diff --git a/hypgraph.cpp b/hypgraph.cpp
index f882b396..349a2f78 100644
--- a/hypgraph.cpp
+++ b/hypgraph.cpp
@@ -1554,8 +1554,15 @@ EX void optimizeview() {
   if(subscreens::split(optimizeview)) return;
   if(dual::split(optimizeview)) return;
   
+  cell *c = centerover;
   transmatrix iView = inverse(View);
   virtualRebase(centerover, iView);
+  if(c != centerover && (sphere || sl3)) {
+    transmatrix T = currentmap->relative_matrix(centerover, c, C0);
+    T = stretch::itranslate(tC0(T)) * T;
+    stretch::mstretch_matrix = T * stretch::mstretch_matrix;
+    }
+    
   View = inverse(iView);
   fixmatrix(View);
 
@@ -1594,6 +1601,7 @@ EX void resetview() {
   DEBBI(DF_GRAPH, ("reset view"));
   // EUCLIDEAN
   NLP = Id;
+  stretch::mstretch_matrix = Id;
   auto lView = View;
   if(cwt.at) {
     centerover = cwt.at;
diff --git a/nonisotropic.cpp b/nonisotropic.cpp
index fe3cc6e4..9facc0d8 100644
--- a/nonisotropic.cpp
+++ b/nonisotropic.cpp
@@ -2192,6 +2192,7 @@ EX namespace rots {
       dynamicval<cell*> m5(centerover, co);
       dynamicval<transmatrix> m2(View, inprod ? pView : ypush(0) * qtm(h));
       if(PURE) View = View * pispin;
+      View = inverse(stretch::mstretch_matrix) * spin(2*d) * View;
       dynamicval<shiftmatrix> m3(playerV, shiftless(Id));
       dynamicval<transmatrix> m4(actual_view_transform, Id);
       dynamicval<shiftmatrix> m6(cwtV, shiftless(Id));
@@ -2289,6 +2290,8 @@ EX namespace stretch {
   EX transmatrix m_itoa, m_atoi, m_pd;
   EX ld ms_christoffel[3][3][3];
   
+  EX transmatrix mstretch_matrix;
+  
   EX void enable_mstretch() {
     mstretch = true;
 
@@ -2327,35 +2330,64 @@ EX namespace stretch {
     
     ld den = (-4*A00*A11*A22 + A00*B12 + B01*A22 - A01*A02*A12 + B02*A11);
     
