//
// Benny's note: I trimmed the original message.
//

From: "Markus Uttenweiler" <Schizo@t-online.de>
Newsgroups: 3dfx.opengl
Subject: Re: Will there be a window-using OpenGl-Driver for Monster3D or similar Voodoo?
Date: Mon, 15 Sep 1997 20:38:42 +0200
NNTP-Posting-Host: p40ae97.m.dip.t-online.de

It's possible to copy the 3dfx backbuffer to a direct draw window in
windowed mode.

Code Example :

/*
   1. Init Glide and Switch bach to 2D Video Card
*/
    //
    // Init Glide
    //
    grGlideInit();

    if (!grSstQueryHardware(&hw))
	return NULL;

    grSstSelect(0);
    grSstWinOpen(NULL,
                 GR_RESOLUTION_640x480,
                 GR_REFRESH_60Hz,
                 GR_COLORFORMAT_RGBA,
                 GR_ORIGIN_LOWER_LEFT,
                 2,
                 0);

    grSstControl(GR_CONTROL_DEACTIVATE);

/*
   2. Render to 3DFX and copy 3DFX Backbuffer to the Direct Draw BackBuffer
*/

    LPDIRECTDRAWSURFACE lpBackBuffer = DDGetBackBuffer();
    HDC             hdc;

    //
    // Shouldn't be here if no buffers, but avoid GPFs anyway
    //
    if (lpBackBuffer == NULL)
	return;

    Render3D();

    GrLfbInfo_t     info;
    info.size = sizeof(GrLfbInfo_t);

    DDSURFACEDESC   ddsd;
    ddsd.dwSize = sizeof(ddsd);

    lpBackBuffer->Lock(NULL, &ddsd, DDLOCK_WAIT, NULL);

    grLfbLock(GR_LFB_READ_ONLY | GR_LFB_IDLE,
	      GR_BUFFER_BACKBUFFER,
	      GR_LFBWRITEMODE_ANY,
	      GR_ORIGIN_ANY,
	      FXFALSE,
	      &info
	);

    char           *s = (char *) ddsd.lpSurface;
    char           *d = (char *) info.lfbPtr;

    for (int i = 0; i < 480; i++) {
        memcpy(s, d, info.strideInBytes);
	s += ddsd.lPitch;
	d += info.strideInBytes;
    }

    grLfbUnlock(GR_LFB_READ_ONLY, GR_BUFFER_BACKBUFFER);
    lpBackBuffer->Unlock(ddsd.lpSurface);

/*
  3. Blit Backbuffer to Display
*/
    DDBLTFX         ddbltfx;
    HRESULT         hr;

    ddbltfx.dwSize = sizeof(ddbltfx);
    ddbltfx.dwFillColor = DDColorMatch(lpSurface, color);

    hr = lpSurface->Blt(lprect,
			NULL,
			NULL,
			DDBLT_COLORFILL | DDBLT_WAIT,
			&ddbltfx);

    return hr == DD_OK;

//------------------------------------------------------------------//