Meh, kind of over trying to roll my own subdivision crap

README.md

@@ -2,17 +2,10 @@
 
 ## Highest priority:
 
-- Add better docs and possibly abstraction to `dcel.rs`, *before*
+- Just scrap `parametric_mesh` as much as possible and use existing
-  it's widely used.  Possibly rename too.
+  tools (e.g. OpenSubdiv) because this DCEL method is just painful for
-- `dcel.rs` needs a helper method for subdivision.
+  what it is and I have some questions on how it can even work
-- Redo `examples::parametric_mesh` along the following lines:
+  theoretically.
-  - DONE: Make a crappy mesh (as a DCEL) like my 'early' method.
-  - Use my method from around 2020-05-21, and my pile of loose notes,
-    to subdivide - with the help of DCEL.
-- Document `parametric_mesh` better. It is pretty hairy and could
-  also benefit from some modularity.
-- parametric_mesh: My err/max_err code seems to sometimes give very high
-  dt values, e.g. if I use just a translation as my transform
 - Get identical or near-identical meshes to `ramhorn_branch` from
   Python.  (Should just be a matter of tweaking parameters.)
 - Look at performance.

src/dcel.rs

@@ -134,10 +134,9 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
         }
 
         for (i,h) in self.halfedges.iter().enumerate() {
-            let twin = if h.has_twin {
+            let twin = if h.has_twin {                format!(", twin half-edge {}", h.twin_halfedge)
-                format!(", twin half-edge {}", h.twin_halfedge)
             } else {
-                String::from("")
+                format!(", no twin")
             };
             let v1 = self.verts[h.vert].v;
             let v2 = self.verts[self.halfedges[h.next_halfedge].vert].v;
@@ -485,22 +484,43 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
         (f_n, [e_n, e_n+1, e_n+2])
     }
 
-    pub fn split_face(&mut self, face: usize, verts: Vec<V>) {
+    /// Splits a face (assumed to be a triangle) in this mesh by splitting
+    /// its half-edges, in order, at the vertices given, and then creating
+    /// half-edges between each pair of them.
+    ///
+    /// This returns; (new face indices, updated face indices).  That is,
+    /// the first vector is new face indices that were created, and the
+    /// second is existing face indices that were reused (but the faces
+    /// were updated).
+    ///
+    /// This splits the given face into 4 smaller faces, and it splits the
+    /// three *bordering* faces each into 2 faces.  That is, this
+    /// increases the number of faces by 6 and the number of vertices
+    /// by 3.
+    ///
+    /// Right now, this requires that every halfedge of `face` has a twin.
+    /// If this is not the case, this returns `None` and does not subdivide.
+    /// This behavior will likely be changed in the future.
+    ///
+    /// Disclaimer: This code is completely awful; just don't use it.
+    pub fn full_subdiv_face(&mut self, face: usize, verts: Vec<V>) -> Option<(Vec<usize>, Vec<usize>)> {
         // 'verts' maps 1:1 to vertices for 'face' (i.e. face_to_verts).
 
         let mut edge_idx = self.faces[face].halfedge;
         let n = verts.len();
 
-        //
+        let mut faces_new = vec![];
-        let new_edges: Vec<(usize, usize)> = verts.iter().map(|v| {
+        let mut faces_upd = vec![];
 
-            println!("DEBUG: halfedge 3: {:?}", self.halfedges[3]);
+        let mut fail = false;
-            println!("DEBUG: halfedge {}: {:?}", self.halfedges[3].next_halfedge, self.halfedges[self.halfedges[3].next_halfedge]);
+        let new_edges: Vec<(usize, usize)> = verts.iter().map(|v| {
 
             // As we iterate over every vertex, we walk the half-edges:
             let mut edge = self.halfedges[edge_idx].clone();
             if !edge.has_twin {
-                panic!("Halfedge {} has no twin, and split_face (for now) requires twins", edge_idx);
+                println!("Halfedge {} has no twin, and split_face (for now) requires twins", edge_idx);
+                fail = true;
+                return (0,0);
             }
             // TODO: Remove the above limitation and just don't try to split
             // nonexistent twins. I think all logic works the same way.
@@ -516,10 +536,8 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
             // Half of edge_idx is split into j_edge.
             // Half of twin_idx (its twin) is split into i_edge.
 
