From dd01cd9af4d90c560f7acdafab38b1016f81ae3d Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Thu, 5 Jan 2023 16:12:23 +0100
Subject: [PATCH] auto-configure Clifford Torus embedding

---
 geometry.cpp | 15 +++++++++++++++
 rug.cpp      |  8 +++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/geometry.cpp b/geometry.cpp
index a6294c03..c22963fc 100644
--- a/geometry.cpp
+++ b/geometry.cpp
@@ -1400,6 +1400,7 @@ EX void switch_always3() {
           vid.wall_height *= -1;
           }
         }
+      if(spatial_embedding == seCliffordTorus) configure_clifford_torus();
       }
     else {
       vid.always3 = false;
@@ -1418,6 +1419,20 @@ EX void switch_always3() {
 #endif
     }
 
+  EX void configure_clifford_torus() {
+    rug::clifford_torus ct;
+
+    euclid_embed_scale = TAU / hypot_d(2, ct.xh);
+    euclid_embed_scale_y = TAU / hypot_d(2, ct.yh) / euclid_embed_scale;
+    euclid_embed_rotate = atan2(ct.xh[1], ct.xh[0]) / degree;
+
+    ld alpha = atan2(ct.xfactor, ct.yfactor);
+
+    vid.depth = alpha - 1;
+    vid.wall_height = min(1 / euclid_embed_scale_mean(), (90._deg - alpha) * 0.9);
+    vid.eye = vid.wall_height / 2 - vid.depth;
+    }
+
   EX }
 
 EX geometry_information *cgip;
diff --git a/rug.cpp b/rug.cpp
index 1b5b8914..7e167f2f 100644
--- a/rug.cpp
+++ b/rug.cpp
@@ -395,8 +395,14 @@ clifford_torus::clifford_torus() {
   auto p1 = to_loc(euc::eu.user_axes[0]);
   auto p2 = to_loc(euc::eu.user_axes[1]);
 
+  bool f = embedded_plane;
+  if(f) geom3::light_flip(true);
   xh = euc::eumove(p1)*C0-C0;
   yh = euc::eumove(p2)*C0-C0;
+  if(f) geom3::light_flip(false);
+  xh[2] = xh[3] = yh[2] = yh[3] = 0;
+  dynamicval<eGeometry> g(geometry, gCubeTiling);
+
   if(nonorientable) yh *= 2;
   
   flipped = false; // sqhypot_d(2, xh) < sqhypot_d(2, yh);
@@ -409,7 +415,7 @@ clifford_torus::clifford_torus() {
   yfactor = sqrt(1/(1+factor2));
   xfactor = factor * yfactor;
                                     
-  T = build_matrix(xh, yh, C0, C03);  
+  T = build_matrix(xh, yh, C02, C03);
   iT = inverse(T);
   }