Add EGL+OpenGLES 3.0 examples

examples/example_glfw_opengles3/Makefile

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+#
+# Cross Platform Makefile
+# Compatible with MSYS2/MINGW, Ubuntu 14.04.1 and Mac OS X
+#
+# You will need GLFW (http://www.glfw.org):
+# Linux:
+#   apt-get install libglfw-dev
+# Mac OS X:
+#   brew install glfw
+# MSYS2:
+#   pacman -S --noconfirm --needed mingw-w64-x86_64-toolchain mingw-w64-x86_64-glfw
+#
+
+#CXX = g++
+#CXX = clang++
+
+EXE = example_glfw_opengles3
+SOURCES = main.cpp
+SOURCES += ../imgui_impl_glfw.cpp ../imgui_impl_opengles3.cpp
+SOURCES += ../../imgui.cpp ../../imgui_demo.cpp ../../imgui_draw.cpp
+SOURCES += ../libs/gl3w/GL/gl3w.c
+OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
+
+UNAME_S := $(shell uname -s)
+
+
+ifeq ($(UNAME_S), Linux) #LINUX
+	ECHO_MESSAGE = "Linux"
+	LIBS = -lEGL -lGLESv2 `pkg-config --static --libs glfw3`
+
+	CXXFLAGS = -I../ -I../../ -I../libs/gl3w `pkg-config --cflags glfw3`
+	CXXFLAGS += -Wall -Wformat -D__EGL__
+	CFLAGS = $(CXXFLAGS)
+endif
+
+ifeq ($(UNAME_S), Darwin) #APPLE
+	ECHO_MESSAGE = "Mac OS X"
+	LIBS = -framework OpenGL -framework Cocoa -framework IOKit -framework CoreVideo
+	#LIBS += -L/usr/local/lib -lglfw3
+	LIBS += -L/usr/local/lib -lglfw
+
+	CXXFLAGS = -I../ -I../../ -I../libs/gl3w -I/usr/local/include
+	CXXFLAGS += -Wall -Wformat
+	CFLAGS = $(CXXFLAGS)
+endif
+
+ifeq ($(findstring MINGW,$(UNAME_S)),MINGW)
+   ECHO_MESSAGE = "Windows"
+   LIBS = -lglfw3 -lgdi32 -lopengl32 -limm32
+
+   CXXFLAGS = -I../ -I../../ -I../libs/gl3w `pkg-config --cflags glfw3`
+   CXXFLAGS += -Wall -Wformat
+   CFLAGS = $(CXXFLAGS)
+endif
+
+
+%.o:%.cpp
+	$(CXX) $(CXXFLAGS) -c -o $@ $<
+
+%.o:../%.cpp
+	$(CXX) $(CXXFLAGS) -c -o $@ $<
+
+%.o:../../%.cpp
+	$(CXX) $(CXXFLAGS) -c -o $@ $<
+
+%.o:../libs/gl3w/GL/%.c
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+all: $(EXE)
+	@echo Build complete for $(ECHO_MESSAGE)
+
+$(EXE): $(OBJS)
+	$(CXX) -o $@ $^ $(CXXFLAGS) $(LIBS)
+
+clean:
+	rm -f $(EXE) $(OBJS)

