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Adding standalone Emscripten example.

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This commit is contained in:
Nicolas "Pixel" Noble 2019-04-13 17:25:06 +02:00
parent 30d81f53cb
commit a936d0669c
4 changed files with 384 additions and 0 deletions
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58
examples/example_emscripten/Makefile Normal file
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#
# Makefile to use with emscripten
# See https://emscripten.org/docs/getting_started/downloads.html
# for installation instructions. This Makefile assumes you have
# loaded emscripten's environment.
#
# Running `make` will produce three files:
# - example_emscripten.html
# - example_emscripten.js
# - example_emscripten.wasm
#
# All three are needed to run the demo.
CC = emcc
CXX = em++
EXE = example_emscripten.html
SOURCES = main.cpp
SOURCES += ../imgui_impl_sdl.cpp ../imgui_impl_opengl3.cpp
SOURCES += ../../imgui.cpp ../../imgui_demo.cpp ../../imgui_draw.cpp ../../imgui_widgets.cpp
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 ALLOW_MEMORY_GROWTH=1 -s BINARYEN_TRAP_MODE=clamp
EMS += -s DISABLE_EXCEPTION_CATCHING=1 -s EXIT_RUNTIME=1
EMS += -s ASSERTIONS=1 -s SAFE_HEAP=1
CPPFLAGS = -I../ -I../../
CPPFLAGS += -g -Wall -Wformat -O3
CPPFLAGS += $(EMS)
LIBS = $(EMS)
LDFLAGS = --shell-file shell_minimal.html
##---------------------------------------------------------------------
## BUILD RULES
##---------------------------------------------------------------------
%.o:%.cpp
$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<
%.o:../%.cpp
$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<
%.o:../../%.cpp
$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<
%.o:../libs/gl3w/GL/%.c
$(CC) $(CPPFLAGS) $(CFLAGS) -c -o $@ $<
all: $(EXE)
@echo Build complete for $(EXE)
$(EXE): $(OBJS)
$(CXX) -o $@ $^ $(LIBS) $(LDFLAGS)
clean:
rm -f $(EXE) $(OBJS) *.js *.wasm

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examples/example_emscripten/README.md Normal file
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# How to Build
- You need to install Emscripten from https://emscripten.org/docs/getting_started/downloads.html, and have the environment variables set, as described in https://emscripten.org/docs/getting_started/downloads.html#installation-instructions
```
em++ -I.. -I../.. main.cpp ../imgui_impl_sdl.cpp ../imgui_impl_opengl3.cpp ../../imgui*.cpp -s USE_SDL=2 -s USE_WEBGL2=1 -s WASM=1 -s FULL_ES3=1 -s ALLOW_MEMORY_GROWTH=1 -s BINARYEN_TRAP_MODE=clamp --shell-file shell_minimal.html -o example-emscripten.html
```

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examples/example_emscripten/main.cpp Normal file
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// dear imgui: standalone example application for Emscripten, using SDL2 + OpenGL3
// This is mostly the same code as the SDL2 + OpenGL3 example, simply with the modifications needed to run on Emscripten.
// It is possible to combine both code into a single source file that will compile properly on Desktop and using Emscripten.
// See https://github.com/ocornut/imgui/pull/2492 as an example on how to do just that.
//
// If you are new to dear imgui, see examples/README.txt and documentation at the top of imgui.cpp.
// (Emscripten is a C++-to-javascript compiler, used to publish executables for the web. See https://emscripten.org/)
#include "imgui.h"
#include "imgui_impl_sdl.h"
#include "imgui_impl_opengl3.h"
#include <stdio.h>
#include <emscripten.h>
#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.
// 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* window = 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)
{
printf("Error: %s\n", SDL_GetError());
return -1;
}
// For the browser using emscripten, we are going to use WebGL2 with GLES3. See the Makefile.emscripten 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";
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_MINOR_VERSION, 0);
// Create window with graphics context
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
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);
vars.gl_context = SDL_GL_CreateContext(vars.window);
if (!vars.gl_context) {
fprintf(stderr, "Failed to initialize WebGL context!\n");
return 1;
}
SDL_GL_SetSwapInterval(1); // Enable vsync
// Setup Dear ImGui context
IMGUI_CHECKVERSION();
ImGui::CreateContext();
ImGuiIO& io = ImGui::GetIO(); (void)io;
//io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
// Setup Dear ImGui style
ImGui::StyleColorsDark();
//ImGui::StyleColorsClassic();
// Setup Platform/Renderer bindings
ImGui_ImplSDL2_InitForOpenGL(vars.window, vars.gl_context);
ImGui_ImplOpenGL3_Init(glsl_version);
// Load Fonts
// - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
// - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
// - If the file cannot be loaded, the function will return NULL. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
// - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
// - Read 'misc/fonts/README.txt' 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 \\ !
//io.Fonts->AddFontDefault();
//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
//io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
//io.Fonts->AddFontFromFileTTF("../../misc/fonts/ProggyTiny.ttf", 10.0f);
//ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
//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);
}
void main_loop(void* arg) {
MainLoopVars* vars = (MainLoopVars*) arg;
ImGuiIO& io = ImGui::GetIO();
// 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.
// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
SDL_Event event;
while (SDL_PollEvent(&event))
{
ImGui_ImplSDL2_ProcessEvent(&event);
// Capture events here, based on io.WantCaptureMouse and io.WantCaptureKeyboard
}
// Start the Dear ImGui frame
ImGui_ImplOpenGL3_NewFrame();
ImGui_ImplSDL2_NewFrame(vars->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)
ImGui::ShowDemoWindow(&vars->show_demo_window);
// 2. Show a simple window that we create ourselves. We use a Begin/End pair to created a named window.
{
static float f = 0.0f;
static int counter = 0;
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("Another Window", &vars->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
if (ImGui::Button("Button")) // Buttons return true when clicked (most widgets return true when edited/activated)
counter++;
ImGui::SameLine();
ImGui::Text("counter = %d", counter);
ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
ImGui::End();
}
// 3. Show another simple window.
if (vars->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::Text("Hello from another window!");
if (ImGui::Button("Close Me"))
vars->show_another_window = false;
ImGui::End();
}
// Rendering
ImGui::Render();
SDL_GL_MakeCurrent(vars->window, vars->gl_context);
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);
glClear(GL_COLOR_BUFFER_BIT);
ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
SDL_GL_SwapWindow(vars->window);
}

