module ecs_utils.imgui_bind;

import bindbc.sdl;
import cimgui.cimgui;

version(WebAssembly)
{
    extern(C):
    bool ImGui_ImplOpenGL3_Init(const char* glsl_version = null);
    void ImGui_ImplOpenGL3_Shutdown();
    void ImGui_ImplOpenGL3_NewFrame();
    void ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data);

    bool ImGui_ImplSDL2_InitForOpenGL(SDL_Window* window, void* sdl_gl_context);
    bool ImGui_ImplSDL2_InitForVulkan(SDL_Window* window);
    bool ImGui_ImplSDL2_InitForD3D(SDL_Window* window);
    void ImGui_ImplSDL2_Shutdown();
    void ImGui_ImplSDL2_NewFrame(SDL_Window* window);
    bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event);
}
else :

import bindbc.sdl;

import glad.gl.gl;

import cimgui.cimgui;

extern(C):

__gshared SDL_Window* g_Window;
__gshared ulong g_Time;
__gshared bool[3] g_MousePressed;
__gshared SDL_Cursor*[ImGuiMouseCursor_COUNT] g_MouseCursors;
__gshared char* g_ClipboardTextData;
__gshared GLuint g_FontTexture = 0;

const (char)* ImGuiImplSDL2GetClipboardText(void*)
{
    if (g_ClipboardTextData)
        SDL_free(g_ClipboardTextData);
    g_ClipboardTextData = SDL_GetClipboardText();
    return g_ClipboardTextData;
}

void ImGuiImplSDL2SetClipboardText(void*, const char* text)
{
    SDL_SetClipboardText(text);
}

bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
{
    ImGuiIO* io = igGetIO();
    switch (event.type)
    {
    case SDL_MOUSEWHEEL:
        {
            if (event.wheel.x > 0) io.MouseWheelH += 1;
            if (event.wheel.x < 0) io.MouseWheelH -= 1;
            if (event.wheel.y > 0) io.MouseWheel += 1;
            if (event.wheel.y < 0) io.MouseWheel -= 1;
            return true;
        }
    case SDL_MOUSEBUTTONDOWN:
        {
            if (event.button.button == SDL_BUTTON_LEFT) g_MousePressed[0] = true;
            if (event.button.button == SDL_BUTTON_RIGHT) g_MousePressed[1] = true;
            if (event.button.button == SDL_BUTTON_MIDDLE) g_MousePressed[2] = true;
            return true;
        }
    case SDL_TEXTINPUT:
        {
            ImGuiIO_AddInputCharactersUTF8(io,event.text.text.ptr);
            return true;
        }
    case SDL_KEYDOWN:
    case SDL_KEYUP:
        {
            int key = event.key.keysym.scancode;
            //IM_ASSERT(key >= 0 && key < IM_ARRAYSIZE(io.KeysDown));
            io.KeysDown[key] = (event.type == SDL_KEYDOWN);
            io.KeyShift = ((SDL_GetModState() & KMOD_SHIFT) != 0);
            io.KeyCtrl = ((SDL_GetModState() & KMOD_CTRL) != 0);
            io.KeyAlt = ((SDL_GetModState() & KMOD_ALT) != 0);
            io.KeySuper = ((SDL_GetModState() & KMOD_GUI) != 0);
            return true;
        }
    default:break;
    }
    return false;
}

bool ImGuiImplSDL2Init(SDL_Window* window)
{
    g_Window = window;

    // Setup back-end capabilities flags
    ImGuiIO* io = igGetIO();
    io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;       // We can honor GetMouseCursor() values (optional)
    io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;        // We can honor io.WantSetMousePos requests (optional, rarely used)
    io.BackendPlatformName = "imgui_impl_sdl";

