SRB2/src/win32/win_vid.c

// Emacs style mode select   -*- C++ -*-
//-----------------------------------------------------------------------------
//
// Copyright (C) 1998-2000 by DooM Legacy Team.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//-----------------------------------------------------------------------------
/// \file
/// \brief win32 video driver for Doom Legacy

#include "../doomdef.h"

#ifdef _WINDOWS

#include <stdlib.h>
#include <stdarg.h>

#include "../d_clisrv.h"
#include "../i_system.h"
#include "../m_argv.h"
#include "../v_video.h"
#include "../st_stuff.h"
#include "../i_video.h"
#include "../z_zone.h"
#include "fabdxlib.h"
#include "../doomstat.h"
#include "win_main.h"
#include "../command.h"
#include "../screen.h"

#ifdef HWRENDER
#include "win_dll.h" // loading the render DLL
#include "../hardware/hw_drv.h" // calling driver init & shutdown
#include "../hardware/hw_main.h" // calling HWR module init & shutdown
#endif

// -------
// Globals
// -------

// this is the CURRENT rendermode!! very important: used by w_wad, and much other code
rendermode_t rendermode = render_soft;
static void OnTop_OnChange(void);
// synchronize page flipping with screen refresh
static CV_PossibleValue_t CV_NeverOnOff[] = {{-1, "Never"}, {0, "Off"}, {1, "On"}, {0, NULL}};
consvar_t cv_vidwait = {"vid_wait", "On", CV_SAVE, CV_OnOff, OnTop_OnChange, 0, NULL, NULL, 0, 0, NULL};
static consvar_t cv_stretch = {"stretch", "On", CV_SAVE|CV_NOSHOWHELP, CV_OnOff, NULL, 0, NULL, NULL, 0, 0, NULL};
static consvar_t cv_ontop = {"ontop", "Never", 0, CV_NeverOnOff, NULL, 0, NULL, NULL, 0, 0, NULL};

boolean highcolor;
int vid_opengl_state = 0;

static BOOL bDIBMode; // means we are using DIB instead of DirectDraw surfaces
static LPBITMAPINFO bmiMain = NULL;
static HDC hDCMain = NULL;

// -----------------
// Video modes stuff
// -----------------

#define MAX_EXTRA_MODES 36
static vmode_t extra_modes[MAX_EXTRA_MODES] = {{NULL, NULL, 0, 0, 0, 0, 0, 0, NULL, NULL, 0}};
static char names[MAX_EXTRA_MODES][10];

static INT32 numvidmodes; // total number of DirectDraw display modes
static vmode_t *pvidmodes; // start of videomodes list.
static vmode_t *pcurrentmode; // the current active videomode.
static BOOL bWinParm;
static INT32 WINAPI VID_SetWindowedDisplayMode(viddef_t *lvid, vmode_t *currentmode);

// this holds description of the startup video mode,
// the resolution is 320x200, windowed on the desktop
static char winmodenames[NUMSPECIALMODES][11] = {
 // W to make sure it's the windowed mode
	"320x200W",
	"640x400W",
	"960x600W",
	"1280x800W"
};
vmode_t specialmodes[NUMSPECIALMODES] =
{
	{
		NULL,
		winmodenames[0], // hehe
		320, 200, //(200.0/320.0)*(320.0/240.0),
		320, 1, // rowbytes, bytes per pixel
		1, 2, // windowed (TRUE), numpages
		NULL,
		VID_SetWindowedDisplayMode, 0
	},
	{
		NULL,
		winmodenames[1], // haha
		640, 400,
		640, 1, // rowbytes, bytes per pixel
		1, 2, // windowed (TRUE), numpages
		NULL,
		VID_SetWindowedDisplayMode, 0
	},
	{
		NULL,
		winmodenames[2], // hihi?
		960, 600,
		960, 1, // rowbytes, bytes per pixel
		1, 2, // windowed (TRUE), numpages
		NULL,
		VID_SetWindowedDisplayMode, 0
	},
	{
		NULL,
		winmodenames[3], // hoho!
		1280, 800,
		1280, 1, // rowbytes, bytes per pixel
		1, 2, // windowed (TRUE), numpages
		NULL,
		VID_SetWindowedDisplayMode, 0
	}
};

// ------
// Protos
// ------
static void VID_Command_NumModes_f(void);
static void VID_Command_ModeInfo_f(void);
static void VID_Command_ModeList_f(void);
static void VID_Command_Mode_f(void);
static INT32 WINAPI VID_SetDirectDrawMode(viddef_t *lvid, vmode_t *currentmode);
static vmode_t *VID_GetModePtr(int modenum);
static VOID VID_Init(VOID);
static BOOL VID_FreeAndAllocVidbuffer(viddef_t *lvid);

