#100310#NeHe学习笔记01

最新推荐文章于 2023-02-15 09:01:43 发布

原创最新推荐文章于 2023-02-15 09:01:43 发布 · 300 阅读

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CC 4.0 BY-SA版权

文章标签：

#null #buffer #initialization #windows #header #keyboard

第一课：

介绍了七个函数，一般一个opengl的基本框架也就这几个函数：

CreateGLWindow()-------创建绘画目标窗口

KillGLWindow()------------正常销毁窗口

WndProc()------------------处理所有窗口消息

WinMain()-------------------程序入口

DrawGLScene()------------进行Opengl绘画

ReSizeGLScene()----------重新设置Opengl的场景大小

InitGL()----------------------对Opengl进行设置

具体调用关系：

WinMain()

{

CreateGLWindow{

ResizeGLScene()&&KillGLWindow()&&InitGL()

}

WndProc(){

ResizeGLScene

}

DrawGLScene()

KillGLWindow()

}

OpenGL框架：

/*
*  This Code Was Created By Jeff Molofee 2000
*  A HUGE Thanks To Fredric Echols For Cleaning Up
*  And Optimizing This Code, Making It More Flexible!
*  If You've Found This Code Useful, Please Let Me Know.
*  Visit My Site At nehe.gamedev.net
*/

#include <windows.h>  // Header File For Windows
#include <gl/gl.h>   // Header File For The OpenGL32 Library
#include <gl/glu.h>   // Header File For The GLu32 Library
#include <gl/glaux.h>  // Header File For The Glaux Library

HDC   hDC=NULL;  // Private GDI Device Context
HGLRC  hRC=NULL;  // Permanent Rendering Context
HWND  hWnd=NULL;  // Holds Our Window Handle
HINSTANCE hInstance;  // Holds The Instance Of The Application

bool keys[256]; // Array Used For The Keyboard Routine
bool active=TRUE; // Window Active Flag Set To TRUE By Default
bool fullscreen=TRUE; // Fullscreen Flag Set To Fullscreen Mode By Default

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); // Declaration For WndProc

GLvoid ReSizeGLScene(GLsizei width, GLsizei height)  // Resize And Initialize The GL Window
{
if (height==0)          // Prevent A Divide By Zero By
{
  height=1;          // Making Height Equal One
}

glViewport(0,0,width,height); // Reset The Current Viewport

glMatrixMode(GL_PROJECTION); // Select The Projection Matrix
glLoadIdentity(); // Reset The Projection Matrix

// Calculate The Aspect Ratio Of The Window
gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix
glLoadIdentity(); // Reset The Modelview Matrix
}

int InitGL(GLvoid)          // All Setup For OpenGL Goes Here
{
glShadeModel(GL_SMOOTH);       // Enable Smooth Shading
glClearColor(0.0f, 0.0f, 0.0f, 0.5f);    // Black Background
glClearDepth(1.0f);         // Depth Buffer Setup
glEnable(GL_DEPTH_TEST);       // Enables Depth Testing
glDepthFunc(GL_LEQUAL);        // The Type Of Depth Testing To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
return TRUE;          // Initialization Went OK
}

int DrawGLScene(GLvoid)         // Here's Where We Do All The Drawing
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glLoadIdentity();         // Reset The Current Modelview Matrix
return TRUE;          // Everything Went OK
}

GLvoid KillGLWindow(GLvoid)        // Properly Kill The Window
{
if (fullscreen)          // Are We In Fullscreen Mode?
{
  ChangeDisplaySettings(NULL,0);     // If So Switch Back To The Desktop
  ShowCursor(TRUE);        // Show Mouse Pointer
}

if (hRC)           // Do We Have A Rendering Context?
{
  if (!wglMakeCurrent(NULL,NULL))     // Are We Able To Release The DC And RC Contexts?
  {
   MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
  }

  if (!wglDeleteContext(hRC))      // Are We Able To Delete The RC?
  {
   MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
  }
  hRC=NULL;          // Set RC To NULL
}

if (hDC && !ReleaseDC(hWnd,hDC))     // Are We Able To Release The DC
{
  MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
  hDC=NULL;          // Set DC To NULL
}

if (hWnd && !DestroyWindow(hWnd))     // Are We Able To Destroy The Window?
{
  MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
  hWnd=NULL;          // Set hWnd To NULL
}

if (!UnregisterClass("OpenGL",hInstance))   // Are We Able To Unregister Class
{
  MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
  hInstance=NULL;         // Set hInstance To NULL
}
}

/* This Code Creates Our OpenGL Window. Parameters Are:     *
* title   - Title To Appear At The Top Of The Window    *
* width   - Width Of The GL Window Or Fullscreen Mode    *
* height   - Height Of The GL Window Or Fullscreen Mode   *
* bits   - Number Of Bits To Use For Color (8/16/24/32)   *
* fullscreenflag - Use Fullscreen Mode (TRUE) Or Windowed Mode (FALSE) */

BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
{
GLuint  PixelFormat;   // Holds The Results After Searching For A Match
WNDCLASS wc;      // Windows Class Structure
DWORD  dwExStyle;    // Window Extended Style
DWORD  dwStyle;    // Window Style
RECT  WindowRect;    // Grabs Rectangle Upper Left / Lower Right Values
WindowRect.left=(long)0;   // Set Left Value To 0
WindowRect.right=(long)width;  // Set Right Value To Requested Width
WindowRect.top=(long)0;    // Set Top Value To 0
WindowRect.bottom=(long)height;  // Set Bottom Value To Requested Height

fullscreen=fullscreenflag; // Set The Global Fullscreen Flag

hInstance   = GetModuleHandle(NULL);    // Grab An Instance For Our Window
wc.style   = CS_HREDRAW | CS_VREDRAW | CS_OWNDC; // Redraw On Size, And Own DC For Window.
wc.lpfnWndProc  = (WNDPROC) WndProc;     // WndProc Handles Messages
wc.cbClsExtra  = 0;         // No Extra Window Data
wc.cbWndExtra  = 0;         // No Extra Window Data
wc.hInstance  = hInstance;       // Set The Instance
wc.hIcon   = LoadIcon(NULL, IDI_WINLOGO);   // Load The Default Icon
wc.hCursor   = LoadCursor(NULL, IDC_ARROW);   // Load The Arrow Pointer
wc.hbrBackground = NULL;         // No Background Required For GL
wc.lpszMenuName  = NULL;         // We Don't Want A Menu
wc.lpszClassName = "OpenGL";        // Set The Class Name

if (!RegisterClass(&wc))         // Attempt To Register The Window Class
{
  MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);
  return FALSE;           // Return FALSE
}

if (fullscreen)            // Attempt Fullscreen Mode?
{
  DEVMODE dmScreenSettings;        // Device Mode
  memset(&dmScreenSettings,0,sizeof(dmScreenSettings)); // Makes Sure Memory's Cleared
  dmScreenSettings.dmSize=sizeof(dmScreenSettings);  // Size Of The Devmode Structure
  dmScreenSettings.dmPelsWidth = width;    // Selected Screen Width
  dmScreenSettings.dmPelsHeight = height;    // Selected Screen Height
  dmScreenSettings.dmBitsPerPel = bits;     // Selected Bits Per Pixel
  dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;

  // Try To Set Selected Mode And Get Results. NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.
  if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)
  {
   // If The Mode Fails, Offer Two Options. Quit Or Use Windowed Mode.
   if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By/nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
   {
    fullscreen=FALSE;  // Windowed Mode Selected. Fullscreen = FALSE
   }
   else
   {
    // Pop Up A Message Box Letting User Know The Program Is Closing.
    MessageBox(NULL,"Program Will Now Close.","ERROR",MB_OK|MB_ICONSTOP);
    return FALSE;         // Return FALSE
   }
  }
}

if (fullscreen)            // Are We Still In Fullscreen Mode?
{
  dwExStyle=WS_EX_APPWINDOW;        // Window Extended Style
  dwStyle=WS_POPUP;          // Windows Style
  ShowCursor(FALSE);          // Hide Mouse Pointer
}
else
{
  dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;   // Window Extended Style
  dwStyle=WS_OVERLAPPEDWINDOW;       // Windows Style
}

AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle); // Adjust Window To True Requested Size

// Create The Window
if (!(hWnd=CreateWindowEx( dwExStyle,       // Extended Style For The Window
        "OpenGL",       // Class Name
        title,        // Window Title
        dwStyle |       // Defined Window Style
        WS_CLIPSIBLINGS |     // Required Window Style
        WS_CLIPCHILDREN,     // Required Window Style
        0, 0,        // Window Position
        WindowRect.right-WindowRect.left, // Calculate Window Width
        WindowRect.bottom-WindowRect.top, // Calculate Window Height
        NULL,        // No Parent Window
        NULL,        // No Menu
        hInstance,       // Instance
        NULL)))        // Dont Pass Anything To WM_CREATE
{
  KillGLWindow();        // Reset The Display
  MessageBox(NULL,"Window Creation Error.","ERROR",MB_OK|MB_ICONEXCLAMATION);
  return FALSE;        // Return FALSE
}

static PIXELFORMATDESCRIPTOR pfd=    // pfd Tells Windows How We Want Things To Be
{
  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
  bits,          // Select Our 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,           // 16Bit 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
};

if (!(hDC=GetDC(hWnd)))       // Did We Get A Device Context?
{
  KillGLWindow();        // Reset The Display
  MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
  return FALSE;        // Return FALSE
}

if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd))) // Did Windows Find A Matching Pixel Format?
{
  KillGLWindow();        // Reset The Display
  MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
  return FALSE;        // Return FALSE
}

if(!SetPixelFormat(hDC,PixelFormat,&pfd))  // Are We Able To Set The Pixel Format?
{
  KillGLWindow();        // Reset The Display
  MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
  return FALSE;        // Return FALSE
}

if (!(hRC=wglCreateContext(hDC)))    // Are We Able To Get A Rendering Context?
{
  KillGLWindow();        // Reset The Display
  MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
  return FALSE;        // Return FALSE
}

if(!wglMakeCurrent(hDC,hRC))     // Try To Activate The Rendering Context
{
  KillGLWindow();        // Reset The Display
  MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
  return FALSE;        // Return FALSE
}