    // Keyboard mapping. ImGui will use those indices to peek into the io.KeysDown[] array.
    io.KeyMap[ImGuiKey_Tab] = SDL_SCANCODE_TAB;
    io.KeyMap[ImGuiKey_LeftArrow] = SDL_SCANCODE_LEFT;
    io.KeyMap[ImGuiKey_RightArrow] = SDL_SCANCODE_RIGHT;
    io.KeyMap[ImGuiKey_UpArrow] = SDL_SCANCODE_UP;
    io.KeyMap[ImGuiKey_DownArrow] = SDL_SCANCODE_DOWN;
    io.KeyMap[ImGuiKey_PageUp] = SDL_SCANCODE_PAGEUP;
    io.KeyMap[ImGuiKey_PageDown] = SDL_SCANCODE_PAGEDOWN;
    io.KeyMap[ImGuiKey_Home] = SDL_SCANCODE_HOME;
    io.KeyMap[ImGuiKey_End] = SDL_SCANCODE_END;
    io.KeyMap[ImGuiKey_Insert] = SDL_SCANCODE_INSERT;
    io.KeyMap[ImGuiKey_Delete] = SDL_SCANCODE_DELETE;
    io.KeyMap[ImGuiKey_Backspace] = SDL_SCANCODE_BACKSPACE;
    io.KeyMap[ImGuiKey_Space] = SDL_SCANCODE_SPACE;
    io.KeyMap[ImGuiKey_Enter] = SDL_SCANCODE_RETURN;
    io.KeyMap[ImGuiKey_Escape] = SDL_SCANCODE_ESCAPE;
    io.KeyMap[ImGuiKey_KeyPadEnter] = SDL_SCANCODE_RETURN2;
    io.KeyMap[ImGuiKey_A] = SDL_SCANCODE_A;
    io.KeyMap[ImGuiKey_C] = SDL_SCANCODE_C;
    io.KeyMap[ImGuiKey_V] = SDL_SCANCODE_V;
    io.KeyMap[ImGuiKey_X] = SDL_SCANCODE_X;
    io.KeyMap[ImGuiKey_Y] = SDL_SCANCODE_Y;
    io.KeyMap[ImGuiKey_Z] = SDL_SCANCODE_Z;

    io.SetClipboardTextFn = &ImGuiImplSDL2SetClipboardText;
    io.GetClipboardTextFn = &ImGuiImplSDL2GetClipboardText;
    io.ClipboardUserData = null;

    g_MouseCursors[ImGuiMouseCursor_Arrow] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_ARROW);
    g_MouseCursors[ImGuiMouseCursor_TextInput] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_IBEAM);
    g_MouseCursors[ImGuiMouseCursor_ResizeAll] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEALL);
    g_MouseCursors[ImGuiMouseCursor_ResizeNS] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENS);
    g_MouseCursors[ImGuiMouseCursor_ResizeEW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEWE);
    g_MouseCursors[ImGuiMouseCursor_ResizeNESW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENESW);
    g_MouseCursors[ImGuiMouseCursor_ResizeNWSE] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENWSE);
    g_MouseCursors[ImGuiMouseCursor_Hand] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_HAND);

    //#ifdef _WIN32
    version(WebAssembly)
    {

    }
    else version(Windows)
    {
        SDL_SysWMinfo wmInfo;
        SDL_VERSION(&wmInfo.version_);
        SDL_GetWindowWMInfo(window, &wmInfo);
        io.ImeWindowHandle = wmInfo.info.win.window;
    }
    //#else
        //(void)window;
    //#endif

    return true;
}

bool ImGuiImplSDL2InitForOpenGL(SDL_Window* window, void* sdl_gl_context)
{
    //(void)sdl_gl_context; // Viewport branch will need this.
    return ImGuiImplSDL2Init(window);
}

void ImGuiImplSDL2Shutdown()
{
    g_Window = null;

    // Destroy last known clipboard data
    if (g_ClipboardTextData)
        SDL_free(g_ClipboardTextData);
    g_ClipboardTextData = null;