#if 0
	// Disable Composition in Vista DWM (Desktop Window Manager) ----------------
static HMODULE DMdll = NULL;
typedef HRESULT (CALLBACK *P_DwmIsCompositionEnabled) (BOOL *pfEnabled);
static P_DwmIsCompositionEnabled pfnDwmIsCompositionEnabled = NULL;
typedef HRESULT (CALLBACK *P_DwmEnableComposition) (BOOL   fEnable);
static P_DwmEnableComposition pfnDwmEnableComposition = NULL;
static BOOL AeroWasEnabled = FALSE;

static inline VOID UnloadDM(VOID)
{
	pfnDwmEnableComposition = NULL;
	pfnDwmIsCompositionEnabled = NULL;
	if (DMdll) FreeLibrary(DMdll);
	DMdll = NULL;
}

static inline BOOL LoadDM(VOID)
{
	if (DMdll)
		return TRUE;

	DMdll = LoadLibraryA("dwmapi.dll");
	if (DMdll)
		I_OutputMsg("dmwapi.dll loaded, Vista's Desktop Window Manager API\n");
	else
		return FALSE;

	pfnDwmIsCompositionEnabled = (P_DwmIsCompositionEnabled)GetProcAddress(DMdll, "DwmIsCompositionEnabled");
	if (pfnDwmIsCompositionEnabled)
		I_OutputMsg("Composition Aero API found, DwmIsCompositionEnabled\n");

	pfnDwmEnableComposition = (P_DwmEnableComposition)GetProcAddress(DMdll, "DwmEnableComposition");
	if (pfnDwmEnableComposition)
		I_OutputMsg("Composition Aero API found, DwmEnableComposition\n");

	return TRUE;
}

static inline VOID DisableAero(VOID)
{
	BOOL pfnDwmEnableCompositiond = FALSE;
	AeroWasEnabled = FALSE;

	if (!LoadDM())
		return;

	if (pfnDwmIsCompositionEnabled && SUCCEEDED(pfnDwmIsCompositionEnabled(&pfnDwmEnableCompositiond)))
		I_OutputMsg("Got the result of DwmIsCompositionEnabled, %i\n", pfnDwmEnableCompositiond);
	else
		return;

	if ((AeroWasEnabled = pfnDwmEnableCompositiond))
		I_OutputMsg("Disable the Aero rendering\n");
	else
		return;

	if (pfnDwmEnableComposition && SUCCEEDED(pfnDwmEnableComposition(FALSE)))
		I_OutputMsg("Aero rendering disabled\n");
	else
		I_OutputMsg("We failed to disable the Aero rendering\n");
}

static inline VOID ResetAero(VOID)
{
	if (pfnDwmEnableComposition && AeroWasEnabled)
	{
		if (SUCCEEDED(pfnDwmEnableComposition(AeroWasEnabled)))
			I_OutputMsg("Aero rendering setting restored\n");
		else
			I_OutputMsg("We failed to restore Aero rendering\n");
	}
	UnloadDM();
}
#endif

// -----------------
// I_StartupGraphics
// Initialize video mode, setup dynamic screen size variables,
// and allocate screens.
// -----------------
void I_StartupGraphics(void)
{
	if (graphics_started)
		return;

#ifdef HWRENDER
	else if (M_CheckParm("-opengl"))
		rendermode = render_opengl;
	else
#endif
		rendermode = render_soft;

	if (dedicated)
		rendermode = render_none;
	else
		VID_Init();

	// register exit code for graphics
	I_AddExitFunc(I_ShutdownGraphics);
	if (!dedicated) graphics_started = true;
}

void VID_StartupOpenGL(void){}

// ------------------
// I_ShutdownGraphics
// Close the screen, restore previous video mode.
// ------------------
void I_ShutdownGraphics(void)
{
#ifdef HWRENDER
	const rendermode_t oldrendermode = rendermode;
#endif

// This is BAD because it makes the I_Error box screw up!
//	rendermode = render_none;

	if (!graphics_started)
		return;

	CONS_Printf("I_ShutdownGraphics: ");

	//FreeConsole();

	//ResetAero();

	// release windowed startup stuff
	if (hDCMain)
	{
		ReleaseDC(hWndMain, hDCMain);
		hDCMain = NULL;
	}
	if (bmiMain)
	{
		GlobalFree(bmiMain);
		bmiMain = NULL;
	}

