diff --git a/drawing.cpp b/drawing.cpp
index 67cdaa2d..ad63a0da 100644
--- a/drawing.cpp
+++ b/drawing.cpp
@@ -1983,6 +1983,8 @@ EX void draw_main() {
     if(ray::in_use && !ray::comparison_mode) {
       ray::cast();
       reset_projection();
+      /* currently incompatible with primitive-based renderer */
+      /* also not implemented in stretch */
       return;
       }
 
@@ -2023,6 +2025,7 @@ EX void draw_main() {
     if(ray::in_use && !ray::comparison_mode) {
       ray::cast();
       reset_projection();
+      if(stretch::in()) return; /*primitive not implemented */
       }
 
     DEBB(DF_GRAPH, ("outcircle"));
diff --git a/geom-exp.cpp b/geom-exp.cpp
index b7aa9b85..a4439263 100644
--- a/geom-exp.cpp
+++ b/geom-exp.cpp
@@ -826,6 +826,20 @@ EX void showEuclideanMenu() {
       });
     }
   
+  if(stretch::applicable()) {
+    dialog::addSelItem(XLAT("stretched geometry"), fts(stretch::factor), 'S');
+    dialog::add_action([] {
+      dialog::editNumber(stretch::factor, -1, 9, 0.1, 0, XLAT("stretched geometry"),
+        XLAT(
+          "Stretch the metric along the fibers. This can currently be done in rotation spaces and in 8-cell, 24-cell and 120-cell. "
+          "Value of 0 means not stretched, -1 means S2xE or H2xE (works only in the limit). "
+          "Only the raycaster is implemented for stretched geometry, so you will see only walls."
+          )
+        );
+      dialog::reaction = ray::reset_raycaster;
+      });
+    }
+  
   dialog::addBreak(100);
   dialog::addSelItem(XLAT("land"), XLAT1(linf[specialland].name), 'l');
   dialog::add_action_push(ge_land_selection);
diff --git a/hypgraph.cpp b/hypgraph.cpp
index 97b12ddc..ccc5449e 100644
--- a/hypgraph.cpp
+++ b/hypgraph.cpp
@@ -2149,7 +2149,7 @@ EX void rotate_view(transmatrix T) {
 
 /** shift the view according to the given tangent vector */
 EX transmatrix get_shift_view_of(const hyperpoint H, const transmatrix V) {
-  if(!nonisotropic && !rots_twist::in()) {
+  if(!nonisotropic && !stretch::in()) {
     return rgpushxto0(direct_exp(lp_iapply(H))) * V;
     }
   else if(!nisot::geodesic_movement) {
@@ -2169,7 +2169,7 @@ EX void shift_view(hyperpoint H) {
   auto oView = View;
   View = get_shift_view_of(H, View);
   auto& wc = current_display->which_copy;
-  if(nonisotropic || rots_twist::in()) {
+  if(nonisotropic || stretch::in()) {
     transmatrix ioldv = eupush(tC0(inverse(oView)));
     transmatrix newv = inverse(eupush(tC0(inverse(View))));
     wc = newv * ioldv * wc;
diff --git a/nonisotropic.cpp b/nonisotropic.cpp
index 020d0536..23feedad 100644
--- a/nonisotropic.cpp
+++ b/nonisotropic.cpp
@@ -1839,8 +1839,6 @@ EX }
 
 EX namespace rots {
 
-  EX ld stretch_factor;
-  
   EX transmatrix uxpush(ld x) { 
     if(sl2) return xpush(x);
     return cspin(1, 3, x) * cspin(0, 2, x);
@@ -2034,16 +2032,21 @@ EX namespace rots {
 
 EX }
 
-/** twisted S2xE */
-EX namespace rots_twist {
+/** stretched rotation space (S3 or SLR) */
+EX namespace stretch {
+
+  EX ld factor;  
 