examples/example_glfw_opengles3/main.cpp

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+// ImGui - standalone example application for GLFW + OpenGL 3, using programmable pipeline
+// If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
+// (GLFW is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.)
+// (GL3W is a helper library to access OpenGL functions since there is no standard header to access modern OpenGL functions easily. Alternatives are GLEW, Glad, etc.)
+
+#include "imgui.h"
+#include "imgui_impl_glfw.h"
+#include "imgui_impl_opengles3.h"
+#include <stdio.h>
+
+#include <GL/gl3w.h>    // This example is using gl3w to access OpenGL functions. You may use another OpenGL loader/header such as: glew, glext, glad, glLoadGen, etc.
+//#include <glew.h>
+//#include <glext.h>
+//#include <glad/glad.h>
+
+#include <GLFW/glfw3.h> // Include glfw3.h after our OpenGL definitions
+
+static void glfw_error_callback(int error, const char* description)
+{
+    fprintf(stderr, "Glfw Error %d: %s\n", error, description);
+}
+
+int main(int, char**)
+{
+    // Setup window
+    glfwSetErrorCallback(glfw_error_callback);
+    if (!glfwInit())
+        return 1;
+
+    // Decide GL+GLSL versions
+#if __APPLE__
+    // GL 3.2 + GLSL 150
+    const char* glsl_version = "#version 150";
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
+    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);  // 3.2+ only
+    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);            // Required on Mac
+#else
+    // GLES 3.0 + GLSL 100
+    const char* glsl_version = "#version 100";
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
+    glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
+    glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_EGL_CONTEXT_API);
+    //glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);  // 3.2+ only
+    //glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);            // 3.0+ only
+#endif
+
+    // Create window with graphics context
+    GLFWwindow* window = glfwCreateWindow(1280, 720, "ImGui GLFW+OpenGLES3 example", NULL, NULL);
+    if (window == NULL)
+        return 1;
+    glfwMakeContextCurrent(window);
+    glfwSwapInterval(1); // Enable vsync
+    gl3wInit();
+
+    // Setup Dear ImGui binding
+    IMGUI_CHECKVERSION();
+    ImGui::CreateContext();
+    ImGuiIO& io = ImGui::GetIO(); (void)io;
+    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
+    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;   // Enable Gamepad Controls
+
+    ImGui_ImplGlfw_InitForOpenGL(window, true);
+    ImGui_ImplOpenGL3_Init(glsl_version);
+
+    // Setup style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
+    // 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);
+
+    bool show_demo_window = true;
+    bool show_another_window = false;
+    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+    // Main loop
+    while (!glfwWindowShouldClose(window))
+    {
+        // 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.
+        glfwPollEvents();
+
+        // Start the ImGui frame
+        ImGui_ImplOpenGL3_NewFrame();
+        ImGui_ImplGlfw_NewFrame();
+        ImGui::NewFrame();
+
+        // 1. Show a simple window.
+        // Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets automatically appears in a window called "Debug".
+        {
+            static float f = 0.0f;
+            static int counter = 0;
+            ImGui::Text("Hello, world!");                           // Display some text (you can use a format string too)
+            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*)&clear_color); // Edit 3 floats representing a color
+
+            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our windows open/close state
+            ImGui::Checkbox("Another Window", &show_another_window);
+
+            if (ImGui::Button("Button"))                            // Buttons return true when clicked (NB: 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);
+        }
+
+        // 2. Show another simple window. In most cases you will use an explicit Begin/End pair to name your windows.
+        if (show_another_window)
+        {
+            ImGui::Begin("Another Window", &show_another_window);
+            ImGui::Text("Hello from another window!");
+            if (ImGui::Button("Close Me"))
+                show_another_window = false;
+            ImGui::End();
+        }
+
+        // 3. Show the ImGui demo window. Most of the sample code is in ImGui::ShowDemoWindow(). Read its code to learn more about Dear ImGui!
+        if (show_demo_window)
+        {
+            ImGui::SetNextWindowPos(ImVec2(650, 20), ImGuiCond_FirstUseEver); // Normally user code doesn't need/want to call this because positions are saved in .ini file anyway. Here we just want to make the demo initial state a bit more friendly!
+            ImGui::ShowDemoWindow(&show_demo_window);
+        }
+
+        // Rendering
+        ImGui::Render();
+        int display_w, display_h;
+        glfwMakeContextCurrent(window);
+        glfwGetFramebufferSize(window, &display_w, &display_h);
+        glViewport(0, 0, display_w, display_h);
+        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+        glClear(GL_COLOR_BUFFER_BIT);
+        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+
+        glfwMakeContextCurrent(window);
+        glfwSwapBuffers(window);
+    }
+
+    // Cleanup
+    ImGui_ImplOpenGL3_Shutdown();
+    ImGui_ImplGlfw_Shutdown();
+    ImGui::DestroyContext();
+
+    glfwDestroyWindow(window);
+    glfwTerminate();
+
+    return 0;
+}