Fixed the build for web using CMake. (#1452)

* Fixed the build for web using CMake.

I found that the build for me was failing and I added some if defined checks in the core.c file where the glfwSetWindowAttrib was used. (error: implicit declaration of function 'glfwSetWindowAttrib' is invalid in C99 [-Werror,-Wimplicit-function-declaration])

I also changed some values in the toolchain file so that it correctly uses the .bat files when on windows.

* Cleaned up the additional variables (they are not important)

* Added more improvements to cmakelists

Added the option to use the system provided Emscripten toolchain to be more uniform with other libraries.

Fixed and issue which prevented example being built from cmake and also building with html extensions properly.

* Fixed ENUM to STRING because of a missed warning

4 files changed, 39 insertions, 9 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c5f2fbd0..6b163526 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,6 +7,13 @@ option(ENABLE_ASAN  "Enable AddressSanitizer (ASAN) for debugging (degrades perf
 option(ENABLE_UBSAN "Enable UndefinedBehaviorSanitizer (UBSan) for debugging" OFF)
 option(ENABLE_MSAN "Enable MemorySanitizer (MSan) for debugging (not recommended to run with ASAN)" OFF)
 
+# This helps support the case where emsdk toolchain file is used
+# either by setting it with -DCMAKE_TOOLCHAIN_FILE=<path_to_emsdk>/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake
+# or by using "emcmake cmake -B build -S ." as described in https://emscripten.org/docs/compiling/Building-Projects.html
+if(EMSCRIPTEN)
+  SET(PLATFORM Web CACHE STRING "Forcing PLATFORM_WEB because EMSCRIPTEN was detected")
+endif()
+
 if(CMAKE_VERSION VERSION_LESS "3.1")
   if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
     set(CMAKE_C_FLAGS "-std=gnu99 ${CMAKE_C_FLAGS}")
diff --git a/cmake/emscripten.cmake b/cmake/emscripten.cmake
index 621ae787..1780dee9 100644
--- a/cmake/emscripten.cmake
+++ b/cmake/emscripten.cmake
@@ -1,12 +1,20 @@
 SET(CMAKE_SYSTEM_NAME Linux)
+SET(CMAKE_SYSTEM_PROCESSOR x86)
+
+if (CMAKE_HOST_WIN32)
+  SET(EMSCRIPTEN_EXTENSION ".bat")
+else ()
+  SET(EMSCRIPTEN_EXTENSION "")
+endif()
+
+SET(CMAKE_C_COMPILER   emcc${EMSCRIPTEN_EXTENSION})
+SET(CMAKE_CXX_COMPILER em++${EMSCRIPTEN_EXTENSION})
 
-SET(CMAKE_C_COMPILER   emcc)
-SET(CMAKE_CXX_COMPILER em++)
 if(NOT DEFINED CMAKE_AR)
-  find_program(CMAKE_AR NAMES emar)
+  find_program(CMAKE_AR NAMES emar${EMSCRIPTEN_EXTENSION})
 endif()
 if(NOT DEFINED CMAKE_RANLIB)
-  find_program(CMAKE_RANLIB NAMES emranlib)
+  find_program(CMAKE_RANLIB NAMES emranlib${EMSCRIPTEN_EXTENSION})
 endif()
 
 set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 08b97ea9..57ba74d4 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -28,7 +28,6 @@ if (APPLE AND NOT CMAKE_SYSTEM STRLESS "Darwin-18.0.0")
   add_definitions(-DGL_SILENCE_DEPRECATION)
   MESSAGE(AUTHOR_WARNING "OpenGL is deprecated starting with macOS 10.14 (Mojave)!")
 endif()
-set(OUTPUT_EXT)
 list(REMOVE_ITEM example_sources ${CMAKE_CURRENT_SOURCE_DIR}/others/rlgl_standalone.c)
 
 include(CheckIncludeFile)
@@ -85,12 +84,12 @@ elseif(${PLATFORM} MATCHES "Web")
   # Since WASM is used, ALLOW_MEMORY_GROWTH has no extra overheads
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -s ALLOW_MEMORY_GROWTH=1 --no-heap-copy")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} --shell-file ${CMAKE_SOURCE_DIR}/src/shell.html")
-  set(OUTPUT_EXT ".html")
+  set(CMAKE_EXECUTABLE_SUFFIX ".html")
 
   # Remove the -rdynamic flag because otherwise emscripten
   # does not generate HTML+JS+WASM files, only a non-working
   # and fat HTML
-  string(REPLACE "-rdynamic" "" CMAKE_SHARED_LIBRARY_LINK_C_FLAGS ${CMAKE_SHARED_LIBRARY_LINK_C_FLAGS})
+  string(REPLACE "-rdynamic" "" CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "${CMAKE_SHARED_LIBRARY_LINK_C_FLAGS}")
 endif()
 
 include_directories(BEFORE SYSTEM others/external/include)
@@ -103,7 +102,7 @@ endif()
 foreach(example_source ${example_sources})
   # Create the basename for the example
   get_filename_component(example_name ${example_source} NAME)
-  string(REPLACE ".c" "${OUTPUT_EXT}" example_name ${example_name})
+  string(REPLACE ".c" "" example_name ${example_name})
 
   # Setup the example
   add_executable(${example_name} ${example_source})
@@ -125,7 +124,7 @@ if (${PLATFORM} MATCHES "Desktop")
   foreach (example_source "others/rlgl_standalone.c")
     # Create the basename for the example
     get_filename_component(example_name ${example_source} NAME)
-    string(REPLACE ".c" "${OUTPUT_EXT}" example_name ${example_name})
+    string(REPLACE ".c" "" example_name ${example_name})
     add_executable(${example_name} ${example_source})
     add_dependencies(${example_name} raylib)
     target_link_libraries(${example_name} ${raylib_LDFLAGS})
diff --git a/src/core.c b/src/core.c
index 12f76609..5ee78779 100644
--- a/src/core.c
+++ b/src/core.c
@@ -1133,15 +1133,19 @@ void SetWindowState(unsigned int flags)
     // State change: FLAG_WINDOW_RESIZABLE
     if (((CORE.Window.flags & FLAG_WINDOW_RESIZABLE) != (flags & FLAG_WINDOW_RESIZABLE)) && ((flags & FLAG_WINDOW_RESIZABLE) > 0)) 
     {
+#if defined(PLATFORM_DESKTOP)
         glfwSetWindowAttrib(CORE.Window.handle, GLFW_RESIZABLE, GLFW_TRUE);
         CORE.Window.flags |= FLAG_WINDOW_RESIZABLE;
+#endif
     }
     
     // State change: FLAG_WINDOW_UNDECORATED
     if (((CORE.Window.flags & FLAG_WINDOW_UNDECORATED) != (flags & FLAG_WINDOW_UNDECORATED)) && (flags & FLAG_WINDOW_UNDECORATED)) 
     {
+#if defined(PLATFORM_DESKTOP)
         glfwSetWindowAttrib(CORE.Window.handle, GLFW_DECORATED, GLFW_FALSE);
         CORE.Window.flags |= FLAG_WINDOW_UNDECORATED;
+#endif
     }
 
     // State change: FLAG_WINDOW_HIDDEN
@@ -1168,15 +1172,19 @@ void SetWindowState(unsigned int flags)
     // State change: FLAG_WINDOW_UNFOCUSED
     if (((CORE.Window.flags & FLAG_WINDOW_UNFOCUSED) != (flags & FLAG_WINDOW_UNFOCUSED)) && ((flags & FLAG_WINDOW_UNFOCUSED) > 0)) 
     {
+#if defined(PLATFORM_DESKTOP)
         glfwSetWindowAttrib(CORE.Window.handle, GLFW_FOCUS_ON_SHOW, GLFW_FALSE);
         CORE.Window.flags |= FLAG_WINDOW_UNFOCUSED;
+#endif
     }
     
     // State change: FLAG_WINDOW_TOPMOST
     if (((CORE.Window.flags & FLAG_WINDOW_TOPMOST) != (flags & FLAG_WINDOW_TOPMOST)) && ((flags & FLAG_WINDOW_TOPMOST) > 0))
     {
+#if defined(PLATFORM_DESKTOP)
         glfwSetWindowAttrib(CORE.Window.handle, GLFW_FLOATING, GLFW_TRUE);
         CORE.Window.flags |= FLAG_WINDOW_TOPMOST;
+#endif
     }
     
     // State change: FLAG_WINDOW_ALWAYS_RUN
@@ -1234,15 +1242,19 @@ void ClearWindowState(unsigned int flags)
     // State change: FLAG_WINDOW_RESIZABLE
     if (((CORE.Window.flags & FLAG_WINDOW_RESIZABLE) > 0) && ((flags & FLAG_WINDOW_RESIZABLE) > 0))
     {
+#if defined(PLATFORM_DESKTOP)
         glfwSetWindowAttrib(CORE.Window.handle, GLFW_RESIZABLE, GLFW_FALSE);
         CORE.Window.flags &= ~FLAG_WINDOW_RESIZABLE;
+#endif
     }
     
     // State change: FLAG_WINDOW_UNDECORATED
     if (((CORE.Window.flags & FLAG_WINDOW_UNDECORATED) > 0) && ((flags & FLAG_WINDOW_UNDECORATED) > 0)) 
     {
+#if defined(PLATFORM_DESKTOP)
         glfwSetWindowAttrib(CORE.Window.handle, GLFW_DECORATED, GLFW_TRUE);
         CORE.Window.flags &= ~FLAG_WINDOW_UNDECORATED;
+#endif
     }
 
     // State change: FLAG_WINDOW_HIDDEN
@@ -1267,15 +1279,19 @@ void ClearWindowState(unsigned int flags)
     // State change: FLAG_WINDOW_UNFOCUSED
     if (((CORE.Window.flags & FLAG_WINDOW_UNFOCUSED) > 0) && ((flags & FLAG_WINDOW_UNFOCUSED) > 0)) 
     {
+#if defined(PLATFORM_DESKTOP)
         glfwSetWindowAttrib(CORE.Window.handle, GLFW_FOCUS_ON_SHOW, GLFW_TRUE);
         CORE.Window.flags &= ~FLAG_WINDOW_UNFOCUSED;
+#endif
     }
     
     // State change: FLAG_WINDOW_TOPMOST
     if (((CORE.Window.flags & FLAG_WINDOW_TOPMOST) > 0) && ((flags & FLAG_WINDOW_TOPMOST) > 0))
     {
+#if defined(PLATFORM_DESKTOP)
         glfwSetWindowAttrib(CORE.Window.handle, GLFW_FLOATING, GLFW_FALSE);
         CORE.Window.flags &= ~FLAG_WINDOW_TOPMOST;
+#endif
     }
     
     // State change: FLAG_WINDOW_ALWAYS_RUN