quakeforge/libs/video/renderer/sw/d_polyse.c

/*
	d_polyse.c

	routines for drawing sets of polygons sharing the same texture
	(used for Alias models)

	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:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

*/
static const char rcsid[] = 
	"$Id$";

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include "QF/render.h"

#include "d_local.h"
#include "r_local.h"

// TODO: put in span spilling to shrink list size
// !!! if this is changed, it must be changed in d_polysa.s too !!!
#define DPS_MAXSPANS		MAXHEIGHT+1		// +1 for spanpackage marking end

// !!! if this is changed, it must be changed in asm_draw.h too !!!
typedef struct spanpackage_s {
	void       *pdest;
	short      *pz;
	int         count;
	byte       *ptex;
	int         sfrac, tfrac, light, zi;
} spanpackage_t;

typedef struct {
	int         isflattop;
	int         numleftedges;
	int        *pleftedgevert0;
	int        *pleftedgevert1;
	int        *pleftedgevert2;
	int         numrightedges;
	int        *prightedgevert0;
	int        *prightedgevert1;
	int        *prightedgevert2;
} edgetable;

int         r_p0[6], r_p1[6], r_p2[6];

byte       *d_pcolormap;

int         d_aflatcolor;
int         d_xdenom;

edgetable  *pedgetable;

edgetable   edgetables[12] = {
	{0, 1, r_p0, r_p2, NULL, 2, r_p0, r_p1, r_p2},
	{0, 2, r_p1, r_p0, r_p2, 1, r_p1, r_p2, NULL},
	{1, 1, r_p0, r_p2, NULL, 1, r_p1, r_p2, NULL},
	{0, 1, r_p1, r_p0, NULL, 2, r_p1, r_p2, r_p0},
	{0, 2, r_p0, r_p2, r_p1, 1, r_p0, r_p1, NULL},
	{0, 1, r_p2, r_p1, NULL, 1, r_p2, r_p0, NULL},
	{0, 1, r_p2, r_p1, NULL, 2, r_p2, r_p0, r_p1},
	{0, 2, r_p2, r_p1, r_p0, 1, r_p2, r_p0, NULL},
	{0, 1, r_p1, r_p0, NULL, 1, r_p1, r_p2, NULL},
	{1, 1, r_p2, r_p1, NULL, 1, r_p0, r_p1, NULL},
	{1, 1, r_p1, r_p0, NULL, 1, r_p2, r_p0, NULL},
	{0, 1, r_p0, r_p2, NULL, 1, r_p0, r_p1, NULL},
};

// FIXME: some of these can become statics
int         a_sstepxfrac, a_tstepxfrac, a_ststepxwhole;
int         r_sstepx, r_tstepx, r_lstepx, r_lstepy, r_sstepy, r_tstepy;
int         r_zistepx, r_zistepy;
int         d_aspancount, d_countextrastep;

spanpackage_t *a_spans;
spanpackage_t *d_pedgespanpackage;
static int  ystart;
byte       *d_pdest, *d_ptex;
short      *d_pz;
int         d_sfrac, d_tfrac, d_light, d_zi;
int         d_ptexextrastep, d_sfracextrastep;
int         d_tfracextrastep, d_lightextrastep, d_pdestextrastep;
int         d_lightbasestep, d_pdestbasestep, d_ptexbasestep;
int         d_sfracbasestep, d_tfracbasestep;
int         d_ziextrastep, d_zibasestep;
int         d_pzextrastep, d_pzbasestep;

typedef struct {
	int         quotient;
	int         remainder;
} adivtab_t;

static adivtab_t adivtab[32 * 32] = {
#include "adivtab.h"
};

byte       *skintable[MAX_LBM_HEIGHT];
int         skinwidth;
byte       *skinstart;

#ifdef PIC
#undef USE_INTEL_ASM //XXX asm pic hack
#endif


void
D_PolysetSetEdgeTable (void)
{
	int         edgetableindex;

	// assume the vertices are already in top to bottom order
	edgetableindex = 0;

