engine.c

小型游戏引擎

	asm3 = (long)globalpalwritten + ((long)getpalookup((long)mulscale16(r,globvis),globalshade)<<8);
	if (!(globalorientation&256))
	{
		mhline(globalbufplc,globaly1*r+globalxpanning-asm1*(xr-xl),(xr-xl)<<16,0L,
			globalx2*r+globalypanning-asm2*(xr-xl),ylookup[yp]+xl+frameoffset);
		return;
	}
	thline(globalbufplc,globaly1*r+globalxpanning-asm1*(xr-xl),(xr-xl)<<16,0L,
		globalx2*r+globalypanning-asm2*(xr-xl),ylookup[yp]+xl+frameoffset);
	transarea += (xr-xl);
}


static int animateoffs(short tilenum, short fakevar)
{
	long i, k, offs;

	offs = 0;
	i = (totalclocklock>>((picanm[tilenum]>>24)&15));
	if ((picanm[tilenum]&63) > 0)
	{
		switch(picanm[tilenum]&192)
		{
			case 64:
				k = (i%((picanm[tilenum]&63)<<1));
				if (k < (picanm[tilenum]&63))
					offs = k;
				else
					offs = (((picanm[tilenum]&63)<<1)-k);
				break;
			case 128:
				offs = (i%((picanm[tilenum]&63)+1));
					break;
			case 192:
				offs = -(i%((picanm[tilenum]&63)+1));
		}
	}
	return(offs);
}


/* renders non-parallaxed ceilings. --ryan. */
static void ceilscan (long x1, long x2, long sectnum)
{
	long i, j, ox, oy, x, y1, y2, twall, bwall;
	sectortype *sec;

	sec = &sector[sectnum];
	if (palookup[sec->ceilingpal] != globalpalwritten)
	{
		globalpalwritten = palookup[sec->ceilingpal];
		setpalookupaddress(globalpalwritten);
	}

	globalzd = sec->ceilingz-globalposz;
	if (globalzd > 0) return;
	globalpicnum = sec->ceilingpicnum;
	if ((unsigned)globalpicnum >= (unsigned)MAXTILES) globalpicnum = 0;
	setgotpic(globalpicnum);
	if ((tilesizx[globalpicnum] <= 0) || (tilesizy[globalpicnum] <= 0)) return;
	if (picanm[globalpicnum]&192) globalpicnum += animateoffs((short)globalpicnum,(short)sectnum);

	if (waloff[globalpicnum] == 0) loadtile(globalpicnum);
	globalbufplc = waloff[globalpicnum];

	globalshade = (long)sec->ceilingshade;
	globvis = globalcisibility;
	if (sec->visibility != 0) globvis = mulscale4(globvis,(long)((unsigned char)(sec->visibility+16)));
	globalorientation = (long)sec->ceilingstat;


	if ((globalorientation&64) == 0)
	{
		globalx1 = singlobalang; globalx2 = singlobalang;
		globaly1 = cosglobalang; globaly2 = cosglobalang;
		globalxpanning = (globalposx<<20);
		globalypanning = -(globalposy<<20);
	}
	else
	{
		j = sec->wallptr;
		ox = wall[wall[j].point2].x - wall[j].x;
		oy = wall[wall[j].point2].y - wall[j].y;
		i = nsqrtasm(ox*ox+oy*oy); if (i == 0) i = 1024; else i = 1048576/i;
		globalx1 = mulscale10(dmulscale10(ox,singlobalang,-oy,cosglobalang),i);
		globaly1 = mulscale10(dmulscale10(ox,cosglobalang,oy,singlobalang),i);
		globalx2 = -globalx1;
		globaly2 = -globaly1;

		ox = ((wall[j].x-globalposx)<<6); oy = ((wall[j].y-globalposy)<<6);
		i = dmulscale14(oy,cosglobalang,-ox,singlobalang);
		j = dmulscale14(ox,cosglobalang,oy,singlobalang);
		ox = i; oy = j;
		globalxpanning = globalx1*ox - globaly1*oy;
		globalypanning = globaly2*ox + globalx2*oy;
	}
	globalx2 = mulscale16(globalx2,viewingrangerecip);
	globaly1 = mulscale16(globaly1,viewingrangerecip);
	globalxshift = (8-(picsiz[globalpicnum]&15));
	globalyshift = (8-(picsiz[globalpicnum]>>4));
	if (globalorientation&8) { globalxshift++; globalyshift++; }

