improved hemisphere model; nicer handling of ballangle

basegraph.cpp

@@ -255,7 +255,7 @@ void stereo::set_viewport(int ed) {
   }    
 
 bool model_needs_depth() {
-  return pmodel == mdBall || pmodel == mdHemisphere;
+  return pmodel == mdBall;
   }
 
 void setGLProjection(color_t col) {

conformal.cpp

@@ -296,6 +296,7 @@ namespace conformal {
   int do_rotate = 1;
   ld model_orientation, halfplane_scale;
   ld ocos, osin;
+  ld cos_ball, sin_ball;
   bool model_straight;
   ld top_z = 5;
 
@@ -413,6 +414,8 @@ namespace conformal {
     }
 
   void configure() {
+    ld ball = -vid.ballangle * M_PI / 180;
+    cos_ball = cos(ball), sin_ball = sin(ball);
     ocos = cos(model_orientation * M_PI / 180);
     osin = sin(model_orientation * M_PI / 180);
     model_straight = (ocos > 1 - 1e-9);

graph.cpp

@@ -5572,8 +5572,8 @@ void drawfullmap() {
     ld z = acosh(tz);
 
     hyperpoint a = xpush0(z);
-    ld ball = -vid.ballangle * M_PI / 180;
-    ld cb = cos(ball), sb = sin(ball);
+    ld cb = conformal::cos_ball;
+    ld sb = conformal::sin_ball;
     
     a[1] = sb * a[2] / -cb;
     a[0] = sqrt(-1 + a[2] * a[2] - a[1] * a[1]);

hyper.h

@@ -1279,6 +1279,7 @@ namespace conformal {
   extern ld model_orientation;
   extern ld halfplane_scale;
   extern ld ocos, osin;
+  extern ld cos_ball, sin_ball;
   extern bool model_straight;
   extern ld top_z;
   
@@ -1286,6 +1287,8 @@ namespace conformal {
   // logical coordinates back to screen coordinates: apply_orientation(y,x)
   template<class A>
   void apply_orientation(A& x, A& y) { if(!model_straight) tie(x,y) = make_pair(x*ocos + y*osin, y*ocos - x*osin); }
+  template<class A>
+  void apply_ball(A& x, A& y) { tie(x,y) = make_pair(x*cos_ball + y*sin_ball, y*cos_ball - x*sin_ball); }
   
   void configure();
   

hypgraph.cpp

@@ -78,14 +78,14 @@ void ballmodel(hyperpoint& ret, double alpha, double d, double zl) {
   ld tzh = vid.ballproj + H[2];
   ld ax = H[0] / tzh;
   ld ay = H[1] / tzh;
-  ld ball = vid.ballangle * M_PI / 180;
   
   ld ca = cos(alpha), sa = sin(alpha);
-  ld cb = cos(ball), sb = sin(ball);
-  
+
   ret[0] = ax * ca;
-  ret[1] = ay * cb + ax * sa * sb;
-  ret[2] = ax * sa * cb - ay * sb;
+  ret[1] = ay;
+  ret[2] = ax * sa;
+  
+  conformal::apply_ball(ret[2], ret[1]);
   }
 
 void apply_depth(hyperpoint &f, ld z) {
@@ -154,7 +154,6 @@ void applymodel(hyperpoint H, hyperpoint& ret) {
     }
   
   if(pmodel == mdHemisphere) {
-    ld ball = vid.ballangle * M_PI / 180;
     using namespace hyperpoint_vec;
     
     switch(cgclass) {
@@ -186,7 +185,9 @@ void applymodel(hyperpoint H, hyperpoint& ret) {
         }
       }
     
-    ret = rotmatrix(M_PI/2 + ball, 1, 2) * ret;
+    swap(ret[1], ret[2]);
+    
+    conformal::apply_ball(ret[2], ret[1]);
     
     ghcheck(ret, H);
     return;
@@ -198,13 +199,11 @@ void applymodel(hyperpoint H, hyperpoint& ret) {
     H[1] /= H[2];
     H[2] = 1 - vid.alpha;
 
-    ld ball = -vid.ballangle * M_PI / 180;
-    ld cb = cos(ball), sb = sin(ball);
-
     ret[0] = H[0] / 3;
-    ret[1] = (1 - H[2]) / 3 * cb - H[1] / 3 * sb;
-    ret[2] = -(-H[1] / 3 * cb - (1 - H[2]) / 3 * sb);
-
+    ret[1] = (1 - H[2]) / 3;
+    ret[2] = H[1] / 3;
+    
+    conformal::apply_ball(ret[2], ret[1]);
     ghcheck(ret,H);
     return;
     }
@@ -218,13 +217,11 @@ void applymodel(hyperpoint H, hyperpoint& ret) {
       H[2] = tz;
       }
 
-    ld ball = -vid.ballangle * M_PI / 180;
-    ld cb = cos(ball), sb = sin(ball);
-
     ret[0] = H[0] / 3;
-    ret[1] = (1 - H[2]) / 3 * cb - H[1] / 3 * sb;
-    ret[2] = -(-H[1] / 3 * cb - (1 - H[2]) / 3 * sb);
-
+    ret[1] = (1 - H[2]) / 3;
+    ret[2] = H[1] / 3;
+    
+    conformal::apply_ball(ret[2], ret[1]);
     ghcheck(ret,H);
     return;
     }

polygons.cpp

@@ -187,23 +187,29 @@ bool two_sided_model() {
   if(pmodel == mdHyperboloid) return !euclid;
   // if(pmodel == mdHemisphere) return true;
   if(pmodel == mdDisk) return sphere;
+  if(pmodel == mdHemisphere) return !euclid;
   return false;
   }
 
-bool correct_side(const hyperpoint& H) {
+int get_side(const hyperpoint& H) {
   if(pmodel == mdDisk && sphere) {
     double curnorm = H[0]*H[0]+H[1]*H[1]+H[2]*H[2];
     double horizon = curnorm / vid.alpha;
-    return (spherespecial>0) ^ (H[2] <= -horizon);
+    return (H[2] <= -horizon) ? -1 : 1;
+    ;
     }
-  if(pmodel == mdHyperboloid && hyperbolic) {
-    ld ball = -vid.ballangle * M_PI / 180;
-    ld cb = cos(ball), sb = sin(ball);
-    return (spherespecial > 0) ^ (
-      sb * H[2] > -cb * H[1]
-      );
+  if(pmodel == mdHyperboloid && hyperbolic)
+    return (conformal::sin_ball * H[2] > -conformal::cos_ball * H[1]) ? -1 : 1;
+  if(pmodel == mdHemisphere || pmodel == mdHyperboloid) {
+    hyperpoint res;
+    applymodel(H, res);
+    return res[2] < 0 ? -1 : 1;
     }
-  return true;
+  return 0;
+  }
+
+bool correct_side(const hyperpoint& H) {
+  return get_side(H) == spherespecial;
   }
 
 void fixpoint(array<float, 3>& hscr, hyperpoint H) {