xash3d-fwgs/ref/soft/r_scan.c

/*
Copyright (C) 1997-2001 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.

*/
// d_scan.c
//
// Portable C scan-level rasterization code, all pixel depths.

#include "r_local.h"

pixel_t	*r_turb_pbase, *r_turb_pdest;
short *r_turb_pz;
fixed16_t		r_turb_s, r_turb_t, r_turb_sstep, r_turb_tstep;
int r_turb_izistep, r_turb_izi;
int				*r_turb_turb;
static int				r_turb_spancount;
int alpha;

void D_DrawTurbulent8Span (void);


#if	!id386

/*
=============
D_DrawTurbulent8Span
=============
*/
void D_DrawTurbulent8Span (void)
{
	int		sturb, tturb;

	do
	{
		sturb = ((r_turb_s + r_turb_turb[(r_turb_t>>16)&(CYCLE-1)])>>16)&63;
		tturb = ((r_turb_t + r_turb_turb[(r_turb_s>>16)&(CYCLE-1)])>>16)&63;
		*r_turb_pdest++ = *(r_turb_pbase + (tturb<<6) + sturb);
		r_turb_s += r_turb_sstep;
		r_turb_t += r_turb_tstep;
	} while (--r_turb_spancount > 0);
}


/*
=============
D_DrawTurbulent8Span
=============
*/
static void D_DrawTurbulent8ZSpan (void)
{
	int		sturb, tturb;

	do
	{
		sturb = ((r_turb_s + r_turb_turb[(r_turb_t>>16)&(CYCLE-1)])>>16)&63;
		tturb = ((r_turb_t + r_turb_turb[(r_turb_s>>16)&(CYCLE-1)])>>16)&63;
		if (*r_turb_pz <= (r_turb_izi >> 16))
		{
			pixel_t btemp = *(r_turb_pbase + (tturb<<6) + sturb);
			if( alpha == 7 )
				*r_turb_pdest = btemp;
			else
				*r_turb_pdest = BLEND_ALPHA( alpha, btemp, *r_turb_pdest);
		}
		r_turb_pdest++;
		r_turb_pz++;
		r_turb_izi += r_turb_izistep;
		r_turb_s += r_turb_sstep;
		r_turb_t += r_turb_tstep;
	} while (--r_turb_spancount > 0);
}

#endif	// !id386


/*
=============
Turbulent8
=============
*/
void Turbulent8 (espan_t *pspan)
{
	int				count;
	fixed16_t		snext, tnext;
	float			sdivz, tdivz, zi, z, du, dv, spancountminus1;
	float			sdivz16stepu, tdivz16stepu, zi16stepu;

	r_turb_turb = sintable + ((int)(gp_cl->time*SPEED)&(CYCLE-1));

	r_turb_sstep = 0;	// keep compiler happy
	r_turb_tstep = 0;	// ditto

	r_turb_pbase = cacheblock;

	sdivz16stepu = d_sdivzstepu * 16;
	tdivz16stepu = d_tdivzstepu * 16;
	zi16stepu = d_zistepu * 16;

	do
	{
		r_turb_pdest = (d_viewbuffer +
				(r_screenwidth * pspan->v) + pspan->u);

		count = pspan->count;

	// calculate the initial s/z, t/z, 1/z, s, and t and clamp
		du = (float)pspan->u;
		dv = (float)pspan->v;

		sdivz = d_sdivzorigin + dv*d_sdivzstepv + du*d_sdivzstepu;
		tdivz = d_tdivzorigin + dv*d_tdivzstepv + du*d_tdivzstepu;
		zi = d_ziorigin + dv*d_zistepv + du*d_zistepu;
		z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

		r_turb_s = (int)(sdivz * z) + sadjust;
		if (r_turb_s > bbextents)
			r_turb_s = bbextents;
		else if (r_turb_s < 0)
			r_turb_s = 0;

		r_turb_t = (int)(tdivz * z) + tadjust;
		if (r_turb_t > bbextentt)
			r_turb_t = bbextentt;
		else if (r_turb_t < 0)
			r_turb_t = 0;

		do
		{
		// calculate s and t at the far end of the span
			if (count >= 16)
				r_turb_spancount = 16;
			else
				r_turb_spancount = count;

			count -= r_turb_spancount;