	// determine which edges are right & left, and the order in which
	// to rasterize them
	if (r_p0[1] >= r_p1[1]) {
		if (r_p0[1] == r_p1[1]) {
			if (r_p0[1] < r_p2[1])
				pedgetable = &edgetables[2];
			else
				pedgetable = &edgetables[5];

			return;
		} else {
			edgetableindex = 1;
		}
	}

	if (r_p0[1] == r_p2[1]) {
		if (edgetableindex)
			pedgetable = &edgetables[8];
		else
			pedgetable = &edgetables[9];

		return;
	} else if (r_p1[1] == r_p2[1]) {
		if (edgetableindex)
			pedgetable = &edgetables[10];
		else
			pedgetable = &edgetables[11];

		return;
	}

	if (r_p0[1] > r_p2[1])
		edgetableindex += 2;

	if (r_p1[1] > r_p2[1])
		edgetableindex += 4;

	pedgetable = &edgetables[edgetableindex];
}

#ifndef USE_INTEL_ASM

void
D_PolysetRecursiveTriangle (int *lp1, int *lp2, int *lp3)
{
	int        *temp;
	int         d;
	int         new[6];
	int         z;
	short      *zbuf;

	d = lp2[0] - lp1[0];
	if (d < -1 || d > 1)
		goto split;
	d = lp2[1] - lp1[1];
	if (d < -1 || d > 1)
		goto split;

	d = lp3[0] - lp2[0];
	if (d < -1 || d > 1)
		goto split2;
	d = lp3[1] - lp2[1];
	if (d < -1 || d > 1)
		goto split2;

	d = lp1[0] - lp3[0];
	if (d < -1 || d > 1)
		goto split3;
	d = lp1[1] - lp3[1];
	if (d < -1 || d > 1) {
	  split3:
		temp = lp1;
		lp1 = lp3;
		lp3 = lp2;
		lp2 = temp;

		goto split;
	}

	return;								// entire tri is filled

  split2:
	temp = lp1;
	lp1 = lp2;
	lp2 = lp3;
	lp3 = temp;

  split:
	// split this edge
	new[0] = (lp1[0] + lp2[0]) >> 1;
	new[1] = (lp1[1] + lp2[1]) >> 1;
	new[2] = (lp1[2] + lp2[2]) >> 1;
	new[3] = (lp1[3] + lp2[3]) >> 1;
	new[5] = (lp1[5] + lp2[5]) >> 1;

	// draw the point if splitting a leading edge
	if (lp2[1] > lp1[1])
		goto nodraw;
	if ((lp2[1] == lp1[1]) && (lp2[0] < lp1[0]))
		goto nodraw;


	z = new[5] >> 16;
	zbuf = zspantable[new[1]] + new[0];
	if (z >= *zbuf) {
		int         pix;

		*zbuf = z;
		pix = d_pcolormap[skintable[new[3] >> 16][new[2] >> 16]];
		d_viewbuffer[d_scantable[new[1]] + new[0]] = pix;
	}

  nodraw:
	// recursively continue
	D_PolysetRecursiveTriangle (lp3, lp1, new);
	D_PolysetRecursiveTriangle (lp3, new, lp2);
}


void
D_DrawSubdiv (void)
{
	mtriangle_t *ptri;
	finalvert_t *pfv, *index0, *index1, *index2;
	int         i;
	int         lnumtriangles;

	pfv = r_affinetridesc.pfinalverts;
	ptri = r_affinetridesc.ptriangles;
	lnumtriangles = r_affinetridesc.numtriangles;

	for (i = 0; i < lnumtriangles; i++) {
		index0 = pfv + ptri[i].vertindex[0];
		index1 = pfv + ptri[i].vertindex[1];
		index2 = pfv + ptri[i].vertindex[2];

		if (((index0->v[1] - index1->v[1]) *
			 (index0->v[0] - index2->v[0]) -
			 (index0->v[0] - index1->v[0]) *
			 (index0->v[1] - index2->v[1])) >= 0) {
			continue;
		}

		d_pcolormap = &((byte *) acolormap)[index0->v[4] & 0xFF00];