    // Destroy SDL mouse cursors
    for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_COUNT; cursor_n++)
        SDL_FreeCursor(g_MouseCursors[cursor_n]);
    //memset(g_MouseCursors, 0, sizeof(g_MouseCursors));
}

static void ImGui_ImplSDL2_UpdateMousePosAndButtons()
{
    ImGuiIO* io = igGetIO();

    // Set OS mouse position if requested (rarely used, only when ImGuiConfigFlags_NavEnableSetMousePos is enabled by user)
    if (io.WantSetMousePos)
        SDL_WarpMouseInWindow(g_Window, cast(int)io.MousePos.x, cast(int)io.MousePos.y);
    else
        io.MousePos = ImVec2(-float.max, -float.max);

    int mx, my;
    Uint32 mouse_buttons = SDL_GetMouseState(&mx, &my);
    io.MouseDown[0] = g_MousePressed[0] || (mouse_buttons & (SDL_PRESSED<<(SDL_BUTTON_LEFT-1))) != 0;  // If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
    io.MouseDown[1] = g_MousePressed[1] || (mouse_buttons & (SDL_PRESSED<<(SDL_BUTTON_RIGHT-1))) != 0;
    io.MouseDown[2] = g_MousePressed[2] || (mouse_buttons & (SDL_PRESSED<<(SDL_BUTTON_MIDDLE-1))) != 0;
    g_MousePressed[0] = g_MousePressed[1] = g_MousePressed[2] = false;

    //#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE && !defined(__EMSCRIPTEN__) && !defined(__ANDROID__) && !(defined(__APPLE__) && TARGET_OS_IOS)
    /*SDL_Window* focused_window = SDL_GetKeyboardFocus();
    if (g_Window == focused_window)
    {
        // SDL_GetMouseState() gives mouse position seemingly based on the last window entered/focused(?)
        // The creation of a new windows at runtime and SDL_CaptureMouse both seems to severely mess up with that, so we retrieve that position globally.
        int wx, wy;
        SDL_GetWindowPosition(focused_window, &wx, &wy);
        SDL_GetGlobalMouseState(&mx, &my);
        mx -= wx;
        my -= wy;
        io.MousePos = ImVec2((float)mx, (float)my);
    }

    // SDL_CaptureMouse() let the OS know e.g. that our imgui drag outside the SDL window boundaries shouldn't e.g. trigger the OS window resize cursor.
    // The function is only supported from SDL 2.0.4 (released Jan 2016)
    bool any_mouse_button_down = ImGui::IsAnyMouseDown();
    SDL_CaptureMouse(any_mouse_button_down ? SDL_TRUE : SDL_FALSE);
//#else*/
    if (SDL_GetWindowFlags(g_Window) & SDL_WINDOW_INPUT_FOCUS)
        io.MousePos = ImVec2(cast(float)mx, cast(float)my);
//#endif
}

static void ImGui_ImplSDL2_UpdateMouseCursor()
{
    ImGuiIO* io = igGetIO();
    if (io.ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange)
        return;

    ImGuiMouseCursor imgui_cursor = igGetMouseCursor();
    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(g_MouseCursors[imgui_cursor] ? g_MouseCursors[imgui_cursor] : g_MouseCursors[ImGuiMouseCursor_Arrow]);
        SDL_ShowCursor(SDL_TRUE);
    }
}

static void ImGui_ImplSDL2_UpdateGamepads()
{
    ImGuiIO* io = igGetIO();
    //memset(io.NavInputs, 0, sizeof(io.NavInputs));
    if ((io.ConfigFlags & ImGuiConfigFlags_NavEnableGamepad) == 0)
        return;

