Fix compilation with latest cmake

.gitmodules

@@ -3,4 +3,4 @@
 	url = https://github.com/madler/zlib
 [submodule "thirdparty/SDL2"]
 	path = thirdparty/SDL2
-	url = https://github.com/spurious/SDL-mirror.git
+	url = https://github.com/libsdl-org/SDL

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.8.7)
+cmake_minimum_required(VERSION 4.0)
 if(CMAKE_MAJOR_VERSION STRGREATER 3)
 	cmake_policy(SET CMP0054 NEW)
 endif()

CMakeModules/FindOrBuild.cmake

@@ -30,16 +30,25 @@ macro(FindOrBuildSDL2)
             set(SDL_AUDIO FALSE)
             set(SDL_JOYSTICK FALSE)
             set(SDL_HAPTIC FALSE)
-            set(SDL_SHARED FALSE)
+            # Forcing static build on Windows as SDL2main is often needed and easier to link statically.
+            # Set SDL_SHARED to OFF *before* adding the subdirectory to influence its build.
+            set(SDL_SHARED OFF CACHE BOOL "Build SDL2 as a static library" FORCE)
         endif()
-        add_subdirectory(${CMAKE_SOURCE_DIR}/thirdparty/SDL2)
+        # Add the subdirectory. This creates targets like SDL2::SDL2, SDL2::SDL2-static, SDL2::SDL2main
+        add_subdirectory(${CMAKE_SOURCE_DIR}/thirdparty/SDL2 ${CMAKE_BINARY_DIR}/thirdparty/SDL2)
         set(SDL2_INCLUDE_DIR ${CMAKE_SOURCE_DIR}/thirdparty/SDL2/include ${CMAKE_BINARY_DIR}/thirdparty/SDL2)
+        # Linking against SDL2::SDL2 below handles includes automatically.
         if(EMSCRIPTEN)
-            set(SDL2_LIBRARY SDL2-static)
+            # Emscripten typically uses static linking
+            set(SDL2_LIBRARY SDL2::SDL2-static) # Use the CMake target
         else()
-            set(SDL2_LIBRARY SDL2)
+            # Link against SDL2 (shared or static based on SDL_SHARED) and SDL2main
+            # SDL2::SDL2 resolves to the correct shared/static target.
+            # SDL2::SDL2main is needed on many platforms, especially Windows.
+            set(SDL2_LIBRARY SDL2::SDL2 SDL2::SDL2main) # Use the CMake targets
         endif()
     elseif(NOT EMSCRIPTEN)
+        # If not building from source, use the find_package module
         find_package(SDL2)
     endif()
 endmacro()
@@ -228,4 +237,3 @@ endmacro()
 macro(FindOrBuildPSPSDK)
     find_package(PSPSDK COMPONENTS psppower pspmpeg pspaudiocodec pspaudiolib pspaudio pspmp3 pspgum pspgu psprtc pspfpu REQUIRED)
 endmacro()
-

thirdparty/libpng/png.h

@@ -474,7 +474,7 @@
 
 #ifndef PNG_VERSION_INFO_ONLY
 /* include the compression library's header */
-#include "../include/zlib.h"
+#include "zlib.h"
 #endif
 
 /* include all user configurable info, including optional assembler routines */