   EX bool applicable() {
-    return among(geometry, gCell120, gECell120, gCell24, gECell24, gCell8, gECell8);
+    return rotspace || among(geometry, gCell120, gECell120, gCell24, gECell24, gCell8, gECell8);
     }
 
-  EX bool in() { return rots::stretch_factor && sphere && (rotspace || applicable()); }
+  EX bool in() {
+    return factor && applicable();
+    }
 
   EX transmatrix translate(hyperpoint h) {
+    if(!sphere) return slr::translate(h);
     return matrix4(
       h[3], -h[2],  h[1],  h[0],
       h[2],  h[3], -h[0],  h[1],
@@ -2056,6 +2059,7 @@ EX namespace rots_twist {
     h[0] = -h[0];
     h[1] = -h[1];
     h[2] = -h[2];
+    if(!sphere) return slr::translate(h);
     return translate(h);
     }
 
@@ -2066,11 +2070,11 @@ EX namespace rots_twist {
     }
   
   hyperpoint isometric_to_actual(const hyperpoint at, const hyperpoint velocity) {
-    return mulz(at, velocity, 1/sqrt(1+rots::stretch_factor));
+    return mulz(at, velocity, 1/sqrt(1+factor));
     }
   
   hyperpoint actual_to_isometric(const hyperpoint at, const hyperpoint velocity) {
-    return mulz(at, velocity, sqrt(1+rots::stretch_factor));
+    return mulz(at, velocity, sqrt(1+factor));
     }
   
   hyperpoint christoffel(const hyperpoint at, const hyperpoint velocity, const hyperpoint transported) {
@@ -2080,7 +2084,9 @@ EX namespace rots_twist {
     
     hyperpoint c;
     
-    auto K = rots::stretch_factor;
+    auto K = factor;
+    
+    if(!sphere) K = -2 - K;
     
     c[0] = -K * (vel[1] * tra[2] + vel[2] * tra[1]);
     c[1] =  K * (vel[0] * tra[2] + vel[2] * tra[0]);
@@ -2089,7 +2095,13 @@ EX namespace rots_twist {
     
     return translate(at) * c;
     }  
-  
+
+  EX ld sqnorm(hyperpoint at, hyperpoint h) {
+    if(sphere)
+      return sqhypot_d(4, h);
+    h = itranslate(at) * h;    
+    return h[0] * h[0] + h[1] * h[1] + h[2] * h[2];
+    }
 EX }
 
 EX namespace nisot {
@@ -2099,8 +2111,8 @@ EX namespace nisot {
     #if CAP_SOLV
     else if(sn::in()) return sn::christoffel(at, velocity, transported);
     #endif
+    else if(stretch::in()) return stretch::christoffel(at, velocity, transported);
     else if(sl2) return slr::christoffel(at, velocity, transported);
-    else if(rots_twist::in()) return rots_twist::christoffel(at, velocity, transported);
     else return point3(0, 0, 0);
     }
 
@@ -2138,15 +2150,15 @@ EX namespace nisot {
 
   EX transmatrix parallel_transport_bare(transmatrix Pos, hyperpoint h) {
   
-    bool stretch = rots_twist::in();
-    
-    if(!stretch) h[3] = 0;
+    bool stretch = stretch::in();
+
+    h[3] = 0;
   
     auto tPos = transpose(Pos);
     
     const ld eps = 1e-4;
     