		if (ptri[i].facesfront) {
			D_PolysetRecursiveTriangle (index0->v, index1->v, index2->v);
		} else {
			int         s0, s1, s2;

			s0 = index0->v[2];
			s1 = index1->v[2];
			s2 = index2->v[2];

			if (index0->flags & ALIAS_ONSEAM)
				index0->v[2] += r_affinetridesc.seamfixupX16;
			if (index1->flags & ALIAS_ONSEAM)
				index1->v[2] += r_affinetridesc.seamfixupX16;
			if (index2->flags & ALIAS_ONSEAM)
				index2->v[2] += r_affinetridesc.seamfixupX16;

			D_PolysetRecursiveTriangle (index0->v, index1->v, index2->v);

			index0->v[2] = s0;
			index1->v[2] = s1;
			index2->v[2] = s2;
		}
	}
}


void
D_DrawNonSubdiv (void)
{
	mtriangle_t *ptri;
	finalvert_t *pfv, *index0, *index1, *index2;
	int         i;
	int         lnumtriangles;

	pfv = r_affinetridesc.pfinalverts;
	ptri = r_affinetridesc.ptriangles;
	lnumtriangles = r_affinetridesc.numtriangles;

	for (i = 0; i < lnumtriangles; i++, ptri++) {
		index0 = pfv + ptri->vertindex[0];
		index1 = pfv + ptri->vertindex[1];
		index2 = pfv + ptri->vertindex[2];

		d_xdenom =
			(index0->v[1] - index1->v[1]) * (index0->v[0] - index2->v[0]) -
			(index0->v[0] - index1->v[0]) * (index0->v[1] - index2->v[1]);

		if (d_xdenom >= 0)
			continue;

		r_p0[0] = index0->v[0];			// u
		r_p0[1] = index0->v[1];			// v
		r_p0[2] = index0->v[2];			// s
		r_p0[3] = index0->v[3];			// t
		r_p0[4] = index0->v[4];			// light
		r_p0[5] = index0->v[5];			// iz

		r_p1[0] = index1->v[0];
		r_p1[1] = index1->v[1];
		r_p1[2] = index1->v[2];
		r_p1[3] = index1->v[3];
		r_p1[4] = index1->v[4];
		r_p1[5] = index1->v[5];

		r_p2[0] = index2->v[0];
		r_p2[1] = index2->v[1];
		r_p2[2] = index2->v[2];
		r_p2[3] = index2->v[3];
		r_p2[4] = index2->v[4];
		r_p2[5] = index2->v[5];

		if (!ptri->facesfront) {
			if (index0->flags & ALIAS_ONSEAM)
				r_p0[2] += r_affinetridesc.seamfixupX16;
			if (index1->flags & ALIAS_ONSEAM)
				r_p1[2] += r_affinetridesc.seamfixupX16;
			if (index2->flags & ALIAS_ONSEAM)
				r_p2[2] += r_affinetridesc.seamfixupX16;
		}

		D_PolysetSetEdgeTable ();
		D_RasterizeAliasPolySmooth ();
	}
}


void
D_PolysetDraw (void)
{
	spanpackage_t spans[DPS_MAXSPANS + 1 +
						((CACHE_SIZE - 1) / sizeof (spanpackage_t)) + 1];

	// one extra because of cache line pretouching

	a_spans = (spanpackage_t *)
		(((long) &spans[0] + CACHE_SIZE - 1) & ~(CACHE_SIZE - 1));

	if (r_affinetridesc.drawtype) {
		D_DrawSubdiv ();
	} else {
		D_DrawNonSubdiv ();
	}
}


void
D_PolysetDrawFinalVerts (finalvert_t *fv, int numverts)
{
	int         i, z;
	short      *zbuf;

	for (i = 0; i < numverts; i++, fv++) {
		// valid triangle coordinates for filling can include the bottom and
		// right clip edges, due to the fill rule; these shouldn't be drawn
		if ((fv->v[0] < r_refdef.vrectright) &&
			(fv->v[1] < r_refdef.vrectbottom)) {
			z = fv->v[5] >> 16;
			zbuf = zspantable[fv->v[1]] + fv->v[0];
			if (z >= *zbuf) {
				int         pix;

