1 files changed, 154 insertions, 0 deletions

diff --git a/src/obj_export.rs b/src/obj_export.rs
new file mode 100644
index 0000000..7998112
--- /dev/null
+++ b/src/obj_export.rs
@@ -0,0 +1,154 @@
+use crate::*;
+
+struct VertAttr<L, F, T, V> {
+    func: F,
+    items: Vec<T>,
+    local: HashMap<usize, Option<usize>>,
+    // global: HashMap<T, usize>,
+    marker: std::marker::PhantomData<(V, L)>,
+}
+
+impl<L, F, T, V> VertAttr<L, F, T, V>
+where
+    F: FnMut(L, &V) -> Option<T>,
+    T: Copy, // + Hash + Eq,
+{
+    fn new(func: F) -> Self {
+        Self {
+            func,
+            items: Vec::new(),
+            local: HashMap::new(),
+            // global: HashMap::new(),
+            marker: std::marker::PhantomData,
+        }
+    }
+
+    fn add(&mut self, local: L, vert_id: usize, vert_data: &V) -> Option<usize> {
+        *self.local.entry(vert_id).or_insert_with(|| {
+            let item = (self.func)(local, vert_data);
+
+            //*self.global.entry(item).or_insert_with(|| {
+            item.map(|item| {
+                self.items.push(item);
+                self.items.len()
+            })
+            //})
+        })
+    }
+}
+
+pub struct ObjExport<'tok, 'brand, 'arena, V, W, VPos, VTex, VNorm> {
+    writer: &'tok mut W,
+    dcel: &'tok Dcel<'brand, 'arena, V>,
+    vertex_pos: VPos,
+    pos_ids: HashMap<usize, usize>,
+    textures: VertAttr<lens!(Face), VTex, (f64, Option<(f64, Option<f64>)>), V>,
+    normals: VertAttr<lens!(Face), VNorm, (f64, f64, f64), V>,
+}
+
+impl<'tok, 'brand, 'arena, V, W, VPos, VTex, VNorm>
+    ObjExport<'tok, 'brand, 'arena, V, W, VPos, VTex, VNorm>
+where
+    W: std::io::Write,
+    VPos: FnMut(&V) -> (f64, f64, f64, Option<f64>),
+    VTex: FnMut(lens!(Face), &V) -> Option<(f64, Option<(f64, Option<f64>)>)>,
+    VNorm: FnMut(lens!(Face), &V) -> Option<(f64, f64, f64)>,
+{
+    pub fn export(
+        writer: &'tok mut W,
+        dcel: &'tok Dcel<'brand, 'arena, V>,
+        vertex_pos: VPos,
+        vertex_texture: VTex,
+        vertex_normal: VNorm,
+    ) -> std::io::Result<()> {
+        Self {
+            writer,
+            dcel,
+            vertex_pos,
+            pos_ids: HashMap::new(),
+            textures: VertAttr::new(vertex_texture),
+            normals: VertAttr::new(vertex_normal),
+        }
+        .write()
+    }
+
+    fn write(&mut self) -> std::io::Result<()> {
+        let mut next_id = 1;
+        for shell in self.dcel.iter_bodies().flat_map(Lens::iter_shells) {
+            for vertex in shell.iter_vertices() {
+                self.pos_ids.insert(vertex.id(), next_id);
+                next_id += 1;
+
+                let (x, y, z, w) = (self.vertex_pos)(vertex.data());
+                write!(self.writer, "v {x} {y} {z}")?;
+                if let Some(w) = w {
+                    write!(self.writer, " {w}")?;
+                }
+                writeln!(self.writer)?;
+            }
+
+            for face in shell.iter_faces() {
+                write!(self.writer, "f")?;
+
+                for inner in face.iter_inner_loops() {
+                    self.write_vertex(face, face.outer_loop().half_edges())?;
+                    for h in inner.iter_half_edges() {
+                        self.write_vertex(face, h)?;
+                    }
+                }
+
+                for h in face.outer_loop().iter_half_edges() {
+                    self.write_vertex(face, h)?;
+                }
+
+                self.textures.local.clear();
+                self.normals.local.clear();
+
+                writeln!(self.writer)?;
+            }
+        }
+
+        for (u, vw) in &self.textures.items {
+            write!(self.writer, "vt {u}")?;
+            if let Some((v, w)) = vw {
+                write!(self.writer, " {v}")?;
+                if let Some(w) = w {
+                    write!(self.writer, " {w}")?;
+                }
+            }
+            writeln!(self.writer)?;
+        }
+
+        for (x, y, z) in &self.normals.items {
+            writeln!(self.writer, "vn {x} {y} {z}")?;
+        }
+
+        Ok(())
+    }
+
+    fn write_vertex(
+        &mut self,
+        face: lens!(Face),
+        half_edge: lens!(HalfEdge),
+    ) -> std::io::Result<()> {
+        let vert = half_edge.origin();
+        write!(self.writer, " {}", self.pos_ids[&vert.id()])?;
+
+        let t = self.textures.add(face, vert.id(), vert.data());
+        let n = self.normals.add(face, vert.id(), vert.data());
+
+        if t.is_some() || n.is_some() {
+            write!(self.writer, "/")?;
+        }
+
+        if let Some(t) = t {
+            write!(self.writer, "{t}")?;
+        }
+
+        if let Some(n) = n {
+            write!(self.writer, "/{n}")?;
+        }
+
+        Ok(())
+    }
+}