code:
// dear imgui: Renderer Backend for modern OpenGL with shaders / programmatic pipeline
// - Desktop GL: 2.x 3.x 4.x
// - Embedded GL: ES 2.0 (WebGL 1.0), ES 3.0 (WebGL 2.0)
// This needs to be used along with a Platform Backend (e.g. GLFW, SDL, Win32, custom..)

// Implemented features:
//  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID!
//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
//  [x] Renderer: Desktop GL only: Support for large meshes (64k+ vertices) with 16-bit indices.

// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
// 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

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
//  2022-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
//  2021-12-15: OpenGL: Using buffer orphaning + glBufferSubData(), seems to fix leaks with multi-viewports with some Intel HD drivers.
//  2021-08-23: OpenGL: Fixed ES 3.0 shader ("#version 300 es") use normal precision floats to avoid wobbly rendering at HD resolutions.
//  2021-08-19: OpenGL: Embed and use our own minimal GL loader (imgui_impl_opengl3_loader.h), removing requirement and support for third-party loader.
//  2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX).
//  2021-06-25: OpenGL: Use OES_vertex_array extension on Emscripten + backup/restore current state.
//  2021-06-21: OpenGL: Destroy individual vertex/fragment shader objects right after they are linked into the main shader.
//  2021-05-24: OpenGL: Access GL_CLIP_ORIGIN when "GL_ARB_clip_control" extension is detected, inside of just OpenGL 4.5 version.
//  2021-05-19: OpenGL: Replaced direct access to ImDrawCmd::TextureId with a call to ImDrawCmd::GetTexID(). (will become a requirement)
//  2021-04-06: OpenGL: Don't try to read GL_CLIP_ORIGIN unless we're OpenGL 4.5 or greater.
//  2021-02-18: OpenGL: Change blending equation to preserve alpha in output buffer.
//  2021-01-03: OpenGL: Backup, setup and restore GL_STENCIL_TEST state.
//  2020-10-23: OpenGL: Backup, setup and restore GL_PRIMITIVE_RESTART state.
//  2020-10-15: OpenGL: Use glGetString(GL_VERSION) instead of glGetIntegerv(GL_MAJOR_VERSION, ...) when the later returns zero (e.g. Desktop GL 2.x)
//  2020-09-17: OpenGL: Fix to avoid compiling/calling glBindSampler() on ES or pre 3.3 context which have the defines set by a loader.
//  2020-07-10: OpenGL: Added support for glad2 OpenGL loader.
//  2020-05-08: OpenGL: Made default GLSL version 150 (instead of 130) on OSX.
//  2020-04-21: OpenGL: Fixed handling of glClipControl(GL_UPPER_LEFT) by inverting projection matrix.
//  2020-04-12: OpenGL: Fixed context version check mistakenly testing for 4.0+ instead of 3.2+ to enable ImGuiBackendFlags_RendererHasVtxOffset.
//  2020-03-24: OpenGL: Added support for glbinding 2.x OpenGL loader.
//  2020-01-07: OpenGL: Added support for glbinding 3.x OpenGL loader.
//  2019-10-25: OpenGL: Using a combination of GL define and runtime GL version to decide whether to use glDrawElementsBaseVertex(). Fix building with pre-3.2 GL loaders.
//  2019-09-22: OpenGL: Detect default GL loader using __has_include compiler facility.
//  2019-09-16: OpenGL: Tweak initialization code to allow application calling ImGui_ImplOpenGL3_CreateFontsTexture() before the first NewFrame() call.
//  2019-05-29: OpenGL: Desktop GL only: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
//  2019-04-30: OpenGL: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
//  2019-03-29: OpenGL: Not calling glBindBuffer more than necessary in the render loop.
//  2019-03-15: OpenGL: Added a GL call + comments in ImGui_ImplOpenGL3_Init() to detect uninitialized GL function loaders early.
//  2019-03-03: OpenGL: Fix support for ES 2.0 (WebGL 1.0).
//  2019-02-20: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read GL_CLIP_ORIGIN even if defined by the headers/loader.
//  2019-02-11: OpenGL: Projecting clipping rectangles correctly using draw_data->FramebufferScale to allow multi-viewports for retina display.
//  2019-02-01: OpenGL: Using GLSL 410 shaders for any version over 410 (e.g. 430, 450).
//  2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window.
//  2018-11-13: OpenGL: Support for GL 4.5's glClipControl(GL_UPPER_LEFT) / GL_CLIP_ORIGIN.
//  2018-08-29: OpenGL: Added support for more OpenGL loaders: glew and glad, with comments indicative that any loader can be used.
//  2018-08-09: OpenGL: Default to OpenGL ES 3 on iOS and Android. GLSL version default to "#version 300 ES".
//  2018-07-30: OpenGL: Support for GLSL 300 ES and 410 core. Fixes for Emscripten compilation.
//  2018-07-10: OpenGL: Support for more GLSL versions (based on the GLSL version string). Added error output when shaders fail to compile/link.
//  2018-06-08: Misc: Extracted imgui_impl_opengl3.cpp/.h away from the old combined GLFW/SDL+OpenGL3 examples.
//  2018-06-08: OpenGL: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle.
//  2018-05-25: OpenGL: Removed unnecessary backup/restore of GL_ELEMENT_ARRAY_BUFFER_BINDING since this is part of the VAO state.
//  2018-05-14: OpenGL: Making the call to glBindSampler() optional so 3.2 context won't fail if the function is a NULL pointer.
//  2018-03-06: OpenGL: Added const char* glsl_version parameter to ImGui_ImplOpenGL3_Init() so user can override the GLSL version e.g. "#version 150".
//  2018-02-23: OpenGL: Create the VAO in the render function so the setup can more easily be used with multiple shared GL context.
//  2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplSdlGL3_RenderDrawData() in the .h file so you can call it yourself.
//  2018-01-07: OpenGL: Changed GLSL shader version from 330 to 150.
//  2017-09-01: OpenGL: Save and restore current bound sampler. Save and restore current polygon mode.
//  2017-05-01: OpenGL: Fixed save and restore of current blend func state.
//  2017-05-01: OpenGL: Fixed save and restore of current GL_ACTIVE_TEXTURE.
//  2016-09-05: OpenGL: Fixed save and restore of current scissor rectangle.
//  2016-07-29: OpenGL: Explicitly setting GL_UNPACK_ROW_LENGTH to reduce issues because SDL changes it. (#752)

//----------------------------------------
// OpenGL    GLSL      GLSL
// version   version   string
//----------------------------------------
//  2.0       110       "#version 110"
//  2.1       120       "#version 120"
//  3.0       130       "#version 130"
//  3.1       140       "#version 140"
//  3.2       150       "#version 150"
//  3.3       330       "#version 330 core"
//  4.0       400       "#version 400 core"
//  4.1       410       "#version 410 core"
//  4.2       420       "#version 410 core"
//  4.3       430       "#version 430 core"
//  ES 2.0    100       "#version 100"      = WebGL 1.0
//  ES 3.0    300       "#version 300 es"   = WebGL 2.0
//----------------------------------------

#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
#define _CRT_SECURE_NO_WARNINGS
#endif

#include "imgui.h"
#include "imgui_impl_opengl3.h"
#include <stdio.h>
#if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier
#include <stddef.h>     // intptr_t
#else
#include <stdint.h>     // intptr_t
#endif

// Clang warnings with -Weverything
#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wold-style-cast"     // warning: use of old-style cast
#pragma clang diagnostic ignored "-Wsign-conversion"    // warning: implicit conversion changes signedness
#if __has_warning("-Wzero-as-null-pointer-constant")
#pragma clang diagnostic ignored "-Wzero-as-null-pointer-constant"
#endif
#endif

// GL includes
#if defined(IMGUI_IMPL_OPENGL_ES2)
#if (defined(__APPLE__) && (TARGET_OS_IOS || TARGET_OS_TV))
#include <OpenGLES/ES2/gl.h>    // Use GL ES 2
#else
#include <GLES2/gl2.h>          // Use GL ES 2
#endif
#if defined(__EMSCRIPTEN__)
#ifndef GL_GLEXT_PROTOTYPES
#define GL_GLEXT_PROTOTYPES
#endif
#include <GLES2/gl2ext.h>
#endif
#elif defined(IMGUI_IMPL_OPENGL_ES3)
#if defined(__APPLE__)
#include <TargetConditionals.h>
#endif
#if (defined(__APPLE__) && (TARGET_OS_IOS || TARGET_OS_TV))
#include <OpenGLES/ES3/gl.h>    // Use GL ES 3
#else
#include <GLES3/gl3.h>          // Use GL ES 3
#endif
#elif !defined(IMGUI_IMPL_OPENGL_LOADER_CUSTOM)
// 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 using our own minimal custom loader based on gl3w.
// In the rest of your app/engine, you can use another loader of your choice (gl3w, glew, glad, glbinding, glext, glLoadGen, etc.).
// If you happen to be developing a new feature for this backend (imgui_impl_opengl3.cpp):
// - You may need to regenerate imgui_impl_opengl3_loader.h to add new symbols. See https://github.com/dearimgui/gl3w_stripped
// - You can temporarily use an unstripped version. See https://github.com/dearimgui/gl3w_stripped/releases
// Changes to this backend using new APIs should be accompanied by a regenerated stripped loader version.
#define IMGL3W_IMPL
#include "imgui_impl_opengl3_loader.h"
#endif

// Vertex arrays are not supported on ES2/WebGL1 unless Emscripten which uses an extension
#ifndef IMGUI_IMPL_OPENGL_ES2
#define IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
#elif defined(__EMSCRIPTEN__)
#define IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
#define glBindVertexArray       glBindVertexArrayOES
#define glGenVertexArrays       glGenVertexArraysOES
#define glDeleteVertexArrays    glDeleteVertexArraysOES
#define GL_VERTEX_ARRAY_BINDING GL_VERTEX_ARRAY_BINDING_OES
#endif

// Desktop GL 2.0+ has glPolygonMode() which GL ES and WebGL don't have.
#ifdef GL_POLYGON_MODE
#define IMGUI_IMPL_HAS_POLYGON_MODE
#endif

// Desktop GL 3.2+ has glDrawElementsBaseVertex() which GL ES and WebGL don't have.
#if !defined(IMGUI_IMPL_OPENGL_ES2) && !defined(IMGUI_IMPL_OPENGL_ES3) && defined(GL_VERSION_3_2)
#define IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET
#endif

// Desktop GL 3.3+ has glBindSampler()
#if !defined(IMGUI_IMPL_OPENGL_ES2) && !defined(IMGUI_IMPL_OPENGL_ES3) && defined(GL_VERSION_3_3)
#define IMGUI_IMPL_OPENGL_MAY_HAVE_BIND_SAMPLER
#endif

// Desktop GL 3.1+ has GL_PRIMITIVE_RESTART state
#if !defined(IMGUI_IMPL_OPENGL_ES2) && !defined(IMGUI_IMPL_OPENGL_ES3) && defined(GL_VERSION_3_1)
#define IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
#endif

// Desktop GL use extension detection
#if !defined(IMGUI_IMPL_OPENGL_ES2) && !defined(IMGUI_IMPL_OPENGL_ES3)
#define IMGUI_IMPL_OPENGL_MAY_HAVE_EXTENSIONS
#endif