				*zbuf = z;
				pix = skintable[fv->v[3] >> 16][fv->v[2] >> 16];
				pix = ((byte *) acolormap)[pix + (fv->v[4] & 0xFF00)];
				d_viewbuffer[d_scantable[fv->v[1]] + fv->v[0]] = pix;
			}
		}
	}
}

#endif // !USE_INTEL_ASM


void
D_PolysetUpdateTables (void)
{
	int         i;
	byte       *s;

	if (r_affinetridesc.skinwidth != skinwidth ||
		r_affinetridesc.pskin != skinstart) {
		skinwidth = r_affinetridesc.skinwidth;
		skinstart = r_affinetridesc.pskin;
		s = skinstart;
		for (i = 0; i < MAX_LBM_HEIGHT; i++, s += skinwidth)
			skintable[i] = s;
	}
}


#ifndef USE_INTEL_ASM
void
D_PolysetScanLeftEdge (int height)
{

	do {
		d_pedgespanpackage->pdest = d_pdest;
		d_pedgespanpackage->pz = d_pz;
		d_pedgespanpackage->count = d_aspancount;
		d_pedgespanpackage->ptex = d_ptex;

		d_pedgespanpackage->sfrac = d_sfrac;
		d_pedgespanpackage->tfrac = d_tfrac;

		// FIXME: need to clamp l, s, t, at both ends?
		d_pedgespanpackage->light = d_light;
		d_pedgespanpackage->zi = d_zi;

		d_pedgespanpackage++;

		errorterm += erroradjustup;
		if (errorterm >= 0) {
			d_pdest += d_pdestextrastep;
			d_pz += d_pzextrastep;
			d_aspancount += d_countextrastep;
			d_ptex += d_ptexextrastep;
			d_sfrac += d_sfracextrastep;
			d_ptex += d_sfrac >> 16;

			d_sfrac &= 0xFFFF;
			d_tfrac += d_tfracextrastep;
			if (d_tfrac & 0x10000) {
				d_ptex += r_affinetridesc.skinwidth;
				d_tfrac &= 0xFFFF;
			}
			d_light += d_lightextrastep;
			d_zi += d_ziextrastep;
			errorterm -= erroradjustdown;
		} else {
			d_pdest += d_pdestbasestep;
			d_pz += d_pzbasestep;
			d_aspancount += ubasestep;
			d_ptex += d_ptexbasestep;
			d_sfrac += d_sfracbasestep;
			d_ptex += d_sfrac >> 16;
			d_sfrac &= 0xFFFF;
			d_tfrac += d_tfracbasestep;
			if (d_tfrac & 0x10000) {
				d_ptex += r_affinetridesc.skinwidth;
				d_tfrac &= 0xFFFF;
			}
			d_light += d_lightbasestep;
			d_zi += d_zibasestep;
		}
	} while (--height);
}
#endif // !USE_INTEL_ASM


void
D_PolysetSetUpForLineScan (fixed8_t startvertu, fixed8_t startvertv,
						   fixed8_t endvertu, fixed8_t endvertv)
{
	double      dm, dn;
	int         tm, tn;
	adivtab_t  *ptemp;

	// TODO: implement x86 version

	errorterm = -1;

	tm = endvertu - startvertu;
	tn = endvertv - startvertv;

	if (((tm <= 16) && (tm >= -15)) && ((tn <= 16) && (tn >= -15))) {
		ptemp = &adivtab[((tm + 15) << 5) + (tn + 15)];
		ubasestep = ptemp->quotient;
		erroradjustup = ptemp->remainder;
		erroradjustdown = tn;
	} else {
		dm = (double) tm;
		dn = (double) tn;

