diff --git a/rogueviz/collatz.cpp b/rogueviz/collatz.cpp
new file mode 100644
index 00000000..02fc64a0
--- /dev/null
+++ b/rogueviz/collatz.cpp
@@ -0,0 +1,336 @@
+#include "../hyper.h"
+#include "rogueviz.h"
+
+namespace rogueviz {
+
+namespace collatz {
+
+  double s2, s3, p2, p3;
+  double cshift = -1;
+  
+  transmatrix T2, T3;
+  
+  edgetype *collatz1, *collatz2;
+  
+  void start() {
+    init(); kind = kCollatz;
+    collatz1 = add_edgetype("1");
+    collatz2 = add_edgetype("2");
+    vdata.resize(1);
+    vertexdata& vd = vdata[0];
+    createViz(0, cwt.at, xpush(cshift));
+    virtualRebase(vd.m);
+    vd.cp = dftcolor;
+    vd.data = 0;
+    addedge(0, 0, 1, false, collatz::collatz1);
+    vd.name = "1";
+    storeall();
+
+    T2 = spin(collatz::s2) * xpush(collatz::p2);
+    T3 = spin(collatz::s3) * xpush(collatz::p3);
+    }
+  
+  void lookup(long long reached, int bits) {
+    while(reached < (1ll<<bits)) {
+      if(reached%3 == 2 && (2*reached-1) % 9 && hrand(100) < 50)
+        reached = (2*reached-1) / 3;
+      else reached *= 2;
+      }
+    printf("reached = %lld\n", reached);
+    vector<string> seq;
+    while(reached>1) { 
+      seq.push_back(llts(reached));
+      if(reached&1) reached += (reached>>1)+1;
+      else reached >>= 1;
+      }
+    // seq.push_back("1");
+    reverse(seq.begin(), seq.end());
+    
+    int id = 0;
+    int next = 0;
+    
+    int steps = 0;
+    while(true) {
+      steps++;
+      if(std::isnan(View[0][0])) exit(1);
+      shmup::turn(100);
+      drawthemap();
+      centerpc(100); optimizeview();
+      fixmatrix(View);
+      bfs(); setdist(cwt.at, 7 - getDistLimit() - genrange_bonus, NULL);
+      vertexdata& vd = vdata[id];
+      for(int e=0; e<isize(vd.edges); e++) {
+        int id2 = vd.edges[e].first;
+        if(vdata[id2].name == seq[next]) {
+          id = id2; next++;
+          cwt.at = vdata[id2].m->base;
+          if(shmup::on) shmup::pc[0]->base = cwt.at;
+          if(next == isize(seq)) goto found;
+          }
+        }
+      }
+    
+    found:
+    printf("steps = %d\n", steps);    
+    }
+
+  void act(vertexdata& vd, cell *c, shmup::monster *m, int i) {
+    if(c->cpdist > 7 && euclid) ;
+    else if(vd.data == 2) {
+      // doubler vertex
+      string s = vd.name;
+      colorpair cp = vd.cp;
+      vd.data = 20;
+      int i0 = isize(vdata);
+      vdata.resize(i0+1);
+      vertexdata& vdn = vdata[i0];
+      createViz(i0, m->base, m->at * collatz::T2);
+      
+      virtualRebase(vdn.m);
+      vdn.cp = perturb(cp);
+      vdn.data = 0;
+      addedge(i, i0, 1, false, collatz::collatz1);
+      vdn.m->store();
+      int carry = 0;
+      string s2 = s;
+      for(int i=isize(s2)-1; i>=0; i--) {
+        int x = 2*(s2[i] - '0') + carry;
+        carry = x>=10;
+        if(carry) x-=10;
+        s2[i] = '0'+x;
+        }
+      if(carry) s2 = "1" + s2;
+      vdn.name = s2;
+      
+      int m3 = 0;
+      for(int i=0; i<isize(s); i++) m3 += s[i] - '0';
+      
+      if(m3 % 3 == 2 && s != "2" && s != "1") {
+        vdata.resize(i0+2);
+        vertexdata& vdn = vdata[i0+1];
+        createViz(i0+1, m->base, m->at * collatz::T3);
+        virtualRebase(vdn.m);
+        vdn.cp = perturb(cp);
+        vdn.data = 0;
+        addedge(i, i0+1, 1, false, collatz::collatz2);
+        vdn.m->store();
+        int carry = -1;
+        string s2 = s;
+        for(int i=isize(s2)-1; i>=0; i--) {
+          carry += 2 * (s2[i] - '0');
+          int ncarry = 0;
+          while(carry % 3) carry += 10, ncarry--;
+          if(carry >= 30) carry -= 30, ncarry += 3;
+          s2[i] = '0'+carry/3;
+          carry = ncarry;
+          }
+        if(s2[0] == '0') s2 = s2.substr(1);
+        vdn.name = s2;
+        vdn.cp = perturb(vdn.cp);
+        }
+      }
+    else if(vd.data < 2) {
+      vd.data++;
+      fixmatrix(vd.m->at);
+      }
+    }
+
+#if CAP_SHOT
+
+// see: https://www.youtube.com/watch?v=4Vu3F95jpQ4&t=6s (Collatz)
