outdated: 41.Volumetric Fog & IPicture Image Loading

#ifndef GL_FRAMEWORK_INCLUDED
#define GL_FRAMEWORK_INCLUDED

#include <windows.h>

typedef struct {                                   // Structure for keyboard stuff
    BOOL keyDown[256];
} Keys;

typedef struct {                                   // Contains information vital to applications 
    HMODULE hInstance;                             // Application Instance
    const char* className;
} Application;

typedef struct {                                   // Window creation info
    Application* application;
    char* title;
    int width;
    int height;
    int bitsPerPixel;
    BOOL isFullScreen;
} GL_WindowInit;

typedef struct {                                   // Contains information vital to a window
    Keys* keys;
    HWND hWnd;                                     // Windows handle
    HDC hDC;                                       // Device context
    HGLRC hRC;                                     // Rendering context
    GL_WindowInit init;
    BOOL isVisible;                                // Window visiable?
    DWORD lastTickCount;                           // Tick counter
} GL_Window;

void TerminateApplication(GL_Window* window);      // Terminate the application

void ToggleFullscreen(GL_Window* window);          // Toggle fullscreen / Windowed mode

BOOL Initialize(GL_Window* window, Keys* keys);

void Deinitialize(void);

void Update(DWORD milliseconds);

void Draw(void);

#endif

#include <Windows.h>
#include <GL\glew.h>
#include <GL\glut.h>
#include "Previous.h"

#define WM_TOGGLEFULLSCREEN (WM_USER+1)                   // Application define message for toggling 
// between fulscreen / windowed mode
static BOOL g_isProgramLooping;                           // Window creation loop, for fullscreen / windowed mode
static BOOL g_createFullScreen;                           // If true, then create window

void TerminateApplication(GL_Window* window)              // Terminate the application
{
    PostMessage(window->hWnd, WM_QUIT, 0, 0);             // Send a WM_QUIT message
    g_isProgramLooping = FALSE;                           // Stop looping of the program
}

void ToggleFullscreen(GL_Window* window)                  // Toggle fullscreen /windowed mode
{
    PostMessage(window->hWnd, WM_TOGGLEFULLSCREEN, 0, 0); // Send a WM_TOGGLEFULLSCREEN message
}

void ReshapeGL(int width, int height)                     // Reshape the window  when it‘s moved or resized
{
    glViewport(0, 0, (GLsizei)(width), (GLsizei)(height)); // Reset the current viewport
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    // Calcutate the aspect ratio of the window
    gluPerspective(45.0f, (GLfloat)(width) / (GLfloat)(height), 1.0, 100.0f);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

BOOL ChangeScreenResolution(int width, int height, int bitsPerPixel)     // Change the screen resolution
{
    DEVMODE dmScreenSettings;                              // Device mode
    ZeroMemory(&dmScreenSettings, sizeof(DEVMODE));        // Make sure memory is cleared
    dmScreenSettings.dmSize = sizeof(DEVMODE);             // Size of the devmode structure
    dmScreenSettings.dmPelsWidth = width;
    dmScreenSettings.dmPelsHeight = height;
    dmScreenSettings.dmBitsPerPel = bitsPerPixel;
    dmScreenSettings.dmFields = DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT;
    if (ChangeDisplaySettings(&dmScreenSettings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL) {
        return FALSE;                                      // Display change failed
    }
    return TRUE;
}

BOOL CreateWindowGL(GL_Window* window)
{
    DWORD windowStyle = WS_OVERLAPPEDWINDOW;                // Define window style
    DWORD windowExtendedStyle = WS_EX_APPWINDOW;            // Define the window‘s extended style

