_or_insert_with(|| item.clone());
let Some(last) = self.last.replace(item.clone()) else {
return self.next();
};
Some((last, item))
}
}
impl<'tok, 'brand, 'arena, V> ObjImport<'tok, 'brand, 'arena, V> {
pub fn import(
dcel: &'tok mut Dcel<'brand, 'arena, V>,
obj: &'tok RawObj,
fun: impl Fn((f32, f32, f32, f32)) -> V,
) -> Result<own!(Body), ObjImportError> {
let body = dcel.new_body();
let shell = *body.add_new_shell(dcel);
let vertices = obj
.positions
.iter()
.map(|&x| *shell.add_new_vertex(fun(x), dcel))
.collect();
let mut imp = ObjImport {
dcel,
obj,
shell,
half_edges: HashMap::new(),
vertices,
};
match imp.import_faces() {
Ok(_) => Ok(body),
Err(x) => {
body.destroy(dcel);
Err(x)
}
}
}
fn iter_polygon(p: &obj::raw::object::Polygon) -> impl DoubleEndedIterator<Item = usize> + '_ {
use either::{Left, Right};
use obj::raw::object::Polygon::*;
match p {
P(v) => Left(Left(v.iter().cloned())),
PT(v) => Left(Right(v.iter().map(|&(x, _)| x))),
PN(v) => Right(Left(v.iter().map(|&(x, _)| x))),
PTN(v) => Right(Right(v.iter().map(|&(x, _, _)| x))),
}
}
fn import_faces(&mut self) -> Result<(), ObjImportError> {
for p in self.obj.polygons.iter() {
if cyclic_windows(Self::iter_polygon(p))
.any(|(a, b)| matches!(self.half_edges.get(&(a, b)), Some(None)))
{
self.import_face(Self::iter_polygon(p).rev())?;
} else {
self.import_face(Self::iter_polygon(p))?;
}
}
if let Some((k, _)) = self.half_edges.iter().find(|(_, v)| v.is_some()) {
Err(UnclaimedHalfEdge(k.1 + 1, k.0 + 1))
} else if let Some((i, _)) = self
.vertices
.iter()
.enumerate()
.find(|(_, x)| x.maybe_outgoing(self.dcel).is_none())
{
Err(StandaloneVertex(i + 1))
} else {
Ok(())
}
}
fn add_half_edge(
&mut self,
loop_: ptr!(Loop),
prev: Option<ptr!(HalfEdge)>,
vertices: [usize; 2],
) -> Result<ptr!(HalfEdge), ObjImportError> {
use std::collections::hash_map::Entry::*;
let [a, b] = vertices;
let v = *self.vertices.get(a).ok_or(InvalidPositionIndex(a + 1))?;
let he = match self.half_edges.entry((a, b)) {
Occupied(mut e) => e.get_mut().take().ok_or(SameHalfEdge(a + 1, b + 1))?,
Vacant(e) => {
let (_, [he1, he2]) = Edge::create(self.shell, self.dcel);
e.insert(None);
self.half_edges.insert((b, a), Some(he2));
he1
}
};
he.update_origin(v, self.dcel);
he.set_loop_(loop_, self.dcel);
if let Some(prev) = prev {
self.dcel.follow(prev, he);
}
Ok(he)
}
fn import_face(&mut self, mut it: impl Iterator<Item = usize>) -> Result<(), ObjImportError> {
let face = *self.shell.add_new_face(self.dcel);
let loop_ = *Loop::new(self.dcel);
loop_.set_face(face, self.dcel);
face.set_outer_loop(loop_, self.dcel);
let fv = it.next().ok_or(EmptyFace)?;
let (fe, le, lv) = it.try_fold((None, None, fv), |(fe, le, a), b| {
let he = self.add_half_edge(loop_, le, [a, b])?;
Ok((fe.or(Some(he)), Some(he), b))
})?;
let fe = fe.ok_or(EmptyFace)?;
let le = self.add_half_edge(loop_, le, [lv, fv])?;
self.dcel.follow(le, fe);
loop_.set_half_edges(fe, self.dcel);
Ok(())
}
}
|
