/*
Copyright (C) 1996-1997 Id Software, Inc.

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.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

// draw.c -- this is the only file outside the refresh that touches the
// vid buffer

#include "quakedef.h"

typedef struct {
	vrect_t	rect;
	int	width;
	int	height;
	byte	*ptexbytes;
	int	rowbytes;
} rectdesc_t;

static	rectdesc_t	r_rectdesc;

byte		*draw_chars;				// 8*8 graphic characters
mpic_t		*draw_disc;
mpic_t		*draw_backtile;

//=============================================================================
/* Support Routines */

typedef struct cachepic_s
{
	char		name[MAX_QPATH];
	cache_user_t	cache;
} cachepic_t;

#define	MAX_CACHED_PICS		128
cachepic_t	menu_cachepics[MAX_CACHED_PICS];
int		menu_numcachepics;

mpic_t *Draw_PicFromWad (char *name)
{
	qpic_t	*p;
	mpic_t	*pic;

	p = W_GetLumpName (name);
	pic = (mpic_t *)p;
	pic->width = p->width;
	pic->alpha = memchr (&pic->data, 255, pic->width * pic->height) != NULL;

	return pic;
}

/*
================
Draw_CachePic
================
*/
mpic_t *Draw_CachePic (char *path)
{
	int		i;
	cachepic_t	*pic;
	qpic_t		*dat;
	
	for (pic = menu_cachepics, i = 0 ; i < menu_numcachepics ; pic++, i++)
		if (!strcmp(path, pic->name))
			break;

	if (i == menu_numcachepics)
	{
		if (menu_numcachepics == MAX_CACHED_PICS)
			Sys_Error ("menu_numcachepics == MAX_CACHED_PICS");
		menu_numcachepics++;
		strcpy (pic->name, path);
	}

	if ((dat = Cache_Check(&pic->cache)))
		return (mpic_t *)dat;

// load the pic from disk
	COM_LoadCacheFile (path, &pic->cache);
	
	if (!(dat = (qpic_t *)pic->cache.data))
		Sys_Error ("Draw_CachePic: failed to load %s", path);

	SwapPic (dat);

	((mpic_t *)dat)->width = dat->width;
	((mpic_t *)dat)->alpha = memchr (&dat->data, 255, dat->width * ((mpic_t *)dat)->height) != NULL;

	return (mpic_t *)dat;
}

/*
===============
Draw_Init
===============
*/
void Draw_Init (void)
{
	draw_chars = W_GetLumpName ("conchars");
	draw_disc = W_GetLumpName ("disc");
	draw_backtile = W_GetLumpName ("backtile");

	r_rectdesc.width = draw_backtile->width;
	r_rectdesc.height = draw_backtile->height;
	r_rectdesc.ptexbytes = draw_backtile->data;
	r_rectdesc.rowbytes = draw_backtile->width;
}

/*
================
Draw_Character

Draws one 8*8 graphics character with 0 being transparent.
It can be clipped to the top of the screen to allow the console to be
smoothly scrolled off.
================
*/
void Draw_Character (int x, int y, int num)
{
	byte	*dest, *source;
	int	drawline, row, col;

	num &= 255;
	
	if (y <= -8)
		return;			// totally off screen

	if (y > vid.height - 8 || x < 0 || x > vid.width - 8)
		return;

	if (num < 0 || num > 255)
		return;

	row = num >> 4;
	col = num & 15;
	source = draw_chars + (row << 10) + (col << 3);

	if (y < 0)
	{	// clipped
		drawline = 8 + y;
		source -= 128*y;
		y = 0;
	}
	else
	{
		drawline = 8;
	}

	dest = vid.buffer + y * vid.rowbytes + x;
	
	while (drawline--)
	{
		if (source[0])
			dest[0] = source[0];
		if (source[1])
			dest[1] = source[1];
		if (source[2])
			dest[2] = source[2];
		if (source[3])
			dest[3] = source[3];
		if (source[4])
			dest[4] = source[4];
		if (source[5])
			dest[5] = source[5];
		if (source[6])
			dest[6] = source[6];
		if (source[7])
			dest[7] = source[7];
		source += 128;
		dest += vid.rowbytes;
	}
}

