stereographic projection added

config.cpp

@@ -1027,6 +1027,7 @@ EX void initConfig() {
   param_f(camera_rot_speed, "camrot", "camera-rot-speed", 1);
 
   param_f(panini_alpha, "panini_alpha", 0);
+  param_f(stereo_alpha, "stereo_alpha", 0);
 
   callhooks(hooks_configfile);
   
@@ -1863,14 +1864,15 @@ EX void explain_detail() {
   }
 
 EX ld max_fov_angle() {
-  if(panini_alpha >= 1 || panini_alpha <= -1) return 360;
+  auto& p = panini_alpha ? panini_alpha : stereo_alpha;
-  return acos(-panini_alpha) * 2 / degree;
+  if(p >= 1 || p <= -1) return 360;
+  return acos(-p) * 2 / degree;
   }
 
 EX void add_edit_fov(char key IS('f'), bool pop IS(false)) {
 
   string sfov = fts(vid.fov) + "°";
-  if(panini_alpha) {
+  if(panini_alpha || stereo_alpha) {
     sfov += " / " + fts(max_fov_angle()) + "°";
     }
   dialog::addSelItem(XLAT("field of view"), sfov, key);
@@ -1897,7 +1899,22 @@ EX void add_edit_fov(char key IS('f'), bool pop IS(false)) {
             "The Panini projection is an alternative perspective projection "
             "which allows very wide field-of-view values. HyperRogue uses "
             "a quick implementation, so parameter values too close to 1 may "
-            "be buggy; try e.g. 0.9 instead.")
+            "be buggy (outside of raycasting); try e.g. 0.9 instead.")
+            );
+        dialog::reaction = reset_all_shaders;
+        dialog::extra_options = [] {
+          add_edit_fov('F', true);
+          };
+        });
+      dialog::addSelItem(XLAT("spherical perspective projection"), fts(stereo_alpha), 'S');
+      dialog::add_action([] {
+        popScreen();
+        dialog::editNumber(stereo_alpha, 0, 1, 0.1, 0, "spherical perspective parameter", 
+          XLAT(
+            "Set to 1 to get stereographic projection, "
+            "which allows very wide field-of-view values. HyperRogue uses "
+            "a quick implementation, so parameter values too close to 1 may "
+            "be buggy (outside of raycasting); try e.g. 0.9 instead.")
             );
         dialog::reaction = reset_all_shaders;
         dialog::extra_options = [] {

graph.cpp

@@ -23,6 +23,7 @@ EX bool wmspatial, wmescher, wmplain, wmblack, wmascii, wmascii3;
 EX bool mmspatial, mmhigh, mmmon, mmitem;
 
 EX ld panini_alpha = 0;
+EX ld stereo_alpha = 0;
 
 EX int detaillevel = 0;
 
@@ -3742,7 +3743,7 @@ EX bool clip_checked = false;
 void make_clipping_planes() {
 #if MAXMDIM >= 4
   clip_checked = false;
-  if(!frustum_culling || PIU(sphere) || experimental || vid.stereo_mode == sODS || panini_alpha) return;
+  if(!frustum_culling || PIU(sphere) || experimental || vid.stereo_mode == sODS || panini_alpha || stereo_alpha) return;
 
   if(WDIM == 3 && pmodel == mdPerspective && !nonisotropic && !in_s2xe())
     threshold = sin_auto(cgi.corner_bonus), xyz_threshold = 0, clip_checked = true;
@@ -4980,7 +4981,7 @@ EX void calcparam() {
   cd->ycenter += cd->scrsize * pconf.yposition;
   
   ld fov = vid.fov * degree / 2;
-  cd->tanfov = sin(fov) / (cos(fov) + panini_alpha);
+  cd->tanfov = sin(fov) / (cos(fov) + (panini_alpha ? panini_alpha : stereo_alpha));
   
   callhooks(hooks_calcparam);
   reset_projection();

models.cpp

@@ -892,6 +892,10 @@ EX namespace models {
       PHASEFROM(2); 
       shift_arg_formula(panini_alpha, reset_all_shaders);
       }
+    else if(argis("-salpha")) { 
+      PHASEFROM(2); 
+      shift_arg_formula(stereo_alpha, reset_all_shaders);
+      }
     else if(argis("-zoom")) { 
       PHASEFROM(2); shift_arg_formula(vpconf.scale);
       }

raycaster.cpp

@@ -436,7 +436,23 @@ void enable_raycaster() {
           "at0.xyz *= hz+alpha;\n"
           "at0.z = hz;\n}"
           " else at0.z = 0.;\n"
-"\n"
+          "\n"
+          ;
+
+      else if(stereo_alpha) fmain += 
+          "mediump float hr = at0.x*at0.x+at0.y*at0.y;\n"
+          "mediump float alpha = " + to_glsl(stereo_alpha) + ";\n"
+          "mediump float A = 1. + hr;\n"
+          "mediump float B = -2.*hr*alpha;\n"
+          "mediump float C = 1. - hr*alpha*alpha;\n"
+          "B /= A; C /= A;\n"
+    
+          "mediump float hz = B / 2. + sqrt(C + B*B/4.);\n"
+          "if(abs(hz) > 1e-3) {"
+          "at0.xyz *= hz+alpha;\n"
+          "at0.z = hz;\n}"
+          " else at0.z = 0.;\n"
+          "\n"
           ;
 
       fmain +=
@@ -1241,6 +1257,9 @@ void enable_raycaster() {
     if(panini_alpha) 
       fmain += panini_shader();
 
+    else if(stereo_alpha) 
+      fmain += stereo_shader();
+
     #ifndef GLES_ONLY
     fmain +=    
       "      gl_FragDepth = (" + to_glsl(-vnear-vfar)+"+t.w*" + to_glsl(2*vnear*vfar)+"/t.z)/" + to_glsl(vnear-vfar)+";\n"

shaders.cpp

@@ -77,6 +77,17 @@ EX string panini_shader() {
     "t.w = 1.;\n";
   }
 
+EX string stereo_shader() {
+  return
+    "t.w += 1.; t *= 2. / t.w; t.w -= 1.;\n"
+    "float s = t.z;\n"
+    "float l = length(t.xyz);\n"
+    "t /= max(l, 1e-2);\n"
+    "t.z += " + glhr::to_glsl(panini_alpha) + ";\n"
+    "t *= l;\n"
+    "t.w = 1.;\n";
+  }
+
 shared_ptr<glhr::GLprogram> write_shader(flagtype shader_flags) {
   string varying, vsh, fsh, vmain = "void main() {\n", fmain = "void main() {\n";
 
@@ -415,6 +426,10 @@ shared_ptr<glhr::GLprogram> write_shader(flagtype shader_flags) {
       vmain += panini_shader();
       shader_flags |= SF_ORIENT;
       }
+    else if((shader_flags & SF_PERS3) && stereo_alpha) {
+      vmain += "t = uPP * t;", vsh += "uniform mediump mat4 uPP;";
+      vmain += stereo_shader();
+      }
       
     vmain += "gl_Position = uP * t;\n";
     }