Examples: Emscripten: Switched to WebGL1/ES2, Added Changelog, Updated links, Added ignore list, Fixed warning with older versions. Removed reliance on C++11 (would warn on some compiler). Improved html template, removed undesirable options, reduced log size. Tweaked main.cpp. (#2494)

docs/CHANGELOG.txt

@@ -54,6 +54,7 @@ Other Changes:
   to using the ImGui::MemAlloc()/MemFree() calls directly.
 - Examples: OpenGL: Added a dummy GL call + comments in ImGui_ImplOpenGL3_Init() to detect uninitialized
   GL function loaders early, and help users understand what they are missing. (#2421)
+- Examples: Emscripten: Added Emscripten+SDL+GLES2 example. (#2494, #2492, #2351, #336) [@nicolasnoble]
 - Examples: OpenGL3: Minor tweaks + not calling glBindBuffer more than necessary in the render loop.
 - Examples: Vulkan: Fixed in-flight buffers issues when using multi-viewports. (#2461, #2348, #2378, #2097)
 - Examples: Vulkan: Added missing support for 32-bit indices (#define ImDrawIdx unsigned int).

docs/README.md

@@ -135,8 +135,7 @@ Languages: (third-party bindings)
 Frameworks:
 - Renderers: DirectX 9/10/11/12, Metal, OpenGL2, OpenGL3+/ES2/ES3, Vulkan: [examples/](https://github.com/ocornut/imgui/tree/master/examples)
 - Platform: GLFW, SDL, Win32, OSX, GLUT: [examples/](https://github.com/ocornut/imgui/tree/master/examples)
-- Framework: Allegro 5, Marmalade: [examples/](https://github.com/ocornut/imgui/tree/master/examples)
+- Framework: Allegro 5, Emscripten, Marmalade: [examples/](https://github.com/ocornut/imgui/tree/master/examples)
-- Unmerged PR: SDL2 + OpenGLES + Emscripten: [#336](https://github.com/ocornut/imgui/pull/336)
 - Unmerged PR: Android: [#421](https://github.com/ocornut/imgui/pull/421)
 - Cinder: [Cinder-ImGui](https://github.com/simongeilfus/Cinder-ImGui)
 - Cocos2d-x: [imguix](https://github.com/c0i/imguix), [#551](https://github.com/ocornut/imgui/issues/551)

docs/TODO.txt

@@ -316,8 +316,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - misc: possible compile-time support for wchar_t instead of char*?
 
  - backend: bgfx? https://gist.github.com/RichardGale/6e2b74bc42b3005e08397236e4be0fd0
- - web/emscriptem: refactor some examples to facilitate integration with emscripten main loop system. (#1713, #336)
+ - emscriptem: with refactored examples, we could provide a direct imgui_impl_emscripten platform layer (see eg. https://github.com/floooh/sokol-samples/blob/master/html5/imgui-emsc.cc#L42)
- - web/emscriptem: with refactored examples, we could provide a direct imgui_impl_emscripten platform layer (see eg. https://github.com/floooh/sokol-samples/blob/master/html5/imgui-emsc.cc#L42)
 
  - remote: make a system like RemoteImGui first-class citizen/project (#75)
 

examples/.gitignore

@@ -27,6 +27,7 @@ xcuserdata
 ## Emscripten output
 *.out.js
 *.out.wasm
+example_emscripten/example_emscripten.*
 
 ## Unix executables
 example_glfw_opengl2/example_glfw_opengl2

examples/README.txt

@@ -122,13 +122,15 @@ List of high-level Frameworks Bindings in this repository: (combine Platform + R
     imgui_impl_allegro5.cpp
     imgui_impl_marmalade.cpp
 