    PIXELFORMATDESCRIPTOR pdf = {
        sizeof(PIXELFORMATDESCRIPTOR),                      // Size of this pixel format descriptor
        1,                                                  // Version Number
        PFD_DRAW_TO_WINDOW |                                // Format must support window
        PFD_SUPPORT_OPENGL |                                // Format must support openGL
        PFD_DOUBLEBUFFER,                                   // Must support double buffering
        PFD_TYPE_RGBA,                                      // Request an RGBA format
        window->init.bitsPerPixel,                          // Select color depth
        0, 0, 0, 0, 0, 0,                                   // Color bits ignored
        0,                                                  // No alpha buffer
        0,                                                  // Shift bit ignored
        0,                                                  // No accumulation buffer
        0, 0, 0, 0,                                         // Accumulation bits ignored
        16,                                                 // 16bits Z-buffer (depth buffer)
        0,                                                  // No stencil buffer
        0,                                                  // No auxiliary buffer
        PFD_MAIN_PLANE,                                     // Main drawing layer
        0,                                                  // Reserved
        0, 0, 0                                             // Layer masks ignored
    };
    RECT windowRect = { 0, 0, window->init.width, window->init.height };   // Window coordiantes

    GLuint PixelFormat;

    if (window->init.isFullScreen == TRUE) {
        if (ChangeScreenResolution(window->init.width, window->init.height, window->init.bitsPerPixel) == FALSE)
        {
            // Fullscreen mode failed, run in windowed mode instead
            MessageBox(HWND_DESKTOP, "Mode Switch Failed.\nRuning In Windowed Mode.",
                "Error", MB_OK | MB_ICONEXCLAMATION);
            window->init.isFullScreen = FALSE;
        }
        else {
            ShowCursor(FALSE);
            windowStyle = WS_POPUP;                         // Popup window
            windowExtendedStyle |= WS_EX_TOPMOST;
        }
    }
    else {
        // Adjust window, account for window borders
        AdjustWindowRectEx(&windowRect, windowStyle, 0, windowExtendedStyle);
    }
    // Create Opengl window
    window->hWnd = CreateWindowEx(windowExtendedStyle,      // Extended style
        window->init.application->className,                // Class name
        window->init.title,                                 // Window title
        windowStyle,                                        // Window style
        0, 0,                                               // Window X,Y position
        windowRect.right - windowRect.left,                 // Window width
        windowRect.bottom - windowRect.top,                 // Window height
        HWND_DESKTOP,                                       // Desktop is window‘s parent
        0,                                                  // No menu
        window->init.application->hInstance,                // Pass the window instance
        window);

    if (window->hWnd == 0) {                                // Was window creation a success?
        return FALSE;
    }
    window->hDC = GetDC(window->hWnd);
    if (window->hDC == 0) {
        DestroyWindow(window->hWnd);
        window->hWnd = 0;
        return FALSE;
    }
    PixelFormat = ChoosePixelFormat(window->hDC, &pdf);     // Find a compatible pixel format
    if (PixelFormat == 0) {
        ReleaseDC(window->hWnd, window->hDC);               // Release device context
        window->hDC = 0;
        DestroyWindow(window->hWnd);
        window->hWnd = 0;
        return FALSE;
    }
    if (SetPixelFormat(window->hDC, PixelFormat, &pdf) == FALSE) {   // Try to set the pixel format
        ReleaseDC(window->hWnd, window->hDC);
        window->hDC = 0;
        DestroyWindow(window->hWnd);
        window->hWnd = 0;
        return FALSE;
    }
    window->hRC = wglCreateContext(window->hDC);            // Try to get a rendering context
    if (window->hRC == 0) {
        ReleaseDC(window->hWnd, window->hDC);
        window->hDC = 0;
        DestroyWindow(window->hWnd);
        window->hWnd = 0;
        return FALSE;
    }
    // Make the rendering context our current rendering context
    if (wglMakeCurrent(window->hDC, window->hRC) == FALSE) {
        wglDeleteContext(window->hRC);                      //  Delete the rendering context
        window->hRC = 0;
        ReleaseDC(window->hWnd, window->hDC);
        window->hDC = 0;
        DestroyWindow(window->hWnd);
        window->hWnd = 0;
        return FALSE;
    }
    ShowWindow(window->hWnd, SW_NORMAL);                    // Make the window visiable
    window->isVisible = TRUE;
    ReshapeGL(window->init.width, window->init.height);     // Reshape our GL window
    ZeroMemory(window->keys, sizeof(Keys));                 // Clear all keys
    window->lastTickCount = GetTickCount();
    return TRUE;
}

