Fix warnings, add some more notes

README.md

@@ -10,7 +10,7 @@ patch up or subdivide the meshes in post-processing.
 These grammars by their nature worked in discrete steps,
 but at one point I tried (unsuccessfully) to extend this
 system to working in a more continuous and parametric
-way.
+way.  (See `parametric_mesh` and any DCEL code.)
 
 I also ran into problems anytime I wanted to produce
 meshes in a way that was more "refining" than "generative".
@@ -21,6 +21,16 @@ from a 'parent' rule, besides being able to connect to its
 vertices - and sometimes the "refining" part of things
 required this in order to work right.
 
+The problems with the parametric/continuous, and the
+aforementioned "refining", were related. The issue is that
+in order to get good meshes, I needed to be able to minimize
+approximation error with the triangles and avoid triangles
+with extreme angles, and there was seemingly no good way to
+do this by incremental construction (like I was trying to
+use elsewhere in my model) - and so its seems I just ended up
+reinventing, badly, a lot of existing work with subdivision
+and meshing.
+
 I've also disliked how much my model felt like it tied me
 down to the "triangle mesh" representation. I haven't
 found a good way to build up higher-level representations
@@ -36,6 +46,18 @@ consider how much those assume the presence of garbage
 collection. Really, I wanted a Lisp, and then the presence of
 a REPL would have been another bonus.
 
+On top of this, my implementation is pretty slow when it is
+using a large number of rules each producing small geometry
+(which is almost literally the only way it *can* be used
+if you want to produce a fairly complex mesh). I did some
+profiling some months ago that showed I was spending the
+vast majority of my time in `extend()` and `clone()` for
+`Vec` - and so I could probably see some huge performance
+gains if I could simply pre-allocate vectors and share geometry
+more. Also, I'm pretty sure this code does some very task-parallel
+elements (e.g. anytime a rule branches), and multithreading should
+be able to exploit this if I care.
+
 If I actually understood my goals enough to put better
 constraints on my model, Rust probably would have been fine.
 As it stands now, the lack of clarity in both my theory
@@ -44,16 +66,11 @@ related to Rust.
 
 ## Highest priority:
 
+- Fix `ramhorn_branch`.
+- Once I've fixed that, see about a refactor that respects the
+  same model, but involves much less ceremony and boilerplate.
 - Figure out the crash bug in `vec_indexed!` if I put a Vertex
   *after* an Arg.
-- Just scrap `parametric_mesh` as much as possible and use existing
-  tools (e.g. OpenSubdiv) because this DCEL method is just painful for
-  what it is and I have some questions on how it can even work
-  theoretically.
-- Connect up the `parametric_mesh` stuff that remains, and worry about
-  perfect meshes later.
-- Get identical or near-identical meshes to `ramhorn_branch` from
-  Python.  (Should just be a matter of tweaking parameters.)
 - Look at performance.
   - Start at `to_mesh_iter()`. The cost of small appends/connects
     seems to be killing performance.
@@ -62,13 +79,6 @@ related to Rust.
     like I should be able to share geometry with the `Rc` (like noted
     above), defer copying until actually needed, and pre-allocate the
     vector to its size (which should be easy to compute).
-- See `automata_scratch/examples.py` and implement some of the tougher
-  examples.
-  - `twisty_torus`, `spiral_nested_2`, & `spiral_nested_3` are all
-    that remain.  To do them, I need to compose transformations (not
-    in the matrix sense), but I also probably need to produce
-    RuleEvals which always have `xf` of identity transformation since
-    the Python code does not 'inherit' transforms unless I tell it to.
 
 ## Important but less critical:
 
@@ -85,7 +95,8 @@ related to Rust.
 
 - Catch-alls:
   - Grep for all TODOs in code, really.
-  - Look at everything in `README.md` in `automata_scratch`.
+  - Look at everything in `README.md` in `automata_scratch`,
+    my old Python code from around 2019-09.
 
 ## If I'm bored:
 
@@ -96,9 +107,6 @@ related to Rust.
 - Would being able to name a rule node (perhaps conditionally under
   some compile-time flag) help for debugging?
 - Use an actual logging framework.
-- Take a square.  Wrap it around to a torus. Now add a twist (about
-  the axis that is normal to the square). This is simple, but it looks
-  pretty cool.
 - How can I take tangled things like the cinquefoil and produce more
   'iterative' versions that still weave around?
 