#ifdef HWRENDER
	if (oldrendermode != render_soft)
	{
		HWR_Shutdown(); // free stuff from the hardware renderer
		HWD.pfnShutdown(); // close 3d card display
		Shutdown3DDriver(); // free the driver DLL
	}
#endif

	// free the last video mode screen buffers
	if (vid.buffer)
	{
		GlobalFree(vid.buffer);
		vid.buffer = NULL;
	}

#ifdef HWRENDER
	if (rendermode == render_soft)
#endif
		CloseDirectDraw();

	graphics_started = false;
}

// --------------
// I_UpdateNoBlit
// --------------
void I_UpdateNoBlit(void)
{
	// what is this?
}

// I_SkipFrame
//
// Returns true if it thinks we can afford to skip this frame
// from PrBoom's src/SDL/i_video.c
static inline boolean I_SkipFrame(void)
{
	static boolean skip = false;

	if (render_soft != rendermode)
		return false;

	skip = !skip;
	switch (gamestate)
	{
		case GS_LEVEL:
			if (!paused)
				return false;
		//case GS_TIMEATTACK: -- sorry optimisation but now we have a cool level platter and that being laggardly looks terrible
#ifndef NONET
		/* FALLTHRU */
		case GS_WAITINGPLAYERS:
#endif
			return skip; // Skip odd frames
		default:
			return false;
	}
}

static void OnTop_OnChange(void)
{
	const UINT uFlags = SWP_NOACTIVATE|SWP_NOMOVE|SWP_NOSIZE|SWP_NOZORDER;
	RECT bounds;
	int x = 0, y = 0, w = 0, h = 0;

	if (!hWndMain || bAppFullScreen || cv_ontop.value == -1)
		return;

	GetWindowRect(hWndMain, &bounds);
	AdjustWindowRectEx(&bounds, GetWindowLong(hWndMain, GWL_STYLE), 0, 0);
	w = bounds.right - (x = bounds.left); h = bounds.bottom - (y = bounds.top);

	if (cv_ontop.value && !paused)
		SetWindowPos(hWndMain, HWND_TOP      , x, y, w, h, uFlags);
	else
		SetWindowPos(hWndMain, HWND_NOTOPMOST, x, y, w, h, uFlags);
}

// --------------
// I_FinishUpdate
// --------------
void I_FinishUpdate(void)
{
	if (rendermode == render_none)
		return;

	if (I_SkipFrame())
		return;

	if (marathonmode)
		SCR_DisplayMarathonInfo();

	// draw captions if enabled
	if (cv_closedcaptioning.value)
		SCR_ClosedCaptions();

	// display a graph of ticrate
	if (cv_ticrate.value)
		SCR_DisplayTicRate();

	if (cv_showping.value && netgame && consoleplayer != serverplayer)
		SCR_DisplayLocalPing();

	//
	if (bDIBMode)
	{
		// paranoia
		if (!hDCMain || !bmiMain || !vid.buffer)
			return;
		// main game loop, still in a window (-win parm)
		SetDIBitsToDevice(hDCMain, 0, 0, vid.width, vid.height, 0, 0, 0, vid.height, vid.buffer, bmiMain,
			DIB_RGB_COLORS);
	}
	else
#ifdef HWRENDER
	if (rendermode != render_soft)
		HWD.pfnFinishUpdate(cv_vidwait.value);
	else
#endif
	{
		// DIRECT DRAW
		// copy virtual screen to real screen
		// can fail when not active (alt-tab)
		if (LockScreen())
		{
			/// \todo use directX blit here!!? a blit might use hardware with access
			/// to main memory on recent hardware, and software blit of directX may be
			/// optimized for p2 or mmx??
			if (ScreenHeight > vid.height)
			{
				UINT8 *ptr = (UINT8 *)ScreenPtr;
				size_t half_excess = ScreenPitch*(ScreenHeight-vid.height)/2;
				memset(ptr, 0x1F, half_excess);
				ptr += half_excess;
				VID_BlitLinearScreen(screens[0], ptr, vid.width*vid.bpp, vid.height,
					vid.width*vid.bpp, ScreenPitch);
				ptr += vid.height*ScreenPitch;
				memset(ptr, 0x1F, half_excess);
			}
			else
				VID_BlitLinearScreen(screens[0], (UINT8 *)ScreenPtr, vid.width*vid.bpp, vid.height,
					vid.width*vid.bpp, ScreenPitch);

