From 27bedb19edc57569682a8651ba9a404470297822 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Tue, 15 Aug 2023 15:19:50 +0200
Subject: [PATCH] fixed a bug which caused the screen to disappear on
 switch-to-fpp

---
 hyperpoint.cpp   | 9 ++++++---
 nonisotropic.cpp | 4 ++--
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/hyperpoint.cpp b/hyperpoint.cpp
index 6e9530d9..7dd382d2 100644
--- a/hyperpoint.cpp
+++ b/hyperpoint.cpp
@@ -1361,14 +1361,17 @@ EX shiftmatrix orthogonal_move(const shiftmatrix& t, double level) {
   return shiftless(orthogonal_move(t.T, level), t.shift);
   }
 
-/** fix a 3x3 matrix into a 4x4 matrix */
-EX transmatrix fix4(transmatrix t) {
+/** fix a 3x3 matrix into a 4x4 matrix, in place */
+EX void fix4(transmatrix& t) {
   #if MAXMDIM > 3
+  if(ldebug) println(hlog, "fix4 performed");
   for(int i=0; i<4; i++) t[3][i] = t[i][3] = i == 3;
   #endif
-  return t;
   }
 
+/** fix a 3x3 matrix into a 4x4 matrix, as a function */
+EX transmatrix fix4_f(transmatrix t) { fix4(t); return t; }
+
 EX transmatrix xyscale(const transmatrix& t, double fac) {
   transmatrix res;
   for(int i=0; i<MXDIM; i++) {
diff --git a/nonisotropic.cpp b/nonisotropic.cpp
index 468f13cb..4f4b830d 100644
--- a/nonisotropic.cpp
+++ b/nonisotropic.cpp
@@ -1391,8 +1391,8 @@ EX namespace hybrid {
       return PIU( currentmap->full_shvid(c1) );
       }
 
-    virtual transmatrix spin_to(cell *c, int d, ld bonus) override { if(d >= c->type-2) return Id; c = get_where(c).first; return fix4( in_underlying([&] { return currentmap->spin_to(c, d, bonus); }) ); }
-    virtual transmatrix spin_from(cell *c, int d, ld bonus) override { if(d >= c->type-2) return Id; c = get_where(c).first; return fix4( in_underlying([&] { return currentmap->spin_from(c, d, bonus); }) ); }
+    virtual transmatrix spin_to(cell *c, int d, ld bonus) override { if(d >= c->type-2) return Id; c = get_where(c).first; return fix4_f( in_underlying([&] { return currentmap->spin_to(c, d, bonus); }) ); }
+    virtual transmatrix spin_from(cell *c, int d, ld bonus) override { if(d >= c->type-2) return Id; c = get_where(c).first; return fix4_f( in_underlying([&] { return currentmap->spin_from(c, d, bonus); }) ); }
 
     subcellshape& get_cellshape(cell *c) override {      
       int id = full_shvid(c);