hemisphere model

basegraph.cpp

@@ -299,7 +299,7 @@ void setGLProjection(int col) {
   //glLineWidth(1.0f);
   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
   
-  if(pmodel == mdBall || pmodel == mdHyperboloid) {
+  if(pmodel == mdBall || pmodel == mdHyperboloid || pmodel == mdHemisphere) {
 #ifdef GL_ES
     glClearDepthf(1.0f);
 #else

conformal.cpp

@@ -543,7 +543,7 @@ namespace conformal {
   const char *modelnames[MODELCOUNT] = {
     "disk", "half-plane", "band", "polygonal", "polynomial",
     "azimuthal equidistant", "azimuthal equi-area", 
-    "ball model", "hyperboloid"
+    "ball model", "hyperboloid", "hemisphere"
     };
   
   void show() {
@@ -561,13 +561,16 @@ namespace conformal {
       XLAT(
         pmodel == mdBand && sphere ? "Mercator" : 
         pmodel == mdHalfplane && euclid ? "inversion" : 
+        pmodel == mdHemisphere && !hyperbolic ? "sphere" :
+        pmodel == mdHyperboloid && euclid ? "plane" :
+        pmodel == mdHyperboloid && sphere ? "sphere" :
         modelnames[pmodel]), 'm');
     dialog::addSelItem(XLAT("rotation"), directions[pmodel][rotation&3], 'r');
     
     if(pmodel == mdBand && sphere)
       dialog::addSelItem(XLAT("scale factor"), fts(vid.scale), 'z');
 
-    if(abs(vid.alpha-1) > 1e-3 && pmodel != mdBall && pmodel != mdHyperboloid) {
+    if(abs(vid.alpha-1) > 1e-3 && pmodel != mdBall && pmodel != mdHyperboloid && pmodel != mdHemisphere) {
       dialog::addBreak(50);
       dialog::addInfo("NOTE: this works 'correctly' only if the Poincaré model/stereographic projection is used.");
       dialog::addBreak(50);
@@ -637,7 +640,7 @@ namespace conformal {
       switchagain: {
         pmodel = eModel((pmodel + (shiftmul > 0 ? 1 : -1) + MODELCOUNT) % MODELCOUNT);
         
-        if(!mdEqui() && pmodel != mdDisk && pmodel != mdPolynomial && pmodel != mdHyperboloid) {
+        if(!mdEqui() && pmodel != mdDisk && pmodel != mdPolynomial && pmodel != mdHyperboloid && pmodel != mdHemisphere) {
           if(sphere && pmodel != mdBand)
               goto switchagain;
           if(euclid && pmodel != mdHalfplane && pmodel != mdBall)

graph.cpp

@@ -452,7 +452,7 @@ void animallegs(const transmatrix& V, eMonster mo, int col, double footphase) {
 void ShadowV(const transmatrix& V, const hpcshape& bp, int prio) {
 #if CAP_POLY
   if(mmspatial) { 
-    if(pmodel == mdHyperboloid || pmodel == mdBall) 
+    if(pmodel == mdHyperboloid || pmodel == mdBall || pmodel == mdHemisphere) 
       return; // shadows break the depth testing
     dynamicval<int> p(poly_outline, OUTLINE_TRANS);
     queuepolyat(V, bp, SHADOW_MON, prio); 
@@ -3038,7 +3038,7 @@ bool noAdjacentChasms(cell *c) {
   }
 
 void floorShadow(cell *c, const transmatrix& V, int col, bool warp) {
-  if(pmodel == mdHyperboloid || pmodel == mdBall) 
+  if(pmodel == mdHyperboloid || pmodel == mdBall || pmodel == mdHemisphere) 
     return; // shadows break the depth testing
   if(shmup::on || nonbitrunc) warp = false;
   dynamicval<int> p(poly_outline, OUTLINE_TRANS);

hyper.h

@@ -1527,7 +1527,9 @@ void setcameraangle(bool b);
 
 enum eModel {
   mdDisk, mdHalfplane, mdBand, mdPolygonal, mdPolynomial,
-  mdEquidistant, mdEquiarea, mdBall, mdHyperboloid, mdGUARD, mdUnchanged };
+  mdEquidistant, mdEquiarea, mdBall, mdHyperboloid, 
+  mdHemisphere,
+  mdGUARD, mdUnchanged };
 
 #define MODELCOUNT ((int) mdGUARD)
 

hypgraph.cpp

@@ -123,6 +123,42 @@ void applymodel(hyperpoint H, hyperpoint& ret) {
     return;
     }
   
+  if(pmodel == mdHemisphere) {
+    ld ball = vid.ballangle * M_PI / 180;
+    using namespace hyperpoint_vec;
+    
+    switch(cgclass) {
+      case gcHyperbolic: {
+        ret = H / H[2];
+        ret[2] = sqrt(1 - sqhypot2(ret));
+        break;
+        }
+        
+      case gcEuclid: {
+        // stereographic projection to a sphere
+        auto hd = hdist0(H) / H[2];
+        if(hd == 0) H[2] = -1;
+        else {
+          ld x = 2 * hd / (1 + hd * hd);
+          ld y = x / hd;
+          H = H * x / (hd * H[2]);
+          H[2] = 1 - y;
+          }
+        break;
+        }
+      
+      case gcSphere: {
+        ret = H;
+        break;
+        }
+      }
+    
+    ret = rotmatrix(0, 2, ball) * ret;
+    
+    ghcheck(ret, H);
+    return;
+    }
+
   if(pmodel == mdHyperboloid) {
 
     ld ball = vid.ballangle * M_PI / 180;