			UnlockScreen();

			// swap screens
			ScreenFlip(cv_vidwait.value);
		}
	}
}

// ---------------
// I_UpdateNoVsync
// ---------------
void I_UpdateNoVsync(void)
{
	int real_vidwait = cv_vidwait.value;
	cv_vidwait.value = 0;
	I_FinishUpdate();
	cv_vidwait.value = real_vidwait;
}

//
// This is meant to be called only by CONS_Printf() while game startup
//
void I_LoadingScreen(LPCSTR msg)
{
	RECT rect;

	// paranoia
	if (!hDCMain || !bmiMain || !vid.buffer)
		return;

	GetClientRect(vid.WndParent, &rect);

	SetDIBitsToDevice(hDCMain, 0, 0, vid.width, vid.height, 0, 0, 0, vid.height, vid.buffer, bmiMain, DIB_RGB_COLORS);

	if (msg)
	{
		if (rect.bottom - rect.top > 32)
			rect.top = rect.bottom - 32; // put msg on bottom of window
		SetBkMode(hDCMain, TRANSPARENT);
		SetTextColor(hDCMain, RGB(0x00, 0x00, 0x00));
		DrawTextA(hDCMain, msg, -1, &rect, DT_WORDBREAK|DT_CENTER);
	}
}

// ------------
// I_ReadScreen
// ------------
void I_ReadScreen(UINT8 *scr)
{
	// DEBUGGING
	if (rendermode != render_soft)
		I_Error("I_ReadScreen: called while in non-software mode");
	VID_BlitLinearScreen(screens[0], scr, vid.width*vid.bpp, vid.height, vid.width*vid.bpp,
		vid.rowbytes);
}

// ------------
// I_SetPalette
// ------------
void I_SetPalette(RGBA_t *palette)
{
	int i;

	if (bDIBMode)
	{
		// set palette in RGBQUAD format, NOT THE SAME ORDER as PALETTEENTRY, grmpf!
		RGBQUAD *pColors;
		pColors = (RGBQUAD *)((LPBYTE)bmiMain + bmiMain->bmiHeader.biSize);
		ZeroMemory(pColors, sizeof (RGBQUAD)*256);
		for (i = 0; i < 256; i++, pColors++, palette++)
		{
			pColors->rgbRed = palette->s.red;
			pColors->rgbGreen = palette->s.green;
			pColors->rgbBlue = palette->s.blue;
		}
	}
	else
#ifdef HWRENDER
	if (rendermode == render_soft)
#endif
	{
		PALETTEENTRY mainpal[256];

		// this clears the 'flag' for each color in palette
		ZeroMemory(mainpal, sizeof mainpal);

		// set palette in PALETTEENTRY format
		for (i = 0; i < 256; i++, palette++)
		{
			mainpal[i].peRed = palette->s.red;
			mainpal[i].peGreen = palette->s.green;
			mainpal[i].peBlue = palette->s.blue;
		}
		SetDDPalette(mainpal);         // set DirectDraw palette
	}
}

//
// return number of video modes in pvidmodes list
// MODES ARE ZERO INDEXED. DO NOT USE (n > nummodes). USE >= INSTEAD.
//
INT32 VID_NumModes(void)
{
	return numvidmodes;
}

// return a video mode number from the dimensions
// returns any available video mode if the mode was not found
INT32 VID_GetModeForSize(INT32 w, INT32 h)
{
	vmode_t *pv = pvidmodes;
	int modenum = 0;

	// Fullscreen resolutions exist
	if (numvidmodes > NUMSPECIALMODES)
	{
		// skip the special modes so that it finds only fullscreen modes
		for (; pv && modenum < NUMSPECIALMODES; pv = pv->pnext, ++modenum);
		for (; pv; pv = pv->pnext, ++modenum)
			if (pv->width == (unsigned)w && pv->height == (unsigned)h)
				return modenum;

		// Try default video mode first
		if (w != cv_scr_width.value || h != cv_scr_height.value)
			return VID_GetModeForSize(cv_scr_width.value, cv_scr_height.value);

		// didn't find, return first fullscreen mode
		return NUMSPECIALMODES;
	}

	// rely only on special (windowed) modes
	for (; pv && modenum < NUMSPECIALMODES; pv = pv->pnext, ++modenum)
		if (pv->width == (unsigned)w && pv->height == (unsigned)h)
			return modenum;