-    /* to do: these formulas are not correct for SL; also the engine currently depends on rotational symmetry, which may not hold */
-
-    c[ 0 ][ 0 ][ 0 ] =  (A01*(A01*A12 - 2*A02*A11) + A02*(2*A01*A22 - A02*A12))/den ;
-    c[ 0 ][ 0 ][ 1 ] =  (A02*(4*A11*A22 - B12)/2 + A12*(2*A01*A22 - A02*A12)/2 - (A00 - A11)*(A01*A12 - 2*A02*A11))/den ;
-    c[ 0 ][ 0 ][ 2 ] =  (-A01*(4*A11*A22 - B12)/2 + A12*(A01*A12 - 2*A02*A11)/2 - (A00 - A22)*(2*A01*A22 - A02*A12))/den ;
-    c[ 0 ][ 1 ][ 0 ] =  (A02*(4*A11*A22 - B12)/2 + A12*(2*A01*A22 - A02*A12)/2 - (A00 - A11)*(A01*A12 - 2*A02*A11))/den ;
-    c[ 0 ][ 1 ][ 1 ] =  (-A01*(A01*A12 - 2*A02*A11) + A12*(4*A11*A22 - B12))/den ;
-    c[ 0 ][ 1 ][ 2 ] =  (B01*A22 - B02*A11 + 4*B11*A22 - A11*B12 - 4*A11*B22 + B12*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
-    c[ 0 ][ 2 ][ 0 ] =  (-A01*(4*A11*A22 - B12)/2 + A12*(A01*A12 - 2*A02*A11)/2 - (A00 - A22)*(2*A01*A22 - A02*A12))/den ;
-    c[ 0 ][ 2 ][ 1 ] =  (B01*A22 - B02*A11 + 4*B11*A22 - A11*B12 - 4*A11*B22 + B12*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
-    c[ 0 ][ 2 ][ 2 ] =  -(A02*(2*A01*A22 - A02*A12) + A12*(4*A11*A22 - B12))/den ;
-    c[ 1 ][ 0 ][ 0 ] =  -(A01*(2*A00*A12 - A01*A02) + A02*(4*A00*A22 - B02))/den ;
-    c[ 1 ][ 0 ][ 1 ] =  (-A02*(2*A01*A22 - A02*A12)/2 - A12*(4*A00*A22 - B02)/2 + (A00 - A11)*(2*A00*A12 - A01*A02))/den ;
-    c[ 1 ][ 0 ][ 2 ] =  (-4*B00*A22 + A00*B02 + A00*B12 + 4*A00*B22 - B01*A22 - B02*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
-    c[ 1 ][ 1 ][ 0 ] =  (-A02*(2*A01*A22 - A02*A12)/2 - A12*(4*A00*A22 - B02)/2 + (A00 - A11)*(2*A00*A12 - A01*A02))/den ;
-    c[ 1 ][ 1 ][ 1 ] =  (A01*(2*A00*A12 - A01*A02) - A12*(2*A01*A22 - A02*A12))/den ;
-    c[ 1 ][ 1 ][ 2 ] =  (A01*(4*A00*A22 - B02)/2 + A02*(2*A00*A12 - A01*A02)/2 + (A11 - A22)*(2*A01*A22 - A02*A12))/den ;
-    c[ 1 ][ 2 ][ 0 ] =  (-4*B00*A22 + A00*B02 + A00*B12 + 4*A00*B22 - B01*A22 - B02*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
-    c[ 1 ][ 2 ][ 1 ] =  (A01*(4*A00*A22 - B02)/2 + A02*(2*A00*A12 - A01*A02)/2 + (A11 - A22)*(2*A01*A22 - A02*A12))/den ;
-    c[ 1 ][ 2 ][ 2 ] =  (A02*(4*A00*A22 - B02) + A12*(2*A01*A22 - A02*A12))/den ;
-    c[ 2 ][ 0 ][ 0 ] =  (A01*(4*A00*A11 - B01) + A02*(2*A00*A12 - A01*A02))/den ;
-    c[ 2 ][ 0 ][ 1 ] =  (4*B00*A11 - A00*B01 - 4*A00*B11 - A00*B12 + B01*A11 + B02*A11)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
-    c[ 2 ][ 0 ][ 2 ] =  (-A01*(A01*A12 - 2*A02*A11)/2 + A12*(4*A00*A11 - B01)/2 - (A00 - A22)*(2*A00*A12 - A01*A02))/den ;
-    c[ 2 ][ 1 ][ 0 ] =  (4*B00*A11 - A00*B01 - 4*A00*B11 - A00*B12 + B01*A11 + B02*A11)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
-    c[ 2 ][ 1 ][ 1 ] =  (-A01*(4*A00*A11 - B01) + A12*(A01*A12 - 2*A02*A11))/den ;
-    c[ 2 ][ 1 ][ 2 ] =  (A00*A01*A12 + 2*A00*A02*A11 - B01*A02 + A01*A11*A12 - A01*A12*A22 - 2*A02*B11 + 2*A02*A11*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
-    c[ 2 ][ 2 ][ 0 ] =  (-A01*(A01*A12 - 2*A02*A11)/2 + A12*(4*A00*A11 - B01)/2 - (A00 - A22)*(2*A00*A12 - A01*A02))/den ;
-    c[ 2 ][ 2 ][ 1 ] =  (A00*A01*A12 + 2*A00*A02*A11 - B01*A02 + A01*A11*A12 - A01*A12*A22 - 2*A02*B11 + 2*A02*A11*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
