From 5c1ab36b166fbf63b1710de65c0ea9410434ba94 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Sat, 7 Jan 2023 23:28:02 +0100
Subject: [PATCH] auto-configure S2xR embedding for Euclidean cylinder

---
 geometry.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/geometry.cpp b/geometry.cpp
index 2bd12bfb..1556ac5f 100644
--- a/geometry.cpp
+++ b/geometry.cpp
@@ -1447,6 +1447,7 @@ EX void switch_always3() {
           }
         }
       if(spatial_embedding == seCliffordTorus) configure_clifford_torus();
+      if(spatial_embedding == seProductS) configure_product_cylinder();
       }
     else {
       vid.always3 = false;
@@ -1489,6 +1490,18 @@ EX void switch_always3() {
     vid.eye = vid.wall_height / 2 - vid.depth;
     }
 
+  EX void configure_product_cylinder() {
+    rug::clifford_torus ct;
+    hyperpoint vec;
+    if(sqhypot_d(2, ct.yh) < 1e-6) vec = ct.yh;
+    else if(sqhypot_d(2, ct.xh) < 1e-6) vec = ct.xh;
+    else vec = hyperpoint(10, 0, 0, 0);
+
+    euclid_embed_scale = TAU / hypot_d(2, vec);
+    euclid_embed_scale_y = 1;
+    euclid_embed_rotate = atan2(vec[1], vec[0]) / degree;
+    }
+
   EX }
 
 EX geometry_information *cgip;