From f6f37b1e45c87566d2c780f938fab9ee8ebcee52 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Tue, 27 Aug 2019 18:59:26 +0200
Subject: [PATCH] Archimedean precise analyzer

---
 archimedean.cpp | 26 ++++++++++++++++++++++++++
 geom-exp.cpp    | 12 +++++++++++-
 geometry.cpp    |  8 ++------
 3 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/archimedean.cpp b/archimedean.cpp
index 8a09de8a..18a6e699 100644
--- a/archimedean.cpp
+++ b/archimedean.cpp
@@ -72,6 +72,8 @@ struct archimedean_tiling {
   
   geometryinfo1& get_geometry();
   eGeometryClass get_class() { return get_geometry().kind; }
+
+  bool get_step_values(int& steps, int& single_step);
   
   ld scale();
   };
@@ -1232,6 +1234,10 @@ EX void show() {
       }
     else dialog::addBreak(100);
 
+    int s, ss;
+    bool b = current.get_step_values(s, ss);
+    println(hlog, "b=", b, " s=", s, " ss=",ss);
+
     if(archimedean) {    
       dialog::addSelItem(XLAT("variations"), gp::operation_name(), 'v');
       dialog::add_action(next_variation);
@@ -1301,6 +1307,26 @@ EX bool is_vertex(heptagon *h) {
   return id_of(h) >= 2 * current.N;
   }
 
+bool archimedean_tiling::get_step_values(int& steps, int& single_step) {
+
+  int nom = -2;
+  int denom = 1;
+  
+  for(int f: arcm::current.faces) {
+    if(int(denom*f)/f != denom) { steps = 0; single_step = 0; return false; }
+    nom = nom * f + (f-2) * denom;
+    denom = denom * f;
+    int g = gcd(nom, denom);
+    nom /= g;
+    denom /= g;
+    }
+    
+  steps = 2 * abs(denom);
+  single_step = abs(nom);
+  if(steps/2 != abs(denom)) return false;
+  return (2 * denom) % nom == 0;  
+  }
+
 EX int valence() {
   if(PURE) return arcm::current.N;
   if(BITRUNCATED) return 3;
diff --git a/geom-exp.cpp b/geom-exp.cpp
index 26fcef9c..b817f44f 100644
--- a/geom-exp.cpp
+++ b/geom-exp.cpp
@@ -444,7 +444,17 @@ void ge_select_tiling(const vector<eGeometry>& lst) {
           if(archimedean) ok = PURE;
           else if(binarytiling || penrose) ok = false;
           else ok = PURE || BITRUNCATED;
-          if(!ok) addMessage(XLAT("Only works with (semi-)regular tilings"));
+          if(!ok) {
+            addMessage(XLAT("Only works with (semi-)regular tilings"));
+            return;
+            }
+          if(archimedean) {
+            int steps, single_step;
+            if(!arcm::current.get_step_values(steps, single_step)) {
+              addMessage(XLAT("That would have %1/%2 levels", its(steps), its(single_step)));
+              return;
+              }
+            }
           }
         set_geometry(targetgeometry);
         start_game();
diff --git a/geometry.cpp b/geometry.cpp
index 183c24fd..0692ffbd 100644
--- a/geometry.cpp
+++ b/geometry.cpp
@@ -576,12 +576,8 @@ void geometry_information::prepare_basics() {
   steps = 0;
   single_step = 1;
   if(hybri && !prod) {
-    if(hybrid::underlying == gArchimedean) {
-      ld s = arcm::current.euclidean_angle_sum - 2;
-      single_step = 2;
-      DEBB(DF_GEOM | DF_POLY, ("1/s = ", 1/s));
-      steps = 4/abs(s) + .5;
-      }
+    if(hybrid::underlying == gArchimedean) 
+      arcm::current.get_step_values(steps, single_step);
     else {
       single_step = S3 * S7 - 2 * S7 - 2 * S3;
       steps = 2 * S7;