	// Try default video mode first
	if (w != cv_scr_width.value || h != cv_scr_height.value)
		return VID_GetModeForSize(cv_scr_width.value, cv_scr_height.value);

	// didn't find, return first windowed mode
	return 0;
}

//
// Enumerate DirectDraw modes available
//
static int nummodes = 0;
static BOOL GetExtraModesCallback(int width, int height, int bpp)
{
#ifdef _DEBUG
	CONS_Printf("mode %d x %d x %d bpp\n", width, height, bpp);
#endif

	// skip all unwanted modes
	if (highcolor && bpp != 15)
		goto skip;
	if (!highcolor && bpp != 8)
		goto skip;

	if (bpp > 16 || width > MAXVIDWIDTH || height > MAXVIDHEIGHT)
		goto skip;

	// check if we have space for this mode
	if (nummodes >= MAX_EXTRA_MODES)
	{
#ifdef _DEBUG
		CONS_Printf("mode skipped (too many)\n");
#endif
		return FALSE;
	}

	// store mode info
	extra_modes[nummodes].pnext = &extra_modes[nummodes+1];
	memset(names[nummodes], 0, 10);
	snprintf(names[nummodes], 9, "%dx%d", width, height);

	extra_modes[nummodes].name = names[nummodes];
	extra_modes[nummodes].width = width;
	extra_modes[nummodes].height = height;

	// exactly, the current FinishUdpate() gets the rowbytes itself after locking the video buffer
	// so for now we put anything here
	extra_modes[nummodes].rowbytes = width;
	extra_modes[nummodes].windowed = false;
	extra_modes[nummodes].misc = 0; // unused
	extra_modes[nummodes].pextradata = NULL;
	extra_modes[nummodes].setmode = VID_SetDirectDrawMode;

	extra_modes[nummodes].numpages = 3; // triple-buffer (but this value is unused)

	extra_modes[nummodes].bytesperpixel = (bpp+1)>>3;

	nummodes++;
skip:
	return TRUE;
}

//
// Collect info about DirectDraw display modes we use
//
static inline VOID VID_GetExtraModes(VOID)
{
	nummodes = 0;
	EnumDirectDrawDisplayModes(GetExtraModesCallback);

	// add the extra modes (not 320x200) at the start of the mode list (if there are any)
	if (nummodes)
	{
		extra_modes[nummodes-1].pnext = NULL;
		pvidmodes = &extra_modes[0];
		numvidmodes += nummodes;
	}
}

// ---------------
// WindowMode_Init
// Add windowed modes to the start of the list,
// mode 0 is used for windowed console startup (works on all computers with no DirectX)
// ---------------
static VOID WindowMode_Init(VOID)
{
	int modenum;

	for (modenum = 0; modenum < NUMSPECIALMODES - 1; modenum++)
		specialmodes[modenum].pnext = &specialmodes[modenum + 1];
	specialmodes[NUMSPECIALMODES-1].pnext = pvidmodes;

	pvidmodes = specialmodes;
	numvidmodes += NUMSPECIALMODES;
}

// *************************************************************************************
// VID_Init
// Initialize Video modes subsystem
// *************************************************************************************
static VOID VID_Init(VOID)
{
#ifdef _DEBUG
	vmode_t *pv;
	int iMode;
#endif

	// if '-win' is specified on the command line, do not add DirectDraw modes
	bWinParm = M_CheckParm("-win");

	COM_AddCommand("vid_nummodes", VID_Command_NumModes_f);
	COM_AddCommand("vid_modeinfo", VID_Command_ModeInfo_f);
	COM_AddCommand("vid_modelist", VID_Command_ModeList_f);
	COM_AddCommand("vid_mode", VID_Command_Mode_f);

	CV_RegisterVar(&cv_vidwait);
	CV_RegisterVar(&cv_stretch);
	CV_RegisterVar(&cv_ontop);

	// setup the videmodes list,
	// note that mode 0 must always be VGA mode 0x13
	pvidmodes = pcurrentmode = NULL;
	numvidmodes = 0;

	//DisableAero();

	// store the main window handle in viddef struct
	SetWindowPos(hWndMain, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOACTIVATE|SWP_NOSENDCHANGING|SWP_NOSIZE|SWP_NOMOVE);
	vid.WndParent = hWndMain;
	vid.buffer = NULL;

	// we startup in windowed mode using DIB bitmap
	// we will use DirectDraw when switching fullScreen and entering main game loop
	bDIBMode = TRUE;
	bAppFullScreen = FALSE;