+Note that Dear ImGui works with Emscripten. 
+The examples_emscripten/ app uses sdl.cpp + opengl3.cpp but other combinations are possible.
 Third-party framework, graphics API and languages bindings are listed at:
 
     https://github.com/ocornut/imgui/wiki/Bindings
 
     Languages: C, C#, ChaiScript, D, Go, Haxe, Java, Lua, Odin, Pascal, PureBasic, Python, Rust, Swift...
-    Frameworks: Cinder, Cocoa (OSX), Cocos2d-x, Emscripten, SFML, GML/GameMaker Studio, Irrlicht, Ogre,
+    Frameworks: Cinder, Cocoa (OSX), Cocos2d-x, SFML, GML/GameMaker Studio, Irrlicht, Ogre, OpenSceneGraph,
-    OpenSceneGraph, openFrameworks, LOVE, NanoRT, Nim Game Lib, Qt3d, SFML, Unreal Engine 4...
+    openFrameworks, LOVE, NanoRT, Nim Game Lib, Qt3d, SFML, Unreal Engine 4...
     Miscellaneous: Software Renderer, RemoteImgui, etc.
 
 
@@ -177,6 +179,12 @@ example_apple_opengl2/
     = main.mm + imgui_impl_osx.mm + imgui_impl_opengl2.cpp
     (NB: you may still want to use GLFW or SDL which will also support Windows, Linux along with OSX.)
 
+example_empscripten:
+    Emcripten + SDL2 + OpenGL3+/ES2/ES3 example.
+    = main.cpp + imgui_impl_sdl.cpp + imgui_impl_opengl3.cpp
+    Note that other examples based on SDL or GLFW + GL could easily be modified to work with Emscripten.
+    We provide this to make the Emscripten differences obvious, and have them not pollute all other examples.
+
 example_glfw_opengl2/
     GLFW + OpenGL2 example (legacy, fixed pipeline).
     = main.cpp + imgui_impl_glfw.cpp + imgui_impl_opengl2.cpp

examples/example_emscripten/Makefile

@@ -21,9 +21,9 @@ SOURCES += ../../imgui.cpp ../../imgui_demo.cpp ../../imgui_draw.cpp ../../imgui
 OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
 UNAME_S := $(shell uname -s)
 
-EMS = -s USE_SDL=2 -s USE_WEBGL2=1 -s WASM=1 -s FULL_ES3=1
+EMS = -s USE_SDL=2 -s WASM=1
 EMS += -s ALLOW_MEMORY_GROWTH=1 -s BINARYEN_TRAP_MODE=clamp
-EMS += -s DISABLE_EXCEPTION_CATCHING=1 -s EXIT_RUNTIME=1
+EMS += -s DISABLE_EXCEPTION_CATCHING=1 -s NO_EXIT_RUNTIME=0
 EMS += -s ASSERTIONS=1 -s SAFE_HEAP=1
 
 CPPFLAGS = -I../ -I../../
@@ -55,4 +55,4 @@ $(EXE): $(OBJS)
 	$(CXX) -o $@ $^ $(LIBS) $(LDFLAGS)
 
 clean:
-	rm -f $(EXE) $(OBJS) *.js *.wasm
+	rm -f $(EXE) $(OBJS) *.js *.wasm *.wasm.pre

examples/example_emscripten/main.cpp

@@ -14,24 +14,16 @@
 #include <SDL.h>
 #include <SDL_opengles2.h>
 
-// Emscripten requires to have full control over the main loop. We're going to store variables from main() to main_loop() here.
+// Emscripten requires to have full control over the main loop. We're going to store our SDL book-keeping variables globally. 
-// This will also hold some of our persistent data across loops. Remember: imgui is immediate mode, and doesn't store state.
 // Having a single function that acts as a loop prevents us to store state in the stack of said function. So we need some location for this.
-struct MainLoopVars {
+SDL_Window*     g_Window = NULL;
-    SDL_Window* window = NULL;
+SDL_GLContext   g_GLContext = NULL;
-    SDL_GLContext gl_context = NULL;
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-};
 
 // For clarity, our main loop code is declared at the end.
 void main_loop(void*);
 
 int main(int, char**)
 {
-    MainLoopVars vars;
-
     // Setup SDL
     if (SDL_Init(SDL_INIT_VIDEO|SDL_INIT_TIMER) != 0)
     {
@@ -39,13 +31,14 @@ int main(int, char**)
         return -1;
     }
 
