quakeforge/libs/video/renderer/sw32/d_polyse.c

800 lines
20 KiB
C
Raw Normal View History

/*
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
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
static __attribute__ ((used)) const char rcsid[] =
"$Id$";
#include "QF/sys.h"
#include "d_local.h"
2001-08-29 01:28:03 +00:00
#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 !!!
2001-08-29 01:28:03 +00:00
#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 {
int 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;
2001-08-29 01:28:03 +00:00
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
2001-08-29 01:28:03 +00:00
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;
int d_pdest;
byte *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"
};
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];
}
static 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];
2001-08-29 01:28:03 +00:00
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));
D_DrawNonSubdiv ();
}
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);
}
static 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;
}
}
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);
// a_sstepxfrac = r_sstepx & 0xFFFF;
// a_tstepxfrac = r_tstepx & 0xFFFF;
// a_ststepxwhole = skinwidth * (r_tstepx >> 16) + (r_sstepx >> 16);
}
static void
D_PolysetDrawSpans (spanpackage_t * pspanpackage)
{
int i, j, texscantable[1024], *texscan;
// LordHavoc: compute skin row table
for (i = 0, j = -r_affinetridesc.skinheight * r_affinetridesc.skinwidth;
i < r_affinetridesc.skinheight*2;i++, j += r_affinetridesc.skinwidth)
texscantable[i] = j;
texscan = texscantable + r_affinetridesc.skinheight;
switch(r_pixbytes) {
case 1:
{
int lcount, count = 0;
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 = (byte *) d_viewbuffer + pspanpackage->pdest;
lptex = pspanpackage->ptex;
lpz = pspanpackage->pz;
lsfrac = pspanpackage->sfrac;
ltfrac = pspanpackage->tfrac;
llight = pspanpackage->light;
lzi = pspanpackage->zi;
// LordHavoc: optimized zbuffer check (switchs between
// loops when state changes, and quickly skips groups
// of hidden pixels)
do
{
if ((lzi >> 16) < *lpz) // hidden
{
count = 0;
goto skiploop8;
}
drawloop8:
*lpz++ = lzi >> 16;
*lpdest++ = ((byte *)acolormap)
[(llight & 0xFF00) | lptex[texscan[ltfrac >> 16] +
(lsfrac >> 16)]];
lzi += r_zistepx;
lsfrac += r_sstepx;
ltfrac += r_tstepx;
llight += r_lstepx;
}
while (--lcount);
goto done8;
do
{
if ((lzi >> 16) >= *lpz) // draw
{
lsfrac += r_sstepx * count;
ltfrac += r_tstepx * count;
llight += r_lstepx * count;
lpdest += count;
goto drawloop8;
}
skiploop8:
count++;
lzi += r_zistepx;
lpz++;
}
while (--lcount);
done8: ;
}
pspanpackage++;
}
while (pspanpackage->count != -999999);
}
break;
case 2:
{
int lcount, count = 0;
short *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 = (short *) d_viewbuffer + 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) // hidden
{
count = 0;
goto skiploop16;
}
drawloop16:
*lpz++ = lzi >> 16;
*lpdest++ = ((short *)acolormap)[(llight & 0xFF00) | lptex[texscan[ltfrac >> 16] + (lsfrac >> 16)]];
lzi += r_zistepx;
lsfrac += r_sstepx;
ltfrac += r_tstepx;
llight += r_lstepx;
}
while (--lcount);
goto done16;
do
{
if ((lzi >> 16) >= *lpz) // draw
{
lsfrac += r_sstepx * count;
ltfrac += r_tstepx * count;
llight += r_lstepx * count;
lpdest += count;
goto drawloop16;
}
skiploop16:
count++;
lzi += r_zistepx;
lpz++;
}
while (--lcount);
done16: ;
}
pspanpackage++;
}
while (pspanpackage->count != -999999);
}
break;
case 4:
{
int lcount, count = 0;
int *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 = (int *) d_viewbuffer + 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) // hidden
{
count = 0;
goto skiploop32;
}
drawloop32:
*lpz++ = lzi >> 16;
*lpdest++ =
vid.colormap32[(llight & 0xFF00) |
lptex[texscan[ltfrac >> 16] +
(lsfrac >> 16)]];
lzi += r_zistepx;
lsfrac += r_sstepx;
ltfrac += r_tstepx;
llight += r_lstepx;
}
while (--lcount);
goto done32;
do
{
if ((lzi >> 16) >= *lpz) // draw
{
lsfrac += r_sstepx * count;
ltfrac += r_tstepx * count;
llight += r_lstepx * count;
lpdest += count;
goto drawloop32;
}
skiploop32:
count++;
lzi += r_zistepx;
lpz++;
}
while (--lcount);
done32: ;
}
pspanpackage++;
}
while (pspanpackage->count != -999999);
}
break;
default:
Sys_Error("D_PolysetDrawSpans: unsupported r_pixbytes %i",
r_pixbytes);
}
}
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];
2001-08-29 01:28:03 +00:00
// 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
2001-08-29 01:28:03 +00:00
// 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;
d_sfrac = plefttop[2] & 0xFFFF;
d_tfrac = plefttop[3] & 0xFFFF;
d_pzbasestep = d_zwidth + ubasestep;
d_pzextrastep = d_pzbasestep + 1;
d_light = plefttop[4];
d_zi = plefttop[5];
d_pdestbasestep = screenwidth + ubasestep;
d_pdestextrastep = d_pdestbasestep + 1;
// LordHavoc: d_pdest has been changed to pixel offset
d_pdest = ystart * screenwidth + plefttop[0];
d_pz = d_pzbuffer + ystart * d_zwidth + plefttop[0];
// TODO: can reuse partial expressions here
2001-08-29 01:28:03 +00:00
// 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;
d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) & 0xFFFF;
d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) & 0xFFFF;
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;
d_sfracextrastep = (r_sstepy + r_sstepx * d_countextrastep) & 0xFFFF;
d_tfracextrastep = (r_tstepy + r_tstepx * d_countextrastep) & 0xFFFF;
d_lightextrastep = d_lightbasestep + working_lstepx;
d_ziextrastep = d_zibasestep + r_zistepx;
D_PolysetScanLeftEdge (initialleftheight);
2001-08-29 01:28:03 +00:00
// 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;
// LordHavoc: d_pdest and relatives have been changed to pixel
// offsets into framebuffer
d_pdest = ystart * screenwidth + plefttop[0];
d_pzbasestep = d_zwidth + ubasestep;
d_pzextrastep = d_pzbasestep + 1;
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;
d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) & 0xFFFF;
d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) & 0xFFFF;
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;
d_sfracextrastep = (r_sstepy + r_sstepx * d_countextrastep) & 0xFFFF;
d_tfracextrastep = (r_tstepy + r_tstepx * d_countextrastep) & 0xFFFF;
d_lightextrastep = d_lightbasestep + working_lstepx;
d_ziextrastep = d_zibasestep + r_zistepx;
D_PolysetScanLeftEdge (height);
}
2001-08-29 01:28:03 +00:00
// 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_PolysetDrawSpans (a_spans);
2001-08-29 01:28:03 +00:00
// 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_PolysetDrawSpans (pstart);
}
}