diff --git a/bigstuff.cpp b/bigstuff.cpp
index 69f1856d..bc2cc4d7 100644
--- a/bigstuff.cpp
+++ b/bigstuff.cpp
@@ -648,38 +648,6 @@ cell *randomDown(cell *c) {
   return tab[hrand(q)];
   }
 
-// which=1 => right, which=-1 => left
-
-typedef int cellfunction(cell*);
-
-int chosenDownId(cell *c, int which, cellfunction* cf) {
-  int d = (*cf)(c)-1;
-  for(int i=0; i<c->type; i++) {
-    if(!c->move(i)) createMov(c, i);
-    if(c->move(i)->mpdist > BARLEV && cf == coastvalEdge) setdist(c->move(i), BARLEV, c);
-    
-    if((*cf)(c->move(i)) == d) {
-      again:
-      int i2 = (i+which+MODFIXER)%c->type;
-      createMov(c, i2);
-      if((*cf)(c->move(i2)) == d) {
-        i = i2; goto again;
-        }
-      else return i;
-      }
-    }
-  
-  return -1;
-  }
-
-// set which=1,bonus=1 to get right neighbor on level
-
-cell *chosenDown(cell *c, int which, int bonus, cellfunction* cf) {
-  int id = chosenDownId(c, which, cf);
-  if(id == -1) return NULL;
-  return createMovR(c, id + bonus);
-  }
-
 int edgeDepth(cell *c) {
   if(c->land == laIvoryTower || c->land == laEndorian || c->land == laDungeon) 
     return coastvalEdge(c);
@@ -698,28 +666,12 @@ int getHauntedDepth(cell *c) {
   return -100;
   }
 
-int towerval(cell *c, cellfunction* cf) {
-  // if(c->land != laEdge) return 0;
-  cell *cp1 = chosenDown(c, 1, 1, cf);
-  if(!cp1) return 0;
-  /* cell *cp2 = chosenDown(cp1, 1, 1);
-  if(!cp2) return 0;
-  cell *cm1 = chosenDown(c, -1, -1);
-  if(!cm1) return 0;
-  cell *cm2 = chosenDown(cm1, -1, -1);
-  if(!cm2) return 0; */
-
-  /* return 
-    (c->type-6) 
-    + 2*(cp1->type-6) + 4*(cp2->type-6) 
-    + 8*(cm1->type-6) +16*(cm2->type-6); */
-  
+int towerval(cell *c, const cellfunction& cf) {
+  cell *cp1 = ts::left_of(c, cf);
+  if(!cp1) return 0;  
   int under = 0;
-  int cfc = (*cf)(c);
-  for(int i=0; i<c->type; i++) {
-    if(c->move(i) && (*cf)(c->move(i)) < cfc)
-      under++;
-    }
+  int cfc = cf(c);
+  forCellEx(c2, c) if(cf(c2) < cfc) under++;
   return (c->type-6) + 2*(cp1->type-6) + 4*under;
   }
 