#ifdef HWRENDER
	// initialize the appropriate display device
	if (rendermode != render_soft)
	{
		const char *drvname = NULL;

		switch (rendermode)
		{
			case render_opengl:
				drvname = "r_opengl.dll";
				break;
			default:
				I_Error("Unknown hardware render mode");
		}

		// load the DLL
		if (drvname && Init3DDriver(drvname))
		{
			int hwdversion = HWD.pfnGetRenderVersion();
			if (hwdversion != VERSION)
				CONS_Alert(CONS_WARNING, M_GetText("This r_opengl version is not supported, use it at your own risk!\n"));

			// perform initialisations
			HWD.pfnInit(I_Error);
			// get available display modes for the device
			HWD.pfnGetModeList(&pvidmodes, &numvidmodes);
		}
		else
		{
			switch (rendermode)
			{
				case render_opengl:
					I_Error("Error initializing OpenGL");
				default:
					break;
			}
			rendermode = render_soft;
		}
	}

	if (rendermode == render_soft)
#endif
		if (!bWinParm)
		{
			if (!CreateDirectDrawInstance())
				bWinParm = TRUE;
			else // get available display modes for the device
				VID_GetExtraModes();
		}

	// the game boots in 320x200 standard VGA, but
	// we need a highcolor mode to run the game in highcolor
	if (highcolor && !numvidmodes)
		I_Error("Cannot run in highcolor - No 15bit highcolor DirectX video mode found.");

	// add windowed mode at the start of the list, very important!
	WindowMode_Init();

	if (!numvidmodes)
		I_Error("No display modes available.");

#ifdef _DEBUG // DEBUG
	for (iMode = 0, pv = pvidmodes; pv; pv = pv->pnext, iMode++)
		I_OutputMsg("#%02d: %dx%dx%dbpp (desc: '%s')\n", iMode, pv->width, pv->height, pv->bytesperpixel, pv->name);
#endif

	// set the startup screen in a window
	VID_SetMode(0);
}

// --------------------------
// VID_SetWindowedDisplayMode
// Display the startup 320x200 console screen into a window on the desktop,
// switching to fullscreen display only when we will enter the main game loop.
// - we can display error message boxes for startup errors
// - we can set the last used resolution only once, when entering the main game loop
// --------------------------
static INT32 WINAPI VID_SetWindowedDisplayMode(viddef_t *lvid, vmode_t *currentmode)
{
	RECT bounds;
	int x = 0, y = 0, w = 0, h = 0;

	UNREFERENCED_PARAMETER(currentmode);

	I_OutputMsg("VID_SetWindowedDisplayMode()\n");


	lvid->u.numpages = 1; // not used
	lvid->direct = NULL; // DOS remains
	lvid->buffer = NULL;

	// allocate screens
	if (!VID_FreeAndAllocVidbuffer(lvid))
		return -1;

	// lvid->buffer should be NULL here!

	bmiMain = GlobalAlloc(GPTR, sizeof (BITMAPINFO) + (sizeof (RGBQUAD)*256));
	if (!bmiMain)
		I_Error("VID_SWDM(): No mem");

	// setup a BITMAPINFO to allow copying our video buffer to the desktop,
	// with color conversion as needed
	bmiMain->bmiHeader.biSize = sizeof (BITMAPINFOHEADER);
	bmiMain->bmiHeader.biWidth = lvid->width;
	bmiMain->bmiHeader.biHeight= -(lvid->height);
	bmiMain->bmiHeader.biPlanes = 1;
	bmiMain->bmiHeader.biBitCount = 8;
	bmiMain->bmiHeader.biCompression = BI_RGB;

	// center window on the desktop
	bounds.left = 0;
	bounds.right = lvid->width;
	bounds.top = 0;
	bounds.bottom = lvid->height;
	AdjustWindowRectEx(&bounds, GetWindowLong(hWndMain, GWL_STYLE), FALSE, GetWindowLong(hWndMain, GWL_EXSTYLE));

	w = bounds.right-bounds.left;
	h = bounds.bottom-bounds.top;
	x = (GetSystemMetrics(SM_CXSCREEN)-w)/2;
	y = (GetSystemMetrics(SM_CYSCREEN)-h)/2;

	if (devparm)
		MoveWindow(hWndMain, x<<1, y<<1, w, h, TRUE);
	else
		MoveWindow(hWndMain, x, y, w, h, TRUE);

