From 32c6228319b179d69c42bf4290c318913c1d15d7 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Sun, 22 Mar 2020 11:27:06 +0100
Subject: [PATCH] arb:: utilities for making Archimedean tilings

---
 arbitrile.cpp   |  5 +++++
 archimedean.cpp | 19 ++++++++++++-------
 util.cpp        | 50 ++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 66 insertions(+), 8 deletions(-)

diff --git a/arbitrile.cpp b/arbitrile.cpp
index 93d38125..3c4b0b03 100644
--- a/arbitrile.cpp
+++ b/arbitrile.cpp
@@ -107,6 +107,11 @@ EX void load(const string& fname) {
     ep.force_eat(")");
     };
   while(true) {
+
+    ep.extra_params["distunit"] = distunit;
+    ep.extra_params["angleunit"] = angleunit;
+    ep.extra_params["angleofs"] = angleofs;
+
     ep.skip_white();
     if(ep.next() == 0) break;
     if(ep.eat("#")) {
diff --git a/archimedean.cpp b/archimedean.cpp
index 652fd226..14b6fbc4 100644
--- a/archimedean.cpp
+++ b/archimedean.cpp
@@ -42,6 +42,7 @@ struct archimedean_tiling {
   
   void make_match(int a, int i, int b, int j);
   void prepare();
+  void compute_sum();
   void compute_geometry();
   
   void parse();
@@ -135,11 +136,20 @@ void archimedean_tiling::make_match(int a, int i, int b, int j) {
 /** mostly to protect the user from entering too large numbers */
 const int MAX_EDGE_ARCM = FULL_EDGE;
 
-void archimedean_tiling::prepare() {
-
+void archimedean_tiling::compute_sum() {
+  N = isize(faces);
   euclidean_angle_sum = 0;
   for(int f: faces) euclidean_angle_sum += (f-2.) / f;
 
+  real_faces = 0, real_face_type = 0;
+  for(int i=0; i<N; i++) if(faces[i] > 2) real_faces++, real_face_type += faces[i];
+  real_face_type /= 2;
+  }
+
+void archimedean_tiling::prepare() {
+
+  compute_sum();
+
   for(int i: faces) if(i > MAX_EDGE_ARCM) {
     errormsg = XLAT("currently no more than %1 edges", its(MAX_EDGE_ARCM));
     errors++;
@@ -161,10 +171,6 @@ void archimedean_tiling::prepare() {
     return;
     }
 
-  real_faces = 0, real_face_type = 0;
-  for(int i=0; i<N; i++) if(faces[i] > 2) real_faces++, real_face_type += faces[i];
-  real_face_type /= 2;
-
   if(real_faces) {
     for(int i=1; i<isize(faces); i++) if(faces[i] == 2 && faces[i-1] == 2) {
       errormsg = XLAT("Not implemented.");
@@ -189,7 +195,6 @@ void archimedean_tiling::prepare() {
 
   /* build the 'adjacent' table */
 
-  N = isize(faces);
   int M = 2 * N + 2;
   adjacent.clear();
   adjacent.resize(M);
diff --git a/util.cpp b/util.cpp
index 27f5e8e6..f5b4ba37 100644
--- a/util.cpp
+++ b/util.cpp
@@ -223,7 +223,55 @@ cld exp_parser::parse(int prio) {
     force_eat(",");
     cld b = rparse(0);
     force_eat(")");
-    return edge_of_triangle_with_angles(M_PI/2, M_PI/real(a), M_PI/real(b));
+    res = edge_of_triangle_with_angles(M_PI/2, M_PI/a, M_PI/b);
+    }
+  else if(eat("arcmedge(")) {
+    vector<int> vals;
+    vals.push_back(iparse(0));
+    while(true) {
+      skip_white();
+      if(eat(",")) vals.push_back(iparse(0));
+      else break;
+      }
+    force_eat(")");
+    arcm::archimedean_tiling test;
+    test.faces = vals;
+    test.compute_sum();
+    test.compute_geometry();
+    res = test.edgelength;
+    if(extra_params.count("distunit"))
+      res /= extra_params["distunit"];
+    }
+  else if(eat("regangle(")) {
+    ld edgelen = rparse(0);
+    if(extra_params.count("distunit")) {
+      println(hlog, "got edgelen = ", edgelen);
+      println(hlog, "distunit = ", real(extra_params["distunit"]));
+      edgelen = real(edgelen * extra_params["distunit"]); 
+      println(hlog, "got edgelen = ", edgelen);
+      }
+    
+    force_eat(",");
+    int edges = iparse(0);
+    force_eat(")");
+    ld alpha = M_PI / edges;
+    ld c = asin_auto(sin_auto(edgelen/2) / sin(alpha));
+    hyperpoint h = xpush(c) * spin(M_PI - 2*alpha) * xpush0(c);
+    res = 2 * atan2(h);
+    if(real(res) < 0) res = -res;
+    while(real(res) > 2 * M_PI) res -= 2 * M_PI;
+    if(real(res) > M_PI) res = 2 * M_PI - res;
+    res = M_PI - res;
+
+    if(extra_params.count("angleofs"))
+      res -= extra_params["angleofs"];
+
+    if(extra_params.count("angleunit"))
+      res /= extra_params["angleunit"];    
+    }
+  else if(eat("test(")) {
+    res = parsepar();
+    println(hlog, "res = ", make_pair(real(res), imag(res)));
     }
   else if(eat("ifp(")) {
     cld cond = parse(0);