BOOL DestroyWindowGL(GL_Window* window)
{
    if (window->hWnd != 0) {
        if (window->hDC != 0) {
            wglMakeCurrent(window->hDC, 0);                 // Setting current active rendering context to zero
            if (window->hRC != 0) {
                wglDeleteContext(window->hRC);
                window->hRC = 0;
            }
            ReleaseDC(window->hWnd, window->hDC);
            window->hDC = 0;
        }
        DestroyWindow(window->hWnd);
        window->hWnd = 0;
    }
    if (window->init.isFullScreen) {
        ChangeDisplaySettings(NULL, 0);                     // Switch back to desktop resolution
        ShowCursor(TRUE);
    }
    return TRUE;
}

// Process window message callback
LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    DWORD tickCount;
    // Get the window context
    GL_Window* window = (GL_Window*)(GetWindowLong(hWnd, GWL_USERDATA));
    switch (uMsg) {                                         // Evaluate window message
    case WM_PAINT:
    {
        tickCount = GetTickCount();
        Update(tickCount - window->lastTickCount);
        window->lastTickCount = tickCount;
        Draw();
        SwapBuffers(window->hDC);
    }
    return 0;

    case WM_SYSCOMMAND:                                     // Intercept system commands
    {
        switch (wParam) {                                   // Check system calls
        case SC_SCREENSAVE:                                 // Screensaver trying to start?
        case SC_MONITORPOWER:                               // Mointer trying to enter powersave?
            return 0;                                           // Prevent form happening
        }
        break;
    }
    return 0;
    case WM_CREATE:
    {
        CREATESTRUCT* creation = (CREATESTRUCT*)(lParam);   // Store window structure pointer
        window = (GL_Window*)(creation->lpCreateParams);
        SetWindowLong(hWnd, GWL_USERDATA, (LONG)(window));
    }
    return 0;

    case WM_CLOSE:
        TerminateApplication(window);
        return 0;

    case WM_SIZE:
        switch (wParam) {
        case SIZE_MINIMIZED:                                 // Was window minimized?
            window->isVisible = FALSE;
            return 0;
        case SIZE_MAXIMIZED:
            window->isVisible = TRUE;
            ReshapeGL(LOWORD(lParam), HIWORD(lParam));
            return 0;
        case SIZE_RESTORED:
            window->isVisible = TRUE;
            ReshapeGL(LOWORD(lParam), HIWORD(lParam));
            return 0;
        }
        break;

    case WM_KEYDOWN:
        if ((wParam >= 0) && (wParam <= 255)) {
            window->keys->keyDown[wParam] = TRUE;            // Set the selected key(wParam) to true
            return 0;
        }
        break;

    case WM_KEYUP:
        if ((wParam >= 0) && (wParam <= 255)) {
            window->keys->keyDown[wParam] = FALSE;
            return 0;
        }
        break;

    case WM_TOGGLEFULLSCREEN:
        g_createFullScreen = (g_createFullScreen == TRUE) ? FALSE : TRUE;
        PostMessage(hWnd, WM_QUIT, 0, 0);
        break;
    }
    return DefWindowProc(hWnd, uMsg, wParam, lParam);        // Pass unhandle message to DefWindowProc
}

