kge/gmain.cc

#include <iostream>

// imgui includes
#include <imgui/imgui.h>
#include <imgui/backends/imgui_impl_sdl2.h>
#include <imgui/backends/imgui_impl_opengl3.h>
#include <SDL2/SDL.h>

#if defined(IMGUI_IMPL_OPENGL_ES2)
#include <SDL2/SDL_opengles2.h>
#else

#include <SDL2/SDL_opengl.h>

#endif

#include "fonts/brassmono.h"


static const float fontPixelSizes[] = {16, 10, 12, 14, 18};


int
main(int argc, char *argv[])
{
	// SDL2 requires main have these parameters, but they're not being used
	// yet.
	(void)argc;
	(void)argv;

	// Should this use the SDL_EVENTS subsystem?
	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) != 0) {
		std::cerr << "kge: failed to initialize SDL" << std::endl;
		std::cerr << "\t" << SDL_GetError() << std::endl;
		return -1;
	}

	// Decide GL+GLSL versions. Taken from the imgui examples.
#if defined(IMGUI_IMPL_OPENGL_ES2)
	// GL ES 2.0 + GLSL 100
	const char* glsl_version = "#version 100";
	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, 2);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
#elif defined(__APPLE__)
	// GL 3.2 Core + GLSL 150
	const char *glsl_version = "#version 150";
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS,
			    SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG); // Always required on Mac
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK,
			    SDL_GL_CONTEXT_PROFILE_CORE);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
#else
	// GL 3.0 + GLSL 130
	const char* glsl_version = "#version 130";
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
#endif

	// From 2.0.18: Enable native IME.
#ifdef SDL_HINT_IME_SHOW_UI
	SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");
#endif

	// 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_WindowFlags window_flags = (SDL_WindowFlags) (SDL_WINDOW_OPENGL |
							  SDL_WINDOW_RESIZABLE |
							  SDL_WINDOW_ALLOW_HIGHDPI);
	SDL_Window *window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL3 example",
					      SDL_WINDOWPOS_CENTERED,
					      SDL_WINDOWPOS_CENTERED, 1280, 720,
					      window_flags);
	SDL_GLContext gl_context = SDL_GL_CreateContext(window);
	SDL_GL_MakeCurrent(window, gl_context);
	SDL_GL_SetSwapInterval(1); // Enable vsync

	// Setup Dear ImGui context
	IMGUI_CHECKVERSION();
	ImGui::CreateContext();
	ImGuiIO &io = ImGui::GetIO();
	(void) io;
	io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;

	// Setup Dear ImGui style
	ImGui::StyleColorsDark();
	//ImGui::StyleColorsLight();

	// Setup Platform/Renderer backends
	ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
	ImGui_ImplOpenGL3_Init(glsl_version);

	for (auto pixelSize: fontPixelSizes) {
		io.Fonts->AddFontFromMemoryCompressedTTF(
		    BrassMono_Regular_compressed_data,
		    BrassMono_Regular_compressed_size, pixelSize);
	}

	bool done = false;
	bool show_demo_window = true;
	bool show_another_window = false;
	ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

	while (!done) {
		// 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, or clear/overwrite your copy of the mouse data.
		// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
		// 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);
			if (event.type == SDL_QUIT)
				done = true;
			if (event.type == SDL_WINDOWEVENT &&
			    event.window.event == SDL_WINDOWEVENT_CLOSE &&
			    event.window.windowID == SDL_GetWindowID(window))
				done = true;
		}

		// Start the Dear ImGui frame
		ImGui_ImplOpenGL3_NewFrame();
		ImGui_ImplSDL2_NewFrame();
		ImGui::NewFrame();

		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 create 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 / io.Framerate, io.Framerate);
			ImGui::End();
		}

		// 3. Show another simple window.
		if (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);

			ImGui::Text("Hello from another window!");
			if (ImGui::Button("Close Me"))
				show_another_window = false;
			ImGui::End();
		}

		// Rendering
		ImGui::Render();
		glViewport(0, 0, (int) io.DisplaySize.x,
			   (int) io.DisplaySize.y);
		glClearColor(clear_color.x * clear_color.w,
			     clear_color.y * clear_color.w,
			     clear_color.z * clear_color.w, clear_color.w);
		glClear(GL_COLOR_BUFFER_BIT);
		ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
		SDL_GL_SwapWindow(window);
	}

	// Cleanup
	ImGui_ImplOpenGL3_Shutdown();
	ImGui_ImplSDL2_Shutdown();
	ImGui::DestroyContext();

	SDL_GL_DeleteContext(gl_context);
	SDL_DestroyWindow(window);
	SDL_Quit();

	return 0;
}