+void collatz_video(const string &fname) {
+  if(kind == kCollatz) {
+    sightrange_bonus = 3;
+    genrange_bonus = 3;
+    dronemode = true; vid.camera_angle = -45; rog3 = true; patterns::whichShape = '8';
+    vid.aurastr = 512;
+    
+    collatz::lookup(763, 60);
+
+    history::create_playerpath(), models::rotation = 1;
+    // pmodel = mdBand;
+
+#define STORYCOUNT 24
+#define T(m,ss) (60*24*(m)+24*(ss))
+#define FRAMECOUNT T(4,55)
+
+printf("framecount = %d\n", FRAMECOUNT);
+
+struct storydata { int s; int e; const char *text; } story[] = {
+  {T(0,14), T(0,17), "I am flying above a tree of numbers."},
+  {T(0,17), T(0,20), "It starts with the number 1."},
+  {T(0,20), T(0,23), "Each number n branches left to 2n."},
+  {T(0,23), T(0,28), "And it branches right to (2n-1)/3 if possible."},
+
+  {T(1, 8), T(1,11), "What I am flying above is not a plane."},
+  {T(1,11), T(1,14), "It is not a sphere either."},
+  {T(1,14), T(1,17), "To be honest, the space I live in..."},
+  {T(1,17), T(1,20), "...is not even Euclidean."},
+  
+  {T(2,12), T(2,15), "Look, angles of a triangle add up to..."},
+  {T(2,15), T(2,18), "...less than 180 degrees in this world."},
+  {T(2,18), T(2,21), "6/7 of 180 degrees, to be exact."},
+  {T(2,21), T(2,24), "Do you see the regular heptagons?"},
+  {T(2,36), T(2,42), "And all these lines are straight."},
+  
+  {T(3, 8), T(3,11), "Lots of space in my world."},
+  {T(3,11), T(3,14), "In 105 steps from the root..."},
+  {T(3,14), T(3,17), "...there are trillions of numbers."},
+  {T(3,17), T(3,20), "That would not fit in your world."},
+
+  {T(4,0),  T(4,3),  "Is every positive number somewhere in the tree?"},
+  {T(4,3),  T(4,6),  "Your mathematicians do not know this yet."},
+  {T(4,6),  T(4,10), "Will you find the answer?"},
+  
+  {T(4,44), T(4,54), "music: Ambient Flow, by Indjenuity"},
+  
+  {T(2,6),  T(2,27), "@triangles"},
+  {T(2,27), T(2,42), "@network"},
+  
+  {0, T(0,7), "@fi"},
+  {T(4,48), T(4,55), "@fo"},
+  
+  {0,0,NULL}
+  };
+
+    int drawtris=0, drawnet=0;
+        
+    for(int i=0; i<FRAMECOUNT; i++) {
+      const char *caption = NULL;
+      int fade = 255;
+      
+      bool dt = false, dn = false;
+      
+      for(int j=0; story[j].text; j++) if(i >= story[j].s && i <= story[j].e) {
+        if(story[j].text[0] != '@')
+          caption = story[j].text;
+        else if(story[j].text[1] == 't')
+          dt = true;
+        else if(story[j].text[1] == 'n')
+          dn = true;
+        else if(story[j].text[2] == 'i')
+          fade = 255 * (i - story[j].s) / (story[j].e-story[j].s);
+        else if(story[j].text[2] == 'o')
+          fade = 255 * (story[j].e - i) / (story[j].e-story[j].s);
+        }
+      
+      if(dt && drawtris < 255) drawtris++;
+      else if(drawtris && !dt) drawtris--;
+
+      linepatterns::patZebraTriangles.color = 0x40FF4000 + drawtris;
+      
+      if(dn && drawnet < 255) drawnet++;
+      else if(drawnet && !dn) drawnet--;
+
+      linepatterns::patZebraLines.color = 0xFF000000 + drawnet;
+      
+      vid.grid = drawnet;
+      
+      history::phase = 1 + (isize(history::v)-3) * i * .95 / FRAMECOUNT;
+      history::movetophase();
+
+      char buf[500];
+      snprintf(buf, 500, fname.c_str(), i);
+      
+      if(i == 0) drawthemap();
+      shmup::turn(100);
+      printf("%s\n", buf);
+      shot::shoty = 1080; shot::shotx = 1920;
+      shot::caption = caption;
+      shot::fade = fade;
+      shot::take(buf);
+      }
+  
+    return;
+    }
+  }
+#endif
+
+string its05(int i) { char buf[64]; sprintf(buf, "%05d", i); return buf; }
+
+int readArgs() {
+#if CAP_COMMANDLINE
+  using namespace arg;
+
+  if(0) ;
+
+  else if(argis("-collatz")) {
+    PHASE(3); 
+    using namespace collatz; 
+    shift(); sscanf(argcs(), "%lf,%lf,%lf,%lf", &s2, &p2, &s3, &p3);
+    start();
+    }
+
+  else if(argis("-collatz-go")) {