-    c[ 2 ][ 2 ][ 2 ] =  -(A02*(2*A00*A12 - A01*A02) + A12*(A01*A12 - 2*A02*A11))/den ;
+    if(sl2) {
+      c[ 0 ][ 0 ][ 0 ] =  (A01*(A01*A12 - 2*A02*A11) - A02*(2*A01*A22 - A02*A12))/den;
+      c[ 0 ][ 0 ][ 1 ] =  (A00*A01*A12 - 2*A00*A02*A11 - A01*A11*A12 + A01*A12*A22 + 2*A02*B11 + 2*A02*A11*A22 - A02*B12)/-den ;
+      c[ 0 ][ 0 ][ 2 ] =  (-A01*(4*A11*A22 - B12)/2 + A12*(A01*A12 - 2*A02*A11)/2 - (A00 + A22)*(2*A01*A22 - A02*A12))/den;
+      c[ 0 ][ 1 ][ 0 ] =  (A00*A01*A12 - 2*A00*A02*A11 - A01*A11*A12 + A01*A12*A22 + 2*A02*B11 + 2*A02*A11*A22 - A02*B12)/-den ;
+      c[ 0 ][ 1 ][ 1 ] =  -(A01*(A01*A12 - 2*A02*A11) + A12*(4*A11*A22 - B12))/den;
+      c[ 0 ][ 1 ][ 2 ] =  (B01*A22 - B02*A11 + 4*B11*A22 - A11*B12 + 4*A11*B22 - B12*A22)/-den ;
+      c[ 0 ][ 2 ][ 0 ] =  (-A01*(4*A11*A22 - B12)/2 + A12*(A01*A12 - 2*A02*A11)/2 - (A00 + A22)*(2*A01*A22 - A02*A12))/den;
+      c[ 0 ][ 2 ][ 1 ] =  (B01*A22 - B02*A11 + 4*B11*A22 - A11*B12 + 4*A11*B22 - B12*A22)/-den ;
+      c[ 0 ][ 2 ][ 2 ] =  -(A02*(2*A01*A22 - A02*A12) + A12*(4*A11*A22 - B12))/den;
+      c[ 1 ][ 0 ][ 0 ] =  (-A01*(2*A00*A12 - A01*A02) + A02*(4*A00*A22 - B02))/den;
+      c[ 1 ][ 0 ][ 1 ] =  (A02*(2*A01*A22 - A02*A12)/2 + A12*(4*A00*A22 - B02)/2 + (A00 - A11)*(2*A00*A12 - A01*A02))/den;
+      c[ 1 ][ 0 ][ 2 ] =  (-4*B00*A22 + A00*B02 + A00*B12 - 4*A00*B22 - B01*A22 + B02*A22)/-den ;
+      c[ 1 ][ 1 ][ 0 ] =  (A02*(2*A01*A22 - A02*A12)/2 + A12*(4*A00*A22 - B02)/2 + (A00 - A11)*(2*A00*A12 - A01*A02))/den;
+      c[ 1 ][ 1 ][ 1 ] =  (A01*(2*A00*A12 - A01*A02) + A12*(2*A01*A22 - A02*A12))/den;
+      c[ 1 ][ 1 ][ 2 ] =  (A01*(4*A00*A22 - B02)/2 + A02*(2*A00*A12 - A01*A02)/2 + (A11 + A22)*(2*A01*A22 - A02*A12))/den;
+      c[ 1 ][ 2 ][ 0 ] =  (-4*B00*A22 + A00*B02 + A00*B12 - 4*A00*B22 - B01*A22 + B02*A22)/-den ;
+      c[ 1 ][ 2 ][ 1 ] =  (A01*(4*A00*A22 - B02)/2 + A02*(2*A00*A12 - A01*A02)/2 + (A11 + A22)*(2*A01*A22 - A02*A12))/den;
+      c[ 1 ][ 2 ][ 2 ] =  (A02*(4*A00*A22 - B02) + A12*(2*A01*A22 - A02*A12))/den;
+      c[ 2 ][ 0 ][ 0 ] =  (A01*(4*A00*A11 - B01) - A02*(2*A00*A12 - A01*A02))/den;
+      c[ 2 ][ 0 ][ 1 ] =  (4*B00*A11 - A00*B01 - 4*A00*B11 + A00*B12 + B01*A11 - B02*A11)/-den ;
+      c[ 2 ][ 0 ][ 2 ] =  (-A01*(A01*A12 - 2*A02*A11)/2 + A12*(4*A00*A11 - B01)/2 - (A00 + A22)*(2*A00*A12 - A01*A02))/den;
+      c[ 2 ][ 1 ][ 0 ] =  (4*B00*A11 - A00*B01 - 4*A00*B11 + A00*B12 + B01*A11 - B02*A11)/-den ;
+      c[ 2 ][ 1 ][ 1 ] =  -(A01*(4*A00*A11 - B01) + A12*(A01*A12 - 2*A02*A11))/den;
+      c[ 2 ][ 1 ][ 2 ] =  (A00*A01*A12 + 2*A00*A02*A11 - B01*A02 + A01*A11*A12 + A01*A12*A22 - 2*A02*B11 - 2*A02*A11*A22)/-den ;
+      c[ 2 ][ 2 ][ 0 ] =  (-A01*(A01*A12 - 2*A02*A11)/2 + A12*(4*A00*A11 - B01)/2 - (A00 + A22)*(2*A00*A12 - A01*A02))/den;
+      c[ 2 ][ 2 ][ 1 ] =  (A00*A01*A12 + 2*A00*A02*A11 - B01*A02 + A01*A11*A12 + A01*A12*A22 - 2*A02*B11 - 2*A02*A11*A22)/-den ;
+      c[ 2 ][ 2 ][ 2 ] =  -(A02*(2*A00*A12 - A01*A02) + A12*(A01*A12 - 2*A02*A11))/den;
+      }
+    else {
+      c[ 0 ][ 0 ][ 0 ] =  (A01*(A01*A12 - 2*A02*A11) + A02*(2*A01*A22 - A02*A12))/den ;