-    if(sl2) {
+    if(sl2 && !stretch) {
       hyperpoint p = slr::to_phigans(tPos[3]);
       for(int i=0; i<3; i++)
         tPos[i] = (slr::to_phigans(tPos[3] + tPos[i] * eps) - p) / eps;
@@ -2162,15 +2174,15 @@ EX namespace nisot {
     auto& vel = h;
     
     array<ld, 4> ms;
-
+    
     if(stretch) {
       for(int i=0; i<3; i++) {
-        ms[i] = sqhypot_d(4, tPos[i]);
-        tPos[i] = rots_twist::isometric_to_actual(at, tPos[i]);
+        ms[i] = stretch::sqnorm(at, tPos[i]);
+        tPos[i] = stretch::isometric_to_actual(at, tPos[i]);
         }
-      ms[3] = sqhypot_d(4, vel);
+      ms[3] = stretch::sqnorm(at, vel);
       if(!ms[3]) return Pos;
-      vel = rots_twist::isometric_to_actual(at, vel);
+      vel = stretch::isometric_to_actual(at, vel);
       }
 
     for(int i=0; i<steps; i++) {
@@ -2200,27 +2212,25 @@ EX namespace nisot {
         at = normalize(at);
         
         auto fix = [&] (hyperpoint& h, ld& m) {
-          h = rots_twist::itranslate(at) * h;
+          h = stretch::itranslate(at) * h;
           h[3] = 0;
-          ld m1 = h[0] * h[0] + h[1] * h[1] + h[2] * h[2] * (1+rots::stretch_factor);
+          ld m1 = h[0] * h[0] + h[1] * h[1] + h[2] * h[2] * (1 + stretch::factor);
           h /= sqrt(m1/m);
-          h = rots_twist::translate(at) * h;
+          h = stretch::translate(at) * h;
           };
 
-        if(i == 0) println(hlog, vel);
-        fix(vel, ms[3]); 
-        if(i == 0) println(hlog, vel);
         for(int i=0; i<3; i++) fix(tPos[i], ms[i]);
+        fix(vel, ms[3]); 
         }
 
       }
 
     if(stretch) {
-      vel = rots_twist::actual_to_isometric(at, vel);
-      for(int i=0; i<3; i++) tPos[i] = rots_twist::actual_to_isometric(at, tPos[i]);
+      vel = stretch::actual_to_isometric(at, vel);
+      for(int i=0; i<3; i++) tPos[i] = stretch::actual_to_isometric(at, tPos[i]);
       }
-                                                                                  
-    if(sl2) {
+    
+    else if(sl2) {
       hyperpoint p = slr::from_phigans(tPos[3]);
       for(int i=0; i<3; i++)
         tPos[i] = (slr::from_phigans(tPos[3] + tPos[i] * eps) - p) / eps;
@@ -2363,7 +2373,7 @@ EX namespace nisot {
       }
     else if(argis("-rot-stretch")) {
       PHASEFROM(2);
-      shift_arg_formula(rots::stretch_factor, ray::reset_raycaster);
+      shift_arg_formula(stretch::factor, ray::reset_raycaster);
       return 0;
       }
     else if(argis("-prodturn")) {
diff --git a/raycaster.cpp b/raycaster.cpp
index 63a60d6b..e158976a 100644
--- a/raycaster.cpp
+++ b/raycaster.cpp
@@ -41,16 +41,16 @@ EX int max_cells = 2048;
 EX bool rays_generate = true;
 
 EX ld& exp_decay_current() {
-  return (sn::in() || hyperbolic) ? exp_decay_exp : exp_decay_poly;
+  return (sn::in() || hyperbolic || sl2) ? exp_decay_exp : exp_decay_poly;
   }
 
 EX int& max_iter_current() {
-  if(nonisotropic || rots_twist::in()) return max_iter_sol;
+  if(nonisotropic || stretch::in()) return max_iter_sol;
   else return max_iter_iso;
   }
 
 ld& maxstep_current() {
-  if(sn::in() || rots_twist::in()) return maxstep_sol;
+  if(sn::in() || stretch::in()) return maxstep_sol;
   else return maxstep_nil;
   }
 