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

    // Update gamepad inputs
    /*#define MAP_BUTTON(NAV_NO, BUTTON_NO)       { io.NavInputs[NAV_NO] = (SDL_GameControllerGetButton(game_controller, BUTTON_NO) != 0) ? 1.0f : 0.0f; }
    #define MAP_ANALOG(NAV_NO, AXIS_NO, V0, V1) { float vn = (float)(SDL_GameControllerGetAxis(game_controller, AXIS_NO) - V0) / (float)(V1 - V0); if (vn > 1.0f) vn = 1.0f; if (vn > 0.0f && io.NavInputs[NAV_NO] < vn) io.NavInputs[NAV_NO] = vn; }
    const int thumb_dead_zone = 8000;           // SDL_gamecontroller.h suggests using this value.
    MAP_BUTTON(ImGuiNavInput_Activate,      SDL_CONTROLLER_BUTTON_A);               // Cross / A
    MAP_BUTTON(ImGuiNavInput_Cancel,        SDL_CONTROLLER_BUTTON_B);               // Circle / B
    MAP_BUTTON(ImGuiNavInput_Menu,          SDL_CONTROLLER_BUTTON_X);               // Square / X
    MAP_BUTTON(ImGuiNavInput_Input,         SDL_CONTROLLER_BUTTON_Y);               // Triangle / Y
    MAP_BUTTON(ImGuiNavInput_DpadLeft,      SDL_CONTROLLER_BUTTON_DPAD_LEFT);       // D-Pad Left
    MAP_BUTTON(ImGuiNavInput_DpadRight,     SDL_CONTROLLER_BUTTON_DPAD_RIGHT);      // D-Pad Right
    MAP_BUTTON(ImGuiNavInput_DpadUp,        SDL_CONTROLLER_BUTTON_DPAD_UP);         // D-Pad Up
    MAP_BUTTON(ImGuiNavInput_DpadDown,      SDL_CONTROLLER_BUTTON_DPAD_DOWN);       // D-Pad Down
    MAP_BUTTON(ImGuiNavInput_FocusPrev,     SDL_CONTROLLER_BUTTON_LEFTSHOULDER);    // L1 / LB
    MAP_BUTTON(ImGuiNavInput_FocusNext,     SDL_CONTROLLER_BUTTON_RIGHTSHOULDER);   // R1 / RB
    MAP_BUTTON(ImGuiNavInput_TweakSlow,     SDL_CONTROLLER_BUTTON_LEFTSHOULDER);    // L1 / LB
    MAP_BUTTON(ImGuiNavInput_TweakFast,     SDL_CONTROLLER_BUTTON_RIGHTSHOULDER);   // R1 / RB
    MAP_ANALOG(ImGuiNavInput_LStickLeft,    SDL_CONTROLLER_AXIS_LEFTX, -thumb_dead_zone, -32768);
    MAP_ANALOG(ImGuiNavInput_LStickRight,   SDL_CONTROLLER_AXIS_LEFTX, +thumb_dead_zone, +32767);
    MAP_ANALOG(ImGuiNavInput_LStickUp,      SDL_CONTROLLER_AXIS_LEFTY, -thumb_dead_zone, -32767);
    MAP_ANALOG(ImGuiNavInput_LStickDown,    SDL_CONTROLLER_AXIS_LEFTY, +thumb_dead_zone, +32767);

    io.BackendFlags |= ImGuiBackendFlags_HasGamepad;
    #undef MAP_BUTTON
    #undef MAP_ANALOG*/
}


__gshared private long frequency;

void ImGuiImplSDL2NewFrame(SDL_Window* window)
{
    ImGuiIO* io = igGetIO();
    assert(ImFontAtlas_IsBuilt(io.Fonts), "Font atlas not built! It is generally built by the renderer back-end. Missing call to renderer _NewFrame() function? e.g. ImGui_ImplOpenGL3_NewFrame().");

    // Setup display size (every frame to accommodate for window resizing)
    int w, h;
    int display_w, display_h;
    SDL_GetWindowSize(window, &w, &h);
    SDL_GL_GetDrawableSize(window, &display_w, &display_h);
    io.DisplaySize = ImVec2(cast(float)w, cast(float)h);
    if (w > 0 && h > 0)
        io.DisplayFramebufferScale = ImVec2(cast(float)display_w / w, cast(float)display_h / h);