+      c[ 0 ][ 0 ][ 1 ] =  (A02*(4*A11*A22 - B12)/2 + A12*(2*A01*A22 - A02*A12)/2 - (A00 - A11)*(A01*A12 - 2*A02*A11))/den ;
+      c[ 0 ][ 0 ][ 2 ] =  (-A01*(4*A11*A22 - B12)/2 + A12*(A01*A12 - 2*A02*A11)/2 - (A00 - A22)*(2*A01*A22 - A02*A12))/den ;
+      c[ 0 ][ 1 ][ 0 ] =  (A02*(4*A11*A22 - B12)/2 + A12*(2*A01*A22 - A02*A12)/2 - (A00 - A11)*(A01*A12 - 2*A02*A11))/den ;
+      c[ 0 ][ 1 ][ 1 ] =  (-A01*(A01*A12 - 2*A02*A11) + A12*(4*A11*A22 - B12))/den ;
+      c[ 0 ][ 1 ][ 2 ] =  (B01*A22 - B02*A11 + 4*B11*A22 - A11*B12 - 4*A11*B22 + B12*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
+      c[ 0 ][ 2 ][ 0 ] =  (-A01*(4*A11*A22 - B12)/2 + A12*(A01*A12 - 2*A02*A11)/2 - (A00 - A22)*(2*A01*A22 - A02*A12))/den ;
+      c[ 0 ][ 2 ][ 1 ] =  (B01*A22 - B02*A11 + 4*B11*A22 - A11*B12 - 4*A11*B22 + B12*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
+      c[ 0 ][ 2 ][ 2 ] =  -(A02*(2*A01*A22 - A02*A12) + A12*(4*A11*A22 - B12))/den ;
+      c[ 1 ][ 0 ][ 0 ] =  -(A01*(2*A00*A12 - A01*A02) + A02*(4*A00*A22 - B02))/den ;
+      c[ 1 ][ 0 ][ 1 ] =  (-A02*(2*A01*A22 - A02*A12)/2 - A12*(4*A00*A22 - B02)/2 + (A00 - A11)*(2*A00*A12 - A01*A02))/den ;
+      c[ 1 ][ 0 ][ 2 ] =  (-4*B00*A22 + A00*B02 + A00*B12 + 4*A00*B22 - B01*A22 - B02*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
+      c[ 1 ][ 1 ][ 0 ] =  (-A02*(2*A01*A22 - A02*A12)/2 - A12*(4*A00*A22 - B02)/2 + (A00 - A11)*(2*A00*A12 - A01*A02))/den ;
+      c[ 1 ][ 1 ][ 1 ] =  (A01*(2*A00*A12 - A01*A02) - A12*(2*A01*A22 - A02*A12))/den ;
+      c[ 1 ][ 1 ][ 2 ] =  (A01*(4*A00*A22 - B02)/2 + A02*(2*A00*A12 - A01*A02)/2 + (A11 - A22)*(2*A01*A22 - A02*A12))/den ;
+      c[ 1 ][ 2 ][ 0 ] =  (-4*B00*A22 + A00*B02 + A00*B12 + 4*A00*B22 - B01*A22 - B02*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
+      c[ 1 ][ 2 ][ 1 ] =  (A01*(4*A00*A22 - B02)/2 + A02*(2*A00*A12 - A01*A02)/2 + (A11 - A22)*(2*A01*A22 - A02*A12))/den ;
+      c[ 1 ][ 2 ][ 2 ] =  (A02*(4*A00*A22 - B02) + A12*(2*A01*A22 - A02*A12))/den ;
+      c[ 2 ][ 0 ][ 0 ] =  (A01*(4*A00*A11 - B01) + A02*(2*A00*A12 - A01*A02))/den ;
+      c[ 2 ][ 0 ][ 1 ] =  (4*B00*A11 - A00*B01 - 4*A00*B11 - A00*B12 + B01*A11 + B02*A11)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
+      c[ 2 ][ 0 ][ 2 ] =  (-A01*(A01*A12 - 2*A02*A11)/2 + A12*(4*A00*A11 - B01)/2 - (A00 - A22)*(2*A00*A12 - A01*A02))/den ;
+      c[ 2 ][ 1 ][ 0 ] =  (4*B00*A11 - A00*B01 - 4*A00*B11 - A00*B12 + B01*A11 + B02*A11)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
+      c[ 2 ][ 1 ][ 1 ] =  (-A01*(4*A00*A11 - B01) + A12*(A01*A12 - 2*A02*A11))/den ;
+      c[ 2 ][ 1 ][ 2 ] =  (A00*A01*A12 + 2*A00*A02*A11 - B01*A02 + A01*A11*A12 - A01*A12*A22 - 2*A02*B11 + 2*A02*A11*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
+      c[ 2 ][ 2 ][ 0 ] =  (-A01*(A01*A12 - 2*A02*A11)/2 + A12*(4*A00*A11 - B01)/2 - (A00 - A22)*(2*A00*A12 - A01*A02))/den ;
+      c[ 2 ][ 2 ][ 1 ] =  (A00*A01*A12 + 2*A00*A02*A11 - B01*A02 + A01*A11*A12 - A01*A12*A22 - 2*A02*B11 + 2*A02*A11*A22)/(4*A00*A11*A22 - A00*B12 - B01*A22 + A01*A02*A12 - B02*A11) ;
+      c[ 2 ][ 2 ][ 2 ] =  -(A02*(2*A00*A12 - A01*A02) + A12*(A01*A12 - 2*A02*A11))/den ;
+      }
     