-    // For the browser using emscripten, we are going to use WebGL2 with GLES3. See the Makefile.emscripten for requirement details.
+    // For the browser using Emscripten, we are going to use WebGL1 with GL ES2. See the Makefile. for requirement details.
     // It is very likely the generated file won't work in many browsers. Firefox is the only sure bet, but I have successfully
     // run this code on Chrome for Android for example.
-    const char* glsl_version = "#version 300 es";
+    const char* glsl_version = "#version 100";
+    //const char* glsl_version = "#version 300 es";
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
-    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
 
     // Create window with graphics context
@@ -55,9 +48,10 @@ int main(int, char**)
     SDL_DisplayMode current;
     SDL_GetCurrentDisplayMode(0, &current);
     SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
-    vars.window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
+    g_Window = SDL_CreateWindow("Dear ImGui Emscripten example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
-    vars.gl_context = SDL_GL_CreateContext(vars.window);
+    g_GLContext = SDL_GL_CreateContext(g_Window);
-    if (!vars.gl_context) {
+    if (!g_GLContext)
+    {
         fprintf(stderr, "Failed to initialize WebGL context!\n");
         return 1;
     }
@@ -74,7 +68,7 @@ int main(int, char**)
     //ImGui::StyleColorsClassic();
 
     // Setup Platform/Renderer bindings
-    ImGui_ImplSDL2_InitForOpenGL(vars.window, vars.gl_context);
+    ImGui_ImplSDL2_InitForOpenGL(g_Window, g_GLContext);
     ImGui_ImplOpenGL3_Init(glsl_version);
 
     // Load Fonts
@@ -93,12 +87,18 @@ int main(int, char**)
     //IM_ASSERT(font != NULL);
 
     // This function call won't return, and will engage in an infinite loop, processing events from the browser, and dispatching them.
-    emscripten_set_main_loop_arg(main_loop, &vars, 0, true);
+    emscripten_set_main_loop_arg(main_loop, NULL, 0, true);
 }
 
-void main_loop(void* arg) {
+void main_loop(void* arg) 
-    MainLoopVars* vars = (MainLoopVars*) arg;
+{
     ImGuiIO& io = ImGui::GetIO();
+    IM_UNUSED(arg); // We can pass this argument as the second parameter of emscripten_set_main_loop_arg(), but we don't use that.
+
+    // Our state (make them static = more or less global) as a convenience to keep the example terse.
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
     // 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.
@@ -114,12 +114,12 @@ void main_loop(void* arg) {
 
     // Start the Dear ImGui frame
     ImGui_ImplOpenGL3_NewFrame();
-    ImGui_ImplSDL2_NewFrame(vars->window);
+    ImGui_ImplSDL2_NewFrame(g_Window);
     ImGui::NewFrame();
 
     // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-    if (vars->show_demo_window)
+    if (show_demo_window)
-        ImGui::ShowDemoWindow(&vars->show_demo_window);
+        ImGui::ShowDemoWindow(&show_demo_window);
 
     // 2. Show a simple window that we create ourselves. We use a Begin/End pair to created a named window.
     {
@@ -129,11 +129,11 @@ void main_loop(void* arg) {
         ImGui::Begin("Hello, world!");                                // Create a window called "Hello, world!" and append into it.
 