		FloorDivMod (dm, dn, &ubasestep, &erroradjustup);

		erroradjustdown = dn;
	}
}


#ifndef USE_INTEL_ASM
void
D_PolysetCalcGradients (int skinwidth)
{
	float       xstepdenominv, ystepdenominv, t0, t1;
	float       p01_minus_p21, p11_minus_p21, p00_minus_p20, p10_minus_p20;

	p00_minus_p20 = r_p0[0] - r_p2[0];
	p01_minus_p21 = r_p0[1] - r_p2[1];
	p10_minus_p20 = r_p1[0] - r_p2[0];
	p11_minus_p21 = r_p1[1] - r_p2[1];

	xstepdenominv = 1.0 / (float) d_xdenom;

	ystepdenominv = -xstepdenominv;

	// ceil () for light so positive steps are exaggerated, negative steps
	// diminished,  pushing us away from underflow toward overflow. Underflow
	// is very visible, overflow is very unlikely, because of ambient lighting
	t0 = r_p0[4] - r_p2[4];
	t1 = r_p1[4] - r_p2[4];
	r_lstepx = (int)
		ceil ((t1 * p01_minus_p21 - t0 * p11_minus_p21) * xstepdenominv);
	r_lstepy = (int)
		ceil ((t1 * p00_minus_p20 - t0 * p10_minus_p20) * ystepdenominv);

	t0 = r_p0[2] - r_p2[2];
	t1 = r_p1[2] - r_p2[2];
	r_sstepx = (int) ((t1 * p01_minus_p21 - t0 * p11_minus_p21) *
					  xstepdenominv);
	r_sstepy = (int) ((t1 * p00_minus_p20 - t0 * p10_minus_p20) *
					  ystepdenominv);

	t0 = r_p0[3] - r_p2[3];
	t1 = r_p1[3] - r_p2[3];
	r_tstepx = (int) ((t1 * p01_minus_p21 - t0 * p11_minus_p21) *
					  xstepdenominv);
	r_tstepy = (int) ((t1 * p00_minus_p20 - t0 * p10_minus_p20) *
					  ystepdenominv);

	t0 = r_p0[5] - r_p2[5];
	t1 = r_p1[5] - r_p2[5];
	r_zistepx = (int) ((t1 * p01_minus_p21 - t0 * p11_minus_p21) *
					   xstepdenominv);
	r_zistepy = (int) ((t1 * p00_minus_p20 - t0 * p10_minus_p20) *
					   ystepdenominv);

#ifdef USE_INTEL_ASM
	a_sstepxfrac = r_sstepx << 16;
	a_tstepxfrac = r_tstepx << 16;
#else
	a_sstepxfrac = r_sstepx & 0xFFFF;
	a_tstepxfrac = r_tstepx & 0xFFFF;
#endif

	a_ststepxwhole = skinwidth * (r_tstepx >> 16) + (r_sstepx >> 16);
}
#endif // !USE_INTEL_ASM


byte        gelmap[256];

void
InitGel (byte * palette)
{
	int         i;
	int         r;

	for (i = 0; i < 256; i++) {
//      r = (palette[i*3]>>4);
		r =
			(palette[i * 3] + palette[i * 3 + 1] +
			 palette[i * 3 + 2]) / (16 * 3);
		gelmap[i] = /* 64 */ 0 + r;
	}
}


#ifndef USE_INTEL_ASM
void
D_PolysetDrawSpans8 (spanpackage_t * pspanpackage)
{
	int         lcount;
	byte       *lpdest;
	byte       *lptex;
	int         lsfrac, ltfrac;
	int         llight;
	int         lzi;
	short      *lpz;

	do {
		lcount = d_aspancount - pspanpackage->count;

		errorterm += erroradjustup;
		if (errorterm >= 0) {
			d_aspancount += d_countextrastep;
			errorterm -= erroradjustdown;
		} else {
			d_aspancount += ubasestep;
		}

		if (lcount) {
			lpdest = pspanpackage->pdest;
			lptex = pspanpackage->ptex;
			lpz = pspanpackage->pz;
			lsfrac = pspanpackage->sfrac;
			ltfrac = pspanpackage->tfrac;
			llight = pspanpackage->light;
			lzi = pspanpackage->zi;

