fixed the errors caused by non_spatial_model giving incorrect results

config.cpp

@@ -3191,6 +3191,8 @@ EX void show3D() {
     }
   #endif
 
+  current_display->set_all(0, 0);
+
   if(0);
   #if CAP_RUG
   else if(rug::rugged && !rug::spatial_rug)

graph.cpp

@@ -1400,6 +1400,8 @@ EX void drawthemap() {
   mmhigh = vid.highlightmode >= 1;
   if(hiliteclick) mmhigh = !mmhigh;
 
+  current_display->set_all(0, 0); /* so that non_spatial_model works correctly */
+  
   spatial_graphics = wmspatial || mmspatial;
   spatial_graphics = spatial_graphics && GDIM == 2;
   #if CAP_RUG

hypgraph.cpp

@@ -29,6 +29,10 @@ EX void camrotate(ld& hx, ld& hy) {
   hx = p[0] / p[2], hy = p[1] / p[2];
   }
 
+/** Does the current model support 3D
+ *  Warning: since it depends on get_shader_flags(), you may need to current_display->set_all(0,0) for it to work correctly.
+ */
+
 EX bool non_spatial_model() {
   if(among(pmodel, mdRotatedHyperboles, mdJoukowsky, mdJoukowskyInverted, mdPolygonal, mdPolynomial))
     return true;