// OpenGL Data
struct ImGui_ImplOpenGL3_Data
{
    GLuint          GlVersion;               // Extracted at runtime using GL_MAJOR_VERSION, GL_MINOR_VERSION queries (e.g. 320 for GL 3.2)
    char            GlslVersionString[32];   // Specified by user or detected based on compile time GL settings.
    GLuint          FontTexture;
    GLuint          ShaderHandle;
    GLint           AttribLocationTex;       // Uniforms location
    GLint           AttribLocationProjMtx;
    GLuint          AttribLocationVtxPos;    // Vertex attributes location
    GLuint          AttribLocationVtxUV;
    GLuint          AttribLocationVtxColor;
    unsigned int    VboHandle, ElementsHandle;
    GLsizeiptr      VertexBufferSize;
    GLsizeiptr      IndexBufferSize;
    bool            HasClipOrigin;

    ImGui_ImplOpenGL3_Data() { memset((void*)this, 0, sizeof(*this)); }
};

// Backend data stored in io.BackendRendererUserData to allow support for multiple Dear ImGui contexts
// It is STRONGLY preferred that you use docking branch with multi-viewports (== single Dear ImGui context + multiple windows) instead of multiple Dear ImGui contexts.
static ImGui_ImplOpenGL3_Data* ImGui_ImplOpenGL3_GetBackendData()
{
    return ImGui::GetCurrentContext() ? (ImGui_ImplOpenGL3_Data*)ImGui::GetIO().BackendRendererUserData : NULL;
}

// Forward Declarations
static void ImGui_ImplOpenGL3_InitPlatformInterface();
static void ImGui_ImplOpenGL3_ShutdownPlatformInterface();

// Functions
bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
{
    ImGuiIO& io = ImGui::GetIO();
    IM_ASSERT(io.BackendRendererUserData == NULL && "Already initialized a renderer backend!");

    // Initialize our loader
#if !defined(IMGUI_IMPL_OPENGL_ES2) && !defined(IMGUI_IMPL_OPENGL_ES3) && !defined(IMGUI_IMPL_OPENGL_LOADER_CUSTOM)
    if (imgl3wInit() != 0)
    {
        fprintf(stderr, "Failed to initialize OpenGL loader!\n");
        return false;
    }
#endif

    // Setup backend capabilities flags
    ImGui_ImplOpenGL3_Data* bd = IM_NEW(ImGui_ImplOpenGL3_Data)();
    io.BackendRendererUserData = (void*)bd;
    io.BackendRendererName = "imgui_impl_opengl3";

    // Query for GL version (e.g. 320 for GL 3.2)
#if !defined(IMGUI_IMPL_OPENGL_ES2)
    GLint major = 0;
    GLint minor = 0;
    glGetIntegerv(GL_MAJOR_VERSION, &major);
    glGetIntegerv(GL_MINOR_VERSION, &minor);
    if (major == 0 && minor == 0)
    {
        // Query GL_VERSION in desktop GL 2.x, the string will start with "<major>.<minor>"
        const char* gl_version = (const char*)glGetString(GL_VERSION);
        sscanf(gl_version, "%d.%d", &major, &minor);
    }
    bd->GlVersion = (GLuint)(major * 100 + minor * 10);
#else
    bd->GlVersion = 200; // GLES 2
#endif

#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET
    if (bd->GlVersion >= 320)
        io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
#endif
    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)

    // Store GLSL version string so we can refer to it later in case we recreate shaders.
    // Note: GLSL version is NOT the same as GL version. Leave this to NULL if unsure.
    if (glsl_version == NULL)
    {
#if defined(IMGUI_IMPL_OPENGL_ES2)
        glsl_version = "#version 100";
#elif defined(IMGUI_IMPL_OPENGL_ES3)
        glsl_version = "#version 300 es";
#elif defined(__APPLE__)
        glsl_version = "#version 150";
#else
        glsl_version = "#version 130";
#endif
    }
    IM_ASSERT((int)strlen(glsl_version) + 2 < IM_ARRAYSIZE(bd->GlslVersionString));
    strcpy(bd->GlslVersionString, glsl_version);
    strcat(bd->GlslVersionString, "\n");

    // Make an arbitrary GL call (we don't actually need the result)
    // IF YOU GET A CRASH HERE: it probably means the OpenGL function loader didn't do its job. Let us know!
    GLint current_texture;
    glGetIntegerv(GL_TEXTURE_BINDING_2D, &current_texture);

    // Detect extensions we support
    bd->HasClipOrigin = (bd->GlVersion >= 450);
#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_EXTENSIONS
    GLint num_extensions = 0;
    glGetIntegerv(GL_NUM_EXTENSIONS, &num_extensions);
    for (GLint i = 0; i < num_extensions; i++)
    {
        const char* extension = (const char*)glGetStringi(GL_EXTENSIONS, i);
        if (extension != NULL && strcmp(extension, "GL_ARB_clip_control") == 0)
            bd->HasClipOrigin = true;
    }
#endif

    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
        ImGui_ImplOpenGL3_InitPlatformInterface();

    return true;
}

void    ImGui_ImplOpenGL3_Shutdown()
{
    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();
    IM_ASSERT(bd != NULL && "No renderer backend to shutdown, or already shutdown?");
    ImGuiIO& io = ImGui::GetIO();

    ImGui_ImplOpenGL3_ShutdownPlatformInterface();
    ImGui_ImplOpenGL3_DestroyDeviceObjects();
    io.BackendRendererName = NULL;
    io.BackendRendererUserData = NULL;
    IM_DELETE(bd);
}

void    ImGui_ImplOpenGL3_NewFrame()
{
    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();
    IM_ASSERT(bd != NULL && "Did you call ImGui_ImplOpenGL3_Init()?");

    if (!bd->ShaderHandle)
        ImGui_ImplOpenGL3_CreateDeviceObjects();
}

static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_width, int fb_height, GLuint vertex_array_object)
{
    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();

    // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, polygon fill
    glEnable(GL_BLEND);
    glBlendEquation(GL_FUNC_ADD);
    glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
    glDisable(GL_CULL_FACE);
    glDisable(GL_DEPTH_TEST);
    glDisable(GL_STENCIL_TEST);
    glEnable(GL_SCISSOR_TEST);
#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
    if (bd->GlVersion >= 310)
        glDisable(GL_PRIMITIVE_RESTART);
#endif
#ifdef IMGUI_IMPL_HAS_POLYGON_MODE
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
#endif

    // Support for GL 4.5 rarely used glClipControl(GL_UPPER_LEFT)
#if defined(GL_CLIP_ORIGIN)
    bool clip_origin_lower_left = true;
    if (bd->HasClipOrigin)
    {
        GLenum current_clip_origin = 0; glGetIntegerv(GL_CLIP_ORIGIN, (GLint*)&current_clip_origin);
        if (current_clip_origin == GL_UPPER_LEFT)
            clip_origin_lower_left = false;
    }
#endif

    // Setup viewport, orthographic projection matrix
    // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
    glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
    float L = draw_data->DisplayPos.x;
    float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
    float T = draw_data->DisplayPos.y;
    float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
#if defined(GL_CLIP_ORIGIN)
    if (!clip_origin_lower_left) { float tmp = T; T = B; B = tmp; } // Swap top and bottom if origin is upper left
#endif
    const float ortho_projection[4][4] =
    {
        { 2.0f/(R-L),   0.0f,         0.0f,   0.0f },
        { 0.0f,         2.0f/(T-B),   0.0f,   0.0f },
        { 0.0f,         0.0f,        -1.0f,   0.0f },
        { (R+L)/(L-R),  (T+B)/(B-T),  0.0f,   1.0f },
    };
    glUseProgram(bd->ShaderHandle);
    glUniform1i(bd->AttribLocationTex, 0);
    glUniformMatrix4fv(bd->AttribLocationProjMtx, 1, GL_FALSE, &ortho_projection[0][0]);

#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_BIND_SAMPLER
    if (bd->GlVersion >= 330)
        glBindSampler(0, 0); // We use combined texture/sampler state. Applications using GL 3.3 may set that otherwise.
#endif

    (void)vertex_array_object;
#ifdef IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
    glBindVertexArray(vertex_array_object);
#endif

    // Bind vertex/index buffers and setup attributes for ImDrawVert
    glBindBuffer(GL_ARRAY_BUFFER, bd->VboHandle);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, bd->ElementsHandle);
    glEnableVertexAttribArray(bd->AttribLocationVtxPos);
    glEnableVertexAttribArray(bd->AttribLocationVtxUV);
    glEnableVertexAttribArray(bd->AttribLocationVtxColor);
    glVertexAttribPointer(bd->AttribLocationVtxPos,   2, GL_FLOAT,         GL_FALSE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, pos));
    glVertexAttribPointer(bd->AttribLocationVtxUV,    2, GL_FLOAT,         GL_FALSE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, uv));
    glVertexAttribPointer(bd->AttribLocationVtxColor, 4, GL_UNSIGNED_BYTE, GL_TRUE,  sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, col));
}

// OpenGL3 Render function.
// Note that this implementation is little overcomplicated because we are saving/setting up/restoring every OpenGL state explicitly.
// This is in order to be able to run within an OpenGL engine that doesn't do so.
void    ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
{
    // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
    int fb_width = (int)(draw_data->DisplaySize.x * draw_data->FramebufferScale.x);
    int fb_height = (int)(draw_data->DisplaySize.y * draw_data->FramebufferScale.y);
    if (fb_width <= 0 || fb_height <= 0)
        return;

    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();

    // Backup GL state
    GLenum last_active_texture; glGetIntegerv(GL_ACTIVE_TEXTURE, (GLint*)&last_active_texture);
    glActiveTexture(GL_TEXTURE0);
    GLuint last_program; glGetIntegerv(GL_CURRENT_PROGRAM, (GLint*)&last_program);
    GLuint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, (GLint*)&last_texture);
#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_BIND_SAMPLER
    GLuint last_sampler; if (bd->GlVersion >= 330) { glGetIntegerv(GL_SAMPLER_BINDING, (GLint*)&last_sampler); } else { last_sampler = 0; }
#endif
    GLuint last_array_buffer; glGetIntegerv(GL_ARRAY_BUFFER_BINDING, (GLint*)&last_array_buffer);
#ifdef IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
    GLuint last_vertex_array_object; glGetIntegerv(GL_VERTEX_ARRAY_BINDING, (GLint*)&last_vertex_array_object);
#endif
#ifdef IMGUI_IMPL_HAS_POLYGON_MODE
    GLint last_polygon_mode[2]; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode);
#endif
    GLint last_viewport[4]; glGetIntegerv(GL_VIEWPORT, last_viewport);
    GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box);
    GLenum last_blend_src_rgb; glGetIntegerv(GL_BLEND_SRC_RGB, (GLint*)&last_blend_src_rgb);
    GLenum last_blend_dst_rgb; glGetIntegerv(GL_BLEND_DST_RGB, (GLint*)&last_blend_dst_rgb);
    GLenum last_blend_src_alpha; glGetIntegerv(GL_BLEND_SRC_ALPHA, (GLint*)&last_blend_src_alpha);
    GLenum last_blend_dst_alpha; glGetIntegerv(GL_BLEND_DST_ALPHA, (GLint*)&last_blend_dst_alpha);
    GLenum last_blend_equation_rgb; glGetIntegerv(GL_BLEND_EQUATION_RGB, (GLint*)&last_blend_equation_rgb);
    GLenum last_blend_equation_alpha; glGetIntegerv(GL_BLEND_EQUATION_ALPHA, (GLint*)&last_blend_equation_alpha);
    GLboolean last_enable_blend = glIsEnabled(GL_BLEND);
    GLboolean last_enable_cull_face = glIsEnabled(GL_CULL_FACE);
    GLboolean last_enable_depth_test = glIsEnabled(GL_DEPTH_TEST);
    GLboolean last_enable_stencil_test = glIsEnabled(GL_STENCIL_TEST);
    GLboolean last_enable_scissor_test = glIsEnabled(GL_SCISSOR_TEST);
#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
    GLboolean last_enable_primitive_restart = (bd->GlVersion >= 310) ? glIsEnabled(GL_PRIMITIVE_RESTART) : GL_FALSE;
#endif