@@ -69,13 +69,13 @@ EX bool available() {
     return true;
   if(nil && S7 == 8)
     return false;
-  if((sn::in() || nil) && pmodel == mdGeodesic)
+  if((sn::in() || nil || sl2) && pmodel == mdGeodesic)
     return true;
   if(euclid && pmodel == mdPerspective && !bt::in())
     return true;
   if(prod && (PURE || BITRUNCATED))
     return true;
-  if(sphere && pmodel == mdPerspective && rots_twist::in())
+  if(pmodel == mdPerspective && stretch::in())
     return true;
   return false;
   }
@@ -83,13 +83,14 @@ EX bool available() {
 /** do we want to use the raycaster? */
 EX bool requested() {
   if(cgflags & qRAYONLY) return true;
-  if(rots_twist::in()) return true;
+  if(stretch::in()) return true;
   if(!want_use) return false;
   #if CAP_TEXTURE
   if(texture::config.tstate == texture::tsActive) return false;
   #endif
   if(!available()) return false;
   if(want_use == 2) return true;
+  if(sphere) return false; /* currently incompatible with primitives */
   return racing::on || quotient;
   }
 
@@ -321,7 +322,7 @@ void enable_raycaster() {
        "return vec2(1, 1);\n"
        "}\n";
    
-   bool stepbased = nonisotropic || rots_twist::in();
+   bool stepbased = nonisotropic || stretch::in();
     
    string fmain = "void main() {\n";
    
@@ -347,6 +348,7 @@ void enable_raycaster() {
       
     if(hyperbolic) fsh += "  mediump float len(mediump vec4 x) { return x[3]; }\n";
     else if(sphere && rotspace) fsh += "  mediump float len(mediump vec4 x) { return 1.+x.x*x.x+x.y*x.y-x.z*x.z-x.w*x.w; }\n";
+    else if(sl2) fsh += "  mediump float len(mediump vec4 x) { return 1.+x.x*x.x+x.y*x.y; }\n";
     else if(sphere) fsh += "  mediump float len(mediump vec4 x) { return 1.-x[3]; }\n";
 
     else fsh += "  mediump float len(mediump vec4 x) { return length(x.xyz); }\n";
@@ -375,7 +377,7 @@ void enable_raycaster() {
       "  mediump vec4 position = vw * vec4(0., 0., 0., 1.);\n"
       "  mediump vec4 tangent = vw * at0;\n";
       
-    if(rots_twist::in()) {
+    if(stretch::in()) {
       fmain += 
         "tangent = s_itranslate(position) * tangent;\n"
         "tangent[2] /= sqrt(1.+stretch);\n"
@@ -495,8 +497,9 @@ void enable_raycaster() {
       fmain +=
         "  if(which == -1 && dist == 0.) return;";    
       }
-      
-    fsh += "const mediump float stretch = float(" + fts(rots::stretch_factor) + ");\n";
+    
+    if(stretch::in() || sl2)
+      fsh += "const mediump float stretch = float(" + fts(stretch::factor) + ");\n";
 
     // shift d units
     if(use_reflect) fmain += 
@@ -549,7 +552,23 @@ void enable_raycaster() {
         "  return vec4(x*vel.y*tra.y - 0.5*dot(vel.yz,tra.zy), -.5*x*dot(vel.yx,tra.xy) + .5 * dot(vel.zx,tra.xz), -.5*(x*x-1.)*dot(vel.yx,tra.xy)+.5*x*dot(vel.zx,tra.xz), 0.);\n"
 //        "  return vec4(0.,0.,0.,0.);\n"
         "  }\n";
-      else if(rots_twist::in()) {
+      else if(sl2) {
+        fsh += "mediump mat4 s_translate(vec4 h) {\n"
+          "return mat4(h.w,h.z,h.y,h.x,-h.z,h.w,-h.x,h.y,h.y,-h.x,h.w,-h.z,h.x,h.y,h.z,h.w);\n"
+          "}\n";
+        fsh += "mediump mat4 s_itranslate(vec4 h) {\n"
+          "h.xyz = -h.xyz; return s_translate(h);\n"
+          "}\n";
+        fsh += "mediump vec4 christoffel(mediump vec4 pos, mediump vec4 vel, mediump vec4 tra) {\n"
+          "vel = s_itranslate(pos) * vel;\n"
+          "tra = s_itranslate(pos) * tra;\n"
+          "return s_translate(pos) * vec4(\n"
+          "  (vel.y*tra.z+vel.z*tra.y) * -(-stretch-2.), "
+          "  (vel.x*tra.z+vel.z*tra.x) * (-stretch-2.), "
+          "  0, 0);\n"
+          "}\n";
+        }
+      else if(stretch::in()) {
         fsh += "mediump mat4 s_translate(vec4 h) {\n"
           "return mat4(h.w,h.z,-h.y,-h.x,-h.z,h.w,h.x,-h.y,h.y,-h.x,h.w,-h.z,h.x,h.y,h.z,h.w);\n"
           "}\n";
@@ -600,7 +619,10 @@ void enable_raycaster() {
         "mediump vec4 acc4 = get_acc(position + vel + acc2/2., vel + acc3/2.);\n"
         "mediump vec4 nposition = position + vel + (acc1+acc2+acc3)/6.;\n";
       