BOOL RegisterWindowClass(Application* application)
{
    WNDCLASSEX windowClass;
    ZeroMemory(&windowClass, sizeof(WNDCLASSEX));            // Make sure memory is cleared
    windowClass.cbSize = sizeof(WNDCLASSEX);                 // Size of the windowClass structure
    windowClass.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;  // Redraws the window for any movement / resizing
    windowClass.lpfnWndProc = (WNDPROC)(WindowProc);         // WindowProc handles message
    windowClass.hInstance = application->hInstance;          // Set the instance
    windowClass.hbrBackground = (HBRUSH)(COLOR_APPWORKSPACE);// Class background brush color
    windowClass.hCursor = LoadCursor(NULL, IDC_ARROW);       // Load the arrow pointer
    windowClass.lpszClassName = application->className;      // Sets the application className
    if (RegisterClassEx(&windowClass) == 0) {
        MessageBox(HWND_DESKTOP, "RegisterClassEx Failed!", "Error", MB_OK | MB_ICONEXCLAMATION);
        return FALSE;
    }
    return TRUE;
}

int WINAPI WinMain(HINSTANCE hIstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    Application application;
    GL_Window window;
    Keys keys;
    BOOL isMessagePumpActive;
    MSG msg;
    DWORD tickCount;

    application.className = "OpenGL";
    application.hInstance = hIstance;

    ZeroMemory(&window, sizeof(GL_Window));
    window.keys = &keys;                                     // Window key structure
    window.init.application = &application;                  // Window application
    window.init.title = "Volumetric Fog Tutorial";           // Window title
    window.init.width = 640;                                 // Window width
    window.init.height = 480;                                // Window height
    window.init.bitsPerPixel = 32;                           // Bits per pixel
    window.init.isFullScreen = TRUE;                         // Fullscreen? (set to TRUE)

    ZeroMemory(&keys, sizeof(Keys));
    if (MessageBox(HWND_DESKTOP, "Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",
        MB_YESNO | MB_ICONQUESTION) == IDNO)
    {
        window.init.isFullScreen = FALSE;
    }
    if (RegisterWindowClass(&application) == FALSE)
    {
        MessageBox(HWND_DESKTOP, "Error Registering Window Class!", "Error", MB_OK | MB_ICONEXCLAMATION);
        return -1;
    }
    g_isProgramLooping = TRUE;
    g_createFullScreen = window.init.isFullScreen;
    while (g_isProgramLooping) {                             // Loop until WM_QUIT is received
        window.init.isFullScreen = g_createFullScreen;       // Set init param of window creation to fullscreen?
        if (CreateWindowGL(&window) == TRUE) {               // Was window creation successful?
                                                             // At this point we should have a window that is setup to render OpenGL
            if (Initialize(&window, &keys) == FALSE) {
                TerminateApplication(&window);               // Close window, this will handle the shutdown
            }
            else {
                isMessagePumpActive = TRUE;
                while (isMessagePumpActive == TRUE) {
                    // Success creating window. Check for window messages
                    if (PeekMessage(&msg, window.hWnd, 0, 0, PM_REMOVE) != 0) {
                        if (msg.message != WM_QUIT) {
                            DispatchMessage(&msg);
                        }
                        else {
                            isMessagePumpActive = FALSE;     // Terminate the message pump
                        }
                    }
                    else {
                        if (window.isVisible == FALSE) {
                            WaitMessage();                   // Application is minimized wait for a message
                        }
                        //else {
                        //    // Process application loop
                        //    tickCount = GetTickCount();      // Get the tick count
                        //    Update(tickCount - window.lastTickCount); // Update the counter
                        //    window.lastTickCount = tickCount;// Set last count to current count
                        //    Draw();                          // Draw screen
                        //    SwapBuffers(window.hDC);
                        //}
                    }
                }
            }
            // Application is finished
            Deinitialize();
            DestroyWindowGL(&window);
        }
        else {
            MessageBox(HWND_DESKTOP, "Error Creating OpenGL Window", "Error", MB_OK | MB_ICONEXCLAMATION);
            g_isProgramLooping = FALSE;
        }
    }
    UnregisterClass(application.className, application.hInstance);    // UnRegister window class
    return 0;
}

