diff --git a/intra.cpp b/intra.cpp
index ca01dd1c..9de7e023 100644
--- a/intra.cpp
+++ b/intra.cpp
@@ -48,10 +48,17 @@ hyperpoint portal_data::to_poco(hyperpoint h) const {
   if(prod && kind == 1) {
     auto dec = product_decompose(h);
     h = dec.second;
-    h[0] /= h[2];
-    h[1] /= h[2];
-    h[2] = dec.first - d;
-    h[3] = 1;
+    if(bt::in()) {
+      h = PIU( deparabolic13(h) );
+      h[2] = dec.first - d;
+      h[3] = 1;
+      }
+    else {
+      h[0] /= h[2];
+      h[1] /= h[2];
+      h[2] = dec.first - d;
+      h[3] = 1;
+      }
     if(d<0) h[2] = -h[2], h[0] = -h[0];
     return h;
     }
@@ -90,6 +97,10 @@ hyperpoint portal_data::from_poco(hyperpoint h) const {
   if(prod && kind == 1) {
     ld xd = h[2];
     if(d<0) xd = -xd, h[0] = -h[0];
+    if(bt::in()) {
+      h[2] = 0;
+      return PIU( parabolic13(h) ) * exp(d+xd);
+      }
     h[2] = 1;
     auto z = product_decompose(h).first;
     return h * exp(d+xd-z);
@@ -100,7 +111,7 @@ hyperpoint portal_data::from_poco(hyperpoint h) const {
     h[1] = sin_auto(h0[0]);
     h[2] = cos_auto(h0[0]) * cos_auto(h0[2]);
     h[3] = 1;
-    return iT * h * exp(-h0[1]);
+    return iT * h * exp(h0[1]);
     }
   else if(hyperbolic && bt::in()) {
     h[2] *= exp(-h[1]);
@@ -123,15 +134,14 @@ EX portal_data make_portal(cellwalker cw, int spin) {
   portal_data id;
   id.scale = 1;
   auto gg = geometry;
-  if(prod && cw.spin == cw.at->type - 1) {
-    id.kind = 1;
-    id.d = product_decompose(fac[0]).first;
-    id.v0 = C0 * exp(id.d);
-    }
-  else if(prod && cw.spin == cw.at->type - 2) {
+  if(prod && cw.spin >= cw.at->type - 2) {
     id.kind = 1;
     id.d = product_decompose(fac[0]).first;
     id.v0 = C0 * exp(id.d);
+    if(bt::in()) {
+      fac.pop_back();
+      id.scale = log(2)/2;
+      }
     }
   else if(prod) {
     id.kind = 0;
@@ -139,7 +149,9 @@ EX portal_data make_portal(cellwalker cw, int spin) {
     id.scale = cgi.plevel;
     for(auto p: fac) id.v0 += p;
     id.v0 /= sqrt(abs(intval(id.v0, Hypc)));
-    id.T = cpush(0, -hdist0(id.v0)) * spintox(id.v0);
+    hyperpoint h = fac[0];
+    h /=  sqrt(abs(intval(h, Hypc)));
+    id.T = cspin(0, 1, -90*degree) * spintox(gpushxto0(id.v0) * h) * gpushxto0(id.v0);
     for(int i=0; i<3; i++) id.T[3][i] = id.T[i][3] = i==3;
     if(debugflags & DF_GEOM)
     for(int a=0; a<4; a++) {
diff --git a/raycaster.cpp b/raycaster.cpp
index 4f1c3e89..20067817 100644
--- a/raycaster.cpp
+++ b/raycaster.cpp
@@ -1011,7 +1011,7 @@ void raygen::emit_intra_portal(int gid1, int gid2) {
     fmain += "mediump vec4 nposition;\n";
     fmain += "if(pconnection.x != .5) {\n"; // kind != 0
     if(1) {
-      string fn = in_h2xe() ? "to_poco_h2xr_h" : "to_poco_s2xr_s";
+      string fn = bt::in() ? "to_poco_h2xr_b" : in_h2xe() ? "to_poco_h2xr_h" : "to_poco_s2xr_s";
       fmain +=
         "    nposition = position + tangent * xspeed * 1e-3;\n"
         "    position = "+fn+"(position);\n"
@@ -1080,7 +1080,7 @@ void raygen::emit_intra_portal(int gid1, int gid2) {
     fmain += "if(pconnection.z != .5) {\n"; // kind != 0
     if(1) {
       string sgn = in_h2xe() ? "-" : "+";
-      string fn = in_h2xe() ? "from_poco_h2xr_h" : "from_poco_s2xr_s";
+      string fn = bt::in() ? "from_poco_h2xr_b" : in_h2xe() ? "from_poco_h2xr_h" : "from_poco_s2xr_s";
 
       fmain +=
       "    if(pconnection.w < .5) { position.z = -position.z; nposition.z = -nposition.z; nposition.x = -nposition.x; position.x = -position.x; }\n"
@@ -1547,19 +1547,6 @@ void raygen::add_functions() {
         "  return res;\n"
         "  }\n\n");
 