			if (count)
			{
			// calculate s/z, t/z, zi->fixed s and t at far end of span,
			// calculate s and t steps across span by shifting
				sdivz += sdivz16stepu;
				tdivz += tdivz16stepu;
				zi += zi16stepu;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 16)
					snext = 16;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 16)
					tnext = 16;	// guard against round-off error on <0 steps

				r_turb_sstep = (snext - r_turb_s) >> 4;
				r_turb_tstep = (tnext - r_turb_t) >> 4;
			}
			else
			{
			// calculate s/z, t/z, zi->fixed s and t at last pixel in span (so
			// can't step off polygon), clamp, calculate s and t steps across
			// span by division, biasing steps low so we don't run off the
			// texture
				spancountminus1 = (float)(r_turb_spancount - 1);
				sdivz += d_sdivzstepu * spancountminus1;
				tdivz += d_tdivzstepu * spancountminus1;
				zi += d_zistepu * spancountminus1;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point
				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 16)
					snext = 16;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 16)
					tnext = 16;	// guard against round-off error on <0 steps

				if (r_turb_spancount > 1)
				{
					r_turb_sstep = (snext - r_turb_s) / (r_turb_spancount - 1);
					r_turb_tstep = (tnext - r_turb_t) / (r_turb_spancount - 1);
				}
			}

			r_turb_s = r_turb_s & ((CYCLE<<16)-1);
			r_turb_t = r_turb_t & ((CYCLE<<16)-1);

			D_DrawTurbulent8Span ();

			r_turb_s = snext;
			r_turb_t = tnext;

		} while (count > 0);

	} while ((pspan = pspan->pnext) != NULL);
}


/*
=============
Turbulent8
=============
*/
void TurbulentZ8 (espan_t *pspan, int alpha1)
{
	int				count;
	fixed16_t		snext, tnext;
	float			sdivz, tdivz, zi, z, du, dv, spancountminus1;
	float			sdivz16stepu, tdivz16stepu, zi16stepu;
	alpha = alpha1;

	if( alpha > 7 )
		alpha = 7;
	if( alpha == 0 )
		return;

	r_turb_turb = sintable + ((int)(gp_cl->time*SPEED)&(CYCLE-1));

	r_turb_sstep = 0;	// keep compiler happy
	r_turb_tstep = 0;	// ditto

	r_turb_pbase = cacheblock;

	sdivz16stepu = d_sdivzstepu * 16;
	tdivz16stepu = d_tdivzstepu * 16;
	zi16stepu = d_zistepu * 16;
	r_turb_izistep = (int)(d_zistepu * 0x8000 * 0x10000);

	do
	{
		r_turb_pdest = (d_viewbuffer +
				(r_screenwidth * pspan->v) + pspan->u);
		r_turb_pz = d_pzbuffer + (d_zwidth * pspan->v) + pspan->u;

		count = pspan->count;

	// calculate the initial s/z, t/z, 1/z, s, and t and clamp
		du = (float)pspan->u;
		dv = (float)pspan->v;

		sdivz = d_sdivzorigin + dv*d_sdivzstepv + du*d_sdivzstepu;
		tdivz = d_tdivzorigin + dv*d_tdivzstepv + du*d_tdivzstepu;
		zi = d_ziorigin + dv*d_zistepv + du*d_zistepu;
		z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point
		r_turb_izi = (int)(zi * 0x8000 * 0x10000);

		r_turb_s = (int)(sdivz * z) + sadjust;
		if (r_turb_s > bbextents)
			r_turb_s = bbextents;
		else if (r_turb_s < 0)
			r_turb_s = 0;

		r_turb_t = (int)(tdivz * z) + tadjust;
		if (r_turb_t > bbextentt)
			r_turb_t = bbextentt;
		else if (r_turb_t < 0)
			r_turb_t = 0;

		do
		{
		// calculate s and t at the far end of the span
			if (count >= 16)
				r_turb_spancount = 16;
			else
				r_turb_spancount = count;

			count -= r_turb_spancount;

			if (count)
			{
			// calculate s/z, t/z, zi->fixed s and t at far end of span,
			// calculate s and t steps across span by shifting
				sdivz += sdivz16stepu;
				tdivz += tdivz16stepu;
				zi += zi16stepu;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 16)
					snext = 16;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 16)
					tnext = 16;	// guard against round-off error on <0 steps

				r_turb_sstep = (snext - r_turb_s) >> 4;
				r_turb_tstep = (tnext - r_turb_t) >> 4;
			}
			else
			{
			// calculate s/z, t/z, zi->fixed s and t at last pixel in span (so
			// can't step off polygon), clamp, calculate s and t steps across
			// span by division, biasing steps low so we don't run off the
			// texture
				spancountminus1 = (float)(r_turb_spancount - 1);
				sdivz += d_sdivzstepu * spancountminus1;
				tdivz += d_tdivzstepu * spancountminus1;
				zi += d_zistepu * spancountminus1;