-            println!("DEBUG: edge_idx={} next_idx={} twin_idx={} i_edge={} j_edge={}", edge_idx, next_idx, twin_idx, i_edge, j_edge);
             // This is where the vertex will be inserted:
             let v_idx = self.num_verts;
-            println!("DEBUG: adding v_idx={}", v_idx);
             self.verts.push(DCELVertex {
                 v: *v,
                 halfedge: i_edge, // j_edge is also fine
@@ -531,7 +549,6 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
 
             twin.twin_halfedge = j_edge;
             let i_next = twin.next_halfedge;
-            println!("DEBUG: new twin of {} = {}; new twin of {} = {}", edge_idx, i_edge, twin_idx, j_edge);
 
             self.halfedges.push(DCELHalfEdge {
                 vert: v_idx,
@@ -541,8 +558,6 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
                 next_halfedge: i_next,
                 prev_halfedge: twin_idx,
             }); // i_edge
-            println!("DEBUG: edge {}: vert {} twin {} next {} prev {} (ends at vertex {})", i_edge, v_idx, edge_idx, i_next, twin_idx, self.halfedges[self.halfedges[twin_idx].next_halfedge].vert);
-
             self.halfedges.push(DCELHalfEdge {
                 vert: v_idx,
                 face: 0, // This is set properly in the next loop
@@ -551,7 +566,6 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
                 next_halfedge: j_next,
                 prev_halfedge: edge_idx,
             }); // j_edge
-            println!("DEBUG: edge {}: vert {} twin {} next {} prev {} (ends at vertex {})", j_edge, v_idx, twin_idx, j_next, edge_idx, self.halfedges[self.halfedges[edge_idx].next_halfedge].vert);
 
             self.num_halfedges += 2;
 
@@ -565,7 +579,9 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
             r
         }).collect();
 
-        println!("DEBUG: {:?}", new_edges);
+        if fail {
+            return None;
+        }
 
         // We then must connect some edges up 'across' vertices
         // in order to form the smaller face at each vertex.
@@ -585,9 +601,6 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
             // And the face here:
             let face_new = self.num_faces;
 
-            println!("DEBUG: i0={} i1={} ep_idx={} en_idx={} e_cross_idx={} e_twin_idx={} face_new={}",
-                i0, i1, ep_idx, en_idx, e_cross_idx, e_twin_idx, face_new);
-
             // So, the vertex for i0 had two halfedges (one pointing in,
             // one pointing out). We split both those half-edges earlier.
             // en_idx & ep_idx are the halves that are nearest the
@@ -604,7 +617,6 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
                 next_halfedge: ep_idx,
                 prev_halfedge: en_idx,
             }); // e_cross_idx
-            println!("DEBUG: edge {}: vert {} twin {} next {} prev {} (ends at vertex {})", e_cross_idx, self.halfedges[en_idx].vert, e_twin_idx, ep_idx, en_idx, self.halfedges[self.halfedges[e_cross_idx].next_halfedge].vert);
 
             // It also requires a twin half-edge. These all form a single
             // central face with each edge sharing a boundary with the
@@ -617,24 +629,21 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
                 next_halfedge: 0, // TODO
                 prev_halfedge: 0, // TODO
             }); // e_twin_idx
-            println!("DEBUG: edge {}: vert {} twin {} next/prev incorrect", e_twin_idx, self.halfedges[ep_idx].vert, e_cross_idx);
-
             self.num_halfedges += 2;
 
             // en/ep also need directed to 'new' edges and each other
             self.halfedges[en_idx].prev_halfedge = ep_idx;
             self.halfedges[en_idx].next_halfedge = e_cross_idx;
-            println!("DEBUG: edge {}: now next {} prev {} ends at vert {}", en_idx, e_cross_idx, ep_idx, self.halfedges[self.halfedges[en_idx].next_halfedge].vert);
 
             self.halfedges[ep_idx].next_halfedge = en_idx;
             self.halfedges[ep_idx].prev_halfedge = e_cross_idx;
-            println!("DEBUG: edge {}: now next {} prev {} ends at vert {}", ep_idx, en_idx, e_cross_idx, self.halfedges[self.halfedges[ep_idx].next_halfedge].vert);
 
             self.halfedges[ep_idx].face = face_new;
 
             self.faces.push(DCELFace {
                 halfedge: e_cross_idx, // en_idx or ep_idx is fine too
-            });
+            }); // face_new
+            faces_new.push(face_new);
             self.num_faces += 1;
 