     for(int i=0; i<3; i++)
     for(int j=0; j<3; j++)
@@ -2642,13 +2674,16 @@ EX namespace nisot {
 
     h[3] = 0;
   
+    if(stretch::in() && stretch::mstretch)
+      Pos = stretch::mstretch_matrix * Pos;
+    
     auto tPos = transpose(Pos);
     
     h = Pos * h;
 
     int steps = rk_steps;
     h /= steps;
-    
+
     auto& at = tPos[3];
     auto& vel = h;
     
@@ -2715,8 +2750,13 @@ EX namespace nisot {
       vel = stretch::actual_to_isometric(at, vel);
       for(int i=0; i<3; i++) tPos[i] = stretch::actual_to_isometric(at, tPos[i]);
       }
+
+    Pos = transpose(tPos);
     
-    return transpose(tPos);
+    if(stretch::in() && stretch::mstretch)
+      Pos = inverse(stretch::mstretch_matrix) * Pos;
+    
+    return Pos;
     }
 
   EX void fixmatrix(transmatrix& T) {
diff --git a/raycaster.cpp b/raycaster.cpp
index 93209231..673de1bd 100644
--- a/raycaster.cpp
+++ b/raycaster.cpp
@@ -109,6 +109,7 @@ struct raycaster : glhr::GLprogram {
   GLint uPosX, uPosY;
   GLint uWallOffset, uSides;
   GLint uITOA, uATOI;
+  GLint uToOrig, uFromOrig;
   
   raycaster(string vsh, string fsh);
   };
@@ -155,6 +156,8 @@ raycaster::raycaster(string vsh, string fsh) : GLprogram(vsh, fsh) {
     
     uITOA = glGetUniformLocation(_program, "uITOA");
     uATOI = glGetUniformLocation(_program, "uATOI");
+    uToOrig = glGetUniformLocation(_program, "uToOrig");
+    uFromOrig = glGetUniformLocation(_program, "uFromOrig");
     }
 
 shared_ptr<raycaster> our_raycaster;
@@ -391,20 +394,31 @@ void enable_raycaster() {
       "  mediump vec4 tangent = vw * at0;\n";
       
