Examples: (Again, but better) made SDL+GL and GLFW+GL examples build with Emscripten. (#2492, #2494, #3699, #3705)

examples/example_glfw_opengl3/main.cpp

@@ -20,6 +20,11 @@
 #pragma comment(lib, "legacy_stdio_definitions")
 #endif
 
+// This example can also compile and run with Emscripten! See 'Makefile.emscripten' for details.
+#ifdef __EMSCRIPTEN__
+#include "../libs/emscripten/emscripten_mainloop_stub.h"
+#endif
+
 static void glfw_error_callback(int error, const char* description)
 {
     fprintf(stderr, "GLFW Error %d: %s\n", error, description);
@@ -85,6 +90,7 @@ int main(int, char**)
     // - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use Freetype for higher quality font rendering.
     // - Read 'docs/FONTS.md' for more instructions and details.
     // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
+    // - Our Emscripten build process allows embedding fonts to be accessible at runtime from the "fonts/" folder. See Makefile.emscripten for details.
     //io.Fonts->AddFontDefault();
     //io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\segoeui.ttf", 18.0f);
     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
@@ -99,7 +105,14 @@ int main(int, char**)
     ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
     // Main loop
+#ifdef __EMSCRIPTEN__
+    // For an Emscripten build we are disabling file-system access, so let's not attempt to do a fopen() of the imgui.ini file.
+    // You may manually call LoadIniSettingsFromMemory() to load settings from your own storage.
+    io.IniFilename = NULL;
+    EMSCRIPTEN_MAINLOOP_BEGIN
+#else
     while (!glfwWindowShouldClose(window))
+#endif
     {
         // Poll and handle events (inputs, window resize, etc.)
         // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
@@ -161,6 +174,9 @@ int main(int, char**)
 
         glfwSwapBuffers(window);
     }
+#ifdef __EMSCRIPTEN__
+    EMSCRIPTEN_MAINLOOP_END;
+#endif
 
     // Cleanup
     ImGui_ImplOpenGL3_Shutdown();