attempt to build web version out of emscripten legacy gl wrapper

apps/demos/platformer/CMakeLists.txt

@@ -6,7 +6,7 @@ if(NOT CMAKE_BUILD_TYPE)
         set(CMAKE_BUILD_TYPE Debug)
 endif()
 
-add_subdirectory($ENV{TWNROOT} $ENV{TWNROOT}/build)
+add_subdirectory($ENV{TWNROOT} ${CMAKE_BINARY_DIR}/twn)
 
 set(SOURCE_FILES
         game.c
@@ -20,4 +20,4 @@ set(SOURCE_FILES
         scenes/ingame.c scenes/ingame.h
 )
 
-use_townengine("${SOURCE_FILES}" ${CMAKE_CURRENT_SOURCE_DIR})
+use_townengine("${SOURCE_FILES}" ${TWN_OUT_DIR})