+    if(kind != kCollatz) { printf("not in Collatz\n"); throw hr_exception(); }
+    shift(); int i = argi(); shift(); int j = argi();
+    if(i <= 0) i = 763;
+    if(j < 0 || j > 61) j = 61;
+    collatz::lookup(i, j);
+    }
+
+  else if(argis("-collatz3")) {
+    PHASE(3); 
+    using namespace collatz; 
+    s2 = p2 = s3 = p3 = 0;
+    start();
+    transmatrix *T = &T2;
+    while(true) {
+      lshift();
+      if(arg::nomore()) break;
+      else if(argis("fd")) { shift(); *T = *T * xpush(argf()); }
+      else if(argcs()[0] == 't') { int x = dimid(argcs()[1]); int y = dimid(argcs()[2]); shift(); *T = *T * hr::cspin(x, y, argf()); }
+      else if(argis("/")) { if(T == &T2) T = &T3; else break; }
+      else break;
+      }
+    unshift();
+    }
+
+  #if CAP_SHOT
+  else if(argis("-rvvideo") && kind == kCollatz) {
+    shift(); collatz_video(arg::args());
+    }
+  #endif
+
+  else if(argis("-cshift")) {
+    shift_arg_formula(collatz::cshift);
+    }
+  else return 1;
+#endif
+  return 0;
+  }
+
+int ah = addHook(hooks_args, 100, readArgs) +
+  addHook(rvtour::hooks_build_rvtour, 100, [] (vector<tour::slide>& v) {
+    using namespace tour;
+    v.push_back(
+      tour::slide{"Collatz conjecture", 51, LEGAL::UNLIMITED | QUICKGEO,
+    "The following slide is a visualization of the Collatz conjecture. "
+    "Press '5' for a spiral rendering of the Collatz conjecture visualization.\n\n"
+    "Note that this, and many other RogueViz visualizations, have "
+    "Euclidean versions (press ESC).\n",
+    rvtour::roguevizslide('d', [] () {
+      rogueviz::dftcolor = 0x206020FF;
+      
+      int fac = euclid ? 2 : 1;
+
+      rogueviz::collatz::s2 = .3;
+      rogueviz::collatz::p2 = .5 * fac;
+      rogueviz::collatz::s3 = -.4;
+      rogueviz::collatz::p3 = .4 * fac;
+
+      rogueviz::showlabels = true;
+      
+      rogueviz::on = true;
+      gmatrix.clear();
+      drawthemap();
+      gmatrix0 = gmatrix;
+
+      rogueviz::collatz::start();
+      })
+    });
+    });
+
+EX }
+
+}
diff --git a/rogueviz/sag.cpp b/rogueviz/sag.cpp
new file mode 100644
index 00000000..f39b8b09
--- /dev/null
+++ b/rogueviz/sag.cpp
@@ -0,0 +1,628 @@
+#include "../hyper.h"
+#include "rogueviz.h"
+
+// SAG visualizer (e.g. Reddit roguelikes, GitHub languages)
+//-----------------------------------------------------------
+
+// see: https://www.youtube.com/watch?v=mDG3_f8R2Ns (SAG boardgames)
+// see: https://www.youtube.com/watch?v=WSyygk_3j9o (SAG roguelikes)
+// see: https://www.youtube.com/watch?v=HWQkDkeEUeM (SAG programming languages)
+
+namespace rogueviz {
+
+namespace sag {
+
+  int sagpar = 0;
+
+  enum eSagmode { sagOff, sagHC, sagSA };
+  
+  eSagmode sagmode; // 0 - off, 1 - hillclimbing, 2 - SA
+
+  const char *sagmodes[3] = {"off", "HC", "SA"};
+  
+  ld temperature = -4;
+  const int INSNAKE = 117;
+  int numsnake;
+  const char *loadfname;
+  
+  #define MAXSNAKETAB 1000
+  int sdist[MAXSNAKETAB][MAXSNAKETAB];
+  int insnaketab = 0;
+
+  vector<cell*> snakecells;
+  vector<int> snakefirst, snakelast;
+  vector<int> snakenode;
+  vector<int> snakeid;
+  vector<int> lpbak;
+  vector<int> wpbak;
+  
+  bool snake_enabled;
+
+  void setsnake(cellwalker& cw, int i) {
+    lpbak[i] = cw.at->landparam;
+    wpbak[i] = cw.at->wparam;
+    cw.at->landparam = i; cw.at->wparam = INSNAKE;
+    // cw.at->monst = moWormtail; cw.at->mondir = cw.spin;
+    snakecells[i] = cw.at;
+    }
+  
+  void snakeswitch() { 
+    for(int i=0; i<numsnake; i++) {
+      cell *c = snakecells[i];
+      int x;
+      x = lpbak[i]; lpbak[i] = c->landparam; c->landparam = x;
+      x = wpbak[i]; wpbak[i] = c->wparam; c->wparam = x;
+      }
+    snake_enabled = !snake_enabled;
+    }
+    
+  void enable_snake() { if(!snake_enabled) snakeswitch(); }
+    
+  void disable_snake() { if(snake_enabled) snakeswitch(); }
+    
+  int snakedist(int i, int j) {
+    if(i < insnaketab && j < insnaketab) return sdist[i][j];
