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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_sky.c
#include "quakedef.h"
#include "r_local.h"
#include "d_local.h"
#define SKY_SPAN_SHIFT 5
#define SKY_SPAN_MAX (1 << SKY_SPAN_SHIFT)
/*
=================
D_Sky_uv_To_st
=================
*/
void D_Sky_uv_To_st (int u, int v, fixed16_t *s, fixed16_t *t)
{
float wu, wv, temp;
vec3_t end;
if (r_refdef.vrect.width >= r_refdef.vrect.height)
temp = (float)r_refdef.vrect.width;
else
temp = (float)r_refdef.vrect.height;
wu = 8192.0 * (float)(u-((int)vid.width>>1)) / temp;
wv = 8192.0 * (float)(((int)vid.height>>1)-v) / temp;
end[0] = 4096*vpn[0] + wu*vright[0] + wv*vup[0];
end[1] = 4096*vpn[1] + wu*vright[1] + wv*vup[1];
end[2] = 4096*vpn[2] + wu*vright[2] + wv*vup[2];
end[2] *= 3;
VectorNormalize (end);
temp = skytime*skyspeed; // TODO: add D_SetupFrame & set this there
*s = (int)((temp + 6*(SKYSIZE/2-1)*end[0]) * 0x10000);
*t = (int)((temp + 6*(SKYSIZE/2-1)*end[1]) * 0x10000);
}
/*
=================
D_DrawSkyScans8
=================
*/
void D_DrawSkyScans8 (espan_t *pspan)
{
int count, spancount, u, v;
unsigned char *pdest;
fixed16_t s, t, snext, tnext, sstep, tstep;
int spancountminus1;
sstep = 0; // keep compiler happy
tstep = 0; // ditto
do
{
pdest = (unsigned char *)((byte *)d_viewbuffer +
(screenwidth * pspan->v) + pspan->u);
count = pspan->count;
// calculate the initial s & t
u = pspan->u;
v = pspan->v;
D_Sky_uv_To_st (u, v, &s, &t);
do
{
if (count >= SKY_SPAN_MAX)
spancount = SKY_SPAN_MAX;
else
spancount = count;
count -= spancount;
if (count)
{
u += spancount;
// calculate s and t at far end of span,
// calculate s and t steps across span by shifting
D_Sky_uv_To_st (u, v, &snext, &tnext);
sstep = (snext - s) >> SKY_SPAN_SHIFT;
tstep = (tnext - t) >> SKY_SPAN_SHIFT;
}
else
{
// calculate s and t at last pixel in span,
// calculate s and t steps across span by division
spancountminus1 = (float)(spancount - 1);
if (spancountminus1 > 0)
{
u += spancountminus1;
D_Sky_uv_To_st (u, v, &snext, &tnext);
sstep = (snext - s) / spancountminus1;
tstep = (tnext - t) / spancountminus1;
}
}
do
{
*pdest++ = r_skysource[((t & R_SKY_TMASK) >> 8) +
((s & R_SKY_SMASK) >> 16)];
s += sstep;
t += tstep;
} while (--spancount > 0);
s = snext;
t = tnext;
} while (count > 0);
} while ((pspan = pspan->pnext) != NULL);
}
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