    // Setup desired GL state
    // Recreate the VAO every time (this is to easily allow multiple GL contexts to be rendered to. VAO are not shared among GL contexts)
    // The renderer would actually work without any VAO bound, but then our VertexAttrib calls would overwrite the default one currently bound.
    GLuint vertex_array_object = 0;
#ifdef IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
    glGenVertexArrays(1, &vertex_array_object);
#endif
    ImGui_ImplOpenGL3_SetupRenderState(draw_data, fb_width, fb_height, vertex_array_object);

    // Will project scissor/clipping rectangles into framebuffer space
    ImVec2 clip_off = draw_data->DisplayPos;         // (0,0) unless using multi-viewports
    ImVec2 clip_scale = draw_data->FramebufferScale; // (1,1) unless using retina display which are often (2,2)

    // Render command lists
    for (int n = 0; n < draw_data->CmdListsCount; n++)
    {
        const ImDrawList* cmd_list = draw_data->CmdLists[n];

        // Upload vertex/index buffers
        GLsizeiptr vtx_buffer_size = (GLsizeiptr)cmd_list->VtxBuffer.Size * (int)sizeof(ImDrawVert);
        GLsizeiptr idx_buffer_size = (GLsizeiptr)cmd_list->IdxBuffer.Size * (int)sizeof(ImDrawIdx);
        if (bd->VertexBufferSize < vtx_buffer_size)
        {
            bd->VertexBufferSize = vtx_buffer_size;
            glBufferData(GL_ARRAY_BUFFER, bd->VertexBufferSize, NULL, GL_STREAM_DRAW);
        }
        if (bd->IndexBufferSize < idx_buffer_size)
        {
            bd->IndexBufferSize = idx_buffer_size;
            glBufferData(GL_ELEMENT_ARRAY_BUFFER, bd->IndexBufferSize, NULL, GL_STREAM_DRAW);
        }
        glBufferSubData(GL_ARRAY_BUFFER, 0, vtx_buffer_size, (const GLvoid*)cmd_list->VtxBuffer.Data);
        glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, idx_buffer_size, (const GLvoid*)cmd_list->IdxBuffer.Data);

        for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
        {
            const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
            if (pcmd->UserCallback != NULL)
            {
                // User callback, registered via ImDrawList::AddCallback()
                // (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to reset render state.)
                if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
                    ImGui_ImplOpenGL3_SetupRenderState(draw_data, fb_width, fb_height, vertex_array_object);
                else
                    pcmd->UserCallback(cmd_list, pcmd);
            }
            else
            {
                // Project scissor/clipping rectangles into framebuffer space
                ImVec2 clip_min((pcmd->ClipRect.x - clip_off.x) * clip_scale.x, (pcmd->ClipRect.y - clip_off.y) * clip_scale.y);
                ImVec2 clip_max((pcmd->ClipRect.z - clip_off.x) * clip_scale.x, (pcmd->ClipRect.w - clip_off.y) * clip_scale.y);
                if (clip_max.x <= clip_min.x || clip_max.y <= clip_min.y)
                    continue;

                // Apply scissor/clipping rectangle (Y is inverted in OpenGL)
                glScissor((int)clip_min.x, (int)((float)fb_height - clip_max.y), (int)(clip_max.x - clip_min.x), (int)(clip_max.y - clip_min.y));

                // Bind texture, Draw
                glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->GetTexID());
#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET
                if (bd->GlVersion >= 320)
                    glDrawElementsBaseVertex(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, (void*)(intptr_t)(pcmd->IdxOffset * sizeof(ImDrawIdx)), (GLint)pcmd->VtxOffset);
                else
#endif
                glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, (void*)(intptr_t)(pcmd->IdxOffset * sizeof(ImDrawIdx)));
            }
        }
    }

    // Destroy the temporary VAO
#ifdef IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
    glDeleteVertexArrays(1, &vertex_array_object);
#endif

    // Restore modified GL state
    glUseProgram(last_program);
    glBindTexture(GL_TEXTURE_2D, last_texture);
#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_BIND_SAMPLER
    if (bd->GlVersion >= 330)
        glBindSampler(0, last_sampler);
#endif
    glActiveTexture(last_active_texture);
#ifdef IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
    glBindVertexArray(last_vertex_array_object);
#endif
    glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);
    glBlendEquationSeparate(last_blend_equation_rgb, last_blend_equation_alpha);
    glBlendFuncSeparate(last_blend_src_rgb, last_blend_dst_rgb, last_blend_src_alpha, last_blend_dst_alpha);
    if (last_enable_blend) glEnable(GL_BLEND); else glDisable(GL_BLEND);
    if (last_enable_cull_face) glEnable(GL_CULL_FACE); else glDisable(GL_CULL_FACE);
    if (last_enable_depth_test) glEnable(GL_DEPTH_TEST); else glDisable(GL_DEPTH_TEST);
    if (last_enable_stencil_test) glEnable(GL_STENCIL_TEST); else glDisable(GL_STENCIL_TEST);
    if (last_enable_scissor_test) glEnable(GL_SCISSOR_TEST); else glDisable(GL_SCISSOR_TEST);
#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
    if (bd->GlVersion >= 310) { if (last_enable_primitive_restart) glEnable(GL_PRIMITIVE_RESTART); else glDisable(GL_PRIMITIVE_RESTART); }
#endif

#ifdef IMGUI_IMPL_HAS_POLYGON_MODE
    glPolygonMode(GL_FRONT_AND_BACK, (GLenum)last_polygon_mode[0]);
#endif
    glViewport(last_viewport[0], last_viewport[1], (GLsizei)last_viewport[2], (GLsizei)last_viewport[3]);
    glScissor(last_scissor_box[0], last_scissor_box[1], (GLsizei)last_scissor_box[2], (GLsizei)last_scissor_box[3]);
    (void)bd; // Not all compilation paths use this
}

bool ImGui_ImplOpenGL3_CreateFontsTexture()
{
    ImGuiIO& io = ImGui::GetIO();
    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();

    // Build texture atlas
    unsigned char* pixels;
    int width, height;
    io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);   // Load as RGBA 32-bit (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory.

    // Upload texture to graphics system
    GLint last_texture;
    glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
    glGenTextures(1, &bd->FontTexture);
    glBindTexture(GL_TEXTURE_2D, bd->FontTexture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
#ifdef GL_UNPACK_ROW_LENGTH // Not on WebGL/ES
    glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
#endif
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);

    // Store our identifier
    io.Fonts->SetTexID((ImTextureID)(intptr_t)bd->FontTexture);

    // Restore state
    glBindTexture(GL_TEXTURE_2D, last_texture);

    return true;
}

void ImGui_ImplOpenGL3_DestroyFontsTexture()
{
    ImGuiIO& io = ImGui::GetIO();
    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();
    if (bd->FontTexture)
    {
        glDeleteTextures(1, &bd->FontTexture);
        io.Fonts->SetTexID(0);
        bd->FontTexture = 0;
    }
}

// If you get an error please report on github. You may try different GL context version or GLSL version. See GL<>GLSL version table at the top of this file.
static bool CheckShader(GLuint handle, const char* desc)
{
    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();
    GLint status = 0, log_length = 0;
    glGetShaderiv(handle, GL_COMPILE_STATUS, &status);
    glGetShaderiv(handle, GL_INFO_LOG_LENGTH, &log_length);
    if ((GLboolean)status == GL_FALSE)
        fprintf(stderr, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to compile %s! With GLSL: %s\n", desc, bd->GlslVersionString);
    if (log_length > 1)
    {
        ImVector<char> buf;
        buf.resize((int)(log_length + 1));
        glGetShaderInfoLog(handle, log_length, NULL, (GLchar*)buf.begin());
        fprintf(stderr, "%s\n", buf.begin());
    }
    return (GLboolean)status == GL_TRUE;
}

// If you get an error please report on GitHub. You may try different GL context version or GLSL version.
static bool CheckProgram(GLuint handle, const char* desc)
{
    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();
    GLint status = 0, log_length = 0;
    glGetProgramiv(handle, GL_LINK_STATUS, &status);
    glGetProgramiv(handle, GL_INFO_LOG_LENGTH, &log_length);
    if ((GLboolean)status == GL_FALSE)
        fprintf(stderr, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to link %s! With GLSL %s\n", desc, bd->GlslVersionString);
    if (log_length > 1)
    {
        ImVector<char> buf;
        buf.resize((int)(log_length + 1));
        glGetProgramInfoLog(handle, log_length, NULL, (GLchar*)buf.begin());
        fprintf(stderr, "%s\n", buf.begin());
    }
    return (GLboolean)status == GL_TRUE;
}

bool    ImGui_ImplOpenGL3_CreateDeviceObjects()
{
    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();

    // Backup GL state
    GLint last_texture, last_array_buffer;
    glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
    glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer);
#ifdef IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
    GLint last_vertex_array;
    glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array);
#endif