diff --git a/complex.cpp b/complex.cpp
index c72c9c5c..4cfea027 100644
--- a/complex.cpp
+++ b/complex.cpp
@@ -3590,8 +3590,10 @@ namespace dungeon {
               c4 = c2->move(i);
             }
           rdepths[i] = c2 && c3 && c4 && (c2->landflags == 3 || c3->landflags == 3 || c4->landflags == 3);
-          c2 = chosenDown(c2, 1, 0); // if(!c2) break;
-          c3 = chosenDown(c3, -1, 0);
+          if(c2) generate_around(c2);
+          if(c3) generate_around(c3);
+          c2 = ts::left_parent(c2, coastvalEdge);
+          c3 = ts::right_parent(c3, coastvalEdge);
           if(!c2) { towerError(c); return; }
           if(!c3) { towerError(c); return; }
           }
@@ -3604,19 +3606,22 @@ namespace dungeon {
       else if(!rdepths[2] && !rdepths[4] && !rdepths[1]) {
         c2 = c;
         c3 = c;
-        cell *c4 = chosenDown(c, 1, 1);
-        cell *c5 = chosenDown(c, -1, -1);
+        generate_around(c);
+        cell *c4 = ts::left_of(c, coastvalEdge);
+        cell *c5 = ts::right_of(c, coastvalEdge);
         for(int i=0; i<3; i++) {
           if(coastvalEdge(c2) == 0) break;
-          if(c2 && c4 && c4->landflags == 3 && c2->landflags != 3 && c4 == chosenDown(c2, 1, 1)) 
+          for(cell *cx: {c2, c3, c4, c5}) if(cx) generate_around(cx);
+
+          if(c2 && c4 && c4->landflags == 3 && c2->landflags != 3 && c4 == ts::left_of(c2, coastvalEdge))
             c->wall = waLadder;
-          if(c3 && c5 && c5->landflags == 3 && c3->landflags != 3 && c5 == chosenDown(c3, -1, -1)) 
+          if(c3 && c5 && c5->landflags == 3 && c3->landflags != 3 && c5 == ts::right_of(c3, coastvalEdge))
             c->wall = waLadder;
           buildEquidistant(c4); buildEquidistant(c5);
-          if(c2) c2 = chosenDown(c2,  1, 0);
-          if(c3) c3 = chosenDown(c3, -1, 0);
-          if(c4) c4 = chosenDown(c4,  1, 0);
-          if(c5) c5 = chosenDown(c5, -1, 0);
+          if(c2) c2 = ts::left_parent(c2, coastvalEdge);
+          if(c3) c3 = ts::right_parent(c3, coastvalEdge);
+          if(c4) c4 = ts::left_parent(c4, coastvalEdge);
+          if(c5) c5 = ts::right_parent(c5, coastvalEdge);
           }
         }
       }
@@ -3645,8 +3650,10 @@ namespace dungeon {
         rdepths[i] = c2 && c3 && c4 && (c2->landflags == 3 || c3->landflags == 3 || c4->landflags == 3);
         if((c2&&c2->landflags == 1) || (c3&&c3->landflags == 1) || (c4&&c4->landflags == 1))
           switchcount++;
-        c2 = chosenDown(c2, 1, 0); // if(!c2) break;
-        c3 = chosenDown(c3, -1, 0);
+        generate_around(c2);
+        generate_around(c3);
+        c2 = ts::left_parent(c2, coastvalEdge);
+        c3 = ts::right_parent(c3, coastvalEdge);
         if(!c2) { towerError(c); return 0; }
         if(!c3) { towerError(c); return 0; }
         }
@@ -3696,8 +3703,9 @@ namespace dungeon {
       int df = dungeonFlags(c);
       
       if(df&1) {
-        int df1 = dungeonFlags(chosenDown(c,1,1));
-        int df2 = dungeonFlags(chosenDown(c,-1,-1));
+        generate_around(c);
+        int df1 = dungeonFlags(ts::left_of(c, coastvalEdge));
+        int df2 = dungeonFlags(ts::right_of(c, coastvalEdge));
         
         c->wparam = 0;
         if(hrand(100) < (c->landparam % 5 == 0 ? 80 : 20)) {
@@ -3725,10 +3733,10 @@ namespace dungeon {
         if(q) downs[hrand(q)]->wall = waLadder;
         */
         cell *c2 = 
-          c->wparam == 1 ? chosenDown(c, 1, 2) :
-          c->wparam == 2 ? chosenDown(c, -1, -2) :
-          c->wparam == 3 ? chosenDown(c, 1, 3) :
-          c->wparam == 4 ? chosenDown(c, -1, -3) :
+          c->wparam == 1 ? ts::add(c, 1, 2, coastvalEdge) :
+          c->wparam == 2 ? ts::add(c, -1, -2, coastvalEdge) :
+          c->wparam == 3 ? ts::add(c, 1, 3, coastvalEdge) :
+          c->wparam == 4 ? ts::add(c, -1, -3, coastvalEdge) :
           NULL;
         
         if(c2) {
diff --git a/expansion.cpp b/expansion.cpp
index c3f4bca2..71f8ec3f 100644
--- a/expansion.cpp
+++ b/expansion.cpp
@@ -315,7 +315,7 @@ void expansion_analyzer::reset() {
   descendants.clear();
   }
 
-template<class T> int type_in(expansion_analyzer& ea, cell *c, const T& f) {
+int type_in(expansion_analyzer& ea, cell *c, const cellfunction& f) {
   if(!ea.N) ea.preliminary_grouping(), ea.reduce_grouping();
   vector<int> res;
   res.push_back(subtype(c) * 4 + 2);
@@ -336,7 +336,7 @@ template<class T> int type_in(expansion_analyzer& ea, cell *c, const T& f) {
   return ret;
   }
 