/*
================
Draw_String
================
*/
void Draw_String (int x, int y, char *str)
{
	while (*str)
	{
		Draw_Character (x, y, *str);
		str++;
		x += 8;
	}
}

/*
================
Draw_Alt_String
================
*/
void Draw_Alt_String (int x, int y, char *str)
{
	while (*str)
	{
		Draw_Character (x, y, (*str) | 0x80);
		str++;
		x += 8;
	}
}

/*
================
Draw_Pixel
================
*/
void Draw_Pixel(int x, int y, byte color)
{
	byte	*dest;

	dest = vid.buffer + y * vid.rowbytes + x;
	*dest = color;
}

#define		NUMCROSSHAIRS	5

static qboolean crosshairdata[NUMCROSSHAIRS][64] = {
	false, false, false, true,  false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, true,  false, false, false, false,
	true,  false, true,  false, true,  false, true,  false,
	false, false, false, true,  false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, true,  false, false, false, false,
	false, false, false, false, false, false, false, false,

	false, false, false, false, false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, true,  false, false, false, false,
	false, false, true,  true,  true,  false, false, false,
	false, false, false, true,  false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, false, false, false, false, false,

	false, false, false, false, false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, true,  false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, false, false, false, false, false,

	true,  false, false, false, false, false, false, true,
	false, true,  false, false, false, false, true, false,
	false, false, true,  false, false, true,  false, false,
	false, false, false, false, false, false, false, false,
	false, false, false, false, false, false, false, false,
	false, false, true,  false, false, true,  false, false,
	false, true,  false, false, false, false, true,  false,
	true,  false, false, false, false, false, false, true,

	false, false, true,  true,  true,  false, false, false, 
	false, false, false, false, false, false, false, false, 
	true,  false, false, false, false, false, true,  false, 
	true,  false, false, true,  false, false, true,  false, 
	true,  false, false, false, false, false, true,  false, 
	false, false, false, false, false, false, false, false, 
	false, false, true,  true,  true,  false, false, false, 
	false, false, false, false, false, false, false, false
};

void Draw_Crosshair (void)
{
	int		x, y, row, col;
	extern	cvar_t	crosshair, cl_crossx, cl_crossy, crosshaircolor, crosshairsize;
	extern	vrect_t	scr_vrect;
	byte		c = (byte)crosshaircolor.value;
	qboolean 	*data;

	if (!crosshair.value)
		return;

	x = scr_vrect.x + scr_vrect.width / 2 + cl_crossx.value; 
	y = scr_vrect.y + scr_vrect.height / 2 + cl_crossy.value;

	if (crosshair.value >= 2 && crosshair.value <= NUMCROSSHAIRS + 1)
	{
		data = crosshairdata[(int)crosshair.value-2];
		for (row=0 ; row<8 ; row++)
		{
			for (col=0 ; col<8 ; col++)
			{
				if (data[row*8+col])
				{
					if (crosshairsize.value >= 3)
					{
						Draw_Pixel (x + 3 * (col-3) - 1, y + 3 * (row-3) - 1, c);
						Draw_Pixel (x + 3 * (col-3) - 1, y + 3 * (row-3), c);
						Draw_Pixel (x + 3 * (col-3) - 1, y + 3 * (row-3) + 1, c);

						Draw_Pixel (x + 3 * (col-3), y + 3 * (row-3) - 1, c);
						Draw_Pixel (x + 3 * (col-3), y + 3 * (row-3), c);
						Draw_Pixel (x + 3 * (col-3), y + 3 * (row-3) + 1, c);

						Draw_Pixel (x + 3 * (col-3) + 1, y + 3 * (row-3) - 1, c);
						Draw_Pixel (x + 3 * (col-3) + 1, y + 3 * (row-3), c);
						Draw_Pixel (x + 3 * (col-3) + 1, y + 3 * (row-3) + 1, c);
					}
					else if (crosshairsize.value >= 2)
					{
						Draw_Pixel (x + 2 * (col-3), y + 2 * (row-3), c);
						Draw_Pixel (x + 2 * (col-3), y + 2 * (row-3) - 1, c);

						Draw_Pixel (x + 2 * (col-3) - 1, y + 2 * (row-3), c);
						Draw_Pixel (x + 2 * (col-3) - 1, y + 2 * (row-3) - 1, c);
					}
					else
					{
						Draw_Pixel (x + col - 3, y + row - 3, c);
					}
				}
			}
		}
	}
	else
		Draw_Character (x - 4, y - 4, '+');
}

