gistfile1.txt

// Dear ImGui: standalone example application for GLFW + OpenGL 3, using programmable pipeline
// (GLFW is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan/Metal graphics context creation, etc.)
// If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
// Read online: https://github.com/ocornut/imgui/tree/master/docs

#define _CRT_SECURE_NO_WARNINGS

#include "imgui.h"
#include "imgui_impl_glfw.h"
#include "imgui_impl_opengl3.h"
#include <stdio.h>
#include <glm/glm.hpp>
#include <vector>
#include <cstdio>
#include <cstdarg>
#include <vector>
#include <cassert>
#include <string>

#include "stb_image.h"

// About Desktop OpenGL function loaders:
//  Modern desktop OpenGL doesn't have a standard portable header file to load OpenGL function pointers.
//  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()
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
#include <glad/gl.h>            // Initialize with gladLoadGL(...) or gladLoaderLoadGL()
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
#define GLFW_INCLUDE_NONE       // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
#include <glbinding/Binding.h>  // Initialize with glbinding::Binding::initialize()
#include <glbinding/gl/gl.h>
using namespace gl;
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3)
#define GLFW_INCLUDE_NONE       // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
#include <glbinding/glbinding.h>// Initialize with glbinding::initialize()
#include <glbinding/gl/gl.h>
using namespace gl;
#else
#include IMGUI_IMPL_OPENGL_LOADER_CUSTOM
#endif

// Include glfw3.h after our OpenGL definitions
#include <GLFW/glfw3.h>

// [Win32] Our example includes a copy of glfw3.lib pre-compiled with VS2010 to maximize ease of testing and compatibility with old VS compilers.
// To link with VS2010-era libraries, VS2015+ requires linking with legacy_stdio_definitions.lib, which we do using this pragma.
// Your own project should not be affected, as you are likely to link with a newer binary of GLFW that is adequate for your version of Visual Studio.
#if defined(_MSC_VER) && (_MSC_VER >= 1900) && !defined(IMGUI_DISABLE_WIN32_FUNCTIONS)
#pragma comment(lib, "legacy_stdio_definitions")
#endif

static void glfw_error_callback(int error, const char* description)
{
    fprintf(stderr, "Glfw Error %d: %s\n", error, description);
}
#if _WIN32
extern "C" __declspec(dllimport) void __stdcall OutputDebugStringA(const char* _str);
#else
#   if defined(__OBJC__)
#       import <Foundation/NSObjCRuntime.h>
#   else
#       include <CoreFoundation/CFString.h>
extern "C" void NSLog(CFStringRef _format, ...);
#   endif
#endif

void debug_output(const char* message)
{
#if _WIN32
    fprintf(stderr, message);
    OutputDebugStringA(message);
#else
#   if defined(__OBJC__)
    NSLog(@"%s", message);
#   else
    NSLog(CFSTR("%s"), message);
#   endif
#endif
}

void trace(const char* format...)
{
    const int kLength = 1024;
    char buffer[kLength + 1] = { 0, };

    va_list argList;
    va_start(argList, format);
    int len = vsnprintf(buffer, kLength, format, argList);
    va_end(argList);
    if (len > kLength)
        len = kLength;
    buffer[len] = '\0';

    debug_output(buffer);
}

GLuint createTexture(int32_t width, int32_t height, float* data)
{
    GLenum format = GL_RGBA;
    GLenum internalFormat = GL_RGBA;

    GLuint instance = 0;
    glGenTextures(1, &instance);
    glActiveTexture(GL_TEXTURE0 + 16 - 1);
    glBindTexture(GL_TEXTURE_2D, instance);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, width, height, 0, format, GL_FLOAT, data);
    glBindTexture(GL_TEXTURE_2D, 0);

    return instance;
}

GLuint createTexture(std::string path)
{
    stbi_set_flip_vertically_on_load(true);

    FILE* fp = fopen(path.c_str(), "rb");
    if (fp == NULL)
        return 0;

    fseek(fp, 0, SEEK_END);
    long length = ftell(fp);
    fseek(fp, 0, SEEK_SET);
    std::vector<char> storage(length);;
    length = (long)fread(storage.data(), 1, length, fp);
    fclose(fp);