@@ -118,3 +126,4 @@ related to Rust.
 - If you *pre* multiply a transformation: you are transforming the
   entire global space.  If you *post* multiply: you are transforming
   the current local space. 
+- Don't reinvent subdivision surfaces.

src/examples.rs

@@ -1,5 +1,5 @@
 use std::rc::Rc;
-use std::f32::consts::{FRAC_PI_2, FRAC_PI_3, FRAC_PI_6, PI};
+use std::f32::consts::{FRAC_PI_2, FRAC_PI_3};
 use std::f32;
 
 use nalgebra::*;
@@ -8,11 +8,11 @@ use rand::Rng;
 use crate::util;
 use crate::util::VecExt;
 use crate::mesh::{Mesh, MeshFunc, VertexUnion, vert_args};
-use crate::xform::{Transform, Vertex, vertex, Mat4, id};
-use crate::rule::{Rule, RuleFn, RuleEval, Child};
+use crate::xform::{Transform, Vertex, vertex, id};
+use crate::rule::{Rule, RuleEval, Child};
 use crate::prim;
 use crate::dcel;
-use crate::dcel::{DCELMesh, VertSpec};
+use crate::dcel::{VertSpec};
 
 pub fn cube_thing() -> Rule<()> {
 
@@ -106,7 +106,7 @@ pub fn barbs(random: bool) -> Rule<()> {
     };
     let main_incr = |random| {
         if random {
-            let t = rand::thread_rng().gen_range(0.75, 1.25);
+            //let t = rand::thread_rng().gen_range(0.75, 1.25);
             let s = rand::thread_rng().gen_range(0.85, 1.10);
             let rz = rand::thread_rng().gen_range(0.05, 0.25);
             let rx = rand::thread_rng().gen_range(0.08, 0.12);
@@ -124,7 +124,7 @@ pub fn barbs(random: bool) -> Rule<()> {
 
     let main = rule_fn!(() => |self_, base_verts| {
         let mut next_verts = base_verts;
-        let (a0, a1) = next_verts.append_indexed(vert_args(0..4));
+        let (a0, _) = next_verts.append_indexed(vert_args(0..4));
 
         // This contributes no faces of its own - just vertices.
         let geom = MeshFunc { verts: next_verts.clone(), faces: vec![] };
@@ -164,17 +164,22 @@ pub fn barbs(random: bool) -> Rule<()> {
     Rule { eval: base, ctxt: () }
 }
 
-pub fn pyramid() -> Rule<()> {
+pub fn sierpinski() -> Rule<()> {
+
+    // Initial height step:
+    let dz = 0.10;
+    // 'Extra' z rotation (0.0 for normal Sierpinski)
+    let dr = 0.1;
+    // Scale factor (0.5 for normal Sierpinski)
+    let s = 0.51;
 
     let rt3 = (3.0).sqrt();
 
-    let dz = 0.10;
-
     // Indices:
     // b+0,b+1,b+2 = base vertices
     // t+0,t+1,t+2 = 'top' vertices above base
     // tm01, tm12, tm20 = midpoints of (t0,t1), (t1,t2), (t2,t0).
-    let (b, t, tm01, tm12, tm20);
+    let (b, t, tm01, tm12, tm20, n);
     let base_verts: Vec<VertexUnion> = {
         let v0 = vertex(rt3/3.0, 0.0, 0.0);
         let v1 = vertex(-rt3/6.0, 1.0/2.0, 0.0);
@@ -192,24 +197,24 @@ pub fn pyramid() -> Rule<()> {
             @tm01 VertexUnion::Vertex((v0b+v1b)/2.0),
             @tm12 VertexUnion::Vertex((v1b+v2b)/2.0),
             @tm20 VertexUnion::Vertex((v2b+v0b)/2.0),
+            @n,
         ]
     };
 
     let tri_split = move |i| {
         let rt3 = (3.0).sqrt();
-        let angle = 2.0 * FRAC_PI_3 * (i as f32);
+        let angle = 2.0 * FRAC_PI_3 * (i as f32) + dr;
         id().
             rotate(&Vector3::z_axis(), angle).
             translate(rt3/12.0, 0.0, 0.0).
-            scale(0.49).
+            scale(s).
             translate(0.0, 0.0, dz)
     };
 
     let split = rule_fn!(() => |_s, base_verts| {
 
         let mut next_verts = base_verts.clone();
-        let mut final_verts = base_verts;
-        let (a0, a1) = next_verts.append_indexed(vert_args(0..3));
+        let (a0, _) = next_verts.append_indexed(vert_args(0..3));
 