#include <Windows.h>
#include <GL/glew.h>
#include <GL/glut.h>
#include <GL/GLUAX.H>
#include <math.h>
#include <stdio.h>
#include <olectl.h>
#include "Previous.h"

#pragma comment(lib, "legacy_stdio_definitions.lib")

#ifndef CDS_FULLSCREEN
#define CDS_FULLSCREEN 4
#endif

GL_Window* g_window;
Keys* g_keys;

GLfloat fogColor[4] = { 0.6f, 0.3f, 0.0f, 1.0f };     // Fog colour
GLfloat camz;                                // Camera Z depth

#define GL_FOG_COORDINATE_SOURCE_EXT 0x8450
#define GL_FOG_COORDINATE_EXT 0x8451

typedef void(APIENTRY* PFNGLFOGCOORDFEXTPROC) (GLfloat coord);   // Declare function prototype

PFNGLFOGCOORDFEXTPROC glFogCoordfEXT = NULL;      // glFogCoordfEXT function
GLuint texture[1];

int BuildTexture(char* szPathName, GLuint& texid)
{
    HDC hdcTemp;
    HBITMAP hbmpTemp;                      // Holds the bitmap temporarily
    IPicture* pPicture;                    // IPicture interface
    OLECHAR wszPath[MAX_PATH + 1];         // Full path to picture (wchar)
    char szPath[MAX_PATH + 1];             // Full path to picture
    long lWidth;
    long lHeight;
    long lWidthPixels;
    long lHeightPixels;
    GLint glMaxTexDim;                     // Maximum texture size

    if (strstr(szPathName, "https://")) {
        strcpy(szPath, szPathName);
    }
    else {
        GetCurrentDirectory(MAX_PATH, szPath);
        strcat(szPath, "\\");
        strcat(szPath, szPathName);
    }
    // Convert from ASCII to Unicode
    MultiByteToWideChar(
        CP_ACP,                // ANSI Codepage
        0,                     // Specifies the handling of unmapped characters
        szPath,                // The wide-character string to be converted
        -1,                    // The width of the wide-character string
        wszPath,               // The translated string
        MAX_PATH               // The maximum size of our file path 256 characters 
        );

    // Load the image
    HRESULT hr = OleLoadPicturePath(wszPath, 0, 0, 0, IID_IPicture, (void**)&pPicture);

    if (FAILED(hr)) {
        return FALSE;
    }

    hdcTemp = CreateCompatibleDC(GetDC(0));    // Create the windows compatible device context
    if (!hdcTemp) {
        pPicture->Release();
        return FALSE;
    }
    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &glMaxTexDim);    // Get maximum texture size supported

    pPicture->get_Width(&lWidth);          // Get IPicture width
    lWidthPixels = MulDiv(lWidth, GetDeviceCaps(hdcTemp, LOGPIXELSX), 2540);  // Convert to pixels
    pPicture->get_Height(&lHeight);          // Get IPicture height
    lHeightPixels = MulDiv(lHeight, GetDeviceCaps(hdcTemp, LOGPIXELSX), 2540);  // Convert to pixels

    if (lWidthPixels <= glMaxTexDim) {
        lWidthPixels = 1 << (int)floor((log((double)lWidthPixels) / log(2.0f)) + 0.5f);
    }
    else {
        lWidthPixels = glMaxTexDim;
    }

    if (lHeightPixels <= glMaxTexDim) {
        lHeightPixels = 1 << (int)floor((log((double)lHeightPixels) / log(2.0f)) + 0.5f);
    }
    else {
        lHeightPixels = glMaxTexDim;
    }