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

    ImGui_ImplSDL2_UpdateMousePosAndButtons();
    ImGui_ImplSDL2_UpdateMouseCursor();

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










bool ImGuiImplOpenGL2Init()
{
    // Setup back-end capabilities flags
    ImGuiIO* io = igGetIO();
    io.BackendRendererName = "imgui_impl_opengl2";
    return true;
}

void ImGuiImplOpenGL2Shutdown()
{
    ImGuiImplOpenGL2DestroyDeviceObjects();
}

void ImGuiImplOpenGL2NewFrame()
{
    if (!g_FontTexture)
        ImGuiImplOpenGL2CreateDeviceObjects();
}

static void ImGuiImplOpenGL2SetupRenderState(ImDrawData* draw_data, int fb_width, int fb_height)
{
    // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers, polygon fill.
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glDisable(GL_CULL_FACE);
    glDisable(GL_DEPTH_TEST);
    //glDisable(GL_LIGHTING);
    //glDisable(GL_COLOR_MATERIAL);
    glEnable(GL_SCISSOR_TEST);
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);
    glEnable(GL_TEXTURE_2D);
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);

    // If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),
    // you may need to backup/reset/restore current shader using the lines below. DO NOT MODIFY THIS FILE! Add the code in your calling function:
    //  GLint last_program;
    //  glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
    //  glUseProgram(0);
    //  ImGui_ImplOpenGL2_RenderDrawData(...);
    //  glUseProgram(last_program)

    // 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, cast(GLsizei)fb_width, cast(GLsizei)fb_height);
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    glLoadIdentity();
    glOrtho(draw_data.DisplayPos.x, draw_data.DisplayPos.x + draw_data.DisplaySize.x, draw_data.DisplayPos.y + draw_data.DisplaySize.y, draw_data.DisplayPos.y, -1.0f, +1.0f);
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glLoadIdentity();
}

// OpenGL2 Render function.
// (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from your main loop)
// Note that this implementation is little overcomplicated because we are saving/setting up/restoring every OpenGL state explicitly, in order to be able to run within any OpenGL engine that doesn't do so.
void ImGuiImplOpenGL2RenderDrawData(ImDrawData* draw_data)
{
    // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
    int fb_width = cast(int)(draw_data.DisplaySize.x * draw_data.FramebufferScale.x);
    int fb_height = cast(int)(draw_data.DisplaySize.y * draw_data.FramebufferScale.y);
    if (fb_width == 0 || fb_height == 0)
        return;

    // Backup GL state
    GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
    GLint[2] last_polygon_mode; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode.ptr);
    GLint[4] last_viewport; glGetIntegerv(GL_VIEWPORT, last_viewport.ptr);
    GLint[4] last_scissor_box; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box.ptr);
    glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT);

    // Setup desired GL state
    ImGuiImplOpenGL2SetupRenderState(draw_data, fb_width, fb_height);

    // 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++)
    {
        ImDrawList* cmd_list = draw_data.CmdLists[n];
        ImDrawVert* vtx_buffer = cmd_list.VtxBuffer.Data;
        ImDrawIdx* idx_buffer = cmd_list.IdxBuffer.Data;
        glVertexPointer(2, GL_FLOAT, ImDrawVert.sizeof, cast(const GLvoid*)(cast(const char*)vtx_buffer + ImDrawVert.pos.offsetof));
        glTexCoordPointer(2, GL_FLOAT, ImDrawVert.sizeof, cast(const GLvoid*)(cast(const char*)vtx_buffer + ImDrawVert.uv.offsetof));
        glColorPointer(4, GL_UNSIGNED_BYTE, ImDrawVert.sizeof, cast(const GLvoid*)(cast(const char*)vtx_buffer + ImDrawVert.col.offsetof));