    // Parse GLSL version string
    int glsl_version = 130;
    sscanf(bd->GlslVersionString, "#version %d", &glsl_version);

    const GLchar* vertex_shader_glsl_120 =
        "uniform mat4 ProjMtx;\n"
        "attribute vec2 Position;\n"
        "attribute vec2 UV;\n"
        "attribute vec4 Color;\n"
        "varying vec2 Frag_UV;\n"
        "varying vec4 Frag_Color;\n"
        "void main()\n"
        "{\n"
        "    Frag_UV = UV;\n"
        "    Frag_Color = Color;\n"
        "    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
        "}\n";

    const GLchar* vertex_shader_glsl_130 =
        "uniform mat4 ProjMtx;\n"
        "in vec2 Position;\n"
        "in vec2 UV;\n"
        "in vec4 Color;\n"
        "out vec2 Frag_UV;\n"
        "out vec4 Frag_Color;\n"
        "void main()\n"
        "{\n"
        "    Frag_UV = UV;\n"
        "    Frag_Color = Color;\n"
        "    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
        "}\n";

    const GLchar* vertex_shader_glsl_300_es =
        "precision highp float;\n"
        "layout (location = 0) in vec2 Position;\n"
        "layout (location = 1) in vec2 UV;\n"
        "layout (location = 2) in vec4 Color;\n"
        "uniform mat4 ProjMtx;\n"
        "out vec2 Frag_UV;\n"
        "out vec4 Frag_Color;\n"
        "void main()\n"
        "{\n"
        "    Frag_UV = UV;\n"
        "    Frag_Color = Color;\n"
        "    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
        "}\n";

    const GLchar* vertex_shader_glsl_410_core =
        "layout (location = 0) in vec2 Position;\n"
        "layout (location = 1) in vec2 UV;\n"
        "layout (location = 2) in vec4 Color;\n"
        "uniform mat4 ProjMtx;\n"
        "out vec2 Frag_UV;\n"
        "out vec4 Frag_Color;\n"
        "void main()\n"
        "{\n"
        "    Frag_UV = UV;\n"
        "    Frag_Color = Color;\n"
        "    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
        "}\n";

    const GLchar* fragment_shader_glsl_120 =
        "#ifdef GL_ES\n"
        "    precision mediump float;\n"
        "#endif\n"
        "uniform sampler2D Texture;\n"
        "varying vec2 Frag_UV;\n"
        "varying vec4 Frag_Color;\n"
        "void main()\n"
        "{\n"
        "    gl_FragColor = Frag_Color * texture2D(Texture, Frag_UV.st);\n"
        "}\n";

    const GLchar* fragment_shader_glsl_130 =
        "uniform sampler2D Texture;\n"
        "in vec2 Frag_UV;\n"
        "in vec4 Frag_Color;\n"
        "out vec4 Out_Color;\n"
        "void main()\n"
        "{\n"
        "    Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
        "}\n";

    const GLchar* fragment_shader_glsl_300_es =
        "precision mediump float;\n"
        "uniform sampler2D Texture;\n"
        "in vec2 Frag_UV;\n"
        "in vec4 Frag_Color;\n"
        "layout (location = 0) out vec4 Out_Color;\n"
        "void main()\n"
        "{\n"
        "    Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
        "}\n";

    const GLchar* fragment_shader_glsl_410_core =
        "in vec2 Frag_UV;\n"
        "in vec4 Frag_Color;\n"
        "uniform sampler2D Texture;\n"
        "layout (location = 0) out vec4 Out_Color;\n"
        "void main()\n"
        "{\n"
        "    Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
        "}\n";

    // Select shaders matching our GLSL versions
    const GLchar* vertex_shader = NULL;
    const GLchar* fragment_shader = NULL;
    if (glsl_version < 130)
    {
        vertex_shader = vertex_shader_glsl_120;
        fragment_shader = fragment_shader_glsl_120;
    }
    else if (glsl_version >= 410)
    {
        vertex_shader = vertex_shader_glsl_410_core;
        fragment_shader = fragment_shader_glsl_410_core;
    }
    else if (glsl_version == 300)
    {
        vertex_shader = vertex_shader_glsl_300_es;
        fragment_shader = fragment_shader_glsl_300_es;
    }
    else
    {
        vertex_shader = vertex_shader_glsl_130;
        fragment_shader = fragment_shader_glsl_130;
    }

    // Create shaders
    const GLchar* vertex_shader_with_version[2] = { bd->GlslVersionString, vertex_shader };
    GLuint vert_handle = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vert_handle, 2, vertex_shader_with_version, NULL);
    glCompileShader(vert_handle);
    CheckShader(vert_handle, "vertex shader");

    const GLchar* fragment_shader_with_version[2] = { bd->GlslVersionString, fragment_shader };
    GLuint frag_handle = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(frag_handle, 2, fragment_shader_with_version, NULL);
    glCompileShader(frag_handle);
    CheckShader(frag_handle, "fragment shader");

    // Link
    bd->ShaderHandle = glCreateProgram();
    glAttachShader(bd->ShaderHandle, vert_handle);
    glAttachShader(bd->ShaderHandle, frag_handle);
    glLinkProgram(bd->ShaderHandle);
    CheckProgram(bd->ShaderHandle, "shader program");

    glDetachShader(bd->ShaderHandle, vert_handle);
    glDetachShader(bd->ShaderHandle, frag_handle);
    glDeleteShader(vert_handle);
    glDeleteShader(frag_handle);

    bd->AttribLocationTex = glGetUniformLocation(bd->ShaderHandle, "Texture");
    bd->AttribLocationProjMtx = glGetUniformLocation(bd->ShaderHandle, "ProjMtx");
    bd->AttribLocationVtxPos = (GLuint)glGetAttribLocation(bd->ShaderHandle, "Position");
    bd->AttribLocationVtxUV = (GLuint)glGetAttribLocation(bd->ShaderHandle, "UV");
    bd->AttribLocationVtxColor = (GLuint)glGetAttribLocation(bd->ShaderHandle, "Color");

    // Create buffers
    glGenBuffers(1, &bd->VboHandle);
    glGenBuffers(1, &bd->ElementsHandle);

    ImGui_ImplOpenGL3_CreateFontsTexture();

    // Restore modified GL state
    glBindTexture(GL_TEXTURE_2D, last_texture);
    glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);
#ifdef IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
    glBindVertexArray(last_vertex_array);
#endif

    return true;
}

void    ImGui_ImplOpenGL3_DestroyDeviceObjects()
{
    ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();
    if (bd->VboHandle)      { glDeleteBuffers(1, &bd->VboHandle); bd->VboHandle = 0; }
    if (bd->ElementsHandle) { glDeleteBuffers(1, &bd->ElementsHandle); bd->ElementsHandle = 0; }
    if (bd->ShaderHandle)   { glDeleteProgram(bd->ShaderHandle); bd->ShaderHandle = 0; }
    ImGui_ImplOpenGL3_DestroyFontsTexture();
}

//--------------------------------------------------------------------------------------------------------
// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
//--------------------------------------------------------------------------------------------------------

static void ImGui_ImplOpenGL3_RenderWindow(ImGuiViewport* viewport, void*)
{
    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
    {
        ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
        glClear(GL_COLOR_BUFFER_BIT);
    }
    ImGui_ImplOpenGL3_RenderDrawData(viewport->DrawData);
}

static void ImGui_ImplOpenGL3_InitPlatformInterface()
{
    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
    platform_io.Renderer_RenderWindow = ImGui_ImplOpenGL3_RenderWindow;
}

static void ImGui_ImplOpenGL3_ShutdownPlatformInterface()
{
    ImGui::DestroyPlatformWindows();
}

#if defined(__clang__)
#pragma clang diagnostic pop
#endif


code:
// dear imgui: Platform Backend for SDL2
// This needs to be used along with a Renderer (e.g. DirectX11, OpenGL3, Vulkan..)
// (Info: SDL2 is a cross-platform general purpose library for handling windows, inputs, graphics context creation, etc.)
// (Prefer SDL 2.0.5+ for full feature support.)

// Implemented features:
//  [X] Platform: Clipboard support.
//  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy SDL_SCANCODE_* values will also be supported unless IMGUI_DISABLE_OBSOLETE_KEYIO is set]
//  [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
//  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
// Missing features:
//  [ ] Platform: SDL2 handling of IME under Windows appears to be broken and it explicitly disable the regular Windows IME. You can restore Windows IME by compiling SDL with SDL_DISABLE_WINDOWS_IME.
//  [ ] Platform: Multi-viewport + Minimized windows seems to break mouse wheel events (at least under Windows).

// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
// 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

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
//  2022-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
//  2022-03-22: Inputs: Fix mouse position issues when dragging outside of boundaries. SDL_CaptureMouse() erroneously still gives out LEAVE events when hovering OS decorations.
//  2022-03-22: Inputs: Added support for extra mouse buttons (SDL_BUTTON_X1/SDL_BUTTON_X2).
//  2022-02-04: Added SDL_Renderer* parameter to ImGui_ImplSDL2_InitForSDLRenderer(), so we can use SDL_GetRendererOutputSize() instead of SDL_GL_GetDrawableSize() when bound to a SDL_Renderer.
//  2022-01-26: Inputs: replaced short-lived io.AddKeyModsEvent() (added two weeks ago) with io.AddKeyEvent() using ImGuiKey_ModXXX flags. Sorry for the confusion.
//  2021-01-20: Inputs: calling new io.AddKeyAnalogEvent() for gamepad support, instead of writing directly to io.NavInputs[].
//  2022-01-17: Inputs: calling new io.AddMousePosEvent(), io.AddMouseButtonEvent(), io.AddMouseWheelEvent() API (1.87+).
//  2022-01-17: Inputs: always update key mods next and before key event (not in NewFrame) to fix input queue with very low framerates.
//  2022-01-12: Update mouse inputs using SDL_MOUSEMOTION/SDL_WINDOWEVENT_LEAVE + fallback to provide it when focused but not hovered/captured. More standard and will allow us to pass it to future input queue API.
//  2022-01-12: Maintain our own copy of MouseButtonsDown mask instead of using ImGui::IsAnyMouseDown() which will be obsoleted.
//  2022-01-10: Inputs: calling new io.AddKeyEvent(), io.AddKeyModsEvent() + io.SetKeyEventNativeData() API (1.87+). Support for full ImGuiKey range.
//  2021-08-17: Calling io.AddFocusEvent() on SDL_WINDOWEVENT_FOCUS_GAINED/SDL_WINDOWEVENT_FOCUS_LOST.
//  2021-07-29: Inputs: MousePos is correctly reported when the host platform window is hovered but not focused (using SDL_GetMouseFocus() + SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH, requires SDL 2.0.5+)
//  2021-06:29: *BREAKING CHANGE* Removed 'SDL_Window* window' parameter to ImGui_ImplSDL2_NewFrame() which was unnecessary.
//  2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX).
//  2021-03-22: Rework global mouse pos availability check listing supported platforms explicitly, effectively fixing mouse access on Raspberry Pi. (#2837, #3950)
//  2020-05-25: Misc: Report a zero display-size when window is minimized, to be consistent with other backends.
//  2020-02-20: Inputs: Fixed mapping for ImGuiKey_KeyPadEnter (using SDL_SCANCODE_KP_ENTER instead of SDL_SCANCODE_RETURN2).
//  2019-12-17: Inputs: On Wayland, use SDL_GetMouseState (because there is no global mouse state).
//  2019-12-05: Inputs: Added support for ImGuiMouseCursor_NotAllowed mouse cursor.
//  2019-07-21: Inputs: Added mapping for ImGuiKey_KeyPadEnter.
//  2019-04-23: Inputs: Added support for SDL_GameController (if ImGuiConfigFlags_NavEnableGamepad is set by user application).
//  2019-03-12: Misc: Preserve DisplayFramebufferScale when main window is minimized.
//  2018-12-21: Inputs: Workaround for Android/iOS which don't seem to handle focus related calls.
//  2018-11-30: Misc: Setting up io.BackendPlatformName so it can be displayed in the About Window.
//  2018-11-14: Changed the signature of ImGui_ImplSDL2_ProcessEvent() to take a 'const SDL_Event*'.
//  2018-08-01: Inputs: Workaround for Emscripten which doesn't seem to handle focus related calls.
//  2018-06-29: Inputs: Added support for the ImGuiMouseCursor_Hand cursor.
//  2018-06-08: Misc: Extracted imgui_impl_sdl.cpp/.h away from the old combined SDL2+OpenGL/Vulkan examples.
//  2018-06-08: Misc: ImGui_ImplSDL2_InitForOpenGL() now takes a SDL_GLContext parameter.
//  2018-05-09: Misc: Fixed clipboard paste memory leak (we didn't call SDL_FreeMemory on the data returned by SDL_GetClipboardText).
//  2018-03-20: Misc: Setup io.BackendFlags ImGuiBackendFlags_HasMouseCursors flag + honor ImGuiConfigFlags_NoMouseCursorChange flag.
//  2018-02-16: Inputs: Added support for mouse cursors, honoring ImGui::GetMouseCursor() value.
//  2018-02-06: Misc: Removed call to ImGui::Shutdown() which is not available from 1.60 WIP, user needs to call CreateContext/DestroyContext themselves.
//  2018-02-06: Inputs: Added mapping for ImGuiKey_Space.
//  2018-02-05: Misc: Using SDL_GetPerformanceCounter() instead of SDL_GetTicks() to be able to handle very high framerate (1000+ FPS).
//  2018-02-05: Inputs: Keyboard mapping is using scancodes everywhere instead of a confusing mixture of keycodes and scancodes.
//  2018-01-20: Inputs: Added Horizontal Mouse Wheel support.
//  2018-01-19: Inputs: When available (SDL 2.0.4+) using SDL_CaptureMouse() to retrieve coordinates outside of client area when dragging. Otherwise (SDL 2.0.3 and before) testing for SDL_WINDOW_INPUT_FOCUS instead of SDL_WINDOW_MOUSE_FOCUS.
//  2018-01-18: Inputs: Added mapping for ImGuiKey_Insert.
//  2017-08-25: Inputs: MousePos set to -FLT_MAX,-FLT_MAX when mouse is unavailable/missing (instead of -1,-1).
//  2016-10-15: Misc: Added a void* user_data parameter to Clipboard function handlers.

