models:: Collignon projection

config.cpp

@@ -439,6 +439,8 @@ EX void initConfig() {
   addsaver(vid.twopoint_param, "twopoint parameter", 1);
   addsaver(vid.stretch, "stretch", 1);
   addsaver(vid.binary_width, "binary-tiling-width", 1);
+  addsaver(vid.collignon_parameter, "collignon-parameter", 1);
+  addsaver(vid.collignon_reflected, "collignon-reflect", false);
 
   addsaver(vid.creature_scale, "3d-creaturescale", 1);
   addsaver(vid.height_width, "3d-heightwidth", 1.5);
@@ -2382,6 +2384,7 @@ EX unordered_map<string, ld&> params = {
   {"fade", shot::fade},
   {"mgrid", vid.multiplier_grid},
   {"mring", vid.multiplier_ring},
+  {"collignon", vid.collignon_parameter},
   #endif
   };
 

drawing.cpp

@@ -686,6 +686,11 @@ int mercator_coord;
 int mercator_loop_min = 0, mercator_loop_max = 0;
 ld mercator_period;
 
+auto pzero(ld t) {
+  if(abs(t) < 1e-6) return 2 * current_display->radius;
+  return t;
+  }
+
 ld period_at(ld y) {
   
   ld m = current_display->radius;
@@ -695,12 +700,14 @@ ld period_at(ld y) {
     case mdBand:
       return m * 4;
     case mdSinusoidal:
-      return m * 2 * cos(y * M_PI);
+      return pzero(m * 2 * cos(y * M_PI));
     case mdMollweide:
-      return (abs(y) > .5-1e-6) ? m * 2 : m * 2 * sqrt(1 - y*y*4);
-    case mdCollignon:
-//      return (y < -.499999) ? m*2 : m*(1+2*y);
-      return (abs(y) < 1e-6) ? m*2 : m*2*y; //  y = signed_sqrt(sin_auto(y) + whatever[0]);
+      return pzero(m * 2 * sqrt(1 - y*y*4));
+    case mdCollignon: {
+      if(vid.collignon_reflected && y > 0) y = -y;
+      y += signed_sqrt(vid.collignon_parameter);
+      return pzero(abs(m*y*2/1.2));
+      }
     default:
       return m * 2;
     }     

hypgraph.cpp

@@ -310,6 +310,8 @@ hyperpoint compute_hybrid(hyperpoint H, int rootid) {
   return ret;
   }
 
+EX ld signed_sqrt(ld x) { return x > 0 ? sqrt(x) : -sqrt(-x); };
+
 EX void applymodel(hyperpoint H, hyperpoint& ret) {
 
   hyperpoint H_orig = H;
@@ -682,23 +684,15 @@ EX void applymodel(hyperpoint H, hyperpoint& ret) {
       break;
 
     case mdCollignon: 
-      find_zlev(H); /* does not look nicely otherwise */
-      if(hyperbolic) H = ypush(-1) * H;
+      find_zlev(H);
       makeband(H, ret, [] (ld& x, ld& y) { 
-        auto signed_sqrt = [] (ld x) { return x > 0 ? sqrt(x) : -sqrt(-x); };
-/*
-        if(sphere) {
-          y = M_PI / 2 - y;
-          x = sin_auto(y/2) * x;
-          y = (sin_auto(y/2) - .5) * M_PI;
-          }
-        if(hyperbolic) {
-          ld mul = signed_sqrt(sinh(y) + 1); 
-          x *= mul;
-          y = mul + signed_sqrt(sinh(1) + 1);
-          }*/
-        y = signed_sqrt(sin_auto(y) + whatever[0]);
-        x *= y;
+        ld sgn = 1;
+        if(vid.collignon_reflected && y > 0) y = -y, sgn = -1;
+        y = signed_sqrt(sin_auto(y) + vid.collignon_parameter);
+        x *= y / 1.2;
+        y -= signed_sqrt(vid.collignon_parameter);
+        y *= sgn;
+        y *= M_PI;
         });
       break;
     

models.cpp

@@ -554,6 +554,18 @@ EX namespace models {
         });
       }
     
+    if(pmodel == mdCollignon) {
+      dialog::addSelItem(XLAT("parameter"), fts(vid.collignon_parameter) + (vid.collignon_reflected ? " (r)" : ""), 'b');
+      dialog::add_action([](){
+        dialog::editNumber(vid.collignon_parameter, -1, 1, .1, 1, XLAT("parameter"), 
+          ""
+          );
+        dialog::extra_options = [] {
+          dialog::addBoolItem_action(XLAT("reflect"), vid.collignon_reflected, 'R');
+          };
+        });
+      }
+    
     if(pmodel == mdSpiral && !euclid) {
       dialog::addSelItem(XLAT("spiral angle"), fts(spiral_angle) + "°", 'x');
       dialog::add_action([](){