			do {
				if ((lzi >> 16) >= *lpz) {
					*lpdest = ((byte *) acolormap)[*lptex + (llight & 0xFF00)];
// gel mapping                  *lpdest = gelmap[*lpdest];
					*lpz = lzi >> 16;
				}
				lpdest++;
				lzi += r_zistepx;
				lpz++;
				llight += r_lstepx;
				lptex += a_ststepxwhole;
				lsfrac += a_sstepxfrac;
				lptex += lsfrac >> 16;
				lsfrac &= 0xFFFF;
				ltfrac += a_tstepxfrac;
				if (ltfrac & 0x10000) {
					lptex += r_affinetridesc.skinwidth;
					ltfrac &= 0xFFFF;
				}
			} while (--lcount);
		}

		pspanpackage++;
	} while (pspanpackage->count != -999999);
}
#endif // !USE_INTEL_ASM


void
D_PolysetFillSpans8 (spanpackage_t * pspanpackage)
{
	int         color;

// FIXME: do z buffering

	color = d_aflatcolor++;

	while (1) {
		int         lcount;
		byte       *lpdest;

		lcount = pspanpackage->count;

		if (lcount == -1)
			return;

		if (lcount) {
			lpdest = pspanpackage->pdest;

			do {
				*lpdest++ = color;
			} while (--lcount);
		}

		pspanpackage++;
	}
}


void
D_RasterizeAliasPolySmooth (void)
{
	int         initialleftheight, initialrightheight;
	int        *plefttop, *prighttop, *pleftbottom, *prightbottom;
	int         working_lstepx, originalcount;

	plefttop = pedgetable->pleftedgevert0;
	prighttop = pedgetable->prightedgevert0;

	pleftbottom = pedgetable->pleftedgevert1;
	prightbottom = pedgetable->prightedgevert1;

	initialleftheight = pleftbottom[1] - plefttop[1];
	initialrightheight = prightbottom[1] - prighttop[1];

	// set the s, t, and light gradients, which are consistent across the
	// triangle, because being a triangle, things are affine
	D_PolysetCalcGradients (r_affinetridesc.skinwidth);

// rasterize the polygon

	// scan out the top (and possibly only) part of the left edge
	D_PolysetSetUpForLineScan (plefttop[0], plefttop[1],
							   pleftbottom[0], pleftbottom[1]);

	d_pedgespanpackage = a_spans;

	ystart = plefttop[1];
	d_aspancount = plefttop[0] - prighttop[0];

	d_ptex = (byte *) r_affinetridesc.pskin + (plefttop[2] >> 16) +
		(plefttop[3] >> 16) * r_affinetridesc.skinwidth;
#ifdef USE_INTEL_ASM
	d_sfrac = (plefttop[2] & 0xFFFF) << 16;
	d_tfrac = (plefttop[3] & 0xFFFF) << 16;
	d_pzbasestep = (d_zwidth + ubasestep) << 1;
	d_pzextrastep = d_pzbasestep + 2;
#else
	d_sfrac = plefttop[2] & 0xFFFF;
	d_tfrac = plefttop[3] & 0xFFFF;
	d_pzbasestep = d_zwidth + ubasestep;
	d_pzextrastep = d_pzbasestep + 1;
#endif
	d_light = plefttop[4];
	d_zi = plefttop[5];

	d_pdestbasestep = screenwidth + ubasestep;
	d_pdestextrastep = d_pdestbasestep + 1;
	d_pdest = (byte *) d_viewbuffer + ystart * screenwidth + plefttop[0];
	d_pz = d_pzbuffer + ystart * d_zwidth + plefttop[0];