    GLenum target = GL_TEXTURE_2D;
    GLenum type = GL_UNSIGNED_BYTE;
    int width = 0, height = 0, nrComponents = 0;
    stbi_uc* imagedata = stbi_load_from_memory(
        (stbi_uc*)storage.data(),
        (int)length, &width, &height, &nrComponents, 0);

    if (!imagedata)
        return 0;

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

    GLuint instance = 0;
    glGenTextures(1, &instance);
    glActiveTexture(GL_TEXTURE0 + 16 - 1);
    glBindTexture(target, instance);
    glTexImage2D(target, 0, GL_RGB, width, height, 0, GL_RGB, type, imagedata);
    glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameterf(target, GL_TEXTURE_MAX_ANISOTROPY, 16);
    glGenerateMipmap(target);
    glBindTexture(GL_TEXTURE_2D, 0);

    stbi_image_free(imagedata);

    glPixelStorei(GL_UNPACK_ALIGNMENT, 4);

    return instance;
}

void bindTexture(GLuint texID, uint8_t slot)
{
    assert(texID != 0);
    glActiveTexture(GL_TEXTURE0 + slot);
    glBindTexture(GL_TEXTURE_2D, texID);
};

GLuint createShader(GLenum type, const char* shaderCode)
{
    GLuint id = glCreateShader(type);
    if (id == 0)
        return 0;

    glShaderSource(id, 1, &shaderCode, 0);
    glCompileShader(id);

    GLint compiled = 0;
    glGetShaderiv(id, GL_COMPILE_STATUS, &compiled);
    if (compiled == GL_FALSE)
    {
        GLint length = 0;
        glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
        std::vector<GLchar> buffer(length + 1);
        glGetShaderInfoLog(id, length, 0, buffer.data());
        trace("%s (%d) %s\n", __FILE__, __LINE__, buffer.data());
        glDeleteShader(id);
        return 0;
    }
    return id;
}

GLuint createProgram(GLuint vertex, GLuint fragment)
{
    GLuint id = glCreateProgram();

    GLint status = 0;
    if (vertex != 0)
    {
        glAttachShader(id, vertex);
        if (fragment != 0)
            glAttachShader(id, fragment);
        glLinkProgram(id);
        glGetProgramiv(id, GL_LINK_STATUS, &status);

        if (status == GL_FALSE)
        {
            const uint32_t kBufferSize = 512u;
            char log[kBufferSize];
            glGetProgramInfoLog(id, sizeof(log), nullptr, log);
            trace("%s:%d %d: %s", __FILE__, __LINE__, status, log);
            return 0;
        }
    }

    if (status == GL_FALSE)
    {
        glDeleteProgram(id);
        id = 0;
        return id;
    }

    return id;
}

struct ProgramDesc
{
    const char* vertexShader = nullptr;
    const char* fragmentShader = nullptr;
};

struct Program
{
    GLuint vertex = 0;
    GLuint framgment = 0;
    GLuint id = 0;
};

GLuint createShader(GLenum type, const char* shaderCode);
GLuint createProgram(GLuint vertex, GLuint fragment);

Program createProgram(const ProgramDesc& desc);
void destroyProgram(Program& program);

Program createProgram(const ProgramDesc& desc)
{
    GLuint vs = createShader(GL_VERTEX_SHADER, desc.vertexShader);
    GLuint fs = createShader(GL_FRAGMENT_SHADER, desc.fragmentShader);

    assert(vs != 0);
    assert(fs != 0);

    GLuint id = createProgram(vs, fs);

    Program program;
    program.vertex = vs;
    program.framgment = fs;
    program.id = id;

    return program;
}

void destroyProgram(Program& program)
{
    glDeleteProgram(program.id);
    glDeleteShader(program.vertex);
    glDeleteShader(program.framgment);

    program.vertex = 0;
    program.framgment = 0;
    program.id = 0;
}


struct vertex_t {
    glm::vec3 position;
    glm::vec2 texcoord;
};

struct VertexArray
{
    GLuint vao = 0;
    GLuint vbo = 0;
    GLuint ibo = 0;
    size_t vertexCount = 0;
    size_t indexCount = 0;
};

VertexArray* createVertexArray(float* vertices, size_t vertexCount, uint32_t* indices, size_t indexCount) {
    GLuint ibo = 0;
    GLuint vbo = 0;
    glGenBuffers(1, &vbo);
    glGenBuffers(1, &ibo);

    const size_t vertexBytes = sizeof(vertex_t)*vertexCount;