ShowWindow(hWnd,SW_SHOW);      // Show The Window
SetForegroundWindow(hWnd);      // Slightly Higher Priority
SetFocus(hWnd);         // Sets Keyboard Focus To The Window
ReSizeGLScene(width, height);     // Set Up Our Perspective GL Screen

if (!InitGL())         // Initialize Our Newly Created GL Window
{
  KillGLWindow();        // Reset The Display
  MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);
  return FALSE;        // Return FALSE
}

return TRUE; // Success
}

LRESULT CALLBACK WndProc( HWND hWnd,   // Handle For This Window
       UINT uMsg,   // Message For This Window
       WPARAM wParam,   // Additional Message Information
       LPARAM lParam)   // Additional Message Information
{
switch (uMsg)         // Check For Windows Messages
{
  case WM_ACTIVATE:       // Watch For Window Activate Message
  {
   if (!HIWORD(wParam))     // Check Minimization State
   {
    active=TRUE;      // Program Is Active
   }
   else
   {
    active=FALSE;      // Program Is No Longer Active
   }

return 0; // Return To The Message Loop
}

  case WM_SYSCOMMAND:       // Intercept System Commands
  {
   switch (wParam)       // Check System Calls
   {
    case SC_SCREENSAVE:     // Screensaver Trying To Start?
    case SC_MONITORPOWER:    // Monitor Trying To Enter Powersave?
    return 0;       // Prevent From Happening
   }
   break;         // Exit
  }

  case WM_CLOSE:        // Did We Receive A Close Message?
  {
   PostQuitMessage(0);      // Send A Quit Message
   return 0;        // Jump Back
  }

  case WM_KEYDOWN:       // Is A Key Being Held Down?
  {
   keys[wParam] = TRUE;     // If So, Mark It As TRUE
   return 0;        // Jump Back
  }

  case WM_KEYUP:        // Has A Key Been Released?
  {
   keys[wParam] = FALSE;     // If So, Mark It As FALSE
   return 0;        // Jump Back
  }

  case WM_SIZE:        // Resize The OpenGL Window
  {
   ReSizeGLScene(LOWORD(lParam),HIWORD(lParam)); // LoWord=Width, HiWord=Height
   return 0;        // Jump Back
  }
}

// Pass All Unhandled Messages To DefWindowProc
return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain( HINSTANCE hInstance,   // Instance
     HINSTANCE hPrevInstance,  // Previous Instance
     LPSTR  lpCmdLine,   // Command Line Parameters
     int   nCmdShow)   // Window Show State
{
MSG  msg;         // Windows Message Structure
BOOL done=FALSE;        // Bool Variable To Exit Loop

// Ask The User Which Screen Mode They Prefer
if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)
{
fullscreen=FALSE; // Windowed Mode
}

// Create Our OpenGL Window
if (!CreateGLWindow("NeHe's OpenGL Framework",640,480,16,fullscreen))
{
return 0; // Quit If Window Was Not Created
}

while(!done)         // Loop That Runs While done=FALSE
{
  if (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) // Is There A Message Waiting?
  {
   if (msg.message==WM_QUIT)    // Have We Received A Quit Message?
   {
    done=TRUE;       // If So done=TRUE
   }
   else         // If Not, Deal With Window Messages
   {
    TranslateMessage(&msg);    // Translate The Message
    DispatchMessage(&msg);    // Dispatch The Message
   }
  }
  else          // If There Are No Messages
  {
   // Draw The Scene. Watch For ESC Key And Quit Messages From DrawGLScene()
   if (active)        // Program Active?
   {
    if (keys[VK_ESCAPE])    // Was ESC Pressed?
    {
     done=TRUE;      // ESC Signalled A Quit
    }
    else        // Not Time To Quit, Update Screen
    {
     DrawGLScene();     // Draw The Scene
     SwapBuffers(hDC);    // Swap Buffers (Double Buffering)
    }
   }

   if (keys[VK_F1])      // Is F1 Being Pressed?
   {
    keys[VK_F1]=FALSE;     // If So Make Key FALSE
    KillGLWindow();      // Kill Our Current Window
    fullscreen=!fullscreen;    // Toggle Fullscreen / Windowed Mode
    // Recreate Our OpenGL Window
    if (!CreateGLWindow("NeHe's OpenGL Framework",640,480,16,fullscreen))
    {
     return 0;      // Quit If Window Was Not Created
    }
   }
  }
}

// Shutdown
KillGLWindow(); // Kill The Window
return (msg.wParam); // Exit The Program
}