// TODO: can reuse partial expressions here

	// for negative steps in x along left edge, bias toward overflow rather
	// than underflow (sort of turning the floor () we did in the gradient
	// calcs into ceil (), but plus a little bit)
	if (ubasestep < 0)
		working_lstepx = r_lstepx - 1;
	else
		working_lstepx = r_lstepx;

	d_countextrastep = ubasestep + 1;
	d_ptexbasestep = ((r_sstepy + r_sstepx * ubasestep) >> 16) +
		((r_tstepy + r_tstepx * ubasestep) >> 16) * r_affinetridesc.skinwidth;
#ifdef USE_INTEL_ASM
	d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) << 16;
	d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) << 16;
#else
	d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) & 0xFFFF;
	d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) & 0xFFFF;
#endif
	d_lightbasestep = r_lstepy + working_lstepx * ubasestep;
	d_zibasestep = r_zistepy + r_zistepx * ubasestep;

	d_ptexextrastep = ((r_sstepy + r_sstepx * d_countextrastep) >> 16) +
		((r_tstepy + r_tstepx * d_countextrastep) >> 16) *
		r_affinetridesc.skinwidth;
#ifdef USE_INTEL_ASM
	d_sfracextrastep = (r_sstepy + r_sstepx * d_countextrastep) << 16;
	d_tfracextrastep = (r_tstepy + r_tstepx * d_countextrastep) << 16;
#else
	d_sfracextrastep = (r_sstepy + r_sstepx * d_countextrastep) & 0xFFFF;
	d_tfracextrastep = (r_tstepy + r_tstepx * d_countextrastep) & 0xFFFF;
#endif
	d_lightextrastep = d_lightbasestep + working_lstepx;
	d_ziextrastep = d_zibasestep + r_zistepx;

	D_PolysetScanLeftEdge (initialleftheight);

	// scan out the bottom part of the left edge, if it exists
	if (pedgetable->numleftedges == 2) {
		int         height;

		plefttop = pleftbottom;
		pleftbottom = pedgetable->pleftedgevert2;

		D_PolysetSetUpForLineScan (plefttop[0], plefttop[1],
								   pleftbottom[0], pleftbottom[1]);

		height = pleftbottom[1] - plefttop[1];

// TODO: make this a function; modularize this function in general

		ystart = plefttop[1];
		d_aspancount = plefttop[0] - prighttop[0];
		d_ptex = (byte *) r_affinetridesc.pskin + (plefttop[2] >> 16) +
			(plefttop[3] >> 16) * r_affinetridesc.skinwidth;
		d_sfrac = 0;
		d_tfrac = 0;
		d_light = plefttop[4];
		d_zi = plefttop[5];

		d_pdestbasestep = screenwidth + ubasestep;
		d_pdestextrastep = d_pdestbasestep + 1;
		d_pdest = (byte *) d_viewbuffer + ystart * screenwidth + plefttop[0];
#ifdef USE_INTEL_ASM
		d_pzbasestep = (d_zwidth + ubasestep) << 1;
		d_pzextrastep = d_pzbasestep + 2;
#else
		d_pzbasestep = d_zwidth + ubasestep;
		d_pzextrastep = d_pzbasestep + 1;
#endif
		d_pz = d_pzbuffer + ystart * d_zwidth + plefttop[0];

		if (ubasestep < 0)
			working_lstepx = r_lstepx - 1;
		else
			working_lstepx = r_lstepx;

		d_countextrastep = ubasestep + 1;
		d_ptexbasestep = ((r_sstepy + r_sstepx * ubasestep) >> 16) +
			((r_tstepy + r_tstepx * ubasestep) >> 16) *
			r_affinetridesc.skinwidth;
#ifdef USE_INTEL_ASM
		d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) << 16;
		d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) << 16;
#else
		d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) & 0xFFFF;
		d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) & 0xFFFF;
#endif
		d_lightbasestep = r_lstepy + working_lstepx * ubasestep;
		d_zibasestep = r_zistepy + r_zistepx * ubasestep;

		d_ptexextrastep = ((r_sstepy + r_sstepx * d_countextrastep) >> 16) +
			((r_tstepy + r_tstepx * d_countextrastep) >> 16) *
			r_affinetridesc.skinwidth;
#ifdef USE_INTEL_ASM
		d_sfracextrastep =
			((r_sstepy + r_sstepx * d_countextrastep) & 0xFFFF) << 16;
		d_tfracextrastep =
			((r_tstepy + r_tstepx * d_countextrastep) & 0xFFFF) << 16;
#else
		d_sfracextrastep = (r_sstepy + r_sstepx * d_countextrastep) & 0xFFFF;
		d_tfracextrastep = (r_tstepy + r_tstepx * d_countextrastep) & 0xFFFF;
#endif
		d_lightextrastep = d_lightbasestep + working_lstepx;
		d_ziextrastep = d_zibasestep + r_zistepx;