	if ((globalorientation&0x4) > 0)
	{
		i = globalxpanning; globalxpanning = globalypanning; globalypanning = i;
		i = globalx2; globalx2 = -globaly1; globaly1 = -i;
		i = globalx1; globalx1 = globaly2; globaly2 = i;
	}
	if ((globalorientation&0x10) > 0) globalx1 = -globalx1, globaly1 = -globaly1, globalxpanning = -globalxpanning;
	if ((globalorientation&0x20) > 0) globalx2 = -globalx2, globaly2 = -globaly2, globalypanning = -globalypanning;
	globalx1 <<= globalxshift; globaly1 <<= globalxshift;
	globalx2 <<= globalyshift;  globaly2 <<= globalyshift;
	globalxpanning <<= globalxshift; globalypanning <<= globalyshift;
	globalxpanning += (((long)sec->ceilingxpanning)<<24);
	globalypanning += (((long)sec->ceilingypanning)<<24);
	globaly1 = (-globalx1-globaly1)*halfxdimen;
	globalx2 = (globalx2-globaly2)*halfxdimen;

	sethlinesizes(picsiz[globalpicnum]&15,picsiz[globalpicnum]>>4,globalbufplc);

	globalx2 += globaly2*(x1-1);
	globaly1 += globalx1*(x1-1);
	globalx1 = mulscale16(globalx1,globalzd);
	globalx2 = mulscale16(globalx2,globalzd);
	globaly1 = mulscale16(globaly1,globalzd);
	globaly2 = mulscale16(globaly2,globalzd);
	globvis = klabs(mulscale10(globvis,globalzd));

	if (!(globalorientation&0x180))
	{
		y1 = umost[x1]; y2 = y1;
		for(x=x1;x<=x2;x++)
		{
			twall = umost[x]-1; bwall = min(uplc[x],dmost[x]);
			if (twall < bwall-1)
			{
				if (twall >= y2)
				{
					while (y1 < y2-1) hline(x-1,++y1);
					y1 = twall;
				}
				else
				{
					while (y1 < twall) hline(x-1,++y1);
					while (y1 > twall) lastx[y1--] = x;
				}
				while (y2 > bwall) hline(x-1,--y2);
				while (y2 < bwall) lastx[y2++] = x;
			}
			else
			{
				while (y1 < y2-1) hline(x-1,++y1);
				if (x == x2) { globalx2 += globaly2; globaly1 += globalx1; break; }
				y1 = umost[x+1]; y2 = y1;
			}
			globalx2 += globaly2; globaly1 += globalx1;
		}
		while (y1 < y2-1) hline(x2,++y1);
		faketimerhandler();
		return;
	}

	switch(globalorientation&0x180)
	{
		case 128:
			msethlineshift(picsiz[globalpicnum]&15,picsiz[globalpicnum]>>4);
			break;
		case 256:
			settransnormal();
			tsethlineshift(picsiz[globalpicnum]&15,picsiz[globalpicnum]>>4);
			break;
		case 384:
			settransreverse();
			tsethlineshift(picsiz[globalpicnum]&15,picsiz[globalpicnum]>>4);
			break;
	}

	y1 = umost[x1]; y2 = y1;
	for(x=x1;x<=x2;x++)
	{
		twall = umost[x]-1; bwall = min(uplc[x],dmost[x]);
		if (twall < bwall-1)
		{
			if (twall >= y2)
			{
				while (y1 < y2-1) slowhline(x-1,++y1);
				y1 = twall;
			}
			else
			{
				while (y1 < twall) slowhline(x-1,++y1);
				while (y1 > twall) lastx[y1--] = x;
			}
			while (y2 > bwall) slowhline(x-1,--y2);
			while (y2 < bwall) lastx[y2++] = x;
		}
		else
		{
			while (y1 < y2-1) slowhline(x-1,++y1);
			if (x == x2) { globalx2 += globaly2; globaly1 += globalx1; break; }
			y1 = umost[x+1]; y2 = y1;
		}
		globalx2 += globaly2; globaly1 += globalx1;
	}
	while (y1 < y2-1) slowhline(x2,++y1);
	faketimerhandler();
}