        for (int cmd_i = 0; cmd_i < cmd_list.CmdBuffer.Size; cmd_i++)
        {
            const ImDrawCmd* pcmd = &cmd_list.CmdBuffer.Data[cmd_i];
            if (pcmd.UserCallback)
            {
                // 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_ImplOpenGL2_SetupRenderState(draw_data, fb_width, fb_height);
                else*/
                    pcmd.UserCallback(cmd_list, pcmd);
            }
            else
            {
                // Project scissor/clipping rectangles into framebuffer space
                ImVec4 clip_rect = ImVec4(0,0,0,0);
                clip_rect.x = (pcmd.ClipRect.x - clip_off.x) * clip_scale.x;
                clip_rect.y = (pcmd.ClipRect.y - clip_off.y) * clip_scale.y;
                clip_rect.z = (pcmd.ClipRect.z - clip_off.x) * clip_scale.x;
                clip_rect.w = (pcmd.ClipRect.w - clip_off.y) * clip_scale.y;

                if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f)
                {
                    // Apply scissor/clipping rectangle
                    glScissor(cast(int)clip_rect.x, cast(int)(fb_height - clip_rect.w), cast(int)(clip_rect.z - clip_rect.x), cast(int)(clip_rect.w - clip_rect.y));

                    // Bind texture, Draw
                    glBindTexture(GL_TEXTURE_2D, cast(GLuint)pcmd.TextureId);
                    glDrawElements(GL_TRIANGLES, cast(GLsizei)pcmd.ElemCount, ImDrawIdx.sizeof == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer);
                }
            }
            idx_buffer += pcmd.ElemCount;
        }
    }

    // Restore modified GL state
    glDisableClientState(GL_COLOR_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
    glDisableClientState(GL_VERTEX_ARRAY);
    glBindTexture(GL_TEXTURE_2D, cast(GLuint)last_texture);
    glMatrixMode(GL_MODELVIEW);
    glPopMatrix();
    glMatrixMode(GL_PROJECTION);
    glPopMatrix();
    glPopAttrib();
    glPolygonMode(GL_FRONT, cast(GLenum)last_polygon_mode[0]); glPolygonMode(GL_BACK, cast(GLenum)last_polygon_mode[1]);
    glViewport(last_viewport[0], last_viewport[1], cast(GLsizei)last_viewport[2], cast(GLsizei)last_viewport[3]);
    glScissor(last_scissor_box[0], last_scissor_box[1], cast(GLsizei)last_scissor_box[2], cast(GLsizei)last_scissor_box[3]);
}

bool ImGuiImplOpenGL2CreateFontsTexture()
{
    // Build texture atlas
    ImGuiIO* io = igGetIO();
    ubyte* pixels;
    int width, height;
    int bpp;
    ImFontAtlas_GetTexDataAsRGBA32(io.Fonts, &pixels, &width, &height, &bpp);   // Load as RGBA 32-bits (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, &g_FontTexture);
    glBindTexture(GL_TEXTURE_2D, g_FontTexture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);

    // Store our identifier
    io.Fonts.TexID = cast(ImTextureID)g_FontTexture;

    // Restore state
    glBindTexture(GL_TEXTURE_2D, last_texture);

    return true;
}

void ImGuiImplOpenGL2DestroyFontsTexture()
{
    if (g_FontTexture)
    {
        ImGuiIO* io = igGetIO();
        glDeleteTextures(1, &g_FontTexture);
        io.Fonts.TexID = null;
        g_FontTexture = 0;
    }
}

bool ImGuiImplOpenGL2CreateDeviceObjects()
{
    return ImGuiImplOpenGL2CreateFontsTexture();
}

void ImGuiImplOpenGL2DestroyDeviceObjects()
{
    ImGuiImplOpenGL2DestroyFontsTexture();
}