/*
================
Draw_TextBox
================
*/
void Draw_TextBox (int x, int y, int width, int lines)
{
	mpic_t	*p;
	int	n, cx, cy;

	// draw left side
	cx = x;
	cy = y;
	p = Draw_CachePic ("gfx/box_tl.lmp");
	Draw_TransPic (cx, cy, p);
	p = Draw_CachePic ("gfx/box_ml.lmp");
	for (n = 0; n < lines; n++)
	{
		cy += 8;
		Draw_TransPic (cx, cy, p);
	}
	p = Draw_CachePic ("gfx/box_bl.lmp");
	Draw_TransPic (cx, cy+8, p);

	// draw middle
	cx += 8;
	while (width > 0)
	{
		cy = y;
		p = Draw_CachePic ("gfx/box_tm.lmp");
		Draw_TransPic (cx, cy, p);
		p = Draw_CachePic ("gfx/box_mm.lmp");
		for (n = 0; n < lines; n++)
		{
			cy += 8;
			if (n == 1)
				p = Draw_CachePic ("gfx/box_mm2.lmp");
			Draw_TransPic (cx, cy, p);
		}
		p = Draw_CachePic ("gfx/box_bm.lmp");
		Draw_TransPic (cx, cy+8, p);
		width -= 2;
		cx += 16;
	}

	// draw right side
	cy = y;
	p = Draw_CachePic ("gfx/box_tr.lmp");
	Draw_TransPic (cx, cy, p);
	p = Draw_CachePic ("gfx/box_mr.lmp");
	for (n = 0; n < lines; n++)
	{
		cy += 8;
		Draw_TransPic (cx, cy, p);
	}
	p = Draw_CachePic ("gfx/box_br.lmp");
	Draw_TransPic (cx, cy+8, p);
}

/*
================
Draw_DebugChar

Draws a single character directly to the upper right corner of the screen.
This is for debugging lockups by drawing different chars in different parts
of the code.
================
*/
void Draw_DebugChar (char num)
{
	byte		*dest, *source;
	int		drawline, row, col;
	extern	byte	*draw_chars;

	if (!vid.direct)
		return;		// don't have direct FB access, so no debugchars...

	drawline = 8;

	row = num>>4;
	col = num&15;
	source = draw_chars + (row<<10) + (col<<3);

	dest = vid.direct + 312;

	while (drawline--)
	{
		dest[0] = source[0];
		dest[1] = source[1];
		dest[2] = source[2];
		dest[3] = source[3];
		dest[4] = source[4];
		dest[5] = source[5];
		dest[6] = source[6];
		dest[7] = source[7];
		source += 128;
		dest += 320;
	}
}

/*
=============
Draw_Pic
=============
*/
void Draw_Pic (int x, int y, mpic_t *pic)
{
	byte	*dest, *source;
	int	v;

	if (pic->alpha)
	{
		Draw_TransPic (x, y, pic);
		return;
	}

	if (x < 0 || x + pic->width > vid.width || y < 0 || y + pic->height > vid.height)
		Sys_Error ("Draw_Pic: bad coordinates");

	source = pic->data;

	dest = vid.buffer + y * vid.rowbytes + x;

	for (v=0 ; v<pic->height ; v++)
	{
		memcpy (dest, source, pic->width);
		dest += vid.rowbytes;
		source += pic->width;
	}
}

void Draw_TransSubPic (int x, int y, mpic_t *pic, int srcx, int srcy, int width, int height);

/*
=============
Draw_SubPic
=============
*/
void Draw_SubPic (int x, int y, mpic_t *pic, int srcx, int srcy, int width, int height)
{
	byte	*dest, *source;
	int	v;

	if (pic->alpha)
	{
		Draw_TransSubPic (x, y, pic, srcx, srcy, width, height);
		return;
	}

	if (x < 0 || x + width > vid.width || y < 0 || y + height > vid.height)
		Sys_Error ("Draw_Pic: bad coordinates");

	source = pic->data + srcy * pic->width + srcx;

	dest = vid.buffer + y * vid.rowbytes + x;

	for (v=0 ; v<height ; v++)
	{
		memcpy (dest, source, width);
		dest += vid.rowbytes;
		source += pic->width;
	}
}