-template<class T> int type_in_quick(expansion_analyzer& ea, cell *c, const T& f) {
+int type_in_quick(expansion_analyzer& ea, cell *c, const cellfunction& f) {
   vector<int> res;
   res.push_back(subtype(c) * 4 + 2);
   int d = f(c);
@@ -409,7 +409,7 @@ int curr_dist(cell *c) {
 
 int position;
 
-template<class T> int type_in_reduced(expansion_analyzer& ea, cell *c, const T& f) {
+int type_in_reduced(expansion_analyzer& ea, cell *c, const cellfunction& f) {
   int a = ea.N;
   int t = type_in(ea, c, f);
   if(expansion.N != a) {
@@ -419,6 +419,69 @@ template<class T> int type_in_reduced(expansion_analyzer& ea, cell *c, const T&
   return t;
   }
 
+// which=1 => right, which=-1 => left
+
+int parent_id(cell *c, int which, const cellfunction& cf) {
+  int d = cf(c)-1;
+  for(int i=0; i<c->type; i++) {
+    
+    if(cf(c->cmove(i)) == d) {
+      again:
+      int i2 = c->c.fix(i+which);
+      if(cf(c->cmove(i2)) == d) {
+        i = i2; goto again;
+        }
+      else return i;
+      }
+    }
+  
+  return -1;
+  }
+
+// set which=1,bonus=1 to get right neighbor on level
+
+void generate_around(cell *c) {
+  forCellCM(c2, c) if(c2->mpdist > BARLEV) setdist(c2, BARLEV, c);
+  }
+  
+namespace ts {
+  cell *verified_add(cell *c, int which, int bonus, const cellfunction& cf) {
+    int id = parent_id(c, which, cf);
+    if(id == -1) return NULL;
+    return c->cmodmove(id + bonus);
+    }
+
+  cell *verified_add_gen(cell *c, int which, int bonus, const cellfunction& cf) {
+    return verified_add(c, which, bonus, cf);
+    }
+  
+  cell *add(cell *c, int which, int bonus, const cellfunction& cf) {
+    int pid = parent_id(c, which, cf);
+    if(pid == -1) pid = 0;
+    return c->cmodmove(pid + bonus);
+    }
+  
+  cell *left_of(cell *c, const cellfunction& cf) {
+    int pid = parent_id(c, 1, cf);
+    if(pid == -1) return c;
+    if(VALENCE == 3) return c->cmodmove(pid+1);
+    else return (cellwalker(c, pid) + wstep - 1).cpeek();
+    }
+
+  cell *right_of(cell *c, const cellfunction& cf) {
+    int pid = parent_id(c, -1, cf);
+    if(pid == -1) return c;
+    if(VALENCE == 3) return c->cmodmove(pid-1);
+    else return (cellwalker(c, pid) + wstep + 1).cpeek();
+    }
+
+  cell *child_number(cell *c, int id, const cellfunction& cf) { 
+    int pid = parent_id(c, 1, cf);
+    if(pid == -1) return c->cmove(id);
+    return c->cmodmove(pid + (VALENCE == 3 ? 2 : 1) + id);
+    }
+  }
+
 bool viewdists = false, use_color_codes = true, use_analyzer = true, show_distance_lists = true;
 
 int first_distance = 0, scrolltime = 0;
@@ -526,7 +589,7 @@ void viewdist_configure_dialog() {
 bool is_descendant(cell *c) {
   if(c == cwt.at) return true;
   if(curr_dist(c) < curr_dist(cwt.at)) return false;
-  return is_descendant(chosenDown(c, -1, 0, curr_dist));
+  return is_descendant(ts::right_parent(c, curr_dist));
   }
 
 const int scrollspeed = 100;
@@ -763,9 +826,7 @@ bool in_segment(cell *left, cell *mid, cell *right) {
   while(true) {
     if(mid == left) return true;
     if(left == right) return false;
-    int v = chosenDownId(left, 1, celldist);
-    if(S3 == 3) left = (cellwalker(left, v) + 1).cpeek();
-    else left = (cellwalker(left, v) + wstep - 1).cpeek();
+    left = ts::right_of(left, celldist);
     }
   }
 