				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point
				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 16)
					snext = 16;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 16)
					tnext = 16;	// guard against round-off error on <0 steps

				if (r_turb_spancount > 1)
				{
					r_turb_sstep = (snext - r_turb_s) / (r_turb_spancount - 1);
					r_turb_tstep = (tnext - r_turb_t) / (r_turb_spancount - 1);
				}
			}

			r_turb_s = r_turb_s & ((CYCLE<<16)-1);
			r_turb_t = r_turb_t & ((CYCLE<<16)-1);

			D_DrawTurbulent8ZSpan ();

			r_turb_s = snext;
			r_turb_t = tnext;

		} while (count > 0);

	} while ((pspan = pspan->pnext) != NULL);
}



//====================
//PGM
/*
=============
NonTurbulent8 - this is for drawing scrolling textures. they're warping water textures
	but the turbulence is automatically 0.
=============
*/
void NonTurbulent8 (espan_t *pspan)
{
	int				count;
	fixed16_t		snext, tnext;
	float			sdivz, tdivz, zi, z, du, dv, spancountminus1;
	float			sdivz16stepu, tdivz16stepu, zi16stepu;

//	r_turb_turb = sintable + ((int)(r_newrefdef.time*SPEED)&(CYCLE-1));
	r_turb_turb = blanktable;

	r_turb_sstep = 0;	// keep compiler happy
	r_turb_tstep = 0;	// ditto

	r_turb_pbase = cacheblock;

	sdivz16stepu = d_sdivzstepu * 16;
	tdivz16stepu = d_tdivzstepu * 16;
	zi16stepu = d_zistepu * 16;

	do
	{
		r_turb_pdest = (d_viewbuffer +
				(r_screenwidth * pspan->v) + pspan->u);

		count = pspan->count;

	// calculate the initial s/z, t/z, 1/z, s, and t and clamp
		du = (float)pspan->u;
		dv = (float)pspan->v;

		sdivz = d_sdivzorigin + dv*d_sdivzstepv + du*d_sdivzstepu;
		tdivz = d_tdivzorigin + dv*d_tdivzstepv + du*d_tdivzstepu;
		zi = d_ziorigin + dv*d_zistepv + du*d_zistepu;
		z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

		r_turb_s = (int)(sdivz * z) + sadjust;
		if (r_turb_s > bbextents)
			r_turb_s = bbextents;
		else if (r_turb_s < 0)
			r_turb_s = 0;

		r_turb_t = (int)(tdivz * z) + tadjust;
		if (r_turb_t > bbextentt)
			r_turb_t = bbextentt;
		else if (r_turb_t < 0)
			r_turb_t = 0;

		do
		{
		// calculate s and t at the far end of the span
			if (count >= 16)
				r_turb_spancount = 16;
			else
				r_turb_spancount = count;

			count -= r_turb_spancount;

			if (count)
			{
			// calculate s/z, t/z, zi->fixed s and t at far end of span,
			// calculate s and t steps across span by shifting
				sdivz += sdivz16stepu;
				tdivz += tdivz16stepu;
				zi += zi16stepu;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 16)
					snext = 16;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 16)
					tnext = 16;	// guard against round-off error on <0 steps

				r_turb_sstep = (snext - r_turb_s) >> 4;
				r_turb_tstep = (tnext - r_turb_t) >> 4;
			}
			else
			{
			// calculate s/z, t/z, zi->fixed s and t at last pixel in span (so
			// can't step off polygon), clamp, calculate s and t steps across
			// span by division, biasing steps low so we don't run off the
			// texture
				spancountminus1 = (float)(r_turb_spancount - 1);
				sdivz += d_sdivzstepu * spancountminus1;
				tdivz += d_tdivzstepu * spancountminus1;
				zi += d_zistepu * spancountminus1;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point
				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 16)
					snext = 16;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 16)
					tnext = 16;	// guard against round-off error on <0 steps

				if (r_turb_spancount > 1)
				{
					r_turb_sstep = (snext - r_turb_s) / (r_turb_spancount - 1);
					r_turb_tstep = (tnext - r_turb_t) / (r_turb_spancount - 1);
				}
			}

			r_turb_s = r_turb_s & ((CYCLE<<16)-1);
			r_turb_t = r_turb_t & ((CYCLE<<16)-1);

			D_DrawTurbulent8Span ();

			r_turb_s = snext;
			r_turb_t = tnext;

		} while (count > 0);

	} while ((pspan = pspan->pnext) != NULL);
}
//PGM
//====================


#if	!id386

int kernel[2][2][2] =
{
   {
		{16384,0},
		{49152,32768}
   }
   ,
   {
	  {32768,49152},
	  {0,16384}
   }
};
#ifndef DISABLE_TEXFILTER
#define SW_TEXFILT (sw_texfilt.value == 1.0f)
#else
#define SW_TEXFILT 0
#endif
/*
=============
D_DrawSpans16

  FIXME: actually make this subdivide by 16 instead of 8!!!
=============
*/
void D_DrawSpans16 (espan_t *pspan)
{
	int				count, spancount;
	pixel_t	*pbase, *pdest;
	fixed16_t		s, t, snext, tnext, sstep, tstep;
	float			sdivz, tdivz, zi, z, du, dv, spancountminus1;
	float			sdivz8stepu, tdivz8stepu, zi8stepu;

	sstep = 0;	// keep compiler happy
	tstep = 0;	// ditto

	pbase = cacheblock;

	sdivz8stepu = d_sdivzstepu * 8;
	tdivz8stepu = d_tdivzstepu * 8;
	zi8stepu = d_zistepu * 8;

	do
	{
		pdest = (d_viewbuffer +
				(r_screenwidth * pspan->v) + pspan->u);

		count = pspan->count;

	// calculate the initial s/z, t/z, 1/z, s, and t and clamp
		du = (float)pspan->u;
		dv = (float)pspan->v;

		sdivz = d_sdivzorigin + dv*d_sdivzstepv + du*d_sdivzstepu;
		tdivz = d_tdivzorigin + dv*d_tdivzstepv + du*d_tdivzstepu;
		zi = d_ziorigin + dv*d_zistepv + du*d_zistepu;
		z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

		s = (int)(sdivz * z) + sadjust;
		if (s > bbextents)
			s = bbextents;
		else if (s < 0)
			s = 0;

		t = (int)(tdivz * z) + tadjust;
		if (t > bbextentt)
			t = bbextentt;
		else if (t < 0)
			t = 0;

		do
		{
		// calculate s and t at the far end of the span
			if (count >= 8)
				spancount = 8;
			else
				spancount = count;

			count -= spancount;

			if (count)
			{
			// calculate s/z, t/z, zi->fixed s and t at far end of span,
			// calculate s and t steps across span by shifting
				sdivz += sdivz8stepu;
				tdivz += tdivz8stepu;
				zi += zi8stepu;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 8)
					snext = 8;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 8)
					tnext = 8;	// guard against round-off error on <0 steps

				sstep = (snext - s) >> 3;
				tstep = (tnext - t) >> 3;
			}
			else
			{
			  // calculate s/z, t/z, zi->fixed s and t at last pixel in span (so
			  // can't step off polygon), clamp, calculate s and t steps across
			  // span by division, biasing steps low so we don't run off the
			  // texture
				spancountminus1 = (float)(spancount - 1);
				sdivz += d_sdivzstepu * spancountminus1;
				tdivz += d_tdivzstepu * spancountminus1;
				zi += d_zistepu * spancountminus1;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point
				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 8)
					snext = 8;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 8)
					tnext = 8;	// guard against round-off error on <0 steps

				if (spancount > 1)
				{
					sstep = (snext - s) / (spancount - 1);
					tstep = (tnext - t) / (spancount - 1);
				}
			  }


			// Drawing phrase
				if (!SW_TEXFILT)
				{
					do
					{
						*pdest++ = *(pbase + (s >> 16) + (t >> 16) * cachewidth);
						s += sstep;
						t += tstep;
					} while (--spancount > 0);
				}
				else
				{
					do
					{
						int idiths = s;
						int iditht = t;

						int X = (pspan->u + spancount) & 1;
						int Y = (pspan->v)&1;

						//Using the kernel
						idiths += kernel[X][Y][0];
						iditht += kernel[X][Y][1];

						idiths = idiths >> 16;
						idiths = idiths ? idiths -1 : idiths;


						iditht = iditht >> 16;
						iditht = iditht ? iditht -1 : iditht;


						*pdest++ = *(pbase + idiths + iditht * cachewidth);
						s += sstep;
						t += tstep;
					} while (--spancount > 0);
				}


		} while (count > 0);

	} while ((pspan = pspan->pnext) != NULL);
}


/*
=============
D_DrawSpans16

  FIXME: actually make this subdivide by 16 instead of 8!!!
=============
*/
void D_AlphaSpans16 (espan_t *pspan)
{
	int				count, spancount;
	pixel_t	*pbase, *pdest;
	fixed16_t		s, t, snext, tnext, sstep, tstep;
	float			sdivz, tdivz, zi, z, du, dv, spancountminus1;
	float			sdivz8stepu, tdivz8stepu, zi8stepu;
	int izi, izistep;
	short *pz;

	sstep = 0;	// keep compiler happy
	tstep = 0;	// ditto

	pbase = cacheblock;

	sdivz8stepu = d_sdivzstepu * 8;
	tdivz8stepu = d_tdivzstepu * 8;
	zi8stepu = d_zistepu * 8;
	izistep = (int)(d_zistepu * 0x8000 * 0x10000);

	do
	{
		pdest = (d_viewbuffer +
				(r_screenwidth * pspan->v) + pspan->u);
		pz = d_pzbuffer + (d_zwidth * pspan->v) + pspan->u;

		count = pspan->count;

	// calculate the initial s/z, t/z, 1/z, s, and t and clamp
		du = (float)pspan->u;
		dv = (float)pspan->v;

		sdivz = d_sdivzorigin + dv*d_sdivzstepv + du*d_sdivzstepu;
		tdivz = d_tdivzorigin + dv*d_tdivzstepv + du*d_tdivzstepu;
		zi = d_ziorigin + dv*d_zistepv + du*d_zistepu;
		izi = (int)(zi * 0x8000 * 0x10000);
		z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

		s = (int)(sdivz * z) + sadjust;
		if (s > bbextents)
			s = bbextents;
		else if (s < 0)
			s = 0;

		t = (int)(tdivz * z) + tadjust;
		if (t > bbextentt)
			t = bbextentt;
		else if (t < 0)
			t = 0;

		do
		{
		// calculate s and t at the far end of the span
			if (count >= 8)
				spancount = 8;
			else
				spancount = count;

			count -= spancount;

			if (count)
			{
			// calculate s/z, t/z, zi->fixed s and t at far end of span,
			// calculate s and t steps across span by shifting
				sdivz += sdivz8stepu;
				tdivz += tdivz8stepu;
				zi += zi8stepu;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 8)
					snext = 8;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 8)
					tnext = 8;	// guard against round-off error on <0 steps

				sstep = (snext - s) >> 3;
				tstep = (tnext - t) >> 3;
			}
			else
			{
			  // calculate s/z, t/z, zi->fixed s and t at last pixel in span (so
			  // can't step off polygon), clamp, calculate s and t steps across
			  // span by division, biasing steps low so we don't run off the
			  // texture
				spancountminus1 = (float)(spancount - 1);
				sdivz += d_sdivzstepu * spancountminus1;
				tdivz += d_tdivzstepu * spancountminus1;
				zi += d_zistepu * spancountminus1;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point
				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 8)
					snext = 8;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 8)
					tnext = 8;	// guard against round-off error on <0 steps

				if (spancount > 1)
				{
					sstep = (snext - s) / (spancount - 1);
					tstep = (tnext - t) / (spancount - 1);
				}
			  }


			// Drawing phrase
				if (!SW_TEXFILT)
				{
					do
					{
						pixel_t btemp;

						btemp = *(pbase + (s >> 16) + (t >> 16) * cachewidth);
						if (btemp != TRANSPARENT_COLOR)
						{
							if (*pz <= (izi >> 16))
							{
								*pdest = btemp;
								*pz    = izi >> 16;
							}
						}
						pdest++;
						pz++;
						izi += izistep;
						s += sstep;
						t += tstep;
					} while (--spancount > 0);
				}
				else
				{
					do
					{
						if (*pz <= (izi >> 16))
						{
							int idiths = s;
							int iditht = t;

							int X = (pspan->u + spancount) & 1;
							int Y = (pspan->v)&1;
							pixel_t btemp;

							//Using the kernel
							idiths += kernel[X][Y][0];
							iditht += kernel[X][Y][1];

							idiths = idiths >> 16;
							idiths = idiths ? idiths -1 : idiths;


							iditht = iditht >> 16;
							iditht = iditht ? iditht -1 : iditht;


							btemp = *(pbase + idiths + iditht * cachewidth);
							if (btemp != TRANSPARENT_COLOR)
							{
								*pdest = btemp;
								*pz    = izi >> 16;
							}
						}
						pdest++;
						pz++;
						s += sstep;
						t += tstep;
					} while (--spancount > 0);
				}


		} while (count > 0);

	} while ((pspan = pspan->pnext) != NULL);
}



/*
=============
D_DrawSpans16

  FIXME: actually make this subdivide by 16 instead of 8!!!
=============
*/
void D_BlendSpans16( espan_t *pspan, int alpha )
{
	int				count, spancount;
	pixel_t	*pbase, *pdest;
	fixed16_t		s, t, snext, tnext, sstep, tstep;
	float			sdivz, tdivz, zi, z, du, dv, spancountminus1;
	float			sdivz8stepu, tdivz8stepu, zi8stepu;
	int izi, izistep;
	short *pz;

	if( alpha > 7 )
		alpha = 7;
	if( alpha == 0 )
		return;

	sstep = 0;	// keep compiler happy
	tstep = 0;	// ditto

	pbase = cacheblock;

	sdivz8stepu = d_sdivzstepu * 8;
	tdivz8stepu = d_tdivzstepu * 8;
	zi8stepu = d_zistepu * 8;
	izistep = (int)(d_zistepu * 0x8000 * 0x10000);

	do
	{
		pdest = (d_viewbuffer +
				(r_screenwidth * pspan->v) + pspan->u);
		pz = d_pzbuffer + (d_zwidth * pspan->v) + pspan->u;

		count = pspan->count;

	// calculate the initial s/z, t/z, 1/z, s, and t and clamp
		du = (float)pspan->u;
		dv = (float)pspan->v;

		sdivz = d_sdivzorigin + dv*d_sdivzstepv + du*d_sdivzstepu;
		tdivz = d_tdivzorigin + dv*d_tdivzstepv + du*d_tdivzstepu;
		zi = d_ziorigin + dv*d_zistepv + du*d_zistepu;
		izi = (int)(zi * 0x8000 * 0x10000);
		z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

		s = (int)(sdivz * z) + sadjust;
		if (s > bbextents)
			s = bbextents;
		else if (s < 0)
			s = 0;

		t = (int)(tdivz * z) + tadjust;
		if (t > bbextentt)
			t = bbextentt;
		else if (t < 0)
			t = 0;

		do
		{
		// calculate s and t at the far end of the span
			if (count >= 8)
				spancount = 8;
			else
				spancount = count;

			count -= spancount;

			if (count)
			{
			// calculate s/z, t/z, zi->fixed s and t at far end of span,
			// calculate s and t steps across span by shifting
				sdivz += sdivz8stepu;
				tdivz += tdivz8stepu;
				zi += zi8stepu;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 8)
					snext = 8;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 8)
					tnext = 8;	// guard against round-off error on <0 steps

				sstep = (snext - s) >> 3;
				tstep = (tnext - t) >> 3;
			}
			else
			{
			  // calculate s/z, t/z, zi->fixed s and t at last pixel in span (so
			  // can't step off polygon), clamp, calculate s and t steps across
			  // span by division, biasing steps low so we don't run off the
			  // texture
				spancountminus1 = (float)(spancount - 1);
				sdivz += d_sdivzstepu * spancountminus1;
				tdivz += d_tdivzstepu * spancountminus1;
				zi += d_zistepu * spancountminus1;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point
				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 8)
					snext = 8;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 8)
					tnext = 8;	// guard against round-off error on <0 steps

				if (spancount > 1)
				{
					sstep = (snext - s) / (spancount - 1);
					tstep = (tnext - t) / (spancount - 1);
				}
			  }


			// Drawing phrase
				if (!SW_TEXFILT)
				{
					do
					{
						if (*pz <= (izi >> 16))
						{
							pixel_t btemp;

							btemp = *(pbase + (s >> 16) + (t >> 16) * cachewidth);

							if( btemp != TRANSPARENT_COLOR )
							{
								if( alpha != 7 )
									btemp = BLEND_ALPHA( alpha, btemp, *pdest);
								*pdest = btemp;
							}
							//*pz    = izi >> 16;
						}
						pdest++;
						pz++;
						izi += izistep;
						s += sstep;
						t += tstep;
					} while (--spancount > 0);
				}
				else
				{
					do
					{
						int idiths = s;
						int iditht = t;

						int X = (pspan->u + spancount) & 1;
						int Y = (pspan->v)&1;
						if (*pz <= (izi >> 16))
						{
							pixel_t btemp;

							//Using the kernel
							idiths += kernel[X][Y][0];
							iditht += kernel[X][Y][1];

							idiths = idiths >> 16;
							idiths = idiths ? idiths -1 : idiths;


							iditht = iditht >> 16;
							iditht = iditht ? iditht -1 : iditht;

							btemp = *(pbase + idiths + iditht * cachewidth);

							if( btemp != TRANSPARENT_COLOR )
							{
								if( alpha != 7 )
									btemp = BLEND_ALPHA( alpha, btemp, *pdest);
								*pdest = btemp;
							}
							//*pz    = izi >> 16;
						}
						pdest++;
						pz++;
						izi += izistep;
						s += sstep;
						t += tstep;
					} while (--spancount > 0);
				}


		} while (count > 0);

	} while ((pspan = pspan->pnext) != NULL);
}



/*
=============
D_DrawSpans16

  FIXME: actually make this subdivide by 16 instead of 8!!!
=============
*/
void D_AddSpans16 (espan_t *pspan)
{
	int				count, spancount;
	pixel_t	*pbase, *pdest;
	fixed16_t		s, t, snext, tnext, sstep, tstep;
	float			sdivz, tdivz, zi, z, du, dv, spancountminus1;
	float			sdivz8stepu, tdivz8stepu, zi8stepu;
	int izi, izistep;
	short *pz;

	sstep = 0;	// keep compiler happy
	tstep = 0;	// ditto

	pbase = cacheblock;

	sdivz8stepu = d_sdivzstepu * 8;
	tdivz8stepu = d_tdivzstepu * 8;
	zi8stepu = d_zistepu * 8;
	izistep = (int)(d_zistepu * 0x8000 * 0x10000);

	do
	{
		pdest = (d_viewbuffer +
				(r_screenwidth * pspan->v) + pspan->u);
		pz = d_pzbuffer + (d_zwidth * pspan->v) + pspan->u;

		count = pspan->count;

	// calculate the initial s/z, t/z, 1/z, s, and t and clamp
		du = (float)pspan->u;
		dv = (float)pspan->v;

		sdivz = d_sdivzorigin + dv*d_sdivzstepv + du*d_sdivzstepu;
		tdivz = d_tdivzorigin + dv*d_tdivzstepv + du*d_tdivzstepu;
		zi = d_ziorigin + dv*d_zistepv + du*d_zistepu;
		izi = (int)(zi * 0x8000 * 0x10000);
		z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

		s = (int)(sdivz * z) + sadjust;
		if (s > bbextents)
			s = bbextents;
		else if (s < 0)
			s = 0;

		t = (int)(tdivz * z) + tadjust;
		if (t > bbextentt)
			t = bbextentt;
		else if (t < 0)
			t = 0;

		do
		{
		// calculate s and t at the far end of the span
			if (count >= 8)
				spancount = 8;
			else
				spancount = count;

			count -= spancount;

			if (count)
			{
			// calculate s/z, t/z, zi->fixed s and t at far end of span,
			// calculate s and t steps across span by shifting
				sdivz += sdivz8stepu;
				tdivz += tdivz8stepu;
				zi += zi8stepu;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point