/*
=============
Draw_TransPic
=============
*/
void Draw_TransPic (int x, int y, mpic_t *pic)
{
	byte	*dest, *source, tbyte;
	int	v, u;

	if (x < 0 || (unsigned)(x + pic->width) > vid.width || y < 0 || (unsigned)(y + pic->height) > vid.height)
		Sys_Error ("Draw_TransPic: bad coordinates");
		
	source = pic->data;

	dest = vid.buffer + y * vid.rowbytes + x;

	if (pic->width & 7)
	{	// general
		for (v=0 ; v<pic->height ; v++)
		{
			for (u=0 ; u<pic->width ; u++)
				if ((tbyte=source[u]) != TRANSPARENT_COLOR)
					dest[u] = tbyte;

			dest += vid.rowbytes;
			source += pic->width;
		}
	}
	else
	{	// unwound
		for (v=0 ; v<pic->height ; v++)
		{
			for (u=0 ; u<pic->width ; u+=8)
			{
				if ((tbyte=source[u]) != TRANSPARENT_COLOR)
					dest[u] = tbyte;
				if ((tbyte=source[u+1]) != TRANSPARENT_COLOR)
					dest[u+1] = tbyte;
				if ((tbyte=source[u+2]) != TRANSPARENT_COLOR)
					dest[u+2] = tbyte;
				if ((tbyte=source[u+3]) != TRANSPARENT_COLOR)
					dest[u+3] = tbyte;
				if ((tbyte=source[u+4]) != TRANSPARENT_COLOR)
					dest[u+4] = tbyte;
				if ((tbyte=source[u+5]) != TRANSPARENT_COLOR)
					dest[u+5] = tbyte;
				if ((tbyte=source[u+6]) != TRANSPARENT_COLOR)
					dest[u+6] = tbyte;
				if ((tbyte=source[u+7]) != TRANSPARENT_COLOR)
					dest[u+7] = tbyte;
			}
			dest += vid.rowbytes;
			source += pic->width;
		}
	}
}

/*
=============
Draw_TransSubPic
=============
*/
void Draw_TransSubPic (int x, int y, mpic_t *pic, int srcx, int srcy, int width, int height)
{
	byte	*dest, *source, tbyte;
	int	v, u;

	if (x < 0 || x + width > vid.width || y < 0 || y + height > vid.height)
		Sys_Error ("Draw_Pic: bad coordinates");
		
	source = pic->data + srcy * pic->width + srcx;

	dest = vid.buffer + y * vid.rowbytes + x;

	if (width & 7)
	{	// general
		for (v=0 ; v<height ; v++)
		{
			for (u=0 ; u<width ; u++)
				if ((tbyte=source[u]) != TRANSPARENT_COLOR)
					dest[u] = tbyte;
	
			dest += vid.rowbytes;
			source += pic->width;
		}
	}
	else
	{	// unwound
		for (v=0 ; v<height ; v++)
		{
			for (u=0 ; u<width ; u+=8)
			{
				if ((tbyte=source[u]) != TRANSPARENT_COLOR)
					dest[u] = tbyte;
				if ((tbyte=source[u+1]) != TRANSPARENT_COLOR)
					dest[u+1] = tbyte;
				if ((tbyte=source[u+2]) != TRANSPARENT_COLOR)
					dest[u+2] = tbyte;
				if ((tbyte=source[u+3]) != TRANSPARENT_COLOR)
					dest[u+3] = tbyte;
				if ((tbyte=source[u+4]) != TRANSPARENT_COLOR)
					dest[u+4] = tbyte;
				if ((tbyte=source[u+5]) != TRANSPARENT_COLOR)
					dest[u+5] = tbyte;
				if ((tbyte=source[u+6]) != TRANSPARENT_COLOR)
					dest[u+6] = tbyte;
				if ((tbyte=source[u+7]) != TRANSPARENT_COLOR)
					dest[u+7] = tbyte;
			}
			dest += vid.rowbytes;
			source += pic->width;
		}
	}
}