/* renders non-parallaxed floors. --ryan. */
static void florscan (long x1, long x2, long sectnum)
{
	long i, j, ox, oy, x, y1, y2, twall, bwall;
	sectortype *sec;

	sec = &sector[sectnum];
	if (palookup[sec->floorpal] != globalpalwritten)
	{
		globalpalwritten = palookup[sec->floorpal];
		setpalookupaddress(globalpalwritten);
	}

	globalzd = globalposz-sec->floorz;
	if (globalzd > 0) return;
	globalpicnum = sec->floorpicnum;
	if ((unsigned)globalpicnum >= (unsigned)MAXTILES) globalpicnum = 0;
	setgotpic(globalpicnum);
	if ((tilesizx[globalpicnum] <= 0) || (tilesizy[globalpicnum] <= 0)) return;
	if (picanm[globalpicnum]&192) globalpicnum += animateoffs((short)globalpicnum,(short)sectnum);

	if (waloff[globalpicnum] == 0) loadtile(globalpicnum);
	globalbufplc = waloff[globalpicnum];

	globalshade = (long)sec->floorshade;
	globvis = globalcisibility;
	if (sec->visibility != 0) globvis = mulscale4(globvis,(long)((unsigned char)(sec->visibility+16)));
	globalorientation = (long)sec->floorstat;


	if ((globalorientation&64) == 0)
	{
		globalx1 = singlobalang; globalx2 = singlobalang;
		globaly1 = cosglobalang; globaly2 = cosglobalang;
		globalxpanning = (globalposx<<20);
		globalypanning = -(globalposy<<20);
	}
	else
	{
		j = sec->wallptr;
		ox = wall[wall[j].point2].x - wall[j].x;
		oy = wall[wall[j].point2].y - wall[j].y;
		i = nsqrtasm(ox*ox+oy*oy); if (i == 0) i = 1024; else i = 1048576/i;
		globalx1 = mulscale10(dmulscale10(ox,singlobalang,-oy,cosglobalang),i);
		globaly1 = mulscale10(dmulscale10(ox,cosglobalang,oy,singlobalang),i);
		globalx2 = -globalx1;
		globaly2 = -globaly1;

		ox = ((wall[j].x-globalposx)<<6); oy = ((wall[j].y-globalposy)<<6);
		i = dmulscale14(oy,cosglobalang,-ox,singlobalang);
		j = dmulscale14(ox,cosglobalang,oy,singlobalang);
		ox = i; oy = j;
		globalxpanning = globalx1*ox - globaly1*oy;
		globalypanning = globaly2*ox + globalx2*oy;
	}
	globalx2 = mulscale16(globalx2,viewingrangerecip);
	globaly1 = mulscale16(globaly1,viewingrangerecip);
	globalxshift = (8-(picsiz[globalpicnum]&15));
	globalyshift = (8-(picsiz[globalpicnum]>>4));
	if (globalorientation&8) { globalxshift++; globalyshift++; }

	if ((globalorientation&0x4) > 0)
	{
		i = globalxpanning; globalxpanning = globalypanning; globalypanning = i;
		i = globalx2; globalx2 = -globaly1; globaly1 = -i;
		i = globalx1; globalx1 = globaly2; globaly2 = i;
	}
	if ((globalorientation&0x10) > 0) globalx1 = -globalx1, globaly1 = -globaly1, globalxpanning = -globalxpanning;
	if ((globalorientation&0x20) > 0) globalx2 = -globalx2, globaly2 = -globaly2, globalypanning = -globalypanning;
	globalx1 <<= globalxshift; globaly1 <<= globalxshift;
	globalx2 <<= globalyshift;  globaly2 <<= globalyshift;
	globalxpanning <<= globalxshift; globalypanning <<= globalyshift;
	globalxpanning += (((long)sec->floorxpanning)<<24);
	globalypanning += (((long)sec->floorypanning)<<24);
	globaly1 = (-globalx1-globaly1)*halfxdimen;
	globalx2 = (globalx2-globaly2)*halfxdimen;

	sethlinesizes(picsiz[globalpicnum]&15,picsiz[globalpicnum]>>4,globalbufplc);

	globalx2 += globaly2*(x1-1);
	globaly1 += globalx1*(x1-1);
	globalx1 = mulscale16(globalx1,globalzd);
	globalx2 = mulscale16(globalx2,globalzd);
	globaly1 = mulscale16(globaly1,globalzd);
	globaly2 = mulscale16(globaly2,globalzd);
	globvis = klabs(mulscale10(globvis,globalzd));

