From 2a354786e4bc93f7f2b76ac73fb8f7884bcc0a0f Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Thu, 16 Mar 2023 14:42:02 +0100
Subject: [PATCH] new projection: horocyclic equal-area

---
 classes.cpp  |  5 ++++-
 hypgraph.cpp | 20 ++++++++++++++++++++
 models.cpp   |  4 ++--
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/classes.cpp b/classes.cpp
index 167be437..ae1d0124 100644
--- a/classes.cpp
+++ b/classes.cpp
@@ -1014,7 +1014,9 @@ enum eModel : int {
   mdWerner, mdAitoff, mdHammer, mdLoximuthal, mdMiller, mdGallStereographic, mdWinkelTripel,
   // 39..48
   mdPoorMan, mdPanini, mdRetroCraig, mdRetroLittrow, mdRetroHammer, mdThreePoint, mdLiePerspective, mdLieOrthogonal, mdRelPerspective, mdRelOrthogonal,
-  // 49..
+  // 49
+  mdHorocyclicEqa,
+  // 50..
   mdGUARD, mdPixel, mdHyperboloidFlat, mdPolynomial, mdManual
   };
 #endif
@@ -1076,6 +1078,7 @@ EX vector<modelinfo> mdinf = {
   {X3("Lie orthogonal"), mf::euc_boring, DEFAULTS},
   {X3("relativistic perspective"), mf::euc_boring, DEFAULTS},
   {X3("relativistic orthogonal"), mf::euc_boring, DEFAULTS},
+  {X3("horocyclic equal-area"), mf::euc_boring, DEFAULTS},
   {X3("guard"), mf::technical, DEFAULTS},
   {X3("pixel"), mf::technical, DEFAULTS},
   {X3("hypflat"), mf::technical, DEFAULTS},
diff --git a/hypgraph.cpp b/hypgraph.cpp
index 9491a128..0a6d9726 100644
--- a/hypgraph.cpp
+++ b/hypgraph.cpp
@@ -780,6 +780,26 @@ EX void apply_other_model(shiftpoint H_orig, hyperpoint& ret, eModel md) {
       break;
       }
 
+    case mdHorocyclicEqa: {
+
+      if(hyperbolic) {
+        models::apply_orientation_yz(H[1], H[2]);
+        models::apply_orientation(H[0], H[1]);
+        }
+
+      ret = hyperbolic ? deparabolic13(H) : H;
+      ret[0] = exp(-ret[0]) - 1;
+      ret *= .5;
+      ret[LDIM] = 1;
+
+      if(hyperbolic) {
+        models::apply_orientation(ret[1], ret[0]);
+        models::apply_orientation_yz(ret[2], ret[1]);
+        }
+
+      break;
+      }
+
     case mdLieOrthogonal: {
       ret = lie_log_correct(H_orig, H);
 
diff --git a/models.cpp b/models.cpp
index 6fbcce6a..23bf03b3 100644
--- a/models.cpp
+++ b/models.cpp
@@ -214,11 +214,11 @@ EX namespace models {
     }    
   
   EX bool has_orientation(eModel m) {
-    if(among(m, mdHorocyclic, mdLieOrthogonal, mdLiePerspective))
+    if(among(m, mdHorocyclic, mdHorocyclicEqa, mdLieOrthogonal, mdLiePerspective))
       return hyperbolic || in_h2xe();
     if(is_perspective(m) && panini_alpha) return true;
     return
-      among(m, mdHalfplane, mdPolynomial, mdPolygonal, mdTwoPoint, mdJoukowsky, mdJoukowskyInverted, mdSpiral, mdSimulatedPerspective, mdTwoHybrid, mdHorocyclic, mdAxial, mdAntiAxial, mdQuadrant,
+      among(m, mdHalfplane, mdPolynomial, mdPolygonal, mdTwoPoint, mdJoukowsky, mdJoukowskyInverted, mdSpiral, mdSimulatedPerspective, mdTwoHybrid, mdHorocyclic, mdHorocyclicEqa, mdAxial, mdAntiAxial, mdQuadrant,
         mdWerner, mdAitoff, mdHammer, mdLoximuthal, mdWinkelTripel, mdThreePoint) || mdBandAny();
     }