Graphics not correctly produced when saving to PDF in Version 12

Question

12.0.0 for Microsoft Windows (64-bit) (April 6, 2019)

How do I get my graphic to look the same in PDF as it does in a Notebook?

This is what the graphic looks like in the FrontEnd:

This is how the same image appears in a PDF file:

This is the code producing the graphics.

    Module[{arc, \[GothicC]a, \[GothicC]b, \[GothicC]c, \
\[ScriptCapitalC]a, \[ScriptCapitalC]b, \[ScriptCapitalC]c, \[Theta]a \
= 2/3 \[Pi], \[Theta]b = 4/3 \[Pi], \[Theta]c = 0
  , \[CapitalTheta], \[CapitalDelta]\[CapitalTheta]
  , \[CapitalDelta]\[Theta]1 = \[Pi], \[CapitalDelta]\[Theta]2 = \
\[Pi]/3, \[GothicCapitalR]}
 , \[GothicC]a = {0, 0}; \[GothicC]b = {1, 
   0}; \[GothicC]c = \[GothicC]b/
   2 + {0, 1} Sqrt[3]/
    2; \[GothicCapitalR][\[Theta]_] := {Cos[\[Theta]], Sin[\[Theta]]};
 arc[\[GothicC]_, \[Theta]_, \[CapitalDelta]\[Theta]_] := (\[GothicC] \
+ \[GothicCapitalR][#]) & /@ 
   Range[\[Theta], \[Theta] + \[CapitalDelta]\[Theta], \
\[CapitalDelta]\[Theta]/180];
 \[CapitalDelta]\[CapitalTheta] = {0, \[Pi], 4/3 \[Pi], 5/3 \[Pi]};
 \[CapitalTheta][\[Theta]_, 
   i_] := \[Theta] + \[CapitalDelta]\[CapitalTheta][[i]];
 
 \[ScriptCapitalC]a = {arc[\[GothicC]a, \[CapitalTheta][\[Theta]a, 
     1], \[CapitalDelta]\[Theta]1], 
   arc[\[GothicC]a, \[CapitalTheta][\[Theta]a, 
     2], \[CapitalDelta]\[Theta]2], 
   arc[\[GothicC]a, \[CapitalTheta][\[Theta]a, 
     3], \[CapitalDelta]\[Theta]2], 
   arc[\[GothicC]a, \[CapitalTheta][\[Theta]a, 
     4], \[CapitalDelta]\[Theta]2]};
 \[ScriptCapitalC]b = {arc[\[GothicC]b, \[CapitalTheta][\[Theta]b, 
     1], \[CapitalDelta]\[Theta]1], 
   arc[\[GothicC]b, \[CapitalTheta][\[Theta]b, 
     2], \[CapitalDelta]\[Theta]2], 
   arc[\[GothicC]b, \[CapitalTheta][\[Theta]b, 
     3], \[CapitalDelta]\[Theta]2], 
   arc[\[GothicC]b, \[CapitalTheta][\[Theta]b, 
     4], \[CapitalDelta]\[Theta]2]};
 \[ScriptCapitalC]c = {arc[\[GothicC]c, \[CapitalTheta][\[Theta]c, 
     1], \[CapitalDelta]\[Theta]1], 
   arc[\[GothicC]c, \[CapitalTheta][\[Theta]c, 
     2], \[CapitalDelta]\[Theta]2], 
   arc[\[GothicC]c, \[CapitalTheta][\[Theta]c, 
     3], \[CapitalDelta]\[Theta]2], 
   arc[\[GothicC]c, \[CapitalTheta][\[Theta]c, 
     4], \[CapitalDelta]\[Theta]2]};
 
