Jeff Molofee - NeHe's OpenGL Tutorials

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)

The only change in this section of code is the line below. It is *VERY IMPORTANT* you change the value from 0 to 1 or some other non zero value. In all of the previous tutorials the value of the line below was 0. In order to use Stencil Buffering this value HAS to be greater than or equal to 1. This value is the number of bits you want to use for the stencil buffer.

1, // Use Stencil Buffer ( * Important * )

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

}

WndProc() has not changed, so we will skip over it.

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

Nothing new here. Typical start to WinMain().

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

}

The only real big change in this section of the code is the new window title to let everyone know the tutorial is about reflections using the stencil buffer. Also notice that we pass the resx, resy and resbpp variables to our window creation procedure instead of the usual 640, 480 and 16.

// Create Our OpenGL Window

if (!CreateGLWindow("Banu Octavian & NeHe's Stencil & Reflection Tutorial", resx, resy, resbpp, 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 Escape Pressed?

{

done=TRUE; // ESC Signalled A Quit

} else // Not Time To Quit, Update Screen

{

DrawGLScene(); // Draw The Scene

SwapBuffers(hDC); // Swap Buffers (Double Buffering)

Instead of checking for key presses in WinMain(), we jump to our keyboard handling routine called ProcessKeyboard(). Notice the ProcessKeyboard() routine is only called if the program is active!

ProcessKeyboard(); // Processed Keyboard Presses

}

}

}

}

// Shutdown

KillGLWindow(); // Kill The Window

return (msg.wParam); // Exit The Program

}

I really hope you've enjoyed this tutorial. I know it could use a little more work. It was one of the more difficult tutorials that I have written. It's easy for me to understand what everything is doing, and what commands I need to use to create cool effects, but when you sit down and actually try to explain things keeping in mind that most people have never even heard of the stencil buffer, it's tough! If you notice anything that could be made clearer or if you find any mistakes in the tutorial please let me know. As always, I want this tutorial to be the best it can possibly be, your feedback is greatly appreciated.

* DOWNLOAD Visual C++Code For This Lesson.

* DOWNLOAD LinuxCode For This Lesson. (Conversion by Gray Fox)

* DOWNLOAD Mac OS X/CocoaCode For This Lesson. (Conversion by Bryan Blackburn)

Welcome to a fairly complex tutorial on shadow casting. The effect this demo creates is literally incredible. Shadows that stretch, bend and wrap around other objects and across walls. Everything in the scene can be moved around in 3D space using keys on the keyboard.

This tutorial takes a fairly different approach — It assumes you have a lot of OpenGL knowledge. You should already understand the stencil buffer, and basic OpenGL setup. If you need to brush up, go back and read the earlier tutorials. Functions such as CreateGLWindow and WinMain will NOTbe explained in this tutorial. Additionally, some fundamental 3D math is assumed, so keep a good textbook handy! (I used my 1st year maths lecture notes from University — I knew they'd come in handy later on! :)