+    if(bounded) return celldistance(snakecells[i], snakecells[j]);
+    int i0 = i, i1 = i, j0 = j, j1 = j;
+    int cost = 0;
+    // intersect
+    while(true) {
+      if(j0 > i1+1) { j0 = snakefirst[j0], j1 = snakelast[j1]; cost++; }
+      else if(i0 > j1+1) { i0 = snakefirst[i0], i1 = snakelast[i1]; cost++; }
+      else if(j1+1 == i0) return cost+1;
+      else if(i1+1 == j0) return cost+1;
+      else return cost;
+      }
+    }
+  
+  void initSnake(int n) {
+    if(bounded) n = isize(currentmap->allcells());
+    numsnake = n;
+    snakecells.resize(numsnake);
+    snakefirst.resize(numsnake);
+    snakelast.resize(numsnake);
+    snakenode.resize(numsnake);
+    lpbak.resize(numsnake);
+    wpbak.resize(numsnake);
+    if(bounded) {
+      for(int i=0; i<n; i++) {
+        cellwalker cw(currentmap->allcells()[i], 0);
+        setsnake(cw, i);
+        }
+      }
+    else {
+      cellwalker cw = cwt;
+      setsnake(cw, 0);
+      cw += wstep;
+      setsnake(cw, 1);
+      for(int i=2; i<=numsnake; i++) {
+        if(i == numsnake && sphere) break;
+        cw += wstep;
+        snakefirst[i-1] = cw.at->landparam;
+        while(cw.at->wparam == INSNAKE) {
+          snakelast[i-1] = cw.at->landparam;
+          cw = cw + wstep + 1 + wstep;
+          }
+        if(i == numsnake) break;
+        setsnake(cw, i); cw += 1;
+        }
+      }
+    int stab = min(numsnake, MAXSNAKETAB);
+    for(int i=0; i<stab; i++)
+    for(int j=0; j<stab; j++)
+      sdist[i][j] = snakedist(i,j);
+    insnaketab = stab;
+    snake_enabled = true;
+    }
+  
+  double costat(int vid, int sid) {
+    if(vid < 0) return 0;
+    double cost = 0;
+    vertexdata& vd = vdata[vid];
+    for(int j=0; j<isize(vd.edges); j++) {
+      edgeinfo *ei = vd.edges[j].second;
+      int t2 = vd.edges[j].first;
+      if(snakeid[t2] != -1) cost += snakedist(sid, snakeid[t2]) * ei->weight2;
+      }
+    /* cell *c = snakecells[id];
+    for(int i=0; i<c->type; i++) {
+      cell *c2 = c->move(i);
+      if(c2 && c2->wparam == INSNAKE && snakenode[c2->landparam] >= 0)
+        cost += 100;
+      } */
+    return cost;
+    }
+  
+  // std::mt19937 los;
+
+  bool infullsa;
+  
+  double cost;
+  int N;
+
+  vector<double> chgs;  
+  
+  edgetype *sag_edge;
+
+  void forgetedges(int id) {
+    for(int i=0; i<isize(vdata[id].edges); i++) 
+      vdata[id].edges[i].second->orig = NULL;
+    }
+  
+  bool chance(double p) {
+    p *= double(hrngen.max()) + 1;
+    auto l = hrngen();
+    auto pv = (decltype(l)) p;
+    if(l < pv) return true;
+    if(l == pv) return chance(p-pv);
+    return false;
+    }
+
+  void saiter() {
+    aiter:
+
+    int t1 = hrand(N);
+    int sid1 = snakeid[t1];
+    
+    int sid2;
+    
+    int s = hrand(6);
+    
+    if(s == 3) s = 2;
+    if(s == 4) s = 5;
+    
+    if((sagpar&1) && (s == 2 || s == 3 || s == 4)) return;
+    
+    if(s == 5) sid2 = hrand(numsnake);
+    
+    else {
+      cell *c;
+      if(s>=2 && isize(vdata[t1].edges)) c = snakecells[snakeid[hrand(isize(vdata[t1].edges))]];
+      else c = snakecells[sid1];
+      
+      int it = s<2 ? (s+1) : s-2;
+      for(int ii=0; ii<it; ii++) {
+        int d = hrand(c->type);
+        c = c->move(d);
+        if(!c) goto aiter;
+        if(c->wparam != INSNAKE) goto aiter;
+        }
+      sid2 = c->landparam;
+      }
+    int t2 = snakenode[sid2];
+    
+    snakenode[sid1] = -1; snakeid[t1] = -1;
+    snakenode[sid2] = -1; if(t2 >= 0) snakeid[t2] = -1;
+    
+    double change = 
+      costat(t1,sid2) + costat(t2,sid1) - costat(t1,sid1) - costat(t2,sid2);
+
+    snakenode[sid1] = t1; snakeid[t1] = sid1;
+    snakenode[sid2] = t2; if(t2 >= 0) snakeid[t2] = sid2;
+    
+    if(change < 0) chgs.push_back(-change);
+      
+    if(change > 0 && (sagmode == sagHC || !chance(exp(-change * exp(-temperature))))) return;
+
+    snakenode[sid1] = t2; snakenode[sid2] = t1;
+    snakeid[t1] = sid2; if(t2 >= 0) snakeid[t2] = sid1;