         RuleEval {
             geom: Rc::new(MeshFunc {
@@ -231,8 +236,12 @@ pub fn pyramid() -> Rule<()> {
                 ],
             }),
             final_geom: Rc::new(MeshFunc {
-                verts: vert_args(t..(t+3)),
-                faces: vec![ 0, 1, 2 ],
+                verts: vert_args(0..n), // just duplicate same verts
+                faces: vec![
+                    t+0, tm01, tm20,
+                    t+1, tm12, tm01,
+                    t+2, tm20, tm12,
+                ],
             }),
             children: vec![
                 child!(_s, tri_split(0), t+0, tm01, tm20),
@@ -494,7 +503,6 @@ pub fn nest_spiral_2() -> Rule<NestSpiral2Ctxt> {
         },
     }
 }
-*/
 
 #[derive(Copy, Clone)]
 pub struct TorusCtxt {
@@ -503,7 +511,6 @@ pub struct TorusCtxt {
     stack: [Transform; 3],
 }
 
-/*
 pub fn twisty_torus() -> Rule<TorusCtxt> {
     let subdiv = 8;
     let seed = vec![

src/lib.rs

@@ -80,7 +80,7 @@ mod tests {
     fn barbs_random() { run_test(examples::barbs(true), 80, "barbs_random", false); }
 
     #[test]
-    fn pyramid() { run_test(examples::pyramid2(), 3, "pyramid2", false); }
+    fn sierpinski() { run_test(examples::sierpinski(), 6, "sierpinski", false); }
     /*
     #[test]
     fn twist() {

src/rule.rs

@@ -96,7 +96,7 @@ macro_rules! child {
 macro_rules! child_iter {
     ( $Rule:expr, $Xform:expr, $Args:expr ) => {
         Child {
-            rule: /*std::rc::Rc::new*/($Rule),
+            rule: /*std::rc::Rc::new*/($Rule).clone(),
             xf: $Xform,
             arg_vals: $Args.collect(), // does this even need a macro?
         }
@@ -366,7 +366,7 @@ pub fn parametric_mesh<F>(frame: Vec<Vertex>, f: F, t0: f32, t1: f32, max_err: f
         panic!("frame must have at least 3 vertices");
     }
 
-    struct frontierVert {
+    struct FrontierVert {
         vert: Vertex, // Vertex position
         t: f32, // Parameter value; f(t) should equal vert
         frame_idx: usize, // Index of 'frame' this sits in the trajectory of
@@ -376,7 +376,7 @@ pub fn parametric_mesh<F>(frame: Vec<Vertex>, f: F, t0: f32, t1: f32, max_err: f
     };
 
     // Init 'frontier' with each 'frame' vertex, and start it at t=t0.
-    let mut frontier: Vec<frontierVert> = frame.iter().enumerate().map(|(i,v)| frontierVert {
+    let mut frontier: Vec<FrontierVert> = frame.iter().enumerate().map(|(i,v)| FrontierVert {
         vert: *v,
         t: t0,
         frame_idx: i,
@@ -402,7 +402,7 @@ pub fn parametric_mesh<F>(frame: Vec<Vertex>, f: F, t0: f32, t1: f32, max_err: f
         // Pick a vertex to advance.
         //
         // Heuristic for now: pick the 'furthest back' (lowest t)
-        let (i,v) = frontier.iter().enumerate().min_by(|(i,f), (j, g)|
+        let (i,v) = frontier.iter().enumerate().min_by(|(_,f), (_, g)|
             f.t.partial_cmp(&g.t).unwrap_or(std::cmp::Ordering::Equal)).unwrap();
         // TODO: Make this less ugly?
 
@@ -456,7 +456,7 @@ pub fn parametric_mesh<F>(frame: Vec<Vertex>, f: F, t0: f32, t1: f32, max_err: f
         ]);
 
         // Replace this vertex in the frontier:
-        frontier[i] = frontierVert {
+        frontier[i] = FrontierVert {
             vert: v_next,
             frame_idx: v.frame_idx,
             mesh_idx: pos,