@@ -775,7 +836,7 @@ int sibling_distance(cell *a, cell *b, int limit) {
     if(a == b) return counting;
     if(limit == 0) return INF;
     counting++; limit--;
-    a = chosenDown(a, 1, 1, celldist);
+    a = ts::right_of(a, celldist);
     }
   }
 
@@ -828,18 +889,20 @@ int hyperbolic_celldistance(cell *c1, cell *c2) {
       }    
     
     if(d >= found_distance) {
-      if(sl_used == sibling_limit) { printf("sibling_limit used: %d\n", sibling_limit); sibling_limit++; }
+      if(sl_used == sibling_limit && IRREGULAR) { 
+        printf("sibling_limit used: %d\n", sibling_limit); sibling_limit++; 
+        }
       return found_distance;
       }
 
     if(d1 >= d2) {
-      cl1 = chosenDown(cl1, -1, 0, celldist);
-      cr1 = chosenDown(cr1,  1, 0, celldist);
+      cl1 = ts::left_parent(cl1, celldist);
+      cr1 = ts::right_parent(cr1, celldist);
       d++; d1--;
       }
     if(d1 < d2) {
-      cl2 = chosenDown(cl2, -1, 0, celldist);
-      cr2 = chosenDown(cr2,  1, 0, celldist);
+      cl2 = ts::left_parent(cl2, celldist);
+      cr2 = ts::right_parent(cr2, celldist);
       d++; d2--;
       }
     }
diff --git a/graph.cpp b/graph.cpp
index 4d26ec6d..778f436b 100644
--- a/graph.cpp
+++ b/graph.cpp
@@ -2424,11 +2424,11 @@ transmatrix applyPatterndir(cell *c, const patterns::patterninfo& si) {
   return V * iddspin(c, 0, M_PI);
   }
 
-transmatrix applyDowndir(cell *c, cellfunction *cf) {
+transmatrix applyDowndir(cell *c, const cellfunction& cf) {
   return ddspin(c, patterns::downdir(c, cf), M_PI);
   }
 
-void set_towerfloor(cell *c, cellfunction *cf = coastvalEdge) {
+void set_towerfloor(cell *c, const cellfunction& cf = coastvalEdge) {
   if(weirdhyperbolic || sphere) {
     set_floor(shFloor);
     return;
@@ -2436,7 +2436,7 @@ void set_towerfloor(cell *c, cellfunction *cf = coastvalEdge) {
   int j = -1;
 
   if(masterless) j = 10;
-  else if((*cf)(c) > 1) { 
+  else if(cf(c) > 1) { 
     int i = towerval(c, cf);
     if(i == 4) j = 0;
     if(i == 5) j = 1;
@@ -4007,7 +4007,8 @@ void drawcell(cell *c, transmatrix V, int spinv, bool mirrored) {
       //   queuepoly(Vf, shLeafFloor[ct6], darkena(fcol, fd, 0xFF));
 
       /* else if(c->land == laPrairie && prairie::isriver(c))
-        set_towerfloor(Vf, c, darkena(fcol, fd, 0xFF), 
+        
+          set_towerfloor(Vf, c, darkena(fcol, fd, 0xFF), 
           prairie::isleft(c) ? river::towerleft : river::towerright); */
       
       else switch(c->land) {
diff --git a/hyper.h b/hyper.h
index c231d09e..64c51481 100644
--- a/hyper.h
+++ b/hyper.h
@@ -518,6 +518,7 @@ struct heptagon {
   heptagon () { heptacount++; }
   ~heptagon () { heptacount--; }
   heptagon *cmove(int d) { return createStep(this, d); }
+  heptagon *cmodmove(int d) { return createStep(this, c.fix(d)); }
   inline int degree(); 
 
   // prevent accidental copying
@@ -541,6 +542,7 @@ struct cell : gcell {
   cell*& move(int d) { return c.move(d); }
   cell*& modmove(int d) { return c.modmove(d); }
   cell* cmove(int d) { return createMov(this, d); }
+  cell* cmodmove(int d) { return createMov(this, c.fix(d)); }
   cell() {}
 