				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 8)
					snext = 8;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 8)
					tnext = 8;	// guard against round-off error on <0 steps

				sstep = (snext - s) >> 3;
				tstep = (tnext - t) >> 3;
			}
			else
			{
			  // calculate s/z, t/z, zi->fixed s and t at last pixel in span (so
			  // can't step off polygon), clamp, calculate s and t steps across
			  // span by division, biasing steps low so we don't run off the
			  // texture
				spancountminus1 = (float)(spancount - 1);
				sdivz += d_sdivzstepu * spancountminus1;
				tdivz += d_tdivzstepu * spancountminus1;
				zi += d_zistepu * spancountminus1;
				z = (float)0x10000 / zi;	// prescale to 16.16 fixed-point
				snext = (int)(sdivz * z) + sadjust;
				if (snext > bbextents)
					snext = bbextents;
				else if (snext < 8)
					snext = 8;	// prevent round-off error on <0 steps from
								//  from causing overstepping & running off the
								//  edge of the texture

				tnext = (int)(tdivz * z) + tadjust;
				if (tnext > bbextentt)
					tnext = bbextentt;
				else if (tnext < 8)
					tnext = 8;	// guard against round-off error on <0 steps

				if (spancount > 1)
				{
					sstep = (snext - s) / (spancount - 1);
					tstep = (tnext - t) / (spancount - 1);
				}
			  }


			// Drawing phrase
				if (!SW_TEXFILT)
				{
					do
					{
						if (*pz <= (izi >> 16))
						{
							pixel_t btemp;

							btemp = *(pbase + (s >> 16) + (t >> 16) * cachewidth);

							if( btemp != TRANSPARENT_COLOR )
							{
								btemp = BLEND_ADD( btemp, *pdest);
								*pdest = btemp;
							}
							//*pz    = izi >> 16;
						}
						pdest++;
						pz++;
						izi += izistep;
						s += sstep;
						t += tstep;
					} while (--spancount > 0);
				}
				else
				{
					do
					{
						int idiths = s;
						int iditht = t;

						int X = (pspan->u + spancount) & 1;
						int Y = (pspan->v)&1;
						if (*pz <= (izi >> 16))
						{
							pixel_t btemp;

							//Using the kernel
							idiths += kernel[X][Y][0];
							iditht += kernel[X][Y][1];

							idiths = idiths >> 16;
							idiths = idiths ? idiths -1 : idiths;


							iditht = iditht >> 16;
							iditht = iditht ? iditht -1 : iditht;

							btemp = *(pbase + idiths + iditht * cachewidth);

							if( btemp != TRANSPARENT_COLOR )
							{
								btemp = BLEND_ADD( btemp, *pdest);
								*pdest = btemp;
							}
							//*pz    = izi >> 16;
						}
						pdest++;
						pz++;
						izi += izistep;
						s += sstep;
						t += tstep;
					} while (--spancount > 0);
				}


		} while (count > 0);

	} while ((pspan = pspan->pnext) != NULL);
}

#endif


#if	!id386

/*
=============
D_DrawZSpans
=============
*/
void D_DrawZSpans (espan_t *pspan)
{
	int				count, doublecount, izistep;
	int				izi;
	short			*pdest;
	unsigned		ltemp;
	float			zi;
	float			du, dv;

// FIXME: check for clamping/range problems
// we count on FP exceptions being turned off to avoid range problems
	izistep = (int)(d_zistepu * 0x8000 * 0x10000);

	do
	{
		pdest = d_pzbuffer + (d_zwidth * pspan->v) + pspan->u;

		count = pspan->count;

	// calculate the initial 1/z
		du = (float)pspan->u;
		dv = (float)pspan->v;

		zi = d_ziorigin + dv*d_zistepv + du*d_zistepu;
	// we count on FP exceptions being turned off to avoid range problems
		izi = (int)(zi * 0x8000 * 0x10000);

		if ((uintptr_t)pdest & 0x02)
		{
			*pdest++ = (short)(izi >> 16);
			izi += izistep;
			count--;
		}

		if ((doublecount = count >> 1) > 0)
		{
			do
			{
				ltemp = izi >> 16;
				izi += izistep;
				ltemp |= izi & 0xFFFF0000;
				izi += izistep;
				*(int *)pdest = ltemp;
				pdest += 2;
			} while (--doublecount > 0);
		}

		if (count & 1)
			*pdest = (short)(izi >> 16);

	} while ((pspan = pspan->pnext) != NULL);
}

#endif