	if (!(globalorientation&0x180))
	{
		y1 = max(dplc[x1],umost[x1]); y2 = y1;
		for(x=x1;x<=x2;x++)
		{
			twall = max(dplc[x],umost[x])-1; bwall = dmost[x];
			if (twall < bwall-1)
			{
				if (twall >= y2)
				{
					while (y1 < y2-1) hline(x-1,++y1);
					y1 = twall;
				}
				else
				{
					while (y1 < twall) hline(x-1,++y1);
					while (y1 > twall) lastx[y1--] = x;
				}
				while (y2 > bwall) hline(x-1,--y2);
				while (y2 < bwall) lastx[y2++] = x;
			}
			else
			{
				while (y1 < y2-1) hline(x-1,++y1);
				if (x == x2) { globalx2 += globaly2; globaly1 += globalx1; break; }
				y1 = max(dplc[x+1],umost[x+1]); y2 = y1;
			}
			globalx2 += globaly2; globaly1 += globalx1;
		}
		while (y1 < y2-1) hline(x2,++y1);
		faketimerhandler();
		return;
	}

	switch(globalorientation&0x180)
	{
		case 128:
			msethlineshift(picsiz[globalpicnum]&15,picsiz[globalpicnum]>>4);
			break;
		case 256:
			settransnormal();
			tsethlineshift(picsiz[globalpicnum]&15,picsiz[globalpicnum]>>4);
			break;
		case 384:
			settransreverse();
			tsethlineshift(picsiz[globalpicnum]&15,picsiz[globalpicnum]>>4);
			break;
	}

	y1 = max(dplc[x1],umost[x1]); y2 = y1;
	for(x=x1;x<=x2;x++)
	{
		twall = max(dplc[x],umost[x])-1; bwall = dmost[x];
		if (twall < bwall-1)
		{
			if (twall >= y2)
			{
				while (y1 < y2-1) slowhline(x-1,++y1);
				y1 = twall;
			}
			else
			{
				while (y1 < twall) slowhline(x-1,++y1);
				while (y1 > twall) lastx[y1--] = x;
			}
			while (y2 > bwall) slowhline(x-1,--y2);
			while (y2 < bwall) lastx[y2++] = x;
		}
		else
		{
			while (y1 < y2-1) slowhline(x-1,++y1);
			if (x == x2) { globalx2 += globaly2; globaly1 += globalx1; break; }
			y1 = max(dplc[x+1],umost[x+1]); y2 = y1;
		}
		globalx2 += globaly2; globaly1 += globalx1;
	}
	while (y1 < y2-1) slowhline(x2,++y1);
	faketimerhandler();
}


/*
 * renders walls and parallaxed skies/floors. Look at parascan() for the
 *  higher level of parallaxing.
 *
 *    x1 == offset of leftmost pixel of wall. 0 is left of surface.
 *    x2 == offset of rightmost pixel of wall. 0 is left of surface.
 *
 *  apparently, walls are always vertical; there are sloping functions
 *   (!!!) er...elsewhere. Only the sides need be vertical, as the top and
 *   bottom of the polygon will need to be angled as the camera perspective
 *   shifts (user spins in a circle, etc.)
 *
 *  uwal is an array of the upper most pixels, and dwal are the lower most.
 *   This must be a list, as the top and bottom of the polygon are not
 *   necessarily horizontal lines.
 *
 *   So, the screen coordinate of the top left of a wall is specified by
 *   uwal[x1], the bottom left by dwal[x1], the top right by uwal[x2], and
 *   the bottom right by dwal[x2]. Every physical point on the edge of the
 *   wall in between is specified by traversing those arrays, one pixel per
 *   element.
 *
 *  --ryan.
 */
static void wallscan(long x1, long x2,
                     short *uwal, short *dwal,
                     long *swal, long *lwal)
{
	long i, x, xnice, ynice, fpalookup;
	long y1ve[4], y2ve[4], u4, d4, z, tsizx, tsizy;
	char bad;

	tsizx = tilesizx[globalpicnum];
	tsizy = tilesizy[globalpicnum];
	setgotpic(globalpicnum);
	if ((tsizx <= 0) || (tsizy <= 0)) return;
	if ((uwal[x1] > ydimen) && (uwal[x2] > ydimen)) return;
	if ((dwal[x1] < 0) && (dwal[x2] < 0)) return;

	if (waloff[globalpicnum] == 0) loadtile