[WASM] Option to use main loop timing 'timeout' instead of 'requestAnimationFrame' (RAF)

CMakeOptions.md

@@ -54,6 +54,7 @@ default is: `navigator.hardwareConcurrency`
 - AX_WASM_ENABLE_DEVTOOLS: whether enable web devtools aka `pause`, `resume`, `step` buttons in webpage, default: `TRUE`
 - AX_WASM_INITIAL_MEMORY: set the wasm initial memory size, default `1024MB`
 - AX_WASM_ISA_SIMD: specify the wasm simd intrinsics type, default `none`, supports `sse`, `neon`, note the `wasm-simd` not support by axmol yet
+- AX_WASM_TIMING_USE_TIMEOUT: force the wasm emscripten loop timing to use `Timeout` with FPS value of `Application::setAnimationInterval` (app still run on focus lost), default is `FALSE` with timing `requestAnimationFrame` (no run on focus lost). See https://emscripten.org/docs/api_reference/emscripten.h.html#c.emscripten_set_main_loop_timing
 
 ## The options for axmol apps
 

core/CMakeLists.txt

@@ -150,6 +150,10 @@ if (WIN32)
     endif()
 endif()
 
+if (WASM)
+    set(AX_WASM_TIMING_USE_TIMEOUT OFF CACHE BOOL "")
+endif()
+
 # axmolver.h
 find_program(GIT_PROG NAMES git)
 if(AX_UPDATE_BUILD_VERSION AND GIT_PROG AND EXISTS "${_AX_ROOT}/.git")
@@ -273,6 +277,9 @@ if(WASM)
       target_link_options(${_AX_CORE_LIB} PUBLIC -sGL_ENABLE_GET_PROC_ADDRESS)
   endif()
   target_link_options(${_AX_CORE_LIB} PUBLIC -lwebsocket.js)
+  if(AX_WASM_TIMING_USE_TIMEOUT)
+    target_compile_definitions(${_AX_CORE_LIB} PUBLIC AX_WASM_TIMING_USE_TIMEOUT=1)
+  endif()
 elseif(AX_ENABLE_MFMEDIA AND NOT WINRT AND FULL_MSVC)
   target_link_options(${_AX_CORE_LIB} PUBLIC "/DELAYLOAD:mf.dll" "/DELAYLOAD:mfplat.dll")
 endif()

core/platform/wasm/Application-wasm.cpp

@@ -196,7 +196,12 @@ int Application::run()
     as the browser’s requestAnimationFrame will make sure you render at a proper smooth rate
     that lines up properly with the browser and monitor.
     */
+#if AX_WASM_TIMING_USE_TIMEOUT
+    double fps = ceil(1.0 / (static_cast<double>(s_animationInterval) / NANOSECONDSPERSECOND));
+    emscripten_set_main_loop(updateFrame, static_cast<int>(fps), false);
+#else
     emscripten_set_main_loop(updateFrame, -1, false);
+#endif
 
     return 0;
 }