-      if(rots_twist::in()) fmain += 
+      if(sl2) fmain += 
+        "nposition = nposition / sqrt(dot(position.zw, position.zw) - dot(nposition.xy, nposition.xy));\n";
+
+      else if(stretch::in()) fmain += 
         "nposition = nposition / sqrt(dot(nposition, nposition));\n";
 
       if(nil) {
@@ -662,7 +684,7 @@ void enable_raycaster() {
         "  mediump vec4 nposition = v;\n";
         }
 
-      bool reg = hyperbolic || sphere || euclid;
+      bool reg = hyperbolic || sphere || euclid || sl2;
 
       if(reg) {
         fsh += "mediump float len_h(vec4 h) { return 1. - h[3]; }\n";
@@ -765,7 +787,7 @@ void enable_raycaster() {
       else fmain +=
         "tangent = ntangent;\n";
       
-      if(rots_twist::in()) {
+      if(stretch::in() || sl2) {
         fmain += 
           "tangent = s_itranslate(position) * tangent;\n"
           "tangent[3] = 0.;\n"
@@ -1306,7 +1328,7 @@ EX void configure() {
       });
     }
 
-  if(nonisotropic || rots_twist::in()) {
+  if(nonisotropic || stretch::in()) {
     dialog::addSelItem(XLAT("max step"), fts(maxstep_current()), 'x');
     dialog::add_action([] {
       dialog::editNumber(maxstep_current(), 1e-6, 1, 0.1, sol ? 0.05 : 0.1, XLAT("max step"), "affects the precision of solving the geodesic equation in Solv");
diff --git a/reg3.cpp b/reg3.cpp
index 4ff1593e..4d71f5f0 100644
--- a/reg3.cpp
+++ b/reg3.cpp
@@ -187,7 +187,7 @@ EX namespace reg3 {
     if(loop == 4) cgi.strafedist = adjcheck;
     else cgi.strafedist = hdist(cgi.adjmoves[0] * C0, cgi.adjmoves[1] * C0);
     
-    if(rots_twist::applicable()) {
+    if(stretch::applicable()) {
       transmatrix T = cspin(0, 2, 90 * degree);
       transmatrix iT = inverse(T);
       for(auto& v: cgi.adjmoves) v = T * v * iT;
@@ -698,14 +698,14 @@ EX namespace reg3 {
         dynamicval<hrmap*> cm(currentmap, binary_map);
         binary_map->virtualRebase(alt, T);
         }
-      
+
       fixmatrix(T);
       auto hT = tC0(T);
       
-      bool hopf = rots_twist::applicable();
+      bool hopf = stretch::applicable();
 
       if(hopf)
-        T = rots_twist::translate(hT);      
+        T = stretch::translate(hT);      
       
       if(DEB) println(hlog, "searching at ", alt, ":", hT);