#include "imgui.h"
#include "imgui_impl_sdl.h"

// SDL
// (the multi-viewports feature requires SDL features supported from SDL 2.0.4+. SDL 2.0.5+ is highly recommended)
#include <SDL.h>
#include <SDL_syswm.h>
#if defined(__APPLE__)
#include <TargetConditionals.h>
#endif

#if SDL_VERSION_ATLEAST(2,0,4) && !defined(__EMSCRIPTEN__) && !defined(__ANDROID__) && !(defined(__APPLE__) && TARGET_OS_IOS)
#define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    1
#else
#define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    0
#endif
#define SDL_HAS_MOUSE_FOCUS_CLICKTHROUGH    SDL_VERSION_ATLEAST(2,0,5)
#define SDL_HAS_WINDOW_ALPHA                SDL_VERSION_ATLEAST(2,0,5)
#define SDL_HAS_ALWAYS_ON_TOP               SDL_VERSION_ATLEAST(2,0,5)
#define SDL_HAS_USABLE_DISPLAY_BOUNDS       SDL_VERSION_ATLEAST(2,0,5)
#define SDL_HAS_PER_MONITOR_DPI             SDL_VERSION_ATLEAST(2,0,4)
#define SDL_HAS_VULKAN                      SDL_VERSION_ATLEAST(2,0,6)
#if !SDL_HAS_VULKAN
static const Uint32 SDL_WINDOW_VULKAN = 0x10000000;
#endif

// SDL Data
struct ImGui_ImplSDL2_Data
{
    SDL_Window*     Window;
    SDL_Renderer*   Renderer;
    Uint64          Time;
    Uint32          MouseWindowID;
    int             MouseButtonsDown;
    SDL_Cursor*     MouseCursors[ImGuiMouseCursor_COUNT];
    int             PendingMouseLeaveFrame;
    char*           ClipboardTextData;
    bool            MouseCanUseGlobalState;
    bool            UseVulkan;

    ImGui_ImplSDL2_Data()   { memset((void*)this, 0, sizeof(*this)); }
};

// Backend data stored in io.BackendPlatformUserData to allow support for multiple Dear ImGui contexts
// It is STRONGLY preferred that you use docking branch with multi-viewports (== single Dear ImGui context + multiple windows) instead of multiple Dear ImGui contexts.
// FIXME: multi-context support is not well tested and probably dysfunctional in this backend.
// FIXME: some shared resources (mouse cursor shape, gamepad) are mishandled when using multi-context.
static ImGui_ImplSDL2_Data* ImGui_ImplSDL2_GetBackendData()
{
    return ImGui::GetCurrentContext() ? (ImGui_ImplSDL2_Data*)ImGui::GetIO().BackendPlatformUserData : NULL;
}

// Forward Declarations
static void ImGui_ImplSDL2_UpdateMonitors();
static void ImGui_ImplSDL2_InitPlatformInterface(SDL_Window* window, void* sdl_gl_context);
static void ImGui_ImplSDL2_ShutdownPlatformInterface();

// Functions
static const char* ImGui_ImplSDL2_GetClipboardText(void*)
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    if (bd->ClipboardTextData)
        SDL_free(bd->ClipboardTextData);
    bd->ClipboardTextData = SDL_GetClipboardText();
    return bd->ClipboardTextData;
}

static void ImGui_ImplSDL2_SetClipboardText(void*, const char* text)
{
    SDL_SetClipboardText(text);
}

static ImGuiKey ImGui_ImplSDL2_KeycodeToImGuiKey(int keycode)
{
    switch (keycode)
    {
        case SDLK_TAB: return ImGuiKey_Tab;
        case SDLK_LEFT: return ImGuiKey_LeftArrow;
        case SDLK_RIGHT: return ImGuiKey_RightArrow;
        case SDLK_UP: return ImGuiKey_UpArrow;
        case SDLK_DOWN: return ImGuiKey_DownArrow;
        case SDLK_PAGEUP: return ImGuiKey_PageUp;
        case SDLK_PAGEDOWN: return ImGuiKey_PageDown;
        case SDLK_HOME: return ImGuiKey_Home;
        case SDLK_END: return ImGuiKey_End;
        case SDLK_INSERT: return ImGuiKey_Insert;
        case SDLK_DELETE: return ImGuiKey_Delete;
        case SDLK_BACKSPACE: return ImGuiKey_Backspace;
        case SDLK_SPACE: return ImGuiKey_Space;
        case SDLK_RETURN: return ImGuiKey_Enter;
        case SDLK_ESCAPE: return ImGuiKey_Escape;
        case SDLK_QUOTE: return ImGuiKey_Apostrophe;
        case SDLK_COMMA: return ImGuiKey_Comma;
        case SDLK_MINUS: return ImGuiKey_Minus;
        case SDLK_PERIOD: return ImGuiKey_Period;
        case SDLK_SLASH: return ImGuiKey_Slash;
        case SDLK_SEMICOLON: return ImGuiKey_Semicolon;
        case SDLK_EQUALS: return ImGuiKey_Equal;
        case SDLK_LEFTBRACKET: return ImGuiKey_LeftBracket;
        case SDLK_BACKSLASH: return ImGuiKey_Backslash;
        case SDLK_RIGHTBRACKET: return ImGuiKey_RightBracket;
        case SDLK_BACKQUOTE: return ImGuiKey_GraveAccent;
        case SDLK_CAPSLOCK: return ImGuiKey_CapsLock;
        case SDLK_SCROLLLOCK: return ImGuiKey_ScrollLock;
        case SDLK_NUMLOCKCLEAR: return ImGuiKey_NumLock;
        case SDLK_PRINTSCREEN: return ImGuiKey_PrintScreen;
        case SDLK_PAUSE: return ImGuiKey_Pause;
        case SDLK_KP_0: return ImGuiKey_Keypad0;
        case SDLK_KP_1: return ImGuiKey_Keypad1;
        case SDLK_KP_2: return ImGuiKey_Keypad2;
        case SDLK_KP_3: return ImGuiKey_Keypad3;
        case SDLK_KP_4: return ImGuiKey_Keypad4;
        case SDLK_KP_5: return ImGuiKey_Keypad5;
        case SDLK_KP_6: return ImGuiKey_Keypad6;
        case SDLK_KP_7: return ImGuiKey_Keypad7;
        case SDLK_KP_8: return ImGuiKey_Keypad8;
        case SDLK_KP_9: return ImGuiKey_Keypad9;
        case SDLK_KP_PERIOD: return ImGuiKey_KeypadDecimal;
        case SDLK_KP_DIVIDE: return ImGuiKey_KeypadDivide;
        case SDLK_KP_MULTIPLY: return ImGuiKey_KeypadMultiply;
        case SDLK_KP_MINUS: return ImGuiKey_KeypadSubtract;
        case SDLK_KP_PLUS: return ImGuiKey_KeypadAdd;
        case SDLK_KP_ENTER: return ImGuiKey_KeypadEnter;
        case SDLK_KP_EQUALS: return ImGuiKey_KeypadEqual;
        case SDLK_LCTRL: return ImGuiKey_LeftCtrl;
        case SDLK_LSHIFT: return ImGuiKey_LeftShift;
        case SDLK_LALT: return ImGuiKey_LeftAlt;
        case SDLK_LGUI: return ImGuiKey_LeftSuper;
        case SDLK_RCTRL: return ImGuiKey_RightCtrl;
        case SDLK_RSHIFT: return ImGuiKey_RightShift;
        case SDLK_RALT: return ImGuiKey_RightAlt;
        case SDLK_RGUI: return ImGuiKey_RightSuper;
        case SDLK_APPLICATION: return ImGuiKey_Menu;
        case SDLK_0: return ImGuiKey_0;
        case SDLK_1: return ImGuiKey_1;
        case SDLK_2: return ImGuiKey_2;
        case SDLK_3: return ImGuiKey_3;
        case SDLK_4: return ImGuiKey_4;
        case SDLK_5: return ImGuiKey_5;
        case SDLK_6: return ImGuiKey_6;
        case SDLK_7: return ImGuiKey_7;
        case SDLK_8: return ImGuiKey_8;
        case SDLK_9: return ImGuiKey_9;
        case SDLK_a: return ImGuiKey_A;
        case SDLK_b: return ImGuiKey_B;
        case SDLK_c: return ImGuiKey_C;
        case SDLK_d: return ImGuiKey_D;
        case SDLK_e: return ImGuiKey_E;
        case SDLK_f: return ImGuiKey_F;
        case SDLK_g: return ImGuiKey_G;
        case SDLK_h: return ImGuiKey_H;
        case SDLK_i: return ImGuiKey_I;
        case SDLK_j: return ImGuiKey_J;
        case SDLK_k: return ImGuiKey_K;
        case SDLK_l: return ImGuiKey_L;
        case SDLK_m: return ImGuiKey_M;
        case SDLK_n: return ImGuiKey_N;
        case SDLK_o: return ImGuiKey_O;
        case SDLK_p: return ImGuiKey_P;
        case SDLK_q: return ImGuiKey_Q;
        case SDLK_r: return ImGuiKey_R;
        case SDLK_s: return ImGuiKey_S;
        case SDLK_t: return ImGuiKey_T;
        case SDLK_u: return ImGuiKey_U;
        case SDLK_v: return ImGuiKey_V;
        case SDLK_w: return ImGuiKey_W;
        case SDLK_x: return ImGuiKey_X;
        case SDLK_y: return ImGuiKey_Y;
        case SDLK_z: return ImGuiKey_Z;
        case SDLK_F1: return ImGuiKey_F1;
        case SDLK_F2: return ImGuiKey_F2;
        case SDLK_F3: return ImGuiKey_F3;
        case SDLK_F4: return ImGuiKey_F4;
        case SDLK_F5: return ImGuiKey_F5;
        case SDLK_F6: return ImGuiKey_F6;
        case SDLK_F7: return ImGuiKey_F7;
        case SDLK_F8: return ImGuiKey_F8;
        case SDLK_F9: return ImGuiKey_F9;
        case SDLK_F10: return ImGuiKey_F10;
        case SDLK_F11: return ImGuiKey_F11;
        case SDLK_F12: return ImGuiKey_F12;
    }
    return ImGuiKey_None;
}

static void ImGui_ImplSDL2_UpdateKeyModifiers(SDL_Keymod sdl_key_mods)
{
    ImGuiIO& io = ImGui::GetIO();
    io.AddKeyEvent(ImGuiKey_ModCtrl, (sdl_key_mods & KMOD_CTRL) != 0);
    io.AddKeyEvent(ImGuiKey_ModShift, (sdl_key_mods & KMOD_SHIFT) != 0);
    io.AddKeyEvent(ImGuiKey_ModAlt, (sdl_key_mods & KMOD_ALT) != 0);
    io.AddKeyEvent(ImGuiKey_ModSuper, (sdl_key_mods & KMOD_GUI) != 0);
}

