Hi,After investigating a bit in the Wine code, it seems that the flickering bug of WoW in OpenGL mode is due to wglGetPbufferDCARB that returns a DC which type is OBJ_MEMDC while it should return a DC which type is OBJ_DC. And since in the current git tree, the DC type of a Pbuffer is OBJ_MEMDC then the code located in lines 1394-1395 of dlls/winex11.drv/opengl.c is executed : the Pbuffer is copied to the screen each time the GL context is made current to the Pbuffer hence the flickering (WoW bounds the GL context alternatively to the screen and to the Pbuffer). The expected behaviour is not to copy the Pbuffer content to the screen since WoW does it itself.
The easiest workaround for this bug would be to make X11DRV_wglGetPbufferDCARB to return the Pbuffer's object->hdc (this fixes the flickering bug). However, I have made some tests with Windows XP and it appears that wglGetPbufferDCARB returns a HDC different from the HDC passed when wglCreatePbufferARB was called. So such a patch would be a dirty hack not a real fix.
I am not familiar enough with Wine to submit a patch so I leave the gurus out there find an elegant solution.
Attached is the code that I used to perform a few tests about Pbuffers on Windows XP (code of interest is located from line 293 to line 298).
Regards, Bertrand.
/*
* 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
DECLARE_HANDLE(HPBUFFERARB);
typedef HPBUFFERARB (APIENTRY * wglCreatePbufferARB_t)(HDC hDC,
int iPixelFormat,
int iWidth,
int iHeight,
const int *piAttribList);
typedef HDC (APIENTRY * wglGetPbufferDCARB_t)(HPBUFFERARB hPbuffer);
typedef int (APIENTRY * wglReleasePbufferDCARB_t)(HPBUFFERARB hPbuffer, HDC
hDC);
typedef BOOL (APIENTRY * wglDestroyPbufferARB_t)(HPBUFFERARB hPbuffer);
wglCreatePbufferARB_t wglCreatePbufferARB = NULL;
wglGetPbufferDCARB_t wglGetPbufferDCARB = NULL;
wglReleasePbufferDCARB_t wglReleasePbufferDCARB = NULL;
wglDestroyPbufferARB_t wglDestroyPbufferARB = NULL;
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
HPBUFFERARB pBuffer = NULL;
#define WGL_PBUFFER_LARGEST_ARB 0x2033
int attrib[] = {WGL_PBUFFER_LARGEST_ARB, 0, 0};
BOOL success;
HDC pBufferHDC;
DWORD type1 = 0;
DWORD type2 = 0;
int result = 0xdeadbeef;
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
}
wglCreatePbufferARB =
(wglCreatePbufferARB_t)wglGetProcAddress("wglCreatePbufferARB");
wglGetPbufferDCARB =
(wglGetPbufferDCARB_t)wglGetProcAddress("wglGetPbufferDCARB");
wglReleasePbufferDCARB =
(wglReleasePbufferDCARB_t)wglGetProcAddress("wglReleasePbufferDCARB");
wglDestroyPbufferARB =
(wglDestroyPbufferARB_t)wglGetProcAddress("wglDestroyPbufferARB");
pBuffer = wglCreatePbufferARB(hDC, PixelFormat, width, height, attrib);
pBufferHDC = wglGetPbufferDCARB(pBuffer);
type1 = GetObjectType(hDC);
type2 = GetObjectType(pBufferHDC);
result = wglReleasePbufferDCARB(pBuffer, pBufferHDC);
success = wglDestroyPbufferARB(pBuffer);
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
}
