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/*
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.

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

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

unsigned char *r_turb_pbase, *r_turb_pdest;
fixed16_t r_turb_s, r_turb_t, r_turb_sstep, r_turb_tstep;
int *r_turb_turb;
int r_turb_spancount;

void D_DrawTurbulent8Span (void);


/*
=============
D_WarpScreen

// this performs a slight compression of the screen at the same time as
// the sine warp, to keep the edges from wrapping
=============
*/
void D_WarpScreen (void)
{
int w, h;
int u,v;
byte *dest;
int *turb;
int *col;
byte **row;
byte *rowptr[MAXHEIGHT+(AMP2*2)];
int column[MAXWIDTH+(AMP2*2)];
float wratio, hratio;

w = r_refdef.vrect.width;
h = r_refdef.vrect.height;

wratio = w / (float)scr_vrect.width;
hratio = h / (float)scr_vrect.height;

for (v=0 ; v<scr_vrect.height+AMP2*2 ; v++)
{
rowptr[v] = d_viewbuffer + (r_refdef.vrect.y * screenwidth) +
(screenwidth * (int)((float)v * hratio * h / (h + AMP2 * 2)));
}

for (u=0 ; u<scr_vrect.width+AMP2*2 ; u++)
{
column[u] = r_refdef.vrect.x +
(int)((float)u * wratio * w / (w + AMP2 * 2));
}

turb = intsintable + ((int)(cl.time*SPEED)&(CYCLE-1));
dest = vid.buffer + scr_vrect.y * vid.rowbytes + scr_vrect.x;

for (v=0 ; v<scr_vrect.height ; v++, dest += vid.rowbytes)
{
col = &column[turb[v]];
row = &rowptr[v];

for (u=0 ; u<scr_vrect.width ; u+=4)
{
dest[u+0] = row[turb[u+0]][col[u+0]];
dest[u+1] = row[turb[u+1]][col[u+1]];
dest[u+2] = row[turb[u+2]][col[u+2]];
dest[u+3] = row[turb[u+3]][col[u+3]];
}
}
}


#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);
}

#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)(cl.time*SPEED)&(CYCLE-1));

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

r_turb_pbase = (unsigned char *)cacheblock;

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

do
{
r_turb_pdest = (unsigned char *)((byte *)d_viewbuffer +
(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);
}


#if !id386

/*
=============
D_DrawSpans8
=============
*/
void D_DrawSpans8 (espan_t *pspan)
{
int count, spancount;
unsigned char *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 = (unsigned char *)cacheblock;

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

do
{
pdest = (unsigned char *)((byte *)d_viewbuffer +
(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);
}
}

do
{
*pdest++ = *(pbase + (s >> 16) + (t >> 16) * cachewidth);
s += sstep;
t += tstep;
} while (--spancount > 0);

s = snext;
t = tnext;

} 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;
double 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 ((long)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
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