/*
=============
Draw_TransPicTranslate
=============
*/
void Draw_TransPicTranslate (int x, int y, mpic_t *pic, byte *translation)
{
	byte	*dest, *source, tbyte;
	int	v, u;

	if (x < 0 || (unsigned)(x + pic->width) > vid.width || y < 0 || (unsigned)(y + pic->height) > vid.height)
		Sys_Error ("Draw_TransPic: bad coordinates");
		
	source = pic->data;

	dest = vid.buffer + y * vid.rowbytes + x;

	if (pic->width & 7)
	{	// general
		for (v=0 ; v<pic->height ; v++)
		{
			for (u=0 ; u<pic->width ; u++)
				if ((tbyte=source[u]) != TRANSPARENT_COLOR)
					dest[u] = translation[tbyte];

			dest += vid.rowbytes;
			source += pic->width;
		}
	}
	else
	{	// unwound
		for (v=0 ; v<pic->height ; v++)
		{
			for (u=0 ; u<pic->width ; u+=8)
			{
				if ((tbyte=source[u]) != TRANSPARENT_COLOR)
					dest[u] = translation[tbyte];
				if ((tbyte=source[u+1]) != TRANSPARENT_COLOR)
					dest[u+1] = translation[tbyte];
				if ((tbyte=source[u+2]) != TRANSPARENT_COLOR)
					dest[u+2] = translation[tbyte];
				if ((tbyte=source[u+3]) != TRANSPARENT_COLOR)
					dest[u+3] = translation[tbyte];
				if ((tbyte=source[u+4]) != TRANSPARENT_COLOR)
					dest[u+4] = translation[tbyte];
				if ((tbyte=source[u+5]) != TRANSPARENT_COLOR)
					dest[u+5] = translation[tbyte];
				if ((tbyte=source[u+6]) != TRANSPARENT_COLOR)
					dest[u+6] = translation[tbyte];
				if ((tbyte=source[u+7]) != TRANSPARENT_COLOR)
					dest[u+7] = translation[tbyte];
			}
			dest += vid.rowbytes;
			source += pic->width;
		}
	}
}

void Draw_CharToConback (int num, byte *dest)
{
	int	x, row, col, drawline;
	byte	*source;

	row = num>>4;
	col = num&15;
	source = draw_chars + (row<<10) + (col<<3);

	drawline = 8;

	while (drawline--)
	{
		for (x=0 ; x<8 ; x++)
			if (source[x])
				dest[x] = source[x];
		source += 128;
		dest += 320;
	}
}

/*
================
Draw_ConsoleBackground
================
*/
void Draw_ConsoleBackground (int lines)
{
	int		x, y, v, f, fstep;
	byte		*src, *dest;
	mpic_t		*conback;
	char		ver[100];
	static	char	saveback[320*8];

	conback = Draw_CachePic ("gfx/conback.lmp");

// hack the version number directly into the pic
	sprintf (ver, "JoeQuake %s", JOEQUAKE_VERSION);
	dest = conback->data + 320 - (strlen(ver)*8 + 11) + 320*186;

	memcpy (saveback, conback->data + 320*186, 320*8);
	for (x=0 ; x < strlen(ver) ; x++)
		Draw_CharToConback (ver[x] | 128, dest + (x<<3));
	
// draw the pic
	dest = vid.buffer;

	for (y=0 ; y<lines ; y++, dest += vid.rowbytes)
	{
		v = (vid.conheight - lines + y)*200/vid.conheight;
		src = conback->data + v*320;
		if (vid.conwidth == 320)
			memcpy (dest, src, vid.conwidth);
		else
		{
			f = 0;
			fstep = 320*0x10000/vid.conwidth;
			for (x=0 ; x<vid.conwidth ; x+=4)
			{
				dest[x] = src[f>>16];
				f += fstep;
				dest[x+1] = src[f>>16];
				f += fstep;
				dest[x+2] = src[f>>16];
				f += fstep;
				dest[x+3] = src[f>>16];
				f += fstep;
			}
		}
	}
	// put it back
	memcpy(conback->data + 320*186, saveback, 320*8);
}