             // We also need to split the opposite side to make the two
@@ -674,8 +683,10 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
             self.faces.push(DCELFace {
                 halfedge: outer2, // base2 or edge_side2 is fine too
             });
+            faces_new.push(self.num_faces);
             self.num_faces += 1;
             self.faces[face1].halfedge = outer1; // base1 or edge_side1 is fine too
+            faces_upd.push(face1);
 
             self.halfedges[outer1].next_halfedge = edge_side1;
             self.halfedges[outer1].prev_halfedge = base1;
@@ -691,13 +702,9 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
             self.halfedges[base2].prev_halfedge = outer2;
             self.halfedges[base2].next_halfedge = edge_side2;
 
-            println!("DEBUG: base1={} base2={} outer1={} outer2={} face1={} face2={} edge_side1={} edge_side2={}",
-                     base1, base2, outer1, outer2, face1, face2, edge_side1, edge_side2);
             e_twin_idx
         }).collect();
 
-        println!("DEBUG: cross_edges={:?}", twin_edges);
-
         for i0 in 0..n {
             let i1 = (i0 + 1) % n;
 
@@ -709,6 +716,9 @@ impl<V: Copy + std::fmt::Debug> DCELMesh<V> {
         // We need something at this index, and the other three already have
         // indices, so reuse it for the smaller central face:
         self.faces[face].halfedge = e_twin_idx;
+        faces_upd.push(face);
+
+        return Some((faces_new, faces_upd));
     }
 
     pub fn convert_mesh<F>(&self, f: F) -> Mesh

src/examples.rs

@@ -1268,11 +1268,11 @@ pub fn test_parametric() -> Mesh {
         vertex( 1.0,  1.0, 0.0),
         vertex( 1.0, -1.0, 0.0),
     ];
-    let base_verts = util::subdivide_cycle(&base_verts, 4);
+    let base_verts = util::subdivide_cycle(&base_verts, 2);
     //let base_verts = util::subdivide_cycle(&base_verts, 16);
 
     let t0 = 0.0;
-    let t1 = 15.0;
+    let t1 = 15;
     let xform = |t: f32| -> Transform {
         id().
             translate(0.0, 0.0, t/5.0).
@@ -1280,7 +1280,7 @@ pub fn test_parametric() -> Mesh {
             scale((0.8).powf(t))
     };
 
-    crate::rule::parametric_mesh(base_verts, xform, t0, t1, 0.001)
+    crate::rule::parametric_mesh(base_verts, xform, t0, t1, 0.01)
 }
 
 pub fn test_dcel(fname: &str) {
@@ -1325,18 +1325,19 @@ pub fn test_dcel(fname: &str) {
     println!("f3 verts: {:?}", mesh.face_to_verts(f3));
     println!("f4 verts: {:?}", mesh.face_to_verts(f4));
 
-    println!("DCEL mesh: ");
+    //println!("DCEL mesh: ");
-    mesh.print();
+    //mesh.print();
 
-    mesh.split_face(f1, vec![
+    let faces = mesh.full_subdiv_face(f1, vec![
         vertex(-0.5, 0.0, 0.0),
         vertex(0.0, 0.5, 0.0),
         vertex(0.0, 0.0, 0.0),
     ]);
+    println!("full_subdiv_face returned: {:?}", faces);
 
-    println!("DCEL mesh after subdiv");
+    //println!("DCEL mesh after subdiv");
-    mesh.check();
+    //mesh.check();
-    mesh.print();
+    //mesh.print();
 
     let mesh_conv = mesh.convert_mesh(|i| i);
 

src/rule.rs

@@ -1,6 +1,7 @@
 use std::borrow::Borrow;
 use std::rc::Rc;
 use std::f32;
+use std::collections::HashMap;
 
 use crate::mesh::{Mesh, MeshFunc, VertexUnion};
 use crate::xform::{Transform, Vertex};
@@ -658,11 +659,25 @@ pub fn parametric_mesh<F>(frame: Vec<Vertex>, f: F, t0: f32, t1: f32, max_err: f
 