		D_PolysetScanLeftEdge (height);
	}
	// scan out the top (and possibly only) part of the right edge, updating
	// the count field
	d_pedgespanpackage = a_spans;

	D_PolysetSetUpForLineScan (prighttop[0], prighttop[1],
							   prightbottom[0], prightbottom[1]);
	d_aspancount = 0;
	d_countextrastep = ubasestep + 1;
	originalcount = a_spans[initialrightheight].count;
	a_spans[initialrightheight].count = -999999;	// mark end of the
													// spanpackages
	D_PolysetDrawSpans8 (a_spans);

	// scan out the bottom part of the right edge, if it exists
	if (pedgetable->numrightedges == 2) {
		int         height;
		spanpackage_t *pstart;

		pstart = a_spans + initialrightheight;
		pstart->count = originalcount;

		d_aspancount = prightbottom[0] - prighttop[0];

		prighttop = prightbottom;
		prightbottom = pedgetable->prightedgevert2;

		height = prightbottom[1] - prighttop[1];

		D_PolysetSetUpForLineScan (prighttop[0], prighttop[1],
								   prightbottom[0], prightbottom[1]);

		d_countextrastep = ubasestep + 1;
		a_spans[initialrightheight + height].count = -999999;
		// mark end of the spanpackages
		D_PolysetDrawSpans8 (pstart);
	}
}


#if 0

void
D_PolysetRecursiveDrawLine (int *lp1, int *lp2)
{
	int         d;
	int         new[6];
	int         ofs;

	d = lp2[0] - lp1[0];
	if (d < -1 || d > 1)
		goto split;
	d = lp2[1] - lp1[1];
	if (d < -1 || d > 1)
		goto split;

	return;								// line is completed

  split:
	// split this edge
	new[0] = (lp1[0] + lp2[0]) >> 1;
	new[1] = (lp1[1] + lp2[1]) >> 1;
	new[5] = (lp1[5] + lp2[5]) >> 1;
	new[2] = (lp1[2] + lp2[2]) >> 1;
	new[3] = (lp1[3] + lp2[3]) >> 1;
	new[4] = (lp1[4] + lp2[4]) >> 1;

	// draw the point
	ofs = d_scantable[new[1]] + new[0];
	if (new[5] > d_pzbuffer[ofs]) {
		int         pix;

		d_pzbuffer[ofs] = new[5];
		pix = skintable[new[3] >> 16][new[2] >> 16];
//		pix = ((byte *)acolormap)[pix + (new[4] & 0xFF00)];
		d_viewbuffer[ofs] = pix;
	}
	// recursively continue
	D_PolysetRecursiveDrawLine (lp1, new);
	D_PolysetRecursiveDrawLine (new, lp2);
}


void
D_PolysetRecursiveTriangle2 (int *lp1, int *lp2, int *lp3)
{
	int         d;
	int         new[4];

	d = lp2[0] - lp1[0];
	if (d < -1 || d > 1)
		goto split;
	d = lp2[1] - lp1[1];
	if (d < -1 || d > 1)
		goto split;
	return;

  split:
	// split this edge
	new[0] = (lp1[0] + lp2[0]) >> 1;
	new[1] = (lp1[1] + lp2[1]) >> 1;
	new[5] = (lp1[5] + lp2[5]) >> 1;
	new[2] = (lp1[2] + lp2[2]) >> 1;
	new[3] = (lp1[3] + lp2[3]) >> 1;
	new[4] = (lp1[4] + lp2[4]) >> 1;

	D_PolysetRecursiveDrawLine (new, lp3);

	// recursively continue
	D_PolysetRecursiveTriangle (lp1, new, lp3);
	D_PolysetRecursiveTriangle (new, lp2, lp3);
}

#endif