   // prevent accidental copying
@@ -643,8 +645,6 @@ int numplayers();
 void removeIvy(cell *c);
 bool cellEdgeUnstable(cell *c, flagtype flags = 0);
 int coastvalEdge(cell *c);
-typedef int cellfunction(cell*);
-int towerval(cell *c, cellfunction* cf = &coastvalEdge);
 #define HRANDMAX 0x7FFFFFFF
 int hrandpos(); // 0 to HRANDMAX
 
@@ -1064,6 +1064,8 @@ extern string mouseovers;
 
 extern struct SDL_Surface *s;
 
+typedef function<int(cell*)> cellfunction;
+
 namespace patterns {
   extern char whichShape;
   extern int canvasback;
@@ -1128,7 +1130,7 @@ namespace patterns {
   void showPattern();
   void val38(cell *c, patterninfo &si, int sub, int pat);
 
-  int downdir(cell *c, cellfunction *cf = coastvalEdge);
+  int downdir(cell *c, const cellfunction& cf = coastvalEdge);
   }
 
 namespace mapeditor { 
@@ -1372,7 +1374,6 @@ extern bool buggyGeneration;
 int buildIvy(cell *c, int children, int minleaf);
 int celldistAltRelative(cell *c);
 int roundTableRadius(cell *c);
-cell *chosenDown(cell *c, int which, int bonus, cellfunction* cf = &coastvalEdge);
 eLand pickLandRPM(eLand old);
 bool bearsCamelot(eLand l);
 
@@ -4203,7 +4204,26 @@ struct expansion_analyzer {
 
 extern expansion_analyzer expansion;
 
-int chosenDownId(cell *c, int which, cellfunction* cf);
+int towerval(cell *c, const cellfunction& cf);
+
+int parent_id(cell *c, int which, const cellfunction& cf);
+
+extern int sibling_limit;
+extern void set_sibling_limit();
+int type_in_reduced(expansion_analyzer& ea, cell *c, const function<int(cell*)>& f);
+
+namespace ts {
+  cell *verified_add(cell *c, int which, int bonus, const cellfunction& cf);
+  cell *add(cell *c, int which, int bonus, const cellfunction& cf);
+  
+  inline cell *left_parent(cell *c, const cellfunction& cf) { return verified_add(c, 1, 0, cf); }
+  inline cell *right_parent(cell *c, const cellfunction& cf) { return verified_add(c, -1, 0, cf); }
+  cell *left_of(cell *c, const cellfunction& cf);
+  cell *right_of(cell *c, const cellfunction& cf);
+  cell *child_number(cell *c, int id, const cellfunction& cf);
+  }
+
+void generate_around(cell *c);
 
 }
 
diff --git a/pattern2.cpp b/pattern2.cpp
index 58d8825c..a2193342 100644
--- a/pattern2.cpp
+++ b/pattern2.cpp
@@ -543,10 +543,8 @@ namespace patterns {
       }
     }
   
-  int downdir(cell *c, cellfunction *cf) {
-    cell *c2 = chosenDown(c, 1, 1, cf);
-    if(!c2) return 0;
-    return neighborId(c, c2);
+  int downdir(cell *c, const cellfunction& cf) {
+    return parent_id(c, 1, cf) + 1;
     }
 
   void applySym0123(int& i, int sub) {
@@ -1025,8 +1023,8 @@ namespace patterns {
       }
     
     else if(pat == PAT_DOWN) {
-      si.id = towerval(c);
-      si.dir = downdir(c);
+      si.id = towerval(c, coastvalEdge);
+      si.dir = downdir(c, coastvalEdge);
       }
     
     else if(pat == PAT_FIELD) {
@@ -2082,14 +2080,14 @@ namespace linepatterns {
         break;
 
       case patTriTree: {
-        cell *parent = chosenDown(c, -1, 0, curr_dist);
+        cell *parent = ts::right_parent(c, curr_dist);
         if(gmatrix.count(parent)) 
           queuelinef(tC0(V), gmatrix[parent]*C0, col, 2 + vid.linequality);
         break;
         }
       
       case patTriOther: {
-        cell *parent = chosenDown(c, -1, 0, curr_dist);
+        cell *parent = ts::right_parent(c, curr_dist);
         forCellEx(c2, c) if(gmatrix.count(c2) && curr_dist(c2) < curr_dist(c) && c2 != parent)
           queuelinef(tC0(V), gmatrix[c2]*C0, col, 2 + vid.linequality);
         break;