show_hyperboloid_flat option

config.cpp

@@ -515,6 +515,7 @@ EX void initConfig() {
   addsaver(vid.binary_width, "binary-tiling-width", 1);
   addsaver(pconf.collignon_parameter, "collignon-parameter", 1);
   addsaver(pconf.collignon_reflected, "collignon-reflect", false);
+  addsaver(pconf.show_hyperboloid_flat, "hyperboloid-flat", true);
 
   addsaver(pconf.aitoff_parameter, "aitoff-parameter");
   addsaver(pconf.miller_parameter, "miller-parameter");

drawing.cpp

@@ -2164,7 +2164,7 @@ EX void reverse_side_priorities() {
 // on the sphere, parts on the back are drawn first
 EX void draw_backside() {
   DEBBI(DF_GRAPH, ("draw_backside"));
-  if(pmodel == mdHyperboloid && hyperbolic) {
+  if(pmodel == mdHyperboloid && hyperbolic && pconf.show_hyperboloid_flat) {
     dynamicval<eModel> dv (pmodel, mdHyperboloidFlat);
     for(auto& ptd: ptds) 
       if(!among(ptd->prio, PPR::MOBILE_ARROW, PPR::OUTCIRCLE, PPR::CIRCLE))

hyper.h

@@ -242,6 +242,7 @@ struct projection_configuration {
   ld model_orientation, halfplane_scale, model_orientation_yz;  
   ld collignon_parameter; 
   ld aitoff_parameter, miller_parameter, loximuthal_parameter, winkel_parameter;
+  bool show_hyperboloid_flat;
   bool collignon_reflected;
   string formula;
   eModel basic_model;
@@ -272,6 +273,7 @@ struct projection_configuration {
     miller_parameter = .8;
     loximuthal_parameter = 0;
     winkel_parameter = .5;
+    show_hyperboloid_flat = true;
     }
   };
 

hypgraph.cpp

@@ -2000,6 +2000,7 @@ EX void draw_model_elements() {
       }
     
     case mdHyperboloid: {
+      if(!pconf.show_hyperboloid_flat) return;
       if(hyperbolic) {
 #if CAP_QUEUE
         curvepoint(point3(0,0,1));

models.cpp

@@ -445,6 +445,8 @@ EX namespace models {
       }
     
     if(among(vpmodel, mdDisk, mdBall, mdHyperboloid, mdRotatedHyperboles, mdPanini)) {
+      dynamicval<eModel> v(vpconf.model, vpconf.model);
+      if(vpmodel == mdHyperboloid) vpconf.model = mdDisk;
       dialog::addSelItem(XLAT("projection distance"), fts(vpconf.alpha) + " (" + current_proj_name() + ")", 'p');
       dialog::add_action(projectionDialog);
       }
@@ -615,6 +617,10 @@ EX namespace models {
         dialog::scaleLog();
         });
       }
+
+    if(vpmodel == mdHyperboloid) {
+      dialog::addBoolItem_action(XLAT("show flat"), pconf.show_hyperboloid_flat, 'b');
+      }
     
     if(vpmodel == mdCollignon) {
       dialog::addSelItem(XLAT("parameter"), fts(vpconf.collignon_parameter) + (vpconf.collignon_reflected ? " (r)" : ""), 'b');