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examples/example_emscripten/shell_minimal.html Normal file
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<!doctype html>
<html lang="en-us">
<head>
<meta charset="utf-8">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Emscripten-Generated Code</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; }
/* the canvas *must not* have any border or padding, or mouse coords will be wrong */
canvas.emscripten { border: 0px none; background-color: black; }
.spinner {
height: 50px;
width: 50px;
margin: 0px auto;
-webkit-animation: rotation .8s linear infinite;
-moz-animation: rotation .8s linear infinite;
-o-animation: rotation .8s linear infinite;
animation: rotation 0.8s linear infinite;
border-left: 10px solid rgb(0,150,240);
border-right: 10px solid rgb(0,150,240);
border-bottom: 10px solid rgb(0,150,240);
border-top: 10px solid rgb(100,0,200);
border-radius: 100%;
background-color: rgb(200,100,250);
}
@-webkit-keyframes rotation {
from {-webkit-transform: rotate(0deg);}
to {-webkit-transform: rotate(360deg);}
}
@-moz-keyframes rotation {
from {-moz-transform: rotate(0deg);}
to {-moz-transform: rotate(360deg);}
}
@-o-keyframes rotation {
from {-o-transform: rotate(0deg);}
to {-o-transform: rotate(360deg);}
}
@keyframes rotation {
from {transform: rotate(0deg);}
to {transform: rotate(360deg);}
}
</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
<input type="checkbox" id="pointerLock" checked>Lock/hide mouse pointer
&nbsp;&nbsp;&nbsp;
<input type="button" value="Fullscreen" onclick="Module.requestFullscreen(document.getElementById('pointerLock').checked,
document.getElementById('resize').checked)">
</div>
<hr/>
<textarea class="emscripten" id="output" rows="8"></textarea>
<hr>
<script type='text/javascript'>
var statusElement = document.getElementById('status');
var progressElement = document.getElementById('progress');
var spinnerElement = document.getElementById('spinner');
var Module = {
preRun: [],
postRun: [],
print: (function() {
var element = document.getElementById('output');
if (element) element.value = ''; // clear browser cache
return function(text) {
if (arguments.length > 1) text = Array.prototype.slice.call(arguments).join(' ');
// These replacements are necessary if you render to raw HTML
//text = text.replace(/&/g, "&amp;");
//text = text.replace(/</g, "&lt;");
//text = text.replace(/>/g, "&gt;");
//text = text.replace('\n', '<br>', 'g');
console.log(text);
if (element) {
element.value += text + "\n";
element.scrollTop = element.scrollHeight; // focus on bottom
}
};
})(),
printErr: function(text) {
if (arguments.length > 1) text = Array.prototype.slice.call(arguments).join(' ');
if (0) { // XXX disabled for safety typeof dump == 'function') {
dump(text + '\n'); // fast, straight to the real console
} else {
console.error(text);
}
},
canvas: (function() {
var canvas = document.getElementById('canvas');
// As a default initial behavior, pop up an alert when webgl context is lost. To make your
// application robust, you may want to override this behavior before shipping!
// See http://www.khronos.org/registry/webgl/specs/latest/1.0/#5.15.2
canvas.addEventListener("webglcontextlost", function(e) { alert('WebGL context lost. You will need to reload the page.'); e.preventDefault(); }, false);
return canvas;
})(),
setStatus: function(text) {
if (!Module.setStatus.last) Module.setStatus.last = { time: Date.now(), text: '' };
if (text === Module.setStatus.last.text) return;
var m = text.match(/([^(]+)\((\d+(\.\d+)?)\/(\d+)\)/);
var now = Date.now();
if (m && now - Module.setStatus.last.time < 30) return; // if this is a progress update, skip it if too soon
Module.setStatus.last.time = now;
Module.setStatus.last.text = text;
if (m) {
text = m[1];
progressElement.value = parseInt(m[2])*100;
progressElement.max = parseInt(m[4])*100;
progressElement.hidden = false;
spinnerElement.hidden = false;
} else {
progressElement.value = null;
progressElement.max = null;
progressElement.hidden = true;
if (!text) spinnerElement.hidden = true;
}
statusElement.innerHTML = text;
},
totalDependencies: 0,
monitorRunDependencies: function(left) {
this.totalDependencies = Math.max(this.totalDependencies, left);
Module.setStatus(left ? 'Preparing... (' + (this.totalDependencies-left) + '/' + this.totalDependencies + ')' : 'All downloads complete.');
}
};
Module.setStatus('Downloading...');
window.onerror = function() {
Module.setStatus('Exception thrown, see JavaScript console');
spinnerElement.style.display = 'none';
Module.setStatus = function(text) {
if (text) Module.printErr('[post-exception status] ' + text);
};
};
</script>
{{{ SCRIPT }}}
</body>
</html>