 Graphics[{Thickness[0.02], 
   Point[{\[GothicC]a, \[GothicC]b, \[GothicC]c}]
   , {Red, Line[\[ScriptCapitalC]a[[1]]], 
    Point[\[GothicC]a + \[GothicCapitalR][\[CapitalTheta][\[Theta]a, 
        1]]]}
   , {Blue, Line[\[ScriptCapitalC]a[[2]]]}
   , {Green, Line[\[ScriptCapitalC]a[[3]]]}
   , {Magenta, Line[\[ScriptCapitalC]a[[4]]]}
   , {Red, Line[\[ScriptCapitalC]b[[1]]]}
   , {Blue, Line[\[ScriptCapitalC]b[[2]]]}
   , {Green, Line[\[ScriptCapitalC]b[[3]]]}
   , {Magenta, Line[\[ScriptCapitalC]b[[4]]]}
   , {Red, Line[\[ScriptCapitalC]c[[1]]]}
   , {Blue, Line[\[ScriptCapitalC]c[[2]]]}
   , {Green, Line[\[ScriptCapitalC]c[[3]]]}
   , {Magenta, Line[\[ScriptCapitalC]c[[4]]]}
   , {Blue
    , Polygon[
     Join[\[ScriptCapitalC]a[[1]], \[ScriptCapitalC]b[[
       4]], \[ScriptCapitalC]c[[2]]]]
    , Polygon[
     Join[\[ScriptCapitalC]b[[1]], \[ScriptCapitalC]c[[
       4]], \[ScriptCapitalC]a[[2]]]]
    , Polygon[
     Join[\[ScriptCapitalC]c[[1]], \[ScriptCapitalC]a[[
       4]], \[ScriptCapitalC]b[[2]]]]
    , Polygon[
     Join[\[ScriptCapitalC]c[[3]], \[ScriptCapitalC]a[[
       3]], \[ScriptCapitalC]b[[3]]]]
    }
   }]
 ]

Answer 1

It seems like there are two main problems.

One is the shape of the polygons

test = Graphics@Polygon[Join[\[ScriptCapitalC]a[[1]], \[ScriptCapitalC]b[[4]], \
\[ScriptCapitalC]c[[2]]]]

Gives this in the PDF:

Plotting the points gives a clue to why:

ListPlot[Join[\[ScriptCapitalC]a[[1]], \[ScriptCapitalC]b[[4]], \
\[ScriptCapitalC]c[[2]]], Joined -> True, AspectRatio -> Automatic]

Changing the order of some points helps:

ListPlot[Join[\[ScriptCapitalC]a[[1]], 
  Reverse@\[ScriptCapitalC]b[[4]], Reverse@\[ScriptCapitalC]c[[2]]], 
 Joined -> True, AspectRatio -> Automatic]

And

test2 = Graphics@Polygon[Join[\[ScriptCapitalC]a[[1]], 
    Reverse@\[ScriptCapitalC]b[[4]], Reverse@\[ScriptCapitalC]c[[2]]]]

Gives the expected PDF:

The other main problem is that the lines are hidden. This can be fixed by drawing the lines after the polygons.

Using both of these workarounds:

Graphics[{
  {Blue, Polygon[
    Join[\[ScriptCapitalC]a[[1]], Reverse@\[ScriptCapitalC]b[[4]], Reverse@\[ScriptCapitalC]c[[2]]]], Polygon[Join[\[ScriptCapitalC]b[[1]], Reverse@\[ScriptCapitalC]c[[4]], Reverse@\[ScriptCapitalC]a[[2]]]], 
   Polygon[Join[\[ScriptCapitalC]c[[1]], Reverse@\[ScriptCapitalC]a[[4]], Reverse@\[ScriptCapitalC]b[[2]]]], Polygon[Join[\[ScriptCapitalC]c[[3]], \[ScriptCapitalC]a[[3]], \
\[ScriptCapitalC]b[[3]]]]},
  Thickness[0.01], Point[{\[GothicC]a, \[GothicC]b, \[GothicC]c}], {Red, Line[\[ScriptCapitalC]a[[1]]], Point[\[GothicC]a + \[GothicCapitalR][\[CapitalTheta][\[Theta]a, 
       1]]]}, {Blue, Line[\[ScriptCapitalC]a[[2]]]}, {Green, Line[\[ScriptCapitalC]a[[3]]]}, {Magenta, Line[\[ScriptCapitalC]a[[4]]]}, {Red, Line[\[ScriptCapitalC]b[[1]]]}, {Blue, Line[\[ScriptCapitalC]b[[2]]]}, {Green, Line[\[ScriptCapitalC]b[[3]]]}, {Magenta, Line[\[ScriptCapitalC]b[[4]]]}, {Red, Line[\[ScriptCapitalC]c[[1]]]}, {Blue, Line[\[ScriptCapitalC]c[[2]]]}, {Green, Line[\[ScriptCapitalC]c[[3]]]}, {Magenta, Line[\[ScriptCapitalC]c[[4]]]}
  }]

Gives PDF: