Fix WASM builds

- Removes the dependency on VCPKG entirely, due to conflicts between VCPKG and Emscripten - Adds an optional submodule target for GLM - Moves CMake code relative to dependencies into their dependency files (mk/cmake/SuperTux/Provide*.cmake) - Updates (and significantly simplifies) the build steps for WASM - Fixes a compilation error in `#ifdef EMSCRIPTEN`-guarded code - Allows using the latest version of Emscripten (3.something) instead of the old 1.40 branch - Removes the need to patch SDL_ttf, and adds an option to use the builds provided by Emscripten - Updates the workflow files to reflect those changes
SuperTux · Jun 26, 2023 · 0dc4025 · 0dc4025
1 parent 617933b
commit 0dc4025
Show file tree

Hide file tree

Showing 17 changed files with 148 additions and 143 deletions.
diff --git a/.github/workflows/wasm.yml b/.github/workflows/wasm.yml
@@ -31,7 +31,7 @@ jobs:
       matrix:
         build_type: ["Release", "Debug"]
 
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
         with:
@@ -46,38 +46,8 @@ jobs:
           sudo apt-get install -y git cmake build-essential curl zip
           git clone https://github.com/emscripten-core/emsdk.git
           cd emsdk
-          ./emsdk install 1.40.1
-          ./emsdk activate 1.40.1
-          # Fixes a bug in emscripten - see https://github.com/emscripten-core/emscripten/issues/13590
-          sed -i "s/\#define MALLOC_ALIGNMENT ((size_t)(2 \* sizeof(void \*)))/#define MALLOC_ALIGNMENT 16/g" upstream/emscripten/system/lib/dlmalloc.c
-          # Fixes a bug with the libjpeg port - see https://github.com/emscripten-core/emscripten/pull/13878
-          sed -i 's/2b581c60ae401a79bbbe748ff2deeda5acd50bfd2ea22e5926e36d34b9ebcffb6580b0ff48e972c1441583e30e21e1ea821ca0423f9c67ce08a31dffabdbe6b7/b2affe9a1688bd49fc033f4682c4a242d4ee612f1affaef532f5adcb4602efc4433c4a52a4b3d69e7440ff1f6413b1b041b419bc90efd6d697999961a9a6afb7/g' upstream/emscripten/tools/ports/libjpeg.py
-          sed -i 's/https:\/\/dl.bintray.com\/homebrew\/mirror\/jpeg-9c.tar.gz/https:\/\/storage.googleapis.com\/webassembly\/emscripten-ports\/jpegsrc.v9c.tar.gz/g' upstream/emscripten/tools/ports/libjpeg.py
-
-      - name: Install vcpkg and dependencies
-        run: |
-          source ~/emsdk/emsdk_env.sh
-          cd ~
-          git clone https://github.com/microsoft/vcpkg
-          ./vcpkg/bootstrap-vcpkg.sh
-          ./vcpkg/vcpkg integrate install
-          ./vcpkg/vcpkg install glbinding:wasm32-emscripten
-          ./vcpkg/vcpkg install libpng:wasm32-emscripten
-          ./vcpkg/vcpkg install libogg:wasm32-emscripten
-          ./vcpkg/vcpkg install libvorbis:wasm32-emscripten
-          ./vcpkg/vcpkg install glm:wasm32-emscripten
-          ./vcpkg/vcpkg install zlib:wasm32-emscripten
-
-      - name: Step To run on failure
-        if: ${{ failure() }}
-        run: | 
-          cat /home/runner/vcpkg/buildtrees/libogg/config-wasm32-emscripten-dbg-CMakeCache.txt.log
-          cat /home/runner/vcpkg/buildtrees/libogg/config-wasm32-emscripten-rel-CMakeCache.txt.log
-          cat /home/runner/vcpkg/buildtrees/libogg/config-wasm32-emscripten-out.log
-
-      - name: Patch SDL_ttf
-        working-directory: external/SDL_ttf
-        run: git apply ../../mk/emscripten/SDL_ttf.patch
+          ./emsdk install latest
+          ./emsdk activate latest
 
       - name: Configure build
         env:
@@ -86,10 +56,8 @@ jobs:
           source ~/emsdk/emsdk_env.sh
           mkdir build
           cd build
-          emcmake cmake -DCMAKE_BUILD_TYPE=${BUILD_TYPE} -DENABLE_OPENGLES2=ON \
-                -DCMAKE_TOOLCHAIN_FILE=~/vcpkg/scripts/buildsystems/vcpkg.cmake\
-                -DVCPKG_TARGET_TRIPLET=wasm32-emscripten -DGLBINDING_ENABLED=ON\
-                -DEMSCRIPTEN=1 -DWARNINGS=ON -DWERROR=ON ..
+          # TODO: Re-add -DWERROR=ON when warnings will be fixed
+          emcmake cmake -DCMAKE_BUILD_TYPE=${BUILD_TYPE} -DWARNINGS=ON ..
 
       - name: Sync data folder
         working-directory: build
@@ -111,7 +79,7 @@ jobs:
         env:
           BUILD_TYPE: ${{ matrix.build_type }}
         run: |
-          rm supertux2.html && cp template.html supertux2.html
+          cp template.html supertux2.html
           mkdir upload/
           mv supertux2* upload/
 
@@ -129,4 +97,5 @@ jobs:
           cd build/upload/
           mv supertux2.html index.html
           zip supertux2.zip *
-          curl -F "archive=@$(pwd)/supertux2.zip" -F "message=$(git log --format=%B -n 1 | head -1)" $UPLOAD_URL
+          # TODO: Decomment (or replace URL with a different host)
+          # curl -F "archive=@$(pwd)/supertux2.zip" -F "message=$(git log --format=%B -n 1 | head -1)" $UPLOAD_URL
diff --git a/.gitmodules b/.gitmodules
@@ -22,3 +22,6 @@
 [submodule "tools/miniswig"]
 	path = tools/miniswig
 	url = https://github.com/WindstilleTeam/miniswig
+[submodule "external/glm"]
+	path = external/glm
+	url = https://github.com/g-truc/glm.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -104,14 +104,16 @@ if(EMSCRIPTEN)
   set(CMAKE_EXECUTABLE_SUFFIX .html)
   set(IS_EMSCRIPTEN_BUILD ON)
 
-  set(USE_FLAGS " -sUSE_SDL=2 -sFULL_ES2=1 -sUSE_SDL_IMAGE=2 -sUSE_FREETYPE=2 -sUSE_PTHREADS=1 -sDISABLE_EXCEPTION_CATCHING=0 --preload-file ${BUILD_CONFIG_DATA_DIR} -sTOTAL_MEMORY=67108864 -sALLOW_MEMORY_GROWTH=1 -sSDL2_IMAGE_FORMATS='[\"png\",\"jpg\"]' --use-preload-plugins")
+  set(EM_USE_FLAGS "-sDISABLE_EXCEPTION_CATCHING=0")
+  set(EM_LINK_FLAGS " -sTOTAL_MEMORY=67108864 -sALLOW_MEMORY_GROWTH=1 -sERROR_ON_UNDEFINED_SYMBOLS=0 --preload-file ${BUILD_CONFIG_DATA_DIR} --use-preload-plugins -lidbfs.js")
   if(CMAKE_BUILD_TYPE MATCHES Debug)
-    set(USE_FLAGS "${USE_FLAGS} -fsanitize=undefined -sSAFE_HEAP=1 -sASSERTIONS=1 -sDEMANGLE_SUPPORT=1")
+    set(EM_USE_FLAGS "${EM_USE_FLAGS} -fsanitize=undefined")
+    set(EM_LINK_FLAGS "${EM_LINK_FLAGS} -fsanitize=undefined -sSAFE_HEAP=1 -sASSERTIONS=1 -sDEMANGLE_SUPPORT=1")
   endif()
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${USE_FLAGS} -sERROR_ON_UNDEFINED_SYMBOLS=0")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${USE_FLAGS} -sERROR_ON_UNDEFINED_SYMBOLS=0")
-  set(CMAKE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} ${USE_FLAGS} -sERROR_ON_UNDEFINED_SYMBOLS=0 -lidbfs.js")
-  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} ${USE_FLAGS} -sERROR_ON_UNDEFINED_SYMBOLS=0 -lidbfs.js")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EM_USE_FLAGS}")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${EM_USE_FLAGS}")
+  set(CMAKE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} ${EM_USE_FLAGS} ${EM_LINK_FLAGS}")
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} ${EM_USE_FLAGS} ${EM_LINK_FLAGS}")
 endif()
 
 # TODO: Add " OR ANDROID OR IOS" to this
@@ -234,7 +236,7 @@ target_link_libraries(supertux2 supertux2_lib)
 set_target_properties(supertux2_lib PROPERTIES OUTPUT_NAME supertux2_lib)
 set_target_properties(supertux2_lib PROPERTIES COMPILE_FLAGS "${SUPERTUX2_EXTRA_WARNING_FLAGS}")
 if(EMSCRIPTEN)
-  target_link_options(supertux2 PUBLIC -sEXPORTED_FUNCTIONS=['_main','_set_resolution','_save_config','_onDownloadProgress','_onDownloadFinished','_onDownloadError','_onDownloadAborted','_getExceptionMessage'] PUBLIC -sEXPORTED_RUNTIME_METHODS=['ccall','cwrap'] PUBLIC -sEXTRA_EXPORTED_RUNTIME_METHODS=['ccall','cwrap'])
+  target_link_options(supertux2 PUBLIC -sEXPORTED_FUNCTIONS=['_main','_set_resolution','_save_config','_onDownloadProgress','_onDownloadFinished','_onDownloadError','_onDownloadAborted','_getExceptionMessage'] PUBLIC -sEXPORTED_RUNTIME_METHODS=['ccall','cwrap'])
 endif()
 
 if(WIN32 AND NOT VCPKG_BUILD)
@@ -261,18 +263,20 @@ if(NOT EMSCRIPTEN)
   target_link_libraries(supertux2_lib PUBLIC LibSDL2 LibSDL2_image)
 endif()
 
-target_link_libraries(supertux2_lib PUBLIC LibSDL2_ttf)
 target_link_libraries(supertux2_lib PUBLIC LibSquirrel)
 target_link_libraries(supertux2_lib PUBLIC LibSqstdlib)
 target_link_libraries(supertux2_lib PUBLIC LibTinygettext)
 target_link_libraries(supertux2_lib PUBLIC LibSexp)
 target_link_libraries(supertux2_lib PUBLIC LibSavePNG)
 target_link_libraries(supertux2_lib PUBLIC LibPartioZip)
 target_link_libraries(supertux2_lib PUBLIC LibOpenAL)
-target_link_libraries(supertux2_lib PUBLIC LibOggVorbis)
 target_link_libraries(supertux2_lib PUBLIC LibGlm)
 target_link_libraries(supertux2_lib PUBLIC LibFmt)
 target_link_libraries(supertux2_lib PUBLIC LibPhysfs)
+if(NOT EMSCRIPTEN)
+  target_link_libraries(supertux2_lib PUBLIC LibSDL2_ttf)
+  target_link_libraries(supertux2_lib PUBLIC LibOggVorbis)
+endif()
 
 if(HAVE_OPENGL)
   target_link_libraries(supertux2_lib PUBLIC LibOpenGL)

diff --git a/INSTALL.md b/INSTALL.md
@@ -463,57 +463,43 @@ toolchain; newer versions are known not to work properly.
 git submodule update --init --recursive
 ```
 
-1. Patch SDL_ttf by applying the patch in `mk/emscripten/SDL_ttf.patch`:
+1. Install [Emscripten](emscripten.org):
 ```
-# For git users:
-git apply mk/emscripten/SDL_ttf.patch
-
-# If you do not have git installed:
-patch -p1 < mk/emscripten/SDL_ttf.patch
-```
-
-2. Install dependencies using Vcpkg (Make sure you enabled Emscripten and ran
-`source .../emsdk_env.sh`!):
-```
-vcpkg integrate install
-vcpkg install --target wasm32-emscripten glbinding libpng libogg libvorbis glm zlib
+git clone https://github.com/emscripten-core/emsdk.git
+cd emsdk
+./emsdk install latest
+./emsdk activate latest
+source ./emsdk_env.sh
 ```
 
-3. Run CMake using Emscripten's wrapper:
+2. Run CMake using Emscripten's wrapper:
 ```
-emcmake cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_OPENGLES2=ON -DCMAKE_TOOLCHAIN_FILE=/path/to/vcpkg/scripts/buildsystems/vcpkg.cmake -DVCPKG_TARGET_TRIPLET=wasm32-emscripten -DGLBINDING_ENABLED=ON -DEMSCRIPTEN=1 ..
+# Make sure you ran `source /path/to/emsdk/emsdk_env.sh` if you opened a new terminal since last step!
+emcmake cmake -DCMAKE_BUILD_TYPE=Release ..
 ```
-Replace `/path/to/vcpkg` with the absolute path to where Vcpkg is installed.
-Note that Debug builds are generally unplayably slow. Also, the
-`-DENABLE_OPENGLES2=ON` flag is optional and will enable using WebGL instead of
-the SDL renderer. Currently, the WebGL renderer is much slower than the SDL
-renderer.
 
-4. Copy data files to the build folder, as Emscripten will package them to make
+3. Copy data files to the build folder, as Emscripten will package them to make
 them usable from WASM:
 ```
 rsync -aP ../data/ data/
 ```
 
-5. Build SuperTux:
+4. Build SuperTux:
 ```
 emmake make -j$(nproc || sysctl -n hw.ncpu || echo 2)
 ```
 
-6. Replace the Emscripten HTML template with SuperTux's custom container:
+5. Replace the Emscripten HTML template with SuperTux's custom container:
 ```
-rm supertux2.html && cp template.html supertux2.html
+cp template.html supertux2.html
 ```
 You may skip the step above you intend to directly open the `template.html` file;
 note that SuperTux won't work if it is not located in the custom template, as it
 requires some custom JavaScript functions to work properly.
 
-7. Run the Emscripten webserver:
+6. Run the Emscripten webserver:
 ```
-# Without --no-browser, Emscripten does not wait for data to finish downloading,
-# which fails the process. It only works by launching Emscripten in no-browser
-# mode, and then by opening the browser manually.
-emrun --no_browser .
+emrun supertux2.html
 ```
 
 You can now play SuperTux by opening `http://localhost:6931/supertux2.html` in

diff --git a/external/glm b/external/glm
diff --git a/mk/cmake/ConfigureChecks.cmake b/mk/cmake/ConfigureChecks.cmake
@@ -11,6 +11,7 @@ check_cxx_source_compiles(
 	HAVE_ICONV_CONST
 )
 
-CHECK_TYPE_SIZE("void*" SIZEOF_VOID_P)
-message(STATUS "Size of void* is ${SIZEOF_VOID_P}")
-
+if(NOT EMSCRIPTEN)
+  CHECK_TYPE_SIZE("void*" SIZEOF_VOID_P)
+  message(STATUS "Size of void* is ${SIZEOF_VOID_P}")
+endif()
diff --git a/mk/cmake/SuperTux/ProvideDiscord.cmake b/mk/cmake/SuperTux/ProvideDiscord.cmake
@@ -3,6 +3,10 @@
 # Some privay-concerned users or free software package managers might need an option to compile ST without the Discord integration.
 option(ENABLE_DISCORD "Compile the Discord integration" OFF)
 
+if(EMSCRIPTEN)
+  set(ENABLE_DISCORD OFF CACHE BOOL "Emscripten does not support Discord integration" FORCE)
+endif()
+
 if(NOT ENABLE_DISCORD)
   message(STATUS "## WARNING : Discord integration will NOT be compiled. To enable Discord, pass -DENABLE_DISCORD=On")
 else()

diff --git a/mk/cmake/SuperTux/ProvideGlm.cmake b/mk/cmake/SuperTux/ProvideGlm.cmake
@@ -1,6 +1,43 @@
-find_package(glm QUIET)
+if(EMSCRIPTEN)
+  option(USE_SYSTEM_GLM "Use the system-provided GLM instead of the external module" OFF)
+else()
+  option(USE_SYSTEM_GLM "Use the system-provided GLM instead of the external module" ON)
+endif()
+
+if(USE_SYSTEM_GLM)
+  find_package(glm QUIET)
+endif()
+
+if(NOT USE_SYSTEM_GLM)
+  if (NOT EXISTS "${CMAKE_SOURCE_DIR}/external/glm/CMakeLists.txt")
+    message(FATAL_ERROR "")
+  endif()
+
+  set(GLM_PREFIX ${CMAKE_BINARY_DIR}/glm/ex)
+  ExternalProject_Add(glm_project
+    SOURCE_DIR "${CMAKE_SOURCE_DIR}/external/glm/"
+    BUILD_BYPRODUCTS
+    "${GLM_PREFIX}/include"
+    CMAKE_ARGS
+    -DCMAKE_BUILD_TYPE=${BUILD_TYPE}
+    -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+    -DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}
+    -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
+    -DCMAKE_CXX_FLAGS=${CMAKE_CXX_FLAGS}
+    -DCMAKE_INSTALL_PREFIX=${GLM_PREFIX}
+    -DBUILD_TESTING=OFF
+    -DINSTALL_INC_DIR=include)
+
+  add_library(LibGlm INTERFACE IMPORTED)
+
+  file(MAKE_DIRECTORY ${GLM_PREFIX}/include)
+
+  set_target_properties(LibGlm PROPERTIES
+    INTERFACE_INCLUDE_DIRECTORIES "${GLM_PREFIX}/include"
+    INTERFACE_COMPILE_DEFINITIONS "GLM_ENABLE_EXPERIMENTAL")
 
-if(glm_FOUND)
+  add_dependencies(LibGlm glm_project)
+elseif(glm_FOUND)
   if(TARGET glm::glm)
     message(STATUS "Found glm")
 

diff --git a/mk/cmake/SuperTux/ProvideOggVorbis.cmake b/mk/cmake/SuperTux/ProvideOggVorbis.cmake
@@ -1,17 +1,24 @@
-find_package(OggVorbis REQUIRED)
+if(EMSCRIPTEN)
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -sUSE_VORBIS=1")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -sUSE_VORBIS=1")
+  set(CMAKE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} -sUSE_VORBIS=1")
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -sUSE_VORBIS=1")
+else()
+  find_package(OggVorbis REQUIRED)
 
-add_library(LibOggVorbis INTERFACE IMPORTED)
-set_target_properties(LibOggVorbis PROPERTIES
-  INTERFACE_INCLUDE_DIRECTORIES "${VORBIS_INCLUDE_DIR}"
-  INTERFACE_LINK_LIBRARIES "${OGGVORBIS_LIBRARIES}"
-  )
+  add_library(LibOggVorbis INTERFACE IMPORTED)
+  set_target_properties(LibOggVorbis PROPERTIES
+    INTERFACE_INCLUDE_DIRECTORIES "${VORBIS_INCLUDE_DIR}"
+    INTERFACE_LINK_LIBRARIES "${OGGVORBIS_LIBRARIES}"
+    )
 
-mark_as_advanced(
-  OGG_LIBRARY
-  VORBISENC_LIBRARY
-  VORBISFILE_LIBRARY
-  VORBIS_INCLUDE_DIR
-  VORBIS_LIBRARY
-  )
+  mark_as_advanced(
+    OGG_LIBRARY
+    VORBISENC_LIBRARY
+    VORBISFILE_LIBRARY
+    VORBIS_INCLUDE_DIR
+    VORBIS_LIBRARY
+    )
+endif()
 
 # EOF #
diff --git a/mk/cmake/SuperTux/ProvideOpenGL.cmake b/mk/cmake/SuperTux/ProvideOpenGL.cmake
@@ -1,5 +1,9 @@
 option(ENABLE_OPENGL "Enable OpenGL support" ON)
-option(ENABLE_OPENGLES2 "Enable OpenGLES2 support" OFF)
+if(EMSCRIPTEN)
+  option(ENABLE_OPENGLES2 "Enable OpenGLES2 support" ON)
+else()
+  option(ENABLE_OPENGLES2 "Enable OpenGLES2 support" OFF)
+endif()
 option(GLBINDING_ENABLED "Use glbinding instead of GLEW" OFF)
 option(GLBINDING_DEBUG_OUTPUT "Enable glbinding debug output for each called OpenGL function" OFF)
 
@@ -10,7 +14,10 @@ if(ENABLE_OPENGL)
     set(HAVE_OPENGL TRUE)
     list(APPEND OPENGL_COMPILE_DEFINITIONS "USE_OPENGLES2")
 
-    if(NOT EMSCRIPTEN)
+    if(EMSCRIPTEN)
+      set(CMAKE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} -sFULL_ES2=1")
+      set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${USE_FLAGS} -sFULL_ES2=1")
+    else()
       pkg_check_modules(GLESV2 REQUIRED glesv2)
       list(APPEND OPENGL_INCLUDE_DIRECTORIES "${GLESV2_INCLUDE_DIRS}")
       list(APPEND OPENGL_LINK_LIBRARIES "${GLESV2_LIBRARIES}")

diff --git a/mk/cmake/SuperTux/ProvidePartioZip.cmake b/mk/cmake/SuperTux/ProvidePartioZip.cmake
@@ -1,4 +1,9 @@
-find_package(ZLIB REQUIRED)
+if(EMSCRIPTEN)
+  set(CMAKE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} -sUSE_ZLIB=1")
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -sUSE_ZLIB=1")
+else()
+  find_package(ZLIB REQUIRED)
+endif()
 
 add_library(LibPartioZip ${CMAKE_CURRENT_SOURCE_DIR}/external/partio_zip/zip_manager.cpp)
 target_link_libraries(LibPartioZip PUBLIC ${ZLIB_LIBRARIES})

diff --git a/mk/cmake/SuperTux/ProvideSDL2.cmake b/mk/cmake/SuperTux/ProvideSDL2.cmake
@@ -12,7 +12,10 @@ if(WIN32)
     find_library(SDL2MAIN_LIBRARIES NAMES SDL2main PATHS "${DEPENDENCY_FOLDER}/lib")
   endif()
 else()
-  if(NOT EMSCRIPTEN)
+  if(EMSCRIPTEN)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -sUSE_SDL=2 -sUSE_SDL_IMAGE=2 -sSDL2_IMAGE_FORMATS='[\"png\",\"jpg\"]'")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -sUSE_SDL=2 -sUSE_SDL_IMAGE=2 -sSDL2_IMAGE_FORMATS='[\"png\",\"jpg\"]'")
+  else()
     if(VCPKG_BUILD)
       find_package(SDL2 CONFIG REQUIRED)
       find_package(sdl2-image CONFIG REQUIRED)

diff --git a/mk/cmake/SuperTux/ProvideSDL2_ttf.cmake b/mk/cmake/SuperTux/ProvideSDL2_ttf.cmake
@@ -3,15 +3,26 @@ if(USE_SYSTEM_SDL2_TTF)
   find_package(SDL2_ttf QUIET)
 endif()
 
-if(TARGET SDL2_ttf)
+if (EMSCRIPTEN)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -sUSE_SDL_TTF=2")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -sUSE_SDL_TTF=2")
+  set(CMAKE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} -sUSE_SDL_TTF=2")
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -sUSE_SDL_TTF=2")
+elseif(TARGET SDL2_ttf)
   message(STATUS "Found preinstalled SDL2_ttf")
 
   add_library(LibSDL2_ttf ALIAS SDL2_ttf)
 else()
   message(STATUS "Could NOT find SDL2_ttf, using external/SDL_ttf fallback")
 
-  ## external/SDL_ttf with patches
-  if(NOT EMSCRIPTEN)
+  # Won't be used in practice - preserved for knowledge
+  if(EMSCRIPTEN)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -sUSE_FREETYPE=1")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -sUSE_FREETYPE=1")
+    set(CMAKE_LINKER_FLAGS "${CMAKE_LINKER_FLAGS} -sUSE_FREETYPE=1")
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -sUSE_FREETYPE=1")
+  else()
+    ## external/SDL_ttf with patches
     if(VCPKG_BUILD)
       find_package(freetype CONFIG REQUIRED)
     else()