+    if(vdata[t1].m) vdata[t1].m->base = snakecells[sid2];
+    if(t2 >= 0 && vdata[t2].m) vdata[t2].m->base = snakecells[sid1];
+    cost += 2*change;
+    
+    if(t1 >= 0) forgetedges(t1);
+    if(t2 >= 0) forgetedges(t2);
+    }
+  
+  void organize() {
+    for(int i=0; i<numsnake; i++) snakenode[i] = -1;
+    vector<int> freenodes;
+    for(int i=0; i<N; i++) 
+      if(snakeid[i] != -1)
+        snakenode[snakeid[i]] = i;
+
+    for(int i=0; i<N; i++) 
+      if(snakeid[i] != -1)
+        if(snakenode[snakeid[i]] != i)
+          snakeid[i] = -1;
+
+    for(int i=0; i<numsnake; i++) 
+      if(snakenode[i] == -1)
+        freenodes.push_back(i);
+    
+    int j = 0;
+    for(int i=0; i<N; i++) 
+      if(snakeid[i] == -1) {
+        snakeid[i] = freenodes[j];
+        snakenode[freenodes[j]] = i;
+        j++;
+        }
+    cost = 0; for(int i=0; i<N; i++) cost += costat(i, i);
+    }
+  
+  void loadsnake(const string& fname) {
+    printf("Loading the sag from: %s\n", fname.c_str());
+    FILE *sf = fopen(fname.c_str(), "rt");
+    if(!sf) { printf("Failed to open file.\n"); exit(1); }
+    if(sf) while(true) {
+      string lab;
+      while(true) {
+        int c = fgetc(sf);
+        if(c == EOF) goto afterload;
+        else if(c == 10 || c == 13 || c == 32 || c == 9) ;
+        else if(c == ',' || c == ';') break;
+        else lab += c;
+        }
+      int sid = -1;
+      int err = fscanf(sf, "%d", &sid);
+      if(sid < 0 || sid >= numsnake || err < 1) sid = -1;
+      if(!labeler.count(lab)) {
+        printf("unknown vertex: %s\n", lab.c_str());
+        }
+      else {
+        int id = getid(lab);
+        snakeid[id] = sid;
+        }
+      }
+    afterload: 
+    if(sf) fclose(sf);
+
+    organize();
+    for(int i=0; i<N; i++) {
+      if(vdata[i].m) vdata[i].m->base = snakecells[sag::snakeid[i]];
+      forgetedges(i);
+      }
+
+    shmup::fixStorage();
+    }
+  
+  vector<edgeinfo> sagedges;
+  
+  /* bool totcmp(int i, int j) {
+    return totwei[i] > totwei[j];
+    } */
+  
+  int ipturn = 100;
+  int numiter = 0;
+  
+  int hightemp = 10;
+  int lowtemp = -15;
+  
+  void dofullsa(int satime) {
+    sagmode = sagSA;
+    enable_snake();
+    int t1 = SDL_GetTicks();
+    
+    while(true) {
+      int t2 = SDL_GetTicks();
+      double d = (t2-t1) / (1000. * satime);
+      if(d > 1) break;
+      temperature = hightemp - (d*(hightemp-lowtemp));
+      chgs.clear();
+      for(int i=0; i<50000; i++) {
+        numiter++;
+        sag::saiter();
+        }
+      DEBB(DF_LOG, (format("it %8d temp %6.4f [1/e at %13.6f] cost = %f ", 
+        numiter, double(sag::temperature), (double) exp(sag::temperature),
+        double(sag::cost))));
+      
+      sort(chgs.begin(), chgs.end());
+      int cc = chgs.size() - 1;
+      DEBB(DF_LOG, (format("%9.4f .. %9.4f .. %9.4f .. %9.4f .. %9.4f\n", 
+        double(chgs[0]), double(chgs[cc/4]), double(chgs[cc/2]), double(chgs[cc*3/4]), double(chgs[cc]))));
+      fflush(stdout);
+      }
+    
+    temperature = -5;
+    disable_snake();
+    sagmode = sagOff;
+    }
+
+  void iterate() {
+    if(!sagmode) return;
+    int t1 = SDL_GetTicks();
+    enable_snake();
+    for(int i=0; i<ipturn; i++) {
+      numiter++;
+      sag::saiter();
+      }
+    disable_snake();
+    int t2 = SDL_GetTicks();
+    int t = t2 - t1;
+    if(t < 50) ipturn *= 2;
+    else if(t > 200) ipturn /= 2;
+    else ipturn = ipturn * 100 / t;
+    DEBB(DF_LOG, ("it %8d temp %6.4f [2:%8.6f,10:%8.6f,50:%8.6f] cost = %f\n", 
+      numiter, double(sag::temperature), 
+      (double) exp(-2 * exp(-sag::temperature)),
+      (double) exp(-10 * exp(-sag::temperature)),
+      (double) exp(-50 * exp(-sag::temperature)),
+      (double) sag::cost));
+    }
+  
+  void savesnake(const string& fname) {
+    FILE *f = fopen(fname.c_str(), "wt");
+    for(int i=0; i<N; i++)
+      fprintf(f, "%s;%d\n", vdata[i].name.c_str(), snakeid[i]);
+    fclose(f);
+    }
+  