/*
==============
R_DrawRect8
==============
*/
void R_DrawRect8 (vrect_t *prect, int rowbytes, byte *psrc, int transparent)
{
	byte	t, *pdest;
	int	i, j, srcdelta, destdelta;

	pdest = vid.buffer + (prect->y * vid.rowbytes) + prect->x;

	srcdelta = rowbytes - prect->width;
	destdelta = vid.rowbytes - prect->width;

	if (transparent)
	{
		for (i=0 ; i<prect->height ; i++)
		{
			for (j=0 ; j<prect->width ; j++)
			{
				t = *psrc;
				if (t != TRANSPARENT_COLOR)
					*pdest = t;

				psrc++;
				pdest++;
			}

			psrc += srcdelta;
			pdest += destdelta;
		}
	}
	else
	{
		for (i=0 ; i<prect->height ; i++)
		{
			memcpy (pdest, psrc, prect->width);
			psrc += rowbytes;
			pdest += vid.rowbytes;
		}
	}
}

/*
=============
Draw_TileClear

This repeats a 64*64 tile graphic to fill the screen around a sized down
refresh window.
=============
*/
void Draw_TileClear (int x, int y, int w, int h)
{
	int	width, height, tileoffsetx, tileoffsety;
	byte	*psrc;
	vrect_t	vr;

	r_rectdesc.rect.x = x;
	r_rectdesc.rect.y = y;
	r_rectdesc.rect.width = w;
	r_rectdesc.rect.height = h;

	vr.y = r_rectdesc.rect.y;
	height = r_rectdesc.rect.height;

	tileoffsety = vr.y % r_rectdesc.height;

	while (height > 0)
	{
		vr.x = r_rectdesc.rect.x;
		width = r_rectdesc.rect.width;

		if (tileoffsety != 0)
			vr.height = r_rectdesc.height - tileoffsety;
		else
			vr.height = r_rectdesc.height;

		if (vr.height > height)
			vr.height = height;

		tileoffsetx = vr.x % r_rectdesc.width;

		while (width > 0)
		{
			if (tileoffsetx != 0)
				vr.width = r_rectdesc.width - tileoffsetx;
			else
				vr.width = r_rectdesc.width;

			if (vr.width > width)
				vr.width = width;

			psrc = r_rectdesc.ptexbytes + (tileoffsety * r_rectdesc.rowbytes) + tileoffsetx;

			R_DrawRect8 (&vr, r_rectdesc.rowbytes, psrc, 0);

			vr.x += vr.width;
			width -= vr.width;
			tileoffsetx = 0;	// only the left tile can be left-clipped
		}

		vr.y += vr.height;
		height -= vr.height;
		tileoffsety = 0;		// only the top tile can be top-clipped
	}
}

/*
=============
Draw_Fill

Fills a box of pixels with a single color
=============
*/
void Draw_Fill (int x, int y, int w, int h, int c)
{
	byte	*dest;
	int	u, v;

	if (x < 0 || x + w > vid.width || y < 0 || y + h > vid.height)
		return;

	dest = vid.buffer + y*vid.rowbytes + x;
	for (v=0 ; v<h ; v++, dest += vid.rowbytes)
		for (u=0 ; u<w ; u++)
			dest[u] = c;
}

//=============================================================================

/*
================
Draw_FadeScreen
================
*/
void Draw_FadeScreen (void)
{
	int	x,y;
	byte	*pbuf;

	VID_UnlockBuffer ();
	S_ExtraUpdate ();
	VID_LockBuffer ();

	for (y=0 ; y<vid.height ; y++)
	{
		int	t;

		pbuf = (byte *)(vid.buffer + vid.rowbytes*y);
		t = (y & 1) << 1;

		for (x=0 ; x<vid.width ; x++)
		{
			if ((x & 3) != t)
				pbuf[x] = 0;
		}
	}

	VID_UnlockBuffer ();
	S_ExtraUpdate ();
	VID_LockBuffer ();
}

//=============================================================================

/*
================
Draw_BeginDisc

Draws the little blue disc in the corner of the screen.
Call before beginning any disc IO.
================
*/
void Draw_BeginDisc (void)
{
	D_BeginDirectRect (vid.width - 24, 0, draw_disc->data, 24, 24);
}

/*
================
Draw_EndDisc

Erases the disc icon.
Call after completing any disc IO
================
*/
void Draw_EndDisc (void)
{
	D_EndDirectRect (vid.width - 24, 0, 24, 24);
}