Fix Windows build: undef TWOPI/HALFPI in GuiHandler.cpp

Reverts the NOGDI approach (broke vfw.h for AVI capture) in favor of
a targeted fix: undef the wingdi.h TWOPI/HALFPI macros directly in
GuiHandler.cpp after the SDL includes. This is the only file where
SDL's transitive windows.h include causes math::TWOPI to be
macro-expanded.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: MarkKropf

CMakeLists.txt

@@ -431,14 +431,6 @@ if(REPORT_LUANAN)
         add_definitions(-DREPORT_LUANAN)
 endif()
 
-### MinGW wingdi.h macro suppression
-# wingdi.h defines TWOPI/HALFPI macros that conflict with math:: namespace
-# constants. NOGDI suppresses wingdi.h while keeping GDI handle types
-# (HDC, HWND etc.) available from windef.h.
-if(MINGW)
-	add_definitions(-DNOGDI)
-endif()
-
 ### streflop
 option(ENABLE_STREFLOP "build Spring with streflop support (REQUIRED FOR MULTIPLAYER)" TRUE)
 

rts/Game/UI/GuiHandler.cpp

@@ -71,6 +71,15 @@
 
 #include "System/Misc/TracyDefs.h"
 
+// MinGW wingdi.h defines TWOPI/HALFPI macros via transitive windows.h
+// includes from SDL headers. Must undef before code uses math::TWOPI.
+#ifdef TWOPI
+#undef TWOPI
+#endif
+#ifdef HALFPI
+#undef HALFPI
+#endif
+
 CONFIG(bool, MiniMapMarker).defaultValue(true).headlessValue(false);
 CONFIG(bool, InvertQueueKey).defaultValue(false);
 

rts/Rendering/AVIGenerator.h

@@ -9,7 +9,6 @@
 #include "System/Misc/NonCopyable.h"
 
 #include <windows.h>
-#include <wingdi.h> // Explicitly include for LPBITMAPINFOHEADER (skipped by NOGDI)
 #include <vfw.h>
 
 #include <string>