+  void loglik() {
+    int indist[30], pedge[30];
+    for(int d=0; d<30; d++) indist[d] = 0, pedge[d] = 0;
+    
+    for(int i=0; i<N; i++)
+    for(int j=0; j<i; j++)
+      indist[snakedist(snakeid[i], snakeid[j])]++;
+      
+    for(int i=0; i<isize(sagedges); i++) {
+      edgeinfo& ei = sagedges[i];
+      if(snakedist(snakeid[ei.i], snakeid[ei.j]) == 0) {
+        printf("zero between %d (%s) and %d (%s)\n", 
+          snakeid[ei.i], vdata[ei.i].name.c_str(),
+          snakeid[ei.j], vdata[ei.j].name.c_str());
+        }
+      if(ei.weight >= sag_edge->visible_from)
+        pedge[snakedist(snakeid[ei.i], snakeid[ei.j])]++;
+      }
+    
+    for(int d=0; d<30; d++) 
+      if(indist[d])
+        printf("%2d: %7d/%7d %7.3lf\n", 
+          d, pedge[d], indist[d], double(pedge[d] * 100. / indist[d]));
+        
+    ld loglik = 0;
+    for(int d=0; d<30; d++) {
+      int p = pedge[d], pq = indist[d];
+      int q = pq - p;
+      if(p && q)
+        loglik += p * log(p) + q * log(q) - pq * log(pq);
+      }
+    
+    println(hlog, "loglikelihood = ", fts(loglik));
+    }
+  
+  void readsag(const char *fname) {
+    maxweight = 0;
+    sag_edge = add_edgetype("SAG edge");
+    fhstream f(fname, "rt");
+    if(!f.f) { printf("Failed to open SAG file: %s\n", fname); exit(1); }
+    // while(fgetc(f) != 10 && fgetc(f) != 13 && !feof(f)) ;
+    while(!feof(f.f)) {
+      string l1, l2;
+      while(true) {
+        int c = fgetc(f.f);
+        if(c == EOF) return;
+        else if(c == ';') break;
+        else if(c == 10 || c == 13 || c == 32 || c == 9) ;
+        else l1 += c;
+        }
+      while(true) {
+        int c = fgetc(f.f);
+        if(c == EOF) return;
+        else if(c == ';') break;
+        else if(c == 10 || c == 13 || c == 32 || c == 9) ;
+        else l2 += c;
+        }
+      ld wei;
+      if(!scan(f, wei)) continue;
+      edgeinfo ei(sag_edge);
+      ei.i = getid(l1);
+      ei.j = getid(l2);
+      ei.weight = wei;
+      sagedges.push_back(ei);
+      }
+    }
+  
+  ld edgepower=1, edgemul=1;
+
+  void read(string fn) {
+    fname = fn;
+    init(); kind = kSAG;
+    temperature = 0; sagmode = sagOff;
+    readsag(fname.c_str());
+    
+    N = isize(vdata);
+    // totwei.resize(N);
+    // for(int i=0; i<N; i++) totwei[i] = 0;
+    
+    for(int i=0; i<N; i++) vdata[i].data = 0;
+    /* for(int i=0; i<isize(sagedges); i++) {
+      edgeinfo& ei = sagedges[i];
+      // maxwei[ei.i] = max(maxwei[ei.i], ei.weight);
+      // maxwei[ei.j] = max(maxwei[ei.j], ei.weight);
+      // totwei[ei.i] += ei.weight;
+      // totwei[ei.j] += ei.weight;
+      } */
+    for(int i=0; i<isize(sagedges); i++) {
+      edgeinfo& ei = sagedges[i];
+      // (ei.weight >= maxwei[ei.i] / 5 || ei.weight >= maxwei[ei.j] / 5);
+
+      ei.weight2 = pow((double) ei.weight, (double) edgepower) * edgemul;
+      // LANG:: pow(ei.weight, .4) / 50;      
+      
+      // ei.weight2 = 0; int w = ei.weight; while(w) { w >>= 1; ei.weight2++; }      
+      /* if(totwei[ei.i] <= 0 || totwei[ei.j] <= 0) {
+        printf("BAD TOTWEI\n");
+        exit(1);
+        }
+      ei.weight2 = 3 * (
+        sqrt(ei.weight * 1. / totwei[ei.i]) * log(totwei[ei.i]) * log(totwei[ei.i]) +
+        sqrt(ei.weight * 1. / totwei[ei.j]) * log(totwei[ei.j]) * log(totwei[ei.j])); */
+      // printf("%f\n", ei.weight2);
+      addedge0(ei.i, ei.j, &ei);
+      }
+  
+    initSnake(N*2);
+    printf("numsnake = %d\n", numsnake);
+    if(numsnake < N) {
+      printf("Error: snake does not fit\n");
+      exit(1);
+      }
+    snakeid.resize(N);
+    for(int i=0; i<N; i++) snakeid[i] = -1;
+    organize();
+    disable_snake();
+
+    for(int i=0; i<N; i++) {
+      int ii = i;
+      vertexdata& vd = vdata[ii];
+      vd.cp = colorpair(dftcolor);
+      createViz(ii, sag::snakecells[sag::snakeid[i]], Id);
+      }
+
+    storeall();
+    }
+
+int readArgs() {
+#if CAP_COMMANDLINE
+  using namespace arg;
+
+  if(0) ;
+
+  else if(argis("-sagmin")) {
+    shift_arg_formula(default_edgetype.visible_from);
+    default_edgetype.visible_from_hi = default_edgetype.visible_from;
+    default_edgetype.visible_from_help = default_edgetype.visible_from;    
+    }
+  else if(argis("-sagminhi")) {
+    shift_arg_formula(default_edgetype.visible_from_hi);
+    }
+  else if(argis("-sagminhelp")) {
+    shift_arg_formula(default_edgetype.visible_from_help);
+    }
+
+// (1) configure edge weights
+  else if(argis("-edgepower")) {
+    shift_arg_formula(sag::edgepower);
+    shift_arg_formula(sag::edgemul);
+    }
+// (1) configure temperature (high, low)
+  else if(argis("-sagtemp")) {
+    shift(); sag::hightemp = argi();
+    shift(); sag::lowtemp = argi();
+    }
+// (2) read the edge data
+  else if(argis("-sagpar")) {
+    PHASE(3);
+    shift();
+    sag::sagpar = argi();
+    }
+  else if(argis("-sag")) {
+    PHASE(3); 
+    shift(); sag::read(args());
+    }
+// (3) load the initial positioning
+  else if(argis("-gload")) {
+    PHASE(3); shift(); sag::loadsnake(args());
+    }
+// (4) perform simulated annealing: -fullsa <time in seconds>
+  else if(argis("-fullsa")) {
+    shift(); sag::dofullsa(argi());
+    }
+// (5) save the positioning
+  else if(argis("-gsave")) {
+    PHASE(3); shift(); sag::savesnake(args());
+    }
+// (6) output loglikelihood
+  else if(argis("-lik")) {
+    sag::loglik();
+    }
+  else return 1;
+#endif
+  return 0;
+  }
+
+bool turn(int delta) {
+  if(!on) return false;
+  if(kind == kSAG) sag::iterate(), timetowait = 0;
+  return false;
+  // shmup::pc[0]->rebase();
+  }
+
+int ah = addHook(hooks_args, 100, readArgs)
+  + addHook(shmup::hooks_turn, 100, turn)
+  + addHook(rogueviz::hooks_close, 100, [] { sag::sagedges.clear(); })
+  + addHook(rogueviz::hooks_rvmenu, 100, [] { 
+    if(kind != kSAG) return;
+    dialog::addSelItem(XLAT("temperature"), fts(sag::temperature), 't');
+    dialog::add_action([] {
+      dialog::editNumber(sag::temperature, sag::lowtemp, sag::hightemp, 1, 0, XLAT("temperature"), "");
+      });
+    dialog::addSelItem(XLAT("SAG mode"), sag::sagmodes[sag::sagmode], 'm'); 
+    dialog::add_action([] { sag::sagmode = sag::eSagmode( (1+sag::sagmode) % 3 ); });
+    })
+  + addHook(rvtour::hooks_build_rvtour, 100, [] (vector<tour::slide>& v) {
+    using namespace rvtour;
+    v.push_back(
+      slide{"Roguelikes", 63, LEGAL::UNLIMITED | QUICKGEO,
+        "A visualization of roguelikes, based on discussion on /r/reddit. "
+        "See: http://www.roguetemple.com/z/hyper/reddit.php",
+        roguevizslide('0', [] () {
+          rogueviz::dftcolor = 0x282828FF;
+    
+          rogueviz::showlabels = true;
+          part(rogueviz::default_edgetype.color, 0) = 181;
+          rogueviz::sag::edgepower = 1;
+          rogueviz::sag::edgemul = 1;
+          
+          rogueviz::on = true;
+          gmatrix.clear();
+          drawthemap();
+          gmatrix0 = gmatrix;
+    
+          rogueviz::sag::read(RVPATH "roguelikes/edges.csv");
+          rogueviz::readcolor(RVPATH "roguelikes/color.csv");
+          rogueviz::sag::loadsnake(RVPATH "roguelikes/" + cname());
+          })    
+        }
+      );
+    v.push_back(slide  {"Programming languages of GitHub", 64, LEGAL::UNLIMITED | QUICKGEO,
+    "A visualization of programming languages.",
+    roguevizslide('0', [] () {
+      rogueviz::dftcolor = 0x282828FF;
+
+      rogueviz::showlabels = true;
+      part(rogueviz::default_edgetype.color, 0) = 128;
+      rogueviz::sag::edgepower = .4;
+      rogueviz::sag::edgemul = .02;
+      
+      rogueviz::on = true;
+      gmatrix.clear();
+      drawthemap();
+      gmatrix0 = gmatrix;
+
+      rogueviz::sag::read(RVPATH "lang/edges.csv");
+      rogueviz::readcolor(RVPATH "lang/color.csv");
+      rogueviz::sag::loadsnake(RVPATH "lang/" + cname());
+      if(euclid) rogueviz::legend.clear();
+      })
+    });
+    
+    v.push_back(slide {"Boardgames", 62, LEGAL::UNLIMITED | QUICKGEO,
+        "A visualization of board games, based on discussions on Reddit.",
+    roguevizslide('0', [] () {
+      rogueviz::dftcolor = 0x282828FF;
+
+      rogueviz::showlabels = true;
+      part(rogueviz::default_edgetype.color, 0) = 157;
+      rogueviz::sag::edgepower = 1;
+      rogueviz::sag::edgemul = 1;
+      
+      rogueviz::on = true;
+      gmatrix.clear();
+      drawthemap();
+      gmatrix0 = gmatrix;
+
+      rogueviz::sag::read(RVPATH "boardgames/edges.csv");
+      rogueviz::readcolor(RVPATH "boardgames/color.csv");
+      rogueviz::sag::loadsnake(RVPATH "boardgames/" + cname());
+      })
+        });
+
+    });
+
+EX }
+
+}
diff --git a/rogueviz/tree.cpp b/rogueviz/tree.cpp
new file mode 100644
index 00000000..215229c3
--- /dev/null
+++ b/rogueviz/tree.cpp
@@ -0,0 +1,126 @@
+#include "../hyper.h"
+#include "rogueviz.h"
+
+// hyper -tol <filename.xml> -- visualize the tree of life,
+//   based on a XML dump from https://tree.opentreeoflife.org/
+
+namespace rogueviz {
+
+namespace tree {
+
+  edgetype *tree_edge;
+
+  struct treevertex {
+    int origid;
+    int parent;
+    int depth;
+    int spos, epos;
+    vector<int> children;
+    };
+  
+  vector<treevertex> tol;
+  
+  void child(int pid, int id) {
+    if(isize(tol) <= id) tol.resize(id+1);
+    
+    treevertex& v = tol[id];
+    v.parent = pid;
+    tol.push_back(v);
+    if(pid >= 0) tol[pid].children.push_back(id);
+    }
+
+  void readnode(FILE *f, int pid) {
+    string lab = "";
+    while(true) {
+      int c = fgetc(f);
+      if(c == EOF) { fprintf(stderr, "Ended prematurely\n"); exit(1); }
+      if(c == ',') break;
+      if(c == ')') { int id = getnewid(lab); child(pid, id); return; }
+      lab += c;
+      }
+    int id = getnewid(lab);
+    child(pid, id);
+    while(true) {
+      int c = fgetc(f);
+//      printf("c=%c at %d/%d\n", c, pid, id);
+      if(c == EOF) { fprintf(stderr, "Ended prematurely\n"); exit(1); }
+      if(c == ' ' || c == 10 || c == 13 || c == 9 || c == ',') continue;
+      else if(c == '(') readnode(f, id);
+      else if(c == ')') break;
+      }
+    }
+  
+  int xpos;
+  void spos(int at, int d) {
+    tol[at].spos = xpos++;
+    tol[at].depth = d;
+    for(int i=0; i<isize(tol[at].children); i++)
+      spos(tol[at].children[i], d+1);
+    tol[at].epos = ++xpos;
+    }
+    
+  void read(string fn) {
+    fname = fn;
+    init(); kind = kTree;
+    tree_edge = add_edgetype("tree edge");
+    printf("Reading the tree of life...\n");
+    FILE *f = fopen(fname.c_str(), "rt");
+    if(!f) { printf("Failed to open tree file: %s\n", fname.c_str()); exit(1); }
+    if(fgetc(f) != '(') {
+      printf("Error: bad format\n");
+      exit(1);
+      }
+    readnode(f, -1);
+    fclose(f);
+    int N = isize(vdata);
+    printf("N = %d\n", N);
+    printf("Assigning spos/epos...\n");
+    spos(0, 0);
+    xpos *= 6;
+    printf("Creating vertices...\n");
+    for(int i=0; i<N; i++) {
+      treevertex& lv = tol[i];
+      vertexdata& vd = vdata[i];
+    
+      transmatrix h = spin((lv.spos + lv.epos) * M_PI / xpos) * xpush(-1.2 + (log(xpos) - log(lv.epos - lv.spos)));
+
+      vd.special = false;
+      vd.m = new shmup::monster;
+      vd.m->pid = i;
+      vd.data = lv.parent;
+      createViz(i, cwt.at, h);
+      vd.cp = dftcolor; 
+      
+      if(tol[i].parent >= 0) 
+        addedge(i, tol[i].parent, 1, true, tree_edge);
+      }
+    
+    for(int i=0; i<isize(vdata); i++) {
+      vertexdata& vd = vdata[i];
+      virtualRebase(vd.m);
+      }
+    
+    printf("Clearing the TOL data...\n");
+    tol.clear();
+    storeall();
+    }
+
+#if CAP_COMMANDLINE
+int readArgs() {
+  using namespace arg;
+
+  if(0) ;
+
+  else if(argis("-tol")) {
+    PHASE(3); shift(); tree::read(args());
+    }
+  
+  else return 1;
+  return 0;
+  }
+
+int ah = addHook(hooks_args, 100, readArgs);
+#endif
+  }
+
+}