-  add_if("deparabolic12",
-        "mediump vec4 deparabolic12(mediump vec4 h) {\n"
-        "  h /= (1. + h.z);\n"
-        "  h[0] -= 1.;\n"
-        "  h /= h.x*h.x + h.y*h.y;\n"
-        "  h[0] += .5;\n"
-        "  mediump vec4 res;\n"
-        "  res.x = (log(2.) + log(-h.x));\n"
-        "  res.y = h.y * 2.;\n"
-        "  res.w = 1.;\n"
-        "  return res;\n"
-        "  }\n\n");
-
   add_if("enparabolic13",
         "mediump vec4 enparabolic13(mediump vec4 h) {\n"
         "  mediump vec4 res;\n"
@@ -1607,6 +1594,18 @@ void raygen::add_functions() {
           "  return pos;\n"
           "  }\n\n");
 
+  add_if("from_poco_h2xr_b",
+          "mediump vec4 from_poco_h2xr_b(mediump vec4 pos) {\n"
+          "  return enparabolic12(pos);\n"
+          "  }\n\n");
+
+  add_if("to_poco_h2xr_b",
+          "mediump vec4 to_poco_h2xr_b(mediump vec4 pos) {\n"
+          "  pos /= sqrt(pos.z*pos.z-pos.x*pos.x-pos.y*pos.y);\n"
+          "  pos = deparabolic12(pos);\n"
+          "  return pos;\n"
+          "  }\n\n");
+
   add_if("from_poco_h2xr_e",
           "mediump vec4 from_poco_h2xr_e(mediump vec4 pos) {\n"
             "  return vec4(sinh(pos[2]) * cosh(pos[0]), sinh(pos[0]), cosh(pos[0]) * cosh(pos[2]), 0);\n"
@@ -1643,6 +1642,29 @@ void raygen::add_functions() {
           "  return vec4(x, 0, asin_clamp(pos[0] / cos(x)), 1);\n"
           "  }\n\n");
 
+  add_if("deparabolic12",
+        "mediump vec4 deparabolic12(mediump vec4 h) {\n"
+        "  h /= (1. + h.z);\n"
+        "  h[0] -= 1.;\n"
+        "  h /= h.x*h.x + h.y*h.y;\n"
+        "  h[0] += .5;\n"
+        "  mediump vec4 res;\n"
+        "  res.x = (log(2.) + log(-h.x));\n"
+        "  res.y = h.y * 2.;\n"
+        "  res.w = 1.;\n"
+        "  return res;\n"
+        "  }\n\n");
+
+  add_if("enparabolic12",
+        "mediump vec4 enparabolic12(mediump vec4 h) {\n"
+        "  mediump vec4 res;\n"
+        "  float diag = h.y*h.y /2.;\n"
+        "  res.x = sinh(h.x) + diag * exp(-h.x);\n"
+        "  res.y = h.y * exp(-h.x);\n"
+        "  res.z = cosh(h.x) + diag * exp(-h.x);\n"
+        "  return res;\n"
+        "  }\n\n");
+
   add_if("len_rotspace", "mediump float len_rotspace(vec4 h) { return 1. - h[3]; }\n");
 
   add_if("len_h3",  "  mediump float len_h3(mediump vec4 x) { return x[3]; }\n");
diff --git a/reg3.cpp b/reg3.cpp
index 092339ce..f82ab441 100644
--- a/reg3.cpp
+++ b/reg3.cpp
@@ -17,7 +17,7 @@ EX hyperpoint final_coords(hyperpoint h) {
   if(sn::in() || !bt::in()) 
     return ultra_normalize(h);
   #if CAP_BT
-  if(bt::in()) 
+  if(bt::in() && !prod)
     return bt::bt_to_minkowski(h);
   #endif
   return h;