Html5 - Tidbits - Epic Wiki

# Html5 - Tidbits

This page is meant to serve as an archive for assorted information regarding HTML5 development.

# Exporting C functions to Javascript

Note

Disclaimer: this is a living document based on current research and experience. This currently does not work.

Somewhere in the project, define a global C function to be called by Javascript

extern "C" { #if PLATFORM_HTML5_BROWSER DEFINE_LOG_CATEGORY_STATIC(LogHTML5, Log, All); void my_func( const char* _string, int _number ) { #ifdef __EMSCRIPTEN_TRACING__ // Log to emscripten emscripten_log( EM_LOG_CONSOLE, TEXT("my_func( %s, %d )"), _string, _number ); #endif // Log to UE console UE_LOG( LogHTML5, Verbose, TEXT("my_func( %s, %d )"), _string, _number ); } #endif }

Append the C function name with a prefixed '_' to this EXPORTED_FUNCTIONS array

// File // /Source/Programs/UnrealBuildTool/HTML5/HTML5ToolChain.cs(87) Result += " -s EXPORTED_FUNCTIONS=\"['_main', '_resize_game', '_on_fatal', '_my_func']\" ";

The Javascript that handles the web interface gets pulled from a template during build, so any changes should be done to that.

// File // /Build/HTML5/GameX.html.template(223+) var UE4 = { ... get my_func() { var fn = Module.cwrap('my_func', null, ['string'],['number'] ); delete UE4["my_func"]; UE4.my_func = fn; return fn; }, ... }; // Now anywhere inside Javascript, you can call UE4.my_func("mystring", 1234);

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