	SetFocus(hWndMain);
	ShowWindow(hWndMain, SW_SHOW);

	hDCMain = GetDC(hWndMain);
	if (!hDCMain)
		I_Error("VID_SWDM(): GetDC FAILED");

	return 1;
}

// ========================================================================
// Returns a vmode_t from the video modes list, given a video mode number.
// ========================================================================
vmode_t *VID_GetModePtr(int modenum)
{
	vmode_t *pv;

	pv = pvidmodes;
	if (!pv)
		I_Error("VID_error: No video mode found\n");

	while (modenum--)
	{
		pv = pv->pnext;
		if (!pv)
			I_Error("VID_error: Mode not available\n");
	}
	return pv;
}

//
// return the name of a video mode
//
const char *VID_GetModeName(INT32 modenum)
{
	return (VID_GetModePtr(modenum))->name;
}

// ========================================================================
// Sets a video mode
// ========================================================================
INT32 VID_SetMode(INT32 modenum)
{
	int vstat;
	vmode_t *pnewmode;

	if (dedicated)
		return 0;

	I_OutputMsg("VID_SetMode(%d)\n", modenum);

	// if mode 0 (windowed) we must not be fullscreen already,
	// if other mode, check it is not mode 0 and existing
	if (modenum >= numvidmodes)
	{
		if (!pcurrentmode)
			modenum = 0; // revert to the default base vid mode
		else
			I_Error("Unknown video mode: %d\n", modenum);
	}
	else if (bAppFullScreen && modenum < NUMSPECIALMODES)
		I_Error("Tried to switch from fullscreen back to windowed mode %d\n", modenum);

	pnewmode = VID_GetModePtr(modenum);

	// dont switch to the same display mode
	if (pnewmode == pcurrentmode)
		return 1;

	// initialize the new mode
	pcurrentmode = pnewmode;

	// initialize vidbuffer size for setmode
	vid.width = pcurrentmode->width;
	vid.height = pcurrentmode->height;
	vid.rowbytes = pcurrentmode->rowbytes;
	vid.bpp = pcurrentmode->bytesperpixel;
	if (modenum) // if not 320x200 windowed mode, it's actually a hack
	{
		if (rendermode == render_opengl)
		{
			// don't accept depth < 16 for OpenGL mode (too much ugly)
			if (cv_scr_depth.value < 16)
				CV_SetValue(&cv_scr_depth,  16);
			vid.bpp = cv_scr_depth.value/8;
			vid.u.windowed = (bWinParm || !cv_fullscreen.value);
			pcurrentmode->bytesperpixel = vid.bpp;
			pcurrentmode->windowed = vid.u.windowed;
		}
	}

	vstat = (*pcurrentmode->setmode)(&vid, pcurrentmode);

	if (vstat == -1)
		I_Error("Not enough mem for VID_SetMode\n");
	else if (vstat == -2)
		I_Error("Couldn't set video mode because it failed the test\n");
	else if (vstat == -3)
		I_Error("Couldn't set video mode because it failed the change?\n");
	else if (!vstat)
		I_Error("Couldn't set video mode %d (%dx%d %d bits)\n", modenum, vid.width, vid.height, (vid.bpp*8));// hardware could not setup mode
	else
		CONS_Printf(M_GetText("Mode changed to %d (%s)\n"), modenum, pcurrentmode->name);

	vid.modenum = modenum;

	// tell game engine to recalc all tables and realloc buffers based on new values
	vid.recalc = 1;

	if (modenum < NUMSPECIALMODES)
	{
		// we are in startup windowed mode
		bAppFullScreen = FALSE;
		bDIBMode = TRUE;
	}
	else
	{
		// we switch to fullscreen
		bAppFullScreen = TRUE;
		bDIBMode = FALSE;
#ifdef HWRENDER
		if (rendermode != render_soft)
		{
			// purge all patch graphics stored in software format
			//Z_FreeTags (PU_PURGELEVEL, PU_PURGELEVEL+100);
			HWR_Startup();
		}
#endif
	}

	I_RestartSysMouse();
	return 1;
}

void VID_CheckRenderer(void) {}
void VID_CheckGLLoaded(rendermode_t oldrender)
{
	(void)oldrender;
}

// ========================================================================
// Free the video buffer of the last video mode,
// allocate a new buffer for the video mode to set.
// ========================================================================
static BOOL VID_FreeAndAllocVidbuffer(viddef_t *lvid)
{
	const DWORD vidbuffersize = (lvid->width * lvid->height * lvid->bpp * NUMSCREENS);

	// free allocated buffer for previous video mode
	if (lvid->buffer)
		GlobalFree(lvid->buffer);