// 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.
// If you have multiple SDL events and some of them are not meant to be used by dear imgui, you may need to filter events based on their windowID field.
bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
{
    ImGuiIO& io = ImGui::GetIO();
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();

    switch (event->type)
    {
        case SDL_MOUSEMOTION:
        {
            ImVec2 mouse_pos((float)event->motion.x, (float)event->motion.y);
            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
            {
                int window_x, window_y;
                SDL_GetWindowPosition(SDL_GetWindowFromID(event->motion.windowID), &window_x, &window_y);
                mouse_pos.x += window_x;
                mouse_pos.y += window_y;
            }
            io.AddMousePosEvent(mouse_pos.x, mouse_pos.y);
            return true;
        }
        case SDL_MOUSEWHEEL:
        {
            float wheel_x = (event->wheel.x > 0) ? 1.0f : (event->wheel.x < 0) ? -1.0f : 0.0f;
            float wheel_y = (event->wheel.y > 0) ? 1.0f : (event->wheel.y < 0) ? -1.0f : 0.0f;
            io.AddMouseWheelEvent(wheel_x, wheel_y);
            return true;
        }
        case SDL_MOUSEBUTTONDOWN:
        case SDL_MOUSEBUTTONUP:
        {
            int mouse_button = -1;
            if (event->button.button == SDL_BUTTON_LEFT) { mouse_button = 0; }
            if (event->button.button == SDL_BUTTON_RIGHT) { mouse_button = 1; }
            if (event->button.button == SDL_BUTTON_MIDDLE) { mouse_button = 2; }
            if (event->button.button == SDL_BUTTON_X1) { mouse_button = 3; }
            if (event->button.button == SDL_BUTTON_X2) { mouse_button = 4; }
            if (mouse_button == -1)
                break;
            io.AddMouseButtonEvent(mouse_button, (event->type == SDL_MOUSEBUTTONDOWN));
            bd->MouseButtonsDown = (event->type == SDL_MOUSEBUTTONDOWN) ? (bd->MouseButtonsDown | (1 << mouse_button)) : (bd->MouseButtonsDown & ~(1 << mouse_button));
            return true;
        }
        case SDL_TEXTINPUT:
        {
            io.AddInputCharactersUTF8(event->text.text);
            return true;
        }
        case SDL_KEYDOWN:
        case SDL_KEYUP:
        {
            ImGui_ImplSDL2_UpdateKeyModifiers((SDL_Keymod)event->key.keysym.mod);
            ImGuiKey key = ImGui_ImplSDL2_KeycodeToImGuiKey(event->key.keysym.sym);
            io.AddKeyEvent(key, (event->type == SDL_KEYDOWN));
            io.SetKeyEventNativeData(key, event->key.keysym.sym, event->key.keysym.scancode, event->key.keysym.scancode); // To support legacy indexing (<1.87 user code). Legacy backend uses SDLK_*** as indices to IsKeyXXX() functions.
            return true;
        }
        case SDL_WINDOWEVENT:
        {
            // - When capturing mouse, SDL will send a bunch of conflicting LEAVE/ENTER event on every mouse move, but the final ENTER tends to be right.
            // - However we won't get a correct LEAVE event for a captured window.
            // - In some cases, when detaching a window from main viewport SDL may send SDL_WINDOWEVENT_ENTER one frame too late,
            //   causing SDL_WINDOWEVENT_LEAVE on previous frame to interrupt drag operation by clear mouse position. This is why
            //   we delay process the SDL_WINDOWEVENT_LEAVE events by one frame. See issue #5012 for details.
            Uint8 window_event = event->window.event;
            if (window_event == SDL_WINDOWEVENT_ENTER)
            {
                bd->MouseWindowID = event->window.windowID;
                bd->PendingMouseLeaveFrame = 0;
            }
            if (window_event == SDL_WINDOWEVENT_LEAVE)
                bd->PendingMouseLeaveFrame = ImGui::GetFrameCount() + 1;
            if (window_event == SDL_WINDOWEVENT_FOCUS_GAINED)
                io.AddFocusEvent(true);
            else if (window_event == SDL_WINDOWEVENT_FOCUS_LOST)
                io.AddFocusEvent(false);
            if (window_event == SDL_WINDOWEVENT_CLOSE || window_event == SDL_WINDOWEVENT_MOVED || window_event == SDL_WINDOWEVENT_RESIZED)
                if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle((void*)SDL_GetWindowFromID(event->window.windowID)))
                {
                    if (window_event == SDL_WINDOWEVENT_CLOSE)
                        viewport->PlatformRequestClose = true;
                    if (window_event == SDL_WINDOWEVENT_MOVED)
                        viewport->PlatformRequestMove = true;
                    if (window_event == SDL_WINDOWEVENT_RESIZED)
                        viewport->PlatformRequestResize = true;
                    return true;
                }
            return true;
        }
    }
    return false;
}

static bool ImGui_ImplSDL2_Init(SDL_Window* window, SDL_Renderer* renderer, void* sdl_gl_context)
{
    ImGuiIO& io = ImGui::GetIO();
    IM_ASSERT(io.BackendPlatformUserData == NULL && "Already initialized a platform backend!");

    // Check and store if we are on a SDL backend that supports global mouse position
    // ("wayland" and "rpi" don't support it, but we chose to use a white-list instead of a black-list)
    bool mouse_can_use_global_state = false;
#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
    const char* sdl_backend = SDL_GetCurrentVideoDriver();
    const char* global_mouse_whitelist[] = { "windows", "cocoa", "x11", "DIVE", "VMAN" };
    for (int n = 0; n < IM_ARRAYSIZE(global_mouse_whitelist); n++)
        if (strncmp(sdl_backend, global_mouse_whitelist[n], strlen(global_mouse_whitelist[n])) == 0)
            mouse_can_use_global_state = true;
#endif

    // Setup backend capabilities flags
    ImGui_ImplSDL2_Data* bd = IM_NEW(ImGui_ImplSDL2_Data)();
    io.BackendPlatformUserData = (void*)bd;
    io.BackendPlatformName = "imgui_impl_sdl";
    io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;           // We can honor GetMouseCursor() values (optional)
    io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;            // We can honor io.WantSetMousePos requests (optional, rarely used)
    if (mouse_can_use_global_state)
        io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;  // We can create multi-viewports on the Platform side (optional)

    // SDL on Linux/OSX doesn't report events for unfocused windows (see https://github.com/ocornut/imgui/issues/4960)
#ifndef __APPLE__
    if (mouse_can_use_global_state)
        io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport;// We can call io.AddMouseViewportEvent() with correct data (optional)
#endif

    bd->Window = window;
    bd->Renderer = renderer;
    bd->MouseCanUseGlobalState = mouse_can_use_global_state;

    io.SetClipboardTextFn = ImGui_ImplSDL2_SetClipboardText;
    io.GetClipboardTextFn = ImGui_ImplSDL2_GetClipboardText;
    io.ClipboardUserData = NULL;

    // Load mouse cursors
    bd->MouseCursors[ImGuiMouseCursor_Arrow] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_ARROW);
    bd->MouseCursors[ImGuiMouseCursor_TextInput] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_IBEAM);
    bd->MouseCursors[ImGuiMouseCursor_ResizeAll] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEALL);
    bd->MouseCursors[ImGuiMouseCursor_ResizeNS] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENS);
    bd->MouseCursors[ImGuiMouseCursor_ResizeEW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEWE);
    bd->MouseCursors[ImGuiMouseCursor_ResizeNESW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENESW);
    bd->MouseCursors[ImGuiMouseCursor_ResizeNWSE] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENWSE);
    bd->MouseCursors[ImGuiMouseCursor_Hand] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_HAND);
    bd->MouseCursors[ImGuiMouseCursor_NotAllowed] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_NO);

    // Set platform dependent data in viewport
    // Our mouse update function expect PlatformHandle to be filled for the main viewport
    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
    main_viewport->PlatformHandle = (void*)window;
#ifdef _WIN32
    SDL_SysWMinfo info;
    SDL_VERSION(&info.version);
    if (SDL_GetWindowWMInfo(window, &info))
        main_viewport->PlatformHandleRaw = (void*)info.info.win.window;
#endif

    // Set SDL hint to receive mouse click events on window focus, otherwise SDL doesn't emit the event.
    // Without this, when clicking to gain focus, our widgets wouldn't activate even though they showed as hovered.
    // (This is unfortunately a global SDL setting, so enabling it might have a side-effect on your application.
    // It is unlikely to make a difference, but if your app absolutely needs to ignore the initial on-focus click:
    // you can ignore SDL_MOUSEBUTTONDOWN events coming right after a SDL_WINDOWEVENT_FOCUS_GAINED)
#if SDL_HAS_MOUSE_FOCUS_CLICKTHROUGH
    SDL_SetHint(SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH, "1");
#endif

    // Update monitors
    ImGui_ImplSDL2_UpdateMonitors();

    // We need SDL_CaptureMouse(), SDL_GetGlobalMouseState() from SDL 2.0.4+ to support multiple viewports.
    // We left the call to ImGui_ImplSDL2_InitPlatformInterface() outside of #ifdef to avoid unused-function warnings.
    if ((io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) && (io.BackendFlags & ImGuiBackendFlags_PlatformHasViewports))
        ImGui_ImplSDL2_InitPlatformInterface(window, sdl_gl_context);

    return true;
}

bool ImGui_ImplSDL2_InitForOpenGL(SDL_Window* window, void* sdl_gl_context)
{
    return ImGui_ImplSDL2_Init(window, NULL, sdl_gl_context);
}

bool ImGui_ImplSDL2_InitForVulkan(SDL_Window* window)
{
#if !SDL_HAS_VULKAN
    IM_ASSERT(0 && "Unsupported");
#endif
    if (!ImGui_ImplSDL2_Init(window, NULL, NULL))
        return false;
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    bd->UseVulkan = true;
    return true;
}

bool ImGui_ImplSDL2_InitForD3D(SDL_Window* window)
{
#if !defined(_WIN32)
    IM_ASSERT(0 && "Unsupported");
#endif
    return ImGui_ImplSDL2_Init(window, NULL, NULL);
}

bool ImGui_ImplSDL2_InitForMetal(SDL_Window* window)
{
    return ImGui_ImplSDL2_Init(window, NULL, NULL);
}

bool ImGui_ImplSDL2_InitForSDLRenderer(SDL_Window* window, SDL_Renderer* renderer)
{
    return ImGui_ImplSDL2_Init(window, renderer, NULL);
}

void ImGui_ImplSDL2_Shutdown()
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    IM_ASSERT(bd != NULL && "No platform backend to shutdown, or already shutdown?");
    ImGuiIO& io = ImGui::GetIO();

