fisheye has parameter

config.cpp

@@ -441,6 +441,7 @@ EX void initConfig() {
   addsaverenum(vid.stereo_mode, "stereo-mode");
   addsaver(vid.euclid_to_sphere, "euclid to sphere projection", 1.5);
   addsaver(vid.twopoint_param, "twopoint parameter", 1);
+  addsaver(vid.fisheye_param, "fisheye parameter", 1);
   addsaver(vid.stretch, "stretch", 1);
   addsaver(vid.binary_width, "binary-tiling-width", 1);
   addsaver(vid.collignon_parameter, "collignon-parameter", 1);
@@ -2438,6 +2439,7 @@ EX unordered_map<string, ld&> params = {
   {"ets", vid.euclid_to_sphere},
   {"stretch", vid.stretch},
   {"twopoint", vid.twopoint_param},
+  {"fisheye", vid.fisheye_param},
   {"bwidth", vid.binary_width},
   #if CAP_ANIMATIONS
   {"aperiod", anims::period},

hyper.h

@@ -228,7 +228,7 @@ enum eStereo { sOFF, sAnaglyph, sLR, sODS };
 
 struct videopar {
   ld scale, alpha, sspeed, mspeed, yshift, camera_angle;
-  ld ballangle, ballproj, euclid_to_sphere, twopoint_param, stretch, binary_width, fixed_facing_dir;
+  ld ballangle, ballproj, euclid_to_sphere, twopoint_param, fisheye_param, stretch, binary_width, fixed_facing_dir;
   int mobilecompasssize;
   int radarsize; // radar for 3D geometries
   ld radarrange;

hypgraph.cpp

@@ -497,6 +497,7 @@ EX void applymodel(hyperpoint H, hyperpoint& ret) {
     case mdFisheye: {
       ld zlev = find_zlev(H);
       H = space_to_perspective(H);
+      H /= vid.fisheye_param;
       H[LDIM] = zlev;
       ret = H / sqrt(1 + sqhypot_d(GDIM+1, H));
       if(GDIM == 3) ret[LDIM] = zlev;

models.cpp

@@ -560,6 +560,16 @@ EX namespace models {
         });
       }
     
+    if(pmodel == mdFisheye) {
+      dialog::addSelItem(XLAT("parameter"), fts(vid.fisheye_param), 'b');
+      dialog::add_action([](){
+        dialog::editNumber(vid.fisheye_param, 1e-3, 10, .1, 1, XLAT("parameter"), 
+          "Size of the fish eye."
+          );
+        dialog::scaleLog();
+        });
+      }
+    
     if(pmodel == mdCollignon) {
       dialog::addSelItem(XLAT("parameter"), fts(vid.collignon_parameter) + (vid.collignon_reflected ? " (r)" : ""), 'b');
       dialog::add_action([](){