	// allocate & clear the new screen buffer
	lvid->buffer = GlobalAlloc(GPTR, vidbuffersize);
	if (!lvid->buffer)
		return FALSE;

	ZeroMemory(lvid->buffer, vidbuffersize);
	I_OutputMsg("VID_FreeAndAllocVidbuffer done, vidbuffersize: %x\n",(UINT32)vidbuffersize);

	return TRUE;
}

// ========================================================================
// Set video mode routine for DirectDraw display modes
// Out: 1 ok,
//              0 hardware could not set mode,
//     -1 no mem
// ========================================================================
static INT32 WINAPI VID_SetDirectDrawMode(viddef_t *lvid, vmode_t *currentmode)
{
	UNREFERENCED_PARAMETER(currentmode);

	I_OutputMsg("VID_SetDirectDrawMode...\n");


	// DD modes do double-buffer page flipping, but the game engine doesn't need this..
	lvid->u.numpages = 2;

	// release ddraw surfaces etc..
	ReleaseChtuff();

	// clean up any old vid buffer lying around, alloc new if needed
	if (!VID_FreeAndAllocVidbuffer(lvid))
		return -1; // no mem

	// should clear video mem here

	// note use lvid->bpp instead of 8...will this be needed? will we support other than 256color
	// in software ?
	if (!InitDirectDrawe(hWndMain, lvid->width, lvid->height, 8, TRUE)) // TRUE currently always full screen
		return 0;               // could not set mode

	// this is NOT used with DirectDraw modes, game engine should never use this directly
	// but rather render to memory bitmap buffer
	lvid->direct = NULL;

	if (!cv_stretch.value && fabsf((float)vid.width/vid.height - ((float)BASEVIDWIDTH/BASEVIDHEIGHT)) > 1.0E-36f)
		vid.height = (int)(vid.width * ((float)BASEVIDHEIGHT/BASEVIDWIDTH));// Adjust the height to match

	return 1;
}

// ========================================================================
//                     VIDEO MODE CONSOLE COMMANDS
// ========================================================================

// vid_nummodes
//
static void VID_Command_NumModes_f(void)
{
	CONS_Printf(M_GetText("%d video mode(s) available(s)\n"), VID_NumModes());
}

// vid_modeinfo <modenum>
//
static void VID_Command_ModeInfo_f(void)
{
	vmode_t *pv;
	int modenum;

	if (COM_Argc() != 2)
		modenum = vid.modenum; // describe the current mode
	else
		modenum = atoi(COM_Argv(1)); // the given mode number

	if (modenum >= VID_NumModes()
	 || (!bWinParm && modenum < NUMSPECIALMODES)) // don't accept the windowed modes
	{
		CONS_Printf(M_GetText("Video mode not present\n"));
		return;
	}

	pv = VID_GetModePtr(modenum);

	CONS_Printf("\x82" "%s\n", VID_GetModeName(modenum));
	CONS_Printf(M_GetText("width: %d\nheight: %d\n"),
		pv->width, pv->height);
	if (rendermode == render_soft)
		CONS_Printf(M_GetText("bytes per scanline: %d\nbytes per pixel: %d\nnumpages: %d\n"),
			pv->rowbytes, pv->bytesperpixel, pv->numpages);
}

// vid_modelist
//
static void VID_Command_ModeList_f(void)
{
	int i, numodes;
	const char *pinfo;
	vmode_t *pv;

	numodes = VID_NumModes();

	// hide windowed modes unless using them
	i = (!bWinParm) ? NUMSPECIALMODES : 0;

	for (; i < numodes; i++)
	{
		pv = VID_GetModePtr(i);
		pinfo = VID_GetModeName(i);

		if (pv->bytesperpixel == 1)
			CONS_Printf("%d: %s\n", i, pinfo);
		else
			CONS_Printf("%d: %s (hicolor)\n", i, pinfo);
	}
}

// vid_mode <modenum>
//
static void VID_Command_Mode_f(void)
{
	int modenum;

	if (COM_Argc() != 2)
	{
		CONS_Printf(M_GetText("vid_mode <modenum> : set video mode, current video mode %i\n"), vid.modenum);
		return;
	}

	modenum = atoi(COM_Argv(1));

	if (modenum >= VID_NumModes()
	 || (!bWinParm && modenum < NUMSPECIALMODES)) // don't accept the windowed modes
		CONS_Printf(M_GetText("Video mode not present\n"));
	else
		setmodeneeded = modenum + 1; // request vid mode change
}
#endif