    BITMAPINFO bi = {0};            // The type of bit map
    DWORD* pBits = 0;

    bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);   // Structure size
    bi.bmiHeader.biBitCount = 32;
    bi.bmiHeader.biWidth = lWidthPixels;              // Power of two width
    bi.bmiHeader.biHeight = lHeightPixels;
    bi.bmiHeader.biCompression = BI_RGB;              // RGB encoding
    bi.bmiHeader.biPlanes = 1;                        // 1 bitplane

    hbmpTemp = CreateDIBSection(hdcTemp, &bi, DIB_RGB_COLORS, (void**)&pBits, 0, 0);
    if (!hbmpTemp) {
        DeleteDC(hdcTemp);
        pPicture->Release();
        return FALSE;
    }
    SelectObject(hdcTemp, hbmpTemp);
    // Render the IPicture on to the bitmap
    pPicture->Render(hdcTemp, 0, 0, lWidthPixels, lHeightPixels, 0, lHeight, lWidth, -lHeight, 0);

    // BGR
    for (long i = 0; i < lWidthPixels * lHeightPixels; ++i) {
        BYTE* pPixel = (BYTE*)(&pBits[i]);              // Grab the current pixel
        BYTE temp = pPixel[0];
        pPixel[0] = pPixel[2];
        pPixel[2] = temp;
        pPixel[3] = 255;
    }

    glGenTextures(1, &texid);
    glBindTexture(GL_TEXTURE_2D, texid);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D, 0, 3, lWidthPixels, lHeightPixels, 0, GL_RGBA, GL_UNSIGNED_BYTE, pBits);

    DeleteObject(hbmpTemp);          // Delete the object
    DeleteDC(hdcTemp);

    pPicture->Release();             // Decrements IPicture reference count

    return TRUE;
}

int Extension_Init()
{
    char Extension_Name[] = "EXT_fog_coord";

    // Allocate memory for our extension string
    char* glextstring = (char*)malloc(strlen((char*)glGetString(GL_EXTENSIONS)) + 1);
    strcpy(glextstring, (char*)glGetString(GL_EXTENSIONS));        // Store

    if (!strstr(glextstring, Extension_Name)) {
        return FALSE;
    }
    free(glextstring);

    // Setup and enable glFogCoordfEXT
    glFogCoordfEXT = (PFNGLFOGCOORDFEXTPROC)wglGetProcAddress("glFogCoordfEXT");
    return TRUE;
}

BOOL Initialize(GL_Window* window, Keys* keys)
{
    g_window = window;
    g_keys = keys;

    if (!Extension_Init()) {          // Fog extension
        return FALSE;
    }

    if (!BuildTexture("data/wall.bmp", texture[0])) {
        return FALSE;
    }

    glEnable(GL_TEXTURE_2D);
    glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
    glClearDepth(1.0f);
    glDepthFunc(GL_LEQUAL);
    glEnable(GL_DEPTH_TEST);
    glShadeModel(GL_SMOOTH);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
    glEnable(GL_FOG);
    glFogi(GL_FOG_MODE, GL_LINEAR);            // Fog fade is linear
    glFogfv(GL_FOG_COLOR, fogColor);           // Set the color
    glFogf(GL_FOG_START, 0.0f);                // Set the fog start (least dense)
    glFogf(GL_FOG_END, 1.0f);                  // Set the fog end (most dense)
    glHint(GL_FOG_HINT, GL_NICEST);            // Per-pixel fog calculation
    glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);   // Set fog based on vertice coordinate
    camz = -19.0f;                             // Set camera Z position to -19
    return TRUE;
}

void Deinitialize(void) {}

void Update(DWORD milliseconds)
{
    if (g_keys->keyDown[VK_ESCAPE] == TRUE)
        TerminateApplication(g_window);
    if (g_keys->keyDown[VK_F1] == TRUE)
        ToggleFullscreen(g_window);

