From fc43a4716bb5af294fc71e9f03a86df97277f5c5 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Wed, 3 Jul 2019 04:53:56 +0200
Subject: [PATCH] new pmodel: Central Inversion (for Euclidean)

---
 classes.cpp   | 1 +
 classes.h     | 2 +-
 conformal.cpp | 3 ++-
 drawing.cpp   | 2 ++
 hypgraph.cpp  | 9 +++++++++
 5 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/classes.cpp b/classes.cpp
index 7c5655cc..ca7c9aeb 100644
--- a/classes.cpp
+++ b/classes.cpp
@@ -589,6 +589,7 @@ const modelinfo models[int(mdPolynomial)+1] = {
   {X3("spiral/ring"), mf::hyper_or_torus | mf::quasiband},
   {X3("native perspective"), 0},
   {X3("azimuthal equi-volume"), mf::azimuthal | mf::equivolume | mf::euc_boring},
+  {X3("central inversion"), mf::azimuthal | mf::conformal},
   {X3(""), 0},
   {X3(""), 0},
   {X3(""), 0},
diff --git a/classes.h b/classes.h
index cf88f555..a6031b01 100644
--- a/classes.h
+++ b/classes.h
@@ -260,7 +260,7 @@ enum eModel {
   mdHemisphere, mdBandEquidistant, mdBandEquiarea, mdSinusoidal, mdTwoPoint, 
   mdFisheye, mdJoukowsky, mdJoukowskyInverted,
   mdRotatedHyperboles, mdSpiral, mdPerspective,
-  mdEquivolume, 
+  mdEquivolume, mdCentralInversion,
   mdGUARD, mdUnchanged, mdHyperboloidFlat, mdPolynomial, mdRug, mdFlatten
   };
 
diff --git a/conformal.cpp b/conformal.cpp
index 9162e298..50202814 100644
--- a/conformal.cpp
+++ b/conformal.cpp
@@ -635,6 +635,7 @@ namespace conformal {
     if(DIM == 2 && pm == mdPerspective) return false;
     if(DIM == 2 && pm == mdEquivolume) return false;
     if(DIM == 3 && among(pm, mdBall, mdHyperboloid, mdFormula, mdPolygonal, mdRotatedHyperboles, mdSpiral, mdHemisphere)) return false;
+    if(pm == mdCentralInversion && !euclid) return false;
     return true;
     }    
   
@@ -751,7 +752,7 @@ namespace conformal {
       eModel m = eModel(i);
       if(m == mdFormula && ISMOBILE) continue;
       if(model_available(m)) {
-        dialog::addBoolItem(get_model_name(m), pmodel == m, "0123456789!@#$%^&*()]" [m]);
+        dialog::addBoolItem(get_model_name(m), pmodel == m, "0123456789!@#$%^&*()]['" [m]);
         dialog::add_action([m] () {
           if(m == mdFormula) {
             edit_formula();
diff --git a/drawing.cpp b/drawing.cpp
index ff9dc279..e847aa03 100644
--- a/drawing.cpp
+++ b/drawing.cpp
@@ -958,6 +958,7 @@ void dqi_poly::draw() {
   if(pmodel == mdJoukowskyInverted && vid.skiprope) can_have_inverse = true;
   if(pmodel == mdDisk && hyperbolic && vid.alpha <= -1) can_have_inverse = true;
   if(pmodel == mdSpiral && vid.skiprope) can_have_inverse = true;
+  if(pmodel == mdCentralInversion) can_have_inverse = true;
     
   if(can_have_inverse && !(poly_flags & POLY_ISSIDE)) {
   
@@ -966,6 +967,7 @@ void dqi_poly::draw() {
         
     else {
       if(d < 0) poly_flags ^= POLY_INVERSE;  
+      if(pmodel == mdCentralInversion) poly_flags ^= POLY_INVERSE;
       compute_side_by_area();
       }
     
diff --git a/hypgraph.cpp b/hypgraph.cpp
index 804a45e2..14dd532a 100644
--- a/hypgraph.cpp
+++ b/hypgraph.cpp
@@ -309,6 +309,15 @@ void applymodel(hyperpoint H, hyperpoint& ret) {
       return;
       }
     
+    case mdCentralInversion: {
+      ld tz = get_tz(H);
+      for(int d=0; d<DIM; d++) ret[d] = H[d] / tz;
+      ld r = 0;
+      for(int d=0; d<DIM; d++) r += ret[d]*ret[d];
+      for(int d=0; d<DIM; d++) ret[d] /= r;
+      return;
+      }
+    
     case mdHalfplane: {
       // Poincare to half-plane