     if(stretch::in()) {
-      fmain += 
-        "tangent = s_itranslate(position) * tangent;\n";
       if(stretch::mstretch) {
         fsh += "mediump uniform mat4 uITOA;\n";
         fsh += "mediump uniform mat4 uATOI;\n";
+        fsh += "mediump uniform mat4 uToOrig;\n";
+        fsh += "mediump uniform mat4 uFromOrig;\n";
+        fsh += "mediump mat4 toOrig;\n";
+        fsh += "mediump mat4 fromOrig;\n";
+        fmain +=
+          "toOrig = uToOrig;\n"
+          "fromOrig = uFromOrig;\n";
+        fmain += 
+          "tangent = s_itranslate(toOrig * position) * toOrig * tangent;\n";
         fmain += 
           "tangent = uITOA * tangent;\n";
+        fmain += 
+          "tangent = fromOrig * s_translate(toOrig * position) * tangent;\n";
         }
-      else 
+      else {
+        fmain += 
+          "tangent = s_itranslate(position) * tangent;\n";
         fmain +=
           "tangent[2] /= " + to_glsl(stretch::not_squared()) + ";\n";
-      fmain +=
-        "tangent = s_translate(position) * tangent;\n";
-        ;
+        fmain +=
+          "tangent = s_translate(position) * tangent;\n";
+        }
       }
     
     if(bi) fmain += "  walloffset = uWallOffset; sides = uSides;\n";
@@ -605,9 +619,9 @@ void enable_raycaster() {
           "}\n";
         if(stretch::mstretch) {
           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 = s_itranslate(toOrig * pos) * toOrig * vel;\n"
+            "tra = s_itranslate(toOrig * pos) * toOrig * tra;\n"
+            "return fromOrig * s_translate(toOrig * pos) * vec4(\n";
           
           for(int i=0; i<3; i++) {
             auto &c = stretch::ms_christoffel;
@@ -926,7 +940,7 @@ void enable_raycaster() {
       
       if((stretch::in() || sl2) && use_christoffel) {
         fmain += 
-          "tangent = s_itranslate(position) * tangent;\n"
+          "tangent = s_itranslate(toOrig * position) * toOrig * tangent;\n"
           "tangent[3] = 0.;\n";
         if(stretch::mstretch)
           fmain +=
@@ -937,7 +951,7 @@ void enable_raycaster() {
               + to_glsl(stretch::squared()) + " * tangent.z * tangent.z;\n";
         fmain +=      
           "tangent /= sqrt(nvelsquared);\n"
-          "tangent = s_translate(position) * tangent;\n";
+          "tangent = fromOrig * s_translate(toOrig * position) * tangent;\n";
         }
       }
     else fmain += 
@@ -1131,7 +1145,13 @@ void enable_raycaster() {
       "  int mid = int(connection.z * 1024.);\n"
       "  mediump mat4 m = " GET("uM", "mid") " * " GET("uM", "walloffset+which") ";\n"
       "  position = m * position;\n"
-      "  tangent = m *  tangent;\n";
+      "  tangent = m * tangent;\n";
+    
+    if(stretch::mstretch) fmain += 
+      "  m = s_itranslate(m*vec4(0,0,0,1)) * m;"
+      "  fromOrig = m * fromOrig;\n"
+      "  m[0][1] = -m[0][1]; m[1][0] = -m[1][0];\n" // inverse
+      "  toOrig = toOrig * m;\n";
     
     if(bi) {
       fmain += 
@@ -1328,6 +1348,11 @@ EX void cast() {
     glUniformMatrix4fv(o->uITOA, 1, 0, glhr::tmtogl_transpose3(stretch::m_itoa).as_array());   
     glUniformMatrix4fv(o->uATOI, 1, 0, glhr::tmtogl_transpose3(stretch::m_atoi).as_array());   
     }
+
+  if(o->uToOrig != -1) {
+    glUniformMatrix4fv(o->uToOrig, 1, 0, glhr::tmtogl_transpose3(msm).as_array());   
+    glUniformMatrix4fv(o->uFromOrig, 1, 0, glhr::tmtogl_transpose3(inverse(msm)).as_array());   
+    }
   
   if(o->uWallOffset != -1) {
     glUniform1i(o->uWallOffset, wall_offset(cs));