    if (g_keys->keyDown[VK_UP] == TRUE && camz < 14.0f)
        camz += (float)(milliseconds) / 100.0f;
    if (g_keys->keyDown[VK_DOWN] == TRUE && camz > -19.0f)
        camz -= (float)(milliseconds) / 100.0f;
}

void Draw(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    glTranslatef(0.0f, 0.0f, camz);

    glBegin(GL_QUADS);                           // Back wall
        glFogCoordfEXT(1.0f); glTexCoord2f(0.0f, 0.0f);
        glVertex3f(-2.5f, -2.5f, -15.0f);
        glFogCoordfEXT(1.0f); glTexCoord2f(1.0f, 0.0f);
        glVertex3f(2.5f, -2.5f, -15.0f);
        glFogCoordfEXT(1.0f); glTexCoord2f(1.0f, 1.0f);
        glVertex3f(2.5f, 2.5f, -15.0f);
        glFogCoordfEXT(1.0f); glTexCoord2f(0.0f, 1.0f);
        glVertex3f(-2.5f, 2.5f, -15.0f);
    glEnd();
    
    glBegin(GL_QUADS);                            // Floor
        glFogCoordfEXT(1.0f); glTexCoord2f(0.0f, 0.0f);
        glVertex3f(-2.5f, -2.5f, -15.0f);
        glFogCoordfEXT(1.0f); glTexCoord2f(1.0f, 0.0f);
        glVertex3f(2.5f, -2.5f, -15.0f);
        glFogCoordfEXT(0.0f); glTexCoord2f(1.0f, 1.0f);
        glVertex3f(2.5f, -2.5f, 15.0f);
        glFogCoordfEXT(0.0f); glTexCoord2f(0.0f, 1.0f);
        glVertex3f(-2.5f, -2.5f, 15.0f);
    glEnd();
    
    glBegin(GL_QUADS);                            // Roof
        glFogCoordfEXT(1.0f); glTexCoord2f(0.0f, 0.0f);
        glVertex3f(-2.5f, 2.5f, -15.0f);
        glFogCoordfEXT(1.0f); glTexCoord2f(1.0f, 0.0f);
        glVertex3f(2.5f, 2.5f, -15.0f);
        glFogCoordfEXT(0.0f); glTexCoord2f(1.0f, 1.0f);
        glVertex3f(2.5f, 2.5f, 15.0f);
        glFogCoordfEXT(0.0f); glTexCoord2f(0.0f, 1.0f);
        glVertex3f(-2.5f, 2.5f, 15.0f);
    glEnd();

    glBegin(GL_QUADS);                            // Right Wall
        glFogCoordfEXT(0.0f); glTexCoord2f(0.0f, 0.0f);
        glVertex3f(2.5f, -2.5f, 15.0f);
        glFogCoordfEXT(0.0f); glTexCoord2f(0.0f, 1.0f);
        glVertex3f(2.5f, 2.5f, 15.0f);
        glFogCoordfEXT(1.0f); glTexCoord2f(1.0f, 1.0f);
        glVertex3f(2.5f, 2.5f, -15.0f);
        glFogCoordfEXT(1.0f); glTexCoord2f(1.0f, 0.0f);
        glVertex3f(2.5f, -2.5f, -15.0f);
    glEnd();

    glBegin(GL_QUADS);                            // Left Wall
        glFogCoordfEXT(0.0f); glTexCoord2f(0.0f, 0.0f);
        glVertex3f(-2.5f, -2.5f, 15.0f);
        glFogCoordfEXT(0.0f); glTexCoord2f(0.0f, 1.0f);
        glVertex3f(-2.5f, 2.5f, 15.0f);
        glFogCoordfEXT(1.0f); glTexCoord2f(1.0f, 1.0f);
        glVertex3f(-2.5f, 2.5f, -15.0f);
        glFogCoordfEXT(1.0f); glTexCoord2f(1.0f, 0.0f);
        glVertex3f(-2.5f, -2.5f, -15.0f);
    glEnd();

    glFlush();
}