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// WOLFHACK.C
#include "WL_DEF.H"
#define MAXVIEWHEIGHT 200
int spanstart[MAXVIEWHEIGHT/2];
fixed stepscale[MAXVIEWHEIGHT/2];
fixed basedist[MAXVIEWHEIGHT/2];
extern char far planepics[8192]; // 4k of ceiling, 4k of floor
int halfheight = 0;
byte far *planeylookup[MAXVIEWHEIGHT/2];
unsigned mirrorofs[MAXVIEWHEIGHT/2];
fixed psin, pcos;
fixed FixedMul (fixed a, fixed b)
{
return (a>>8)*(b>>8);
}
int mr_rowofs;
int mr_count;
int mr_xstep;
int mr_ystep;
int mr_xfrac;
int mr_yfrac;
int mr_dest;
/*
==============
=
= DrawSpans
=
= Height ranges from 0 (infinity) to viewheight/2 (nearest)
==============
*/
void DrawSpans (int x1, int x2, int height)
{
fixed length;
int ofs;
int prestep;
fixed startxfrac, startyfrac;
int x, startx, count, plane, startplane;
byte far *toprow, far *dest;
toprow = planeylookup[height]+bufferofs;
mr_rowofs = mirrorofs[height];
mr_xstep = (psin<<1)/height;
mr_ystep = (pcos<<1)/height;
length = basedist[height];
startxfrac = (viewx + FixedMul(length,pcos));
startyfrac = (viewy - FixedMul(length,psin));
// draw two spans simultaniously
plane = startplane = x1&3;
prestep = viewwidth/2 - x1;
do
{
outportb (SC_INDEX+1,1<<plane);
mr_xfrac = startxfrac - (mr_xstep>>2)*prestep;
mr_yfrac = startyfrac - (mr_ystep>>2)*prestep;
startx = x1>>2;
mr_dest = (unsigned)toprow + startx;
mr_count = ((x2-plane)>>2) - startx + 1;
x1++;
prestep--;
if (mr_count)
MapRow ();
plane = (plane+1)&3;
} while (plane != startplane);
}
/*
===================
=
= SetPlaneViewSize
=
===================
*/
void SetPlaneViewSize (void)
{
int x,y;
byte far *dest, far *src;
halfheight = viewheight>>1;
for (y=0 ; y<halfheight ; y++)
{
planeylookup[y] = (byte far *)0xa0000000l + (halfheight-1-y)*SCREENBWIDE;;
mirrorofs[y] = (y*2+1)*SCREENBWIDE;
stepscale[y] = y*GLOBAL1/32;
if (y>0)
basedist[y] = GLOBAL1/2*scale/y;
}
src = PM_GetPage(0);
dest = planepics;
for (x=0 ; x<4096 ; x++)
{
*dest = *src++;
dest += 2;
}
src = PM_GetPage(1);
dest = planepics+1;
for (x=0 ; x<4096 ; x++)
{
*dest = *src++;
dest += 2;
}
}
/*
===================
=
= DrawPlanes
=
===================
*/
void DrawPlanes (void)
{
int height, lastheight;
int x;
if (viewheight>>1 != halfheight)
SetPlaneViewSize (); // screen size has changed
psin = viewsin;
if (psin < 0)
psin = -(psin&0xffff);
pcos = viewcos;
if (pcos < 0)
pcos = -(pcos&0xffff);
//
// loop over all columns
//
lastheight = halfheight;
for (x=0 ; x<viewwidth ; x++)
{
height = wallheight[x]>>3;
if (height < lastheight)
{ // more starts
do
{
spanstart[--lastheight] = x;
} while (lastheight > height);
}
else if (height > lastheight)
{ // draw spans
if (height > halfheight)
height = halfheight;
for ( ; lastheight < height ; lastheight++)
DrawSpans (spanstart[lastheight], x-1, lastheight);
}
}
height = halfheight;
for ( ; lastheight < height ; lastheight++)
DrawSpans (spanstart[lastheight], x-1, lastheight);
}
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