     // A stack of face indices for faces in 'mesh' that are still
     // undergoing subdivision
-    let mut stack: Vec<usize> = (0..mesh.num_faces).collect();
 
-    while !stack.is_empty() {
+    let mut stack: HashMap<usize, usize> = (0..mesh.num_faces).map(|i| (i, 0)).collect();
-        let face = stack.pop().unwrap();
+
-        println!("DEBUG: Examining face: {:?}", face);
+    let max_subdiv = 1;
+
+    // This is masked off because it's just horrible:
+    while false && !stack.is_empty() {
+
+        let (face, count) = match stack.iter().next() {
+            None => break,
+            Some((f, c)) => (*f, *c),
+        };
+        stack.remove(&face);
+
+        println!("DEBUG: Examining face: {:?} ({} subdivs)", face, count);
+
+        if count >= max_subdiv {
+            continue;
+        }
 
         let v_idx = mesh.face_to_verts(face);
         if v_idx.len() != 3 {
@@ -703,17 +718,18 @@ pub fn parametric_mesh<F>(frame: Vec<Vertex>, f: F, t0: f32, t1: f32, max_err: f
 
         let d = p.xyz().dot(&normal);
 
+        if d.is_nan() {
+            println!("DEBUG: p={:?} normal={:?}", p, normal);
+            println!("DEBUG: a={:?} b={:?}", a, b);
+            println!("DEBUG: v0={:?} v1={:?} v2={:?}", v0, v1, v2);
+            //panic!("Distance is NaN?");
+            println!("DEBUG: distance is NaN?");
+            continue;
+        }
+
         println!("DEBUG: t_mid={} v_mid={},{},{} p={},{},{}", t_mid, v_mid.x, v_mid.y, v_mid.z, p.x, p.y, p.z);
         println!("DEBUG: d={}", d);
 
-        // DEBUG
-        /*
-        let n = verts.len();
-        verts.push(p);
-        faces.push(face.verts[0]);
-        faces.push(face.verts[1]);
-        faces.push(n);
-         */
         if (d <= max_err) {
             // This triangle is already in the mesh, and already popped
             // off of the stack. We're done.
@@ -728,28 +744,35 @@ pub fn parametric_mesh<F>(frame: Vec<Vertex>, f: F, t0: f32, t1: f32, max_err: f
 
         // This split is done in 'parameter' space:
         let pairs = [(0,1), (1,2), (0,2)];
-        let mut mids: Vec<Vertex> = pairs.iter().map(|(i,j)| {
+        let mut mids: Vec<VertexTrajectory> = pairs.iter().map(|(i,j)| {
             let t = (tr[*i].t + tr[*j].t) / 2.0;
             let v = (tr[*i].frame_vert + tr[*j].frame_vert) / 2.0;
-            f(t).mtx * v
+            VertexTrajectory {
+                vert: f(t).mtx * v,
+                frame_vert: v,
+                t: t,
+            }
         }).collect();
 
-        // DEBUG
+        // TODO: Get indices of added faces and put these on the stack too
-        //let n = verts.len();
+        match mesh.full_subdiv_face(face, mids) {
-        // Index n+0 is (0,1), n+1 is (1,2), n+2 is (0,2)
+            None => {},
-        /*
+            Some((new, upd)) => {
-        verts.append(&mut mids);
+
-        faces[face.face] = n + 0;
+                // The 'updated' faces can remain on the stack if they
-        faces[face.face + 1] = n + 1;
+                // already were there.  If they were taken off of the stack
-        faces[face.face + 2] = n + 2;
+                // because they were too small, they are now even smaller,
-        faces.extend_from_slice(&[
+                // so it is fine to leave them off.
-            face.verts[0], n + 0, n + 2,
+                stack.extend(new.iter().map(|i| (*i, count + 1)));
-            face.verts[1], n + 1, n + 0,
+                stack.extend(upd.iter().map(|i| (*i, count + 1)));
-            face.verts[2], n + 2, n + 1,
+                // TODO: Why does the resultant mesh have holes if I do this
-            //n + 0,         n + 1, n + 2,
+                // and then increase max_subdiv?
-        ]);
+            },
-        */
+        }
+
    }
 
+    //mesh.print();
+
     return mesh.convert_mesh(|i| i.vert );
 }