Examples: add Gtk3/OpenGL3 example

Author: llandwerlin-intel

examples/.gitignore

@@ -33,6 +33,7 @@ example_glfw_opengl2/example_glfw_opengl2
 example_glfw_opengl3/example_glfw_opengl3
 example_sdl_opengl2/example_sdl_opengl2
 example_sdl_opengl3/example_sdl_opengl3
+example_gtk3_opengl3/example_gtk3_opengl3
 
 ## Dear ImGui Ini files
 imgui.ini

examples/example_gtk3_opengl3/Makefile

@@ -0,0 +1,48 @@
+#
+# You will need GTK+ 3.0 :
+# Linux:
+#   apt-get install libgtk-3-dev
+#
+
+#CXX = g++
+#CXX = clang++
+
+EXE = example_gtk3_opengl3
+SOURCES = main.cpp
+SOURCES += ../imgui_impl_gtk3.cpp ../imgui_impl_opengl3.cpp
+SOURCES += ../../imgui.cpp ../../imgui_demo.cpp ../../imgui_draw.cpp ../../imgui_widgets.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 = -lGL `pkg-config --libs gtk+-3.0 epoxy` -ldl
+
+	CXXFLAGS = -I../ -I../../ -I../libs/gl3w `pkg-config --cflags gtk+-3.0`
+	CXXFLAGS += -Wall -Wformat -Wno-deprecated-declarations -Wno-parentheses
+	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_gtk3_opengl3/main.cpp

@@ -0,0 +1,167 @@
+// 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_gtk3.h"
+#include "imgui_impl_opengl3.h"
+#include <stdio.h>
+
+// About OpenGL function loaders: modern OpenGL doesn't have a standard header file and requires individual function pointers to be loaded manually.
+// Helper libraries are often used for this purpose! Here we are supporting a few common ones: gl3w, glew, glad.
+// You may use another loader/header of your choice (glext, glLoadGen, etc.), or chose to manually implement your own.
+#if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
+#include <GL/gl3w.h>    // Initialize with gl3wInit()
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
+#include <GL/glew.h>    // Initialize with glewInit()
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
+#include <glad/glad.h>  // Initialize with gladLoadGL()
+#else
+#include IMGUI_IMPL_OPENGL_LOADER_CUSTOM
+#endif
+
+#include <gtk/gtk.h>
+
+static gboolean render_area(GtkGLArea* area, GdkGLContext* context)
+{
+    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);
+
+    // Start the Dear ImGui frame
+    ImGui_ImplOpenGL3_NewFrame();
+    ImGui_ImplGtk3_NewFrame();
+    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 (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.
+    {
+        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", &show_demo_window);      // Edit bools storing our window open/close state
+        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*)&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 (show_another_window)
+    {
+        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"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+    glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+    glClear(GL_COLOR_BUFFER_BIT);
+    ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+
+    // Queue another rendering request.
+    gtk_gl_area_queue_render(area);
+
+    return TRUE;
+}
+
+static void realize_area(GtkGLArea* area)
+{
+    // 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_ImplGtk3_Init(GTK_WIDGET(area), true);
+    ImGui_ImplOpenGL3_Init("#version 130");
+
+    // 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);
+}
+
+static void unrealize_area(GtkGLArea* area)
+{
+    gtk_gl_area_make_current(area);
+
+    // Cleanup
+    ImGui_ImplOpenGL3_Shutdown();
+    ImGui_ImplGtk3_Shutdown();
+    ImGui::DestroyContext();
+}
+
+int main(int argc, char** argv)
+{
+    gtk_init(&argc, &argv);
+
+    // Create window with graphics context
+    GtkWidget* window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+    gtk_window_set_title(GTK_WINDOW(window), "Dear ImGui GTK+3 & OpenGL3 example");
+    g_signal_connect(window, "delete-event", G_CALLBACK(gtk_main_quit), NULL);
+    gtk_window_resize(GTK_WINDOW(window), 1280, 720);
+
+    GtkWidget* gl_area = gtk_gl_area_new();
+    gtk_gl_area_set_auto_render(GTK_GL_AREA(gl_area), TRUE);
+    g_signal_connect(gl_area, "realize", G_CALLBACK(realize_area), NULL);
+    g_signal_connect(gl_area, "unrealize", G_CALLBACK(unrealize_area), NULL);
+    g_signal_connect(gl_area, "render", G_CALLBACK(render_area), NULL);
+    gtk_container_add(GTK_CONTAINER(window), gl_area);
+
+    gtk_widget_show_all(window);
+
+    gtk_gl_area_make_current(GTK_GL_AREA(gl_area));
+
+    // Initialize OpenGL loader
+#if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
+    bool err = gl3wInit() != 0;
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
+    bool err = glewInit() != GLEW_OK;
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
+    bool err = gladLoadGL() != 0;
+#endif
+    if (err)
+    {
+        fprintf(stderr, "Failed to initialize OpenGL loader!\n");
+        return 1;
+    }
+
+    // Main loop
+    gtk_main();
+
+    return 0;
+}