         ImGui::Text("This is some useful text.");                     // Display some text (you can use a format strings too)
-        ImGui::Checkbox("Demo Window", &vars->show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Demo Window", &show_demo_window);            // Edit bools storing our window open/close state
-        ImGui::Checkbox("Another Window", &vars->show_another_window);
+        ImGui::Checkbox("Another Window", &show_another_window);
 
         ImGui::SliderFloat("float", &f, 0.0f, 1.0f);                  // Edit 1 float using a slider from 0.0f to 1.0f
-        ImGui::ColorEdit3("clear color", (float*)&vars->clear_color); // Edit 3 floats representing a color
+        ImGui::ColorEdit3("clear color", (float*)&clear_color);       // Edit 3 floats representing a color
 
         if (ImGui::Button("Button"))                                  // Buttons return true when clicked (most widgets return true when edited/activated)
             counter++;
@@ -145,21 +145,21 @@ void main_loop(void* arg) {
     }
 
     // 3. Show another simple window.
-    if (vars->show_another_window)
+    if (show_another_window)
     {
-        ImGui::Begin("Another Window", &vars->show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Begin("Another Window", &show_another_window);         // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
         ImGui::Text("Hello from another window!");
         if (ImGui::Button("Close Me"))
-            vars->show_another_window = false;
+            show_another_window = false;
         ImGui::End();
     }
 
     // Rendering
     ImGui::Render();
-    SDL_GL_MakeCurrent(vars->window, vars->gl_context);
+    SDL_GL_MakeCurrent(g_Window, g_GLContext);
     glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
-    glClearColor(vars->clear_color.x, vars->clear_color.y, vars->clear_color.z, vars->clear_color.w);
+    glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
     glClear(GL_COLOR_BUFFER_BIT);
     ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
-    SDL_GL_SwapWindow(vars->window);
+    SDL_GL_SwapWindow(g_Window);
 }

examples/example_emscripten/shell_minimal.html

@@ -3,15 +3,19 @@
   <head>
     <meta charset="utf-8">
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
-    <title>Emscripten-Generated Code</title>
+    <title>Dear ImGui Emscripten example</title>
     <style>
       .emscripten { padding-right: 0; margin-left: auto; margin-right: auto; display: block; }
       textarea.emscripten { font-family: monospace; width: 80%; }
       div.emscripten { text-align: center; }
-      div.emscripten_border { border: 1px solid black; }
+      /* div.emscripten_border { border: 1px solid black; } */
       /* the canvas *must not* have any border or padding, or mouse coords will be wrong */
       canvas.emscripten { border: 0px none; background-color: black; }
 
+      a:link { color: #000000; }
+      a:visited { color: #000000; }
+      a:active { color: #000000; }
+
       .spinner {
         height: 50px;
         width: 50px;
@@ -47,27 +51,23 @@
     </style>
   </head>
   <body>
-    <hr/>
     <figure style="overflow:visible;" id="spinner"><div class="spinner"></div><center style="margin-top:0.5em"><strong>emscripten</strong></center></figure>
     <div class="emscripten" id="status">Downloading...</div>
     <div class="emscripten">
       <progress value="0" max="100" id="progress" hidden=1></progress>
     </div>
-    <div class="emscripten_border">
-      <canvas class="emscripten" id="canvas" oncontextmenu="event.preventDefault()"></canvas>
-    </div>
-    <hr/>
     <div class="emscripten">
-      <input type="checkbox" id="resize">Resize canvas
+      <canvas class="emscripten" id="canvas" oncontextmenu="event.preventDefault()"></canvas>
-      <input type="checkbox" id="pointerLock" checked>Lock/hide mouse pointer
+      Example compiled from <a href="https://github.com/ocornut/imgui">https://github.com/ocornut/imgui</a>
-      &nbsp;&nbsp;&nbsp;
-      <input type="button" value="Fullscreen" onclick="Module.requestFullscreen(document.getElementById('pointerLock').checked, 
-                                                                                document.getElementById('resize').checked)">
     </div>
+    <br>
+    <div class="emscripten">
+      <input type="button" value="Fullscreen" onclick="Module.requestFullscreen(false, document.getElementById('resize').checked)">
+      <!-- <input type="checkbox" id="resize">Resize canvas -->
+    </div>
+    <br>
 
-    <hr/>
+    <textarea class="emscripten" id="output" rows="4"></textarea>
-    <textarea class="emscripten" id="output" rows="8"></textarea>
-    <hr>
     <script type='text/javascript'>
       var statusElement = document.getElementById('status');
       var progressElement = document.getElementById('progress');