    GLuint vao = 0;
    glCreateVertexArrays(1, &vao);
    glBindVertexArray(vao);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, vertexBytes, vertices, GL_DYNAMIC_DRAW);

    const size_t indexBytes = sizeof(uint32_t) * indexCount;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indexBytes, indices, GL_DYNAMIC_DRAW);

    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);

    GLsizei stride = sizeof(vertex_t);
    auto positionOffset = (const void*)offsetof(vertex_t, position);
    auto texcoordOffset = (const void*)offsetof(vertex_t, texcoord);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, stride, positionOffset);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, stride, texcoordOffset);

    glBindVertexArray(0);

    auto vtxArr = new VertexArray();
    if (vtxArr) {
        vtxArr->vao = vao;
        vtxArr->vbo = vbo;
        vtxArr->ibo = ibo;
        vtxArr->vertexCount = vertexCount;
        vtxArr->indexCount = indexCount;
    }
    return vtxArr;
}

int main(int, char**)
{
    // Setup window
    glfwSetErrorCallback(glfw_error_callback);
    if (!glfwInit())
        return 1;

    // Decide GL+GLSL versions
#ifdef __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
    // GL 3.0 + GLSL 130
    const char* glsl_version = "#version 130";
    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);            // 3.0+ only
#endif

    // Create window with graphics context
    GLFWwindow* window = glfwCreateWindow(1280, 720, "Dear ImGui GLFW+OpenGL3 example", NULL, NULL);
    if (window == NULL)
        return 1;
    glfwMakeContextCurrent(window);
    glfwSwapInterval(1); // Enable vsync

    // 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;
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
    bool err = gladLoadGL(glfwGetProcAddress) == 0; // glad2 recommend using the windowing library loader instead of the (optionally) bundled one.
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
    bool err = false;
    glbinding::Binding::initialize();
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3)
    bool err = false;
    glbinding::initialize([](const char* name) { return (glbinding::ProcAddress)glfwGetProcAddress(name); });
#else
    bool err = false; // If you use IMGUI_IMPL_OPENGL_LOADER_CUSTOM, your loader is likely to requires some form of initialization.
#endif
    if (err)
    {
        fprintf(stderr, "Failed to initialize OpenGL loader!\n");
        return 1;
    }

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

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

    // Setup Platform/Renderer backends
    ImGui_ImplGlfw_InitForOpenGL(window, true);
    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 'docs/FONTS.md' 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);

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

    std::vector<float> vertices = {
        -1.0, -1.0, 0.0, 0.0, 0.0,
        +3.0, -1.0, 0.0, 2.0, 0.0,
        -1.0, +3.0, 0.0, 0.0, 2.0,
    };
    std::vector<uint32_t> indices = {
        0, 1, 2
    };

    auto vertexArray = createVertexArray(
        vertices.data(),
        vertices.size(),
        indices.data(),
        indices.size());

    const char* vertexShader = R"__(
attribute vec3 a_position;
attribute vec2 a_texcoord;
varying vec2 v_texcoord;

void main() {
    gl_Position = vec4(a_position, 1.0);
    v_texcoord = a_texcoord;
}
)__";
    const char* fragmentShader = R"__(
#ifdef GL_ES
    precision mediump float;
#endif
varying vec2 v_texcoord;
uniform sampler2D u_texture;

void main() {
    gl_FragColor = texture2D(u_texture, v_texcoord);
}
)__";
    auto program = createProgram({vertexShader, fragmentShader});
    glUseProgram(program.id);

    GLuint tmu = 0;
    GLint sampler = glGetUniformLocation(program.id, "u_texture");
    assert(sampler >= 0);
    glUniform1i(sampler, tmu++);

    glUseProgram(0);

    GLuint texture = createTexture("checker.jpg");

    // 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 Dear ImGui frame
        ImGui_ImplOpenGL3_NewFrame();
        ImGui_ImplGlfw_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();
        int display_w, display_h;
        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);

        glUseProgram(program.id);
        bindTexture(texture, 0);
        glBindVertexArray(vertexArray->vao);
        glDrawArrays(GL_TRIANGLES, 0, 3);
        glUseProgram(0);

        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

        glfwSwapBuffers(window);
    }

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

    glfwDestroyWindow(window);
    glfwTerminate();

    return 0;
}