    ImGui_ImplSDL2_ShutdownPlatformInterface();

    if (bd->ClipboardTextData)
        SDL_free(bd->ClipboardTextData);
    for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_COUNT; cursor_n++)
        SDL_FreeCursor(bd->MouseCursors[cursor_n]);

    io.BackendPlatformName = NULL;
    io.BackendPlatformUserData = NULL;
    IM_DELETE(bd);
}

// This code is incredibly messy because some of the functions we need for full viewport support are not available in SDL < 2.0.4.
static void ImGui_ImplSDL2_UpdateMouseData()
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    ImGuiIO& io = ImGui::GetIO();

    // We forward mouse input when hovered or captured (via SDL_MOUSEMOTION) or when focused (below)
#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
    // SDL_CaptureMouse() let the OS know e.g. that our imgui drag outside the SDL window boundaries shouldn't e.g. trigger other operations outside
    SDL_CaptureMouse(bd->MouseButtonsDown != 0 ? SDL_TRUE : SDL_FALSE);
    SDL_Window* focused_window = SDL_GetKeyboardFocus();
    const bool is_app_focused = (focused_window && (bd->Window == focused_window || ImGui::FindViewportByPlatformHandle((void*)focused_window)));
#else
    SDL_Window* focused_window = bd->Window;
    const bool is_app_focused = (SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_INPUT_FOCUS) != 0; // SDL 2.0.3 and non-windowed systems: single-viewport only
#endif

    if (is_app_focused)
    {
        // (Optional) Set OS mouse position from Dear ImGui if requested (rarely used, only when ImGuiConfigFlags_NavEnableSetMousePos is enabled by user)
        if (io.WantSetMousePos)
        {
#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
                SDL_WarpMouseGlobal((int)io.MousePos.x, (int)io.MousePos.y);
            else
#endif
                SDL_WarpMouseInWindow(bd->Window, (int)io.MousePos.x, (int)io.MousePos.y);
        }

        // (Optional) Fallback to provide mouse position when focused (SDL_MOUSEMOTION already provides this when hovered or captured)
        if (bd->MouseCanUseGlobalState && bd->MouseButtonsDown == 0)
        {
            // Single-viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
            // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
            int mouse_x, mouse_y, window_x, window_y;
            SDL_GetGlobalMouseState(&mouse_x, &mouse_y);
            if (!(io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable))
            {
                SDL_GetWindowPosition(focused_window, &window_x, &window_y);
                mouse_x -= window_x;
                mouse_y -= window_y;
            }
            io.AddMousePosEvent((float)mouse_x, (float)mouse_y);
        }
    }

    // (Optional) When using multiple viewports: call io.AddMouseViewportEvent() with the viewport the OS mouse cursor is hovering.
    // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, Dear imGui will ignore this field and infer the information using its flawed heuristic.
    // - [!] SDL backend does NOT correctly ignore viewports with the _NoInputs flag.
    //       Some backend are not able to handle that correctly. If a backend report an hovered viewport that has the _NoInputs flag (e.g. when dragging a window
    //       for docking, the viewport has the _NoInputs flag in order to allow us to find the viewport under), then Dear ImGui is forced to ignore the value reported
    //       by the backend, and use its flawed heuristic to guess the viewport behind.
    // - [X] SDL backend correctly reports this regardless of another viewport behind focused and dragged from (we need this to find a useful drag and drop target).
    if (io.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport)
    {
        ImGuiID mouse_viewport_id = 0;
        if (SDL_Window* sdl_mouse_window = SDL_GetWindowFromID(bd->MouseWindowID))
            if (ImGuiViewport* mouse_viewport = ImGui::FindViewportByPlatformHandle((void*)sdl_mouse_window))
                mouse_viewport_id = mouse_viewport->ID;
        io.AddMouseViewportEvent(mouse_viewport_id);
    }
}

static void ImGui_ImplSDL2_UpdateMouseCursor()
{
    ImGuiIO& io = ImGui::GetIO();
    if (io.ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange)
        return;
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();

    ImGuiMouseCursor imgui_cursor = ImGui::GetMouseCursor();
    if (io.MouseDrawCursor || imgui_cursor == ImGuiMouseCursor_None)
    {
        // Hide OS mouse cursor if imgui is drawing it or if it wants no cursor
        SDL_ShowCursor(SDL_FALSE);
    }
    else
    {
        // Show OS mouse cursor
        SDL_SetCursor(bd->MouseCursors[imgui_cursor] ? bd->MouseCursors[imgui_cursor] : bd->MouseCursors[ImGuiMouseCursor_Arrow]);
        SDL_ShowCursor(SDL_TRUE);
    }
}

static void ImGui_ImplSDL2_UpdateGamepads()
{
    ImGuiIO& io = ImGui::GetIO();
    if ((io.ConfigFlags & ImGuiConfigFlags_NavEnableGamepad) == 0)
        return;

    // Get gamepad
    io.BackendFlags &= ~ImGuiBackendFlags_HasGamepad;
    SDL_GameController* game_controller = SDL_GameControllerOpen(0);
    if (!game_controller)
        return;
    io.BackendFlags |= ImGuiBackendFlags_HasGamepad;

    // Update gamepad inputs
    #define IM_SATURATE(V)                      (V < 0.0f ? 0.0f : V > 1.0f ? 1.0f : V)
    #define MAP_BUTTON(KEY_NO, BUTTON_NO)       { io.AddKeyEvent(KEY_NO, SDL_GameControllerGetButton(game_controller, BUTTON_NO) != 0); }
    #define MAP_ANALOG(KEY_NO, AXIS_NO, V0, V1) { float vn = (float)(SDL_GameControllerGetAxis(game_controller, AXIS_NO) - V0) / (float)(V1 - V0); vn = IM_SATURATE(vn); io.AddKeyAnalogEvent(KEY_NO, vn > 0.1f, vn); }
    const int thumb_dead_zone = 8000;           // SDL_gamecontroller.h suggests using this value.
    MAP_BUTTON(ImGuiKey_GamepadStart,           SDL_CONTROLLER_BUTTON_START);
    MAP_BUTTON(ImGuiKey_GamepadBack,            SDL_CONTROLLER_BUTTON_BACK);
    MAP_BUTTON(ImGuiKey_GamepadFaceDown,        SDL_CONTROLLER_BUTTON_A);              // Xbox A, PS Cross
    MAP_BUTTON(ImGuiKey_GamepadFaceRight,       SDL_CONTROLLER_BUTTON_B);              // Xbox B, PS Circle
    MAP_BUTTON(ImGuiKey_GamepadFaceLeft,        SDL_CONTROLLER_BUTTON_X);              // Xbox X, PS Square
    MAP_BUTTON(ImGuiKey_GamepadFaceUp,          SDL_CONTROLLER_BUTTON_Y);              // Xbox Y, PS Triangle
    MAP_BUTTON(ImGuiKey_GamepadDpadLeft,        SDL_CONTROLLER_BUTTON_DPAD_LEFT);
    MAP_BUTTON(ImGuiKey_GamepadDpadRight,       SDL_CONTROLLER_BUTTON_DPAD_RIGHT);
    MAP_BUTTON(ImGuiKey_GamepadDpadUp,          SDL_CONTROLLER_BUTTON_DPAD_UP);
    MAP_BUTTON(ImGuiKey_GamepadDpadDown,        SDL_CONTROLLER_BUTTON_DPAD_DOWN);
    MAP_BUTTON(ImGuiKey_GamepadL1,              SDL_CONTROLLER_BUTTON_LEFTSHOULDER);
    MAP_BUTTON(ImGuiKey_GamepadR1,              SDL_CONTROLLER_BUTTON_RIGHTSHOULDER);
    MAP_ANALOG(ImGuiKey_GamepadL2,              SDL_CONTROLLER_AXIS_TRIGGERLEFT,  0.0f, 32767);
    MAP_ANALOG(ImGuiKey_GamepadR2,              SDL_CONTROLLER_AXIS_TRIGGERRIGHT, 0.0f, 32767);
    MAP_BUTTON(ImGuiKey_GamepadL3,              SDL_CONTROLLER_BUTTON_LEFTSTICK);
    MAP_BUTTON(ImGuiKey_GamepadR3,              SDL_CONTROLLER_BUTTON_RIGHTSTICK);
    MAP_ANALOG(ImGuiKey_GamepadLStickLeft,      SDL_CONTROLLER_AXIS_LEFTX,  -thumb_dead_zone, -32768);
    MAP_ANALOG(ImGuiKey_GamepadLStickRight,     SDL_CONTROLLER_AXIS_LEFTX,  +thumb_dead_zone, +32767);
    MAP_ANALOG(ImGuiKey_GamepadLStickUp,        SDL_CONTROLLER_AXIS_LEFTY,  -thumb_dead_zone, -32768);
    MAP_ANALOG(ImGuiKey_GamepadLStickDown,      SDL_CONTROLLER_AXIS_LEFTY,  +thumb_dead_zone, +32767);
    MAP_ANALOG(ImGuiKey_GamepadRStickLeft,      SDL_CONTROLLER_AXIS_RIGHTX, -thumb_dead_zone, -32768);
    MAP_ANALOG(ImGuiKey_GamepadRStickRight,     SDL_CONTROLLER_AXIS_RIGHTX, +thumb_dead_zone, +32767);
    MAP_ANALOG(ImGuiKey_GamepadRStickUp,        SDL_CONTROLLER_AXIS_RIGHTY, -thumb_dead_zone, -32768);
    MAP_ANALOG(ImGuiKey_GamepadRStickDown,      SDL_CONTROLLER_AXIS_RIGHTY, +thumb_dead_zone, +32767);
    #undef MAP_BUTTON
    #undef MAP_ANALOG
}

// FIXME-PLATFORM: SDL doesn't have an event to notify the application of display/monitor changes
static void ImGui_ImplSDL2_UpdateMonitors()
{
    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
    platform_io.Monitors.resize(0);
    int display_count = SDL_GetNumVideoDisplays();
    for (int n = 0; n < display_count; n++)
    {
        // Warning: the validity of monitor DPI information on Windows depends on the application DPI awareness settings, which generally needs to be set in the manifest or at runtime.
        ImGuiPlatformMonitor monitor;
        SDL_Rect r;
        SDL_GetDisplayBounds(n, &r);
        monitor.MainPos = monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
        monitor.MainSize = monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
#if SDL_HAS_USABLE_DISPLAY_BOUNDS
        SDL_GetDisplayUsableBounds(n, &r);
        monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
        monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
#endif
#if SDL_HAS_PER_MONITOR_DPI
        float dpi = 0.0f;
        if (!SDL_GetDisplayDPI(n, &dpi, NULL, NULL))
            monitor.DpiScale = dpi / 96.0f;
#endif
        platform_io.Monitors.push_back(monitor);
    }
}

void ImGui_ImplSDL2_NewFrame()
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    IM_ASSERT(bd != NULL && "Did you call ImGui_ImplSDL2_Init()?");
    ImGuiIO& io = ImGui::GetIO();

    // Setup display size (every frame to accommodate for window resizing)
    int w, h;
    int display_w, display_h;
    SDL_GetWindowSize(bd->Window, &w, &h);
    if (SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_MINIMIZED)
        w = h = 0;
    if (bd->Renderer != NULL)
        SDL_GetRendererOutputSize(bd->Renderer, &display_w, &display_h);
    else
        SDL_GL_GetDrawableSize(bd->Window, &display_w, &display_h);
    io.DisplaySize = ImVec2((float)w, (float)h);
    if (w > 0 && h > 0)
        io.DisplayFramebufferScale = ImVec2((float)display_w / w, (float)display_h / h);

    // Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
    static Uint64 frequency = SDL_GetPerformanceFrequency();
    Uint64 current_time = SDL_GetPerformanceCounter();
    io.DeltaTime = bd->Time > 0 ? (float)((double)(current_time - bd->Time) / frequency) : (float)(1.0f / 60.0f);
    bd->Time = current_time;

    if (bd->PendingMouseLeaveFrame && bd->PendingMouseLeaveFrame >= ImGui::GetFrameCount() && bd->MouseButtonsDown == 0)
    {
        bd->MouseWindowID = 0;
        bd->PendingMouseLeaveFrame = 0;
        io.AddMousePosEvent(-FLT_MAX, -FLT_MAX);
    }

    ImGui_ImplSDL2_UpdateMouseData();
    ImGui_ImplSDL2_UpdateMouseCursor();

    // Update game controllers (if enabled and available)
    ImGui_ImplSDL2_UpdateGamepads();
}

//--------------------------------------------------------------------------------------------------------
// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
//--------------------------------------------------------------------------------------------------------

// Helper structure we store in the void* RenderUserData field of each ImGuiViewport to easily retrieve our backend data.
struct ImGui_ImplSDL2_ViewportData
{
    SDL_Window*     Window;
    Uint32          WindowID;
    bool            WindowOwned;
    SDL_GLContext   GLContext;

    ImGui_ImplSDL2_ViewportData() { Window = NULL; WindowID = 0; WindowOwned = false; GLContext = NULL; }
    ~ImGui_ImplSDL2_ViewportData() { IM_ASSERT(Window == NULL && GLContext == NULL); }
};

static void ImGui_ImplSDL2_CreateWindow(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    ImGui_ImplSDL2_ViewportData* vd = IM_NEW(ImGui_ImplSDL2_ViewportData)();
    viewport->PlatformUserData = vd;

    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
    ImGui_ImplSDL2_ViewportData* main_viewport_data = (ImGui_ImplSDL2_ViewportData*)main_viewport->PlatformUserData;

    // Share GL resources with main context
    bool use_opengl = (main_viewport_data->GLContext != NULL);
    SDL_GLContext backup_context = NULL;
    if (use_opengl)
    {
        backup_context = SDL_GL_GetCurrentContext();
        SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
        SDL_GL_MakeCurrent(main_viewport_data->Window, main_viewport_data->GLContext);
    }

    Uint32 sdl_flags = 0;
    sdl_flags |= use_opengl ? SDL_WINDOW_OPENGL : (bd->UseVulkan ? SDL_WINDOW_VULKAN : 0);
    sdl_flags |= SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_ALLOW_HIGHDPI;
    sdl_flags |= SDL_WINDOW_HIDDEN;
    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? SDL_WINDOW_BORDERLESS : 0;
    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? 0 : SDL_WINDOW_RESIZABLE;
#if !defined(_WIN32)
    // See SDL hack in ImGui_ImplSDL2_ShowWindow().
    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon) ? SDL_WINDOW_SKIP_TASKBAR : 0;
#endif
#if SDL_HAS_ALWAYS_ON_TOP
    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_TopMost) ? SDL_WINDOW_ALWAYS_ON_TOP : 0;
#endif
    vd->Window = SDL_CreateWindow("No Title Yet", (int)viewport->Pos.x, (int)viewport->Pos.y, (int)viewport->Size.x, (int)viewport->Size.y, sdl_flags);
    vd->WindowOwned = true;
    if (use_opengl)
    {
        vd->GLContext = SDL_GL_CreateContext(vd->Window);
        SDL_GL_SetSwapInterval(0);
    }
    if (use_opengl && backup_context)
        SDL_GL_MakeCurrent(vd->Window, backup_context);

    viewport->PlatformHandle = (void*)vd->Window;
#if defined(_WIN32)
    SDL_SysWMinfo info;
    SDL_VERSION(&info.version);
    if (SDL_GetWindowWMInfo(vd->Window, &info))
        viewport->PlatformHandleRaw = info.info.win.window;
#endif
}

static void ImGui_ImplSDL2_DestroyWindow(ImGuiViewport* viewport)
{
    if (ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData)
    {
        if (vd->GLContext && vd->WindowOwned)
            SDL_GL_DeleteContext(vd->GLContext);
        if (vd->Window && vd->WindowOwned)
            SDL_DestroyWindow(vd->Window);
        vd->GLContext = NULL;
        vd->Window = NULL;
        IM_DELETE(vd);
    }
    viewport->PlatformUserData = viewport->PlatformHandle = NULL;
}

static void ImGui_ImplSDL2_ShowWindow(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
#if defined(_WIN32)
    HWND hwnd = (HWND)viewport->PlatformHandleRaw;

    // SDL hack: Hide icon from task bar
    // Note: SDL 2.0.6+ has a SDL_WINDOW_SKIP_TASKBAR flag which is supported under Windows but the way it create the window breaks our seamless transition.
    if (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon)
    {
        LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
        ex_style &= ~WS_EX_APPWINDOW;
        ex_style |= WS_EX_TOOLWINDOW;
        ::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
    }

    // SDL hack: SDL always activate/focus windows :/
    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
    {
        ::ShowWindow(hwnd, SW_SHOWNA);
        return;
    }
#endif

    SDL_ShowWindow(vd->Window);
}

static ImVec2 ImGui_ImplSDL2_GetWindowPos(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    int x = 0, y = 0;
    SDL_GetWindowPosition(vd->Window, &x, &y);
    return ImVec2((float)x, (float)y);
}

static void ImGui_ImplSDL2_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_SetWindowPosition(vd->Window, (int)pos.x, (int)pos.y);
}

static ImVec2 ImGui_ImplSDL2_GetWindowSize(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    int w = 0, h = 0;
    SDL_GetWindowSize(vd->Window, &w, &h);
    return ImVec2((float)w, (float)h);
}

static void ImGui_ImplSDL2_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_SetWindowSize(vd->Window, (int)size.x, (int)size.y);
}

static void ImGui_ImplSDL2_SetWindowTitle(ImGuiViewport* viewport, const char* title)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_SetWindowTitle(vd->Window, title);
}

#if SDL_HAS_WINDOW_ALPHA
static void ImGui_ImplSDL2_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_SetWindowOpacity(vd->Window, alpha);
}
#endif

static void ImGui_ImplSDL2_SetWindowFocus(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_RaiseWindow(vd->Window);
}

static bool ImGui_ImplSDL2_GetWindowFocus(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    return (SDL_GetWindowFlags(vd->Window) & SDL_WINDOW_INPUT_FOCUS) != 0;
}

static bool ImGui_ImplSDL2_GetWindowMinimized(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    return (SDL_GetWindowFlags(vd->Window) & SDL_WINDOW_MINIMIZED) != 0;
}

static void ImGui_ImplSDL2_RenderWindow(ImGuiViewport* viewport, void*)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    if (vd->GLContext)
        SDL_GL_MakeCurrent(vd->Window, vd->GLContext);
}

static void ImGui_ImplSDL2_SwapBuffers(ImGuiViewport* viewport, void*)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    if (vd->GLContext)
    {
        SDL_GL_MakeCurrent(vd->Window, vd->GLContext);
        SDL_GL_SwapWindow(vd->Window);
    }
}

// Vulkan support (the Vulkan renderer needs to call a platform-side support function to create the surface)
// SDL is graceful enough to _not_ need <vulkan/vulkan.h> so we can safely include this.
#if SDL_HAS_VULKAN
#include <SDL_vulkan.h>
static int ImGui_ImplSDL2_CreateVkSurface(ImGuiViewport* viewport, ImU64 vk_instance, const void* vk_allocator, ImU64* out_vk_surface)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    (void)vk_allocator;
    SDL_bool ret = SDL_Vulkan_CreateSurface(vd->Window, (VkInstance)vk_instance, (VkSurfaceKHR*)out_vk_surface);
    return ret ? 0 : 1; // ret ? VK_SUCCESS : VK_NOT_READY
}
#endif // SDL_HAS_VULKAN

static void ImGui_ImplSDL2_InitPlatformInterface(SDL_Window* window, void* sdl_gl_context)
{
    // Register platform interface (will be coupled with a renderer interface)
    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
    platform_io.Platform_CreateWindow = ImGui_ImplSDL2_CreateWindow;
    platform_io.Platform_DestroyWindow = ImGui_ImplSDL2_DestroyWindow;
    platform_io.Platform_ShowWindow = ImGui_ImplSDL2_ShowWindow;
    platform_io.Platform_SetWindowPos = ImGui_ImplSDL2_SetWindowPos;
    platform_io.Platform_GetWindowPos = ImGui_ImplSDL2_GetWindowPos;
    platform_io.Platform_SetWindowSize = ImGui_ImplSDL2_SetWindowSize;
    platform_io.Platform_GetWindowSize = ImGui_ImplSDL2_GetWindowSize;
    platform_io.Platform_SetWindowFocus = ImGui_ImplSDL2_SetWindowFocus;
    platform_io.Platform_GetWindowFocus = ImGui_ImplSDL2_GetWindowFocus;
    platform_io.Platform_GetWindowMinimized = ImGui_ImplSDL2_GetWindowMinimized;
    platform_io.Platform_SetWindowTitle = ImGui_ImplSDL2_SetWindowTitle;
    platform_io.Platform_RenderWindow = ImGui_ImplSDL2_RenderWindow;
    platform_io.Platform_SwapBuffers = ImGui_ImplSDL2_SwapBuffers;
#if SDL_HAS_WINDOW_ALPHA
    platform_io.Platform_SetWindowAlpha = ImGui_ImplSDL2_SetWindowAlpha;
#endif
#if SDL_HAS_VULKAN
    platform_io.Platform_CreateVkSurface = ImGui_ImplSDL2_CreateVkSurface;
#endif

    // Register main window handle (which is owned by the main application, not by us)
    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
    ImGui_ImplSDL2_ViewportData* vd = IM_NEW(ImGui_ImplSDL2_ViewportData)();
    vd->Window = window;
    vd->WindowID = SDL_GetWindowID(window);
    vd->WindowOwned = false;
    vd->GLContext = sdl_gl_context;
    main_viewport->PlatformUserData = vd;
    main_viewport->PlatformHandle = vd->Window;
}

static void ImGui_ImplSDL2_ShutdownPlatformInterface()
{
    ImGui::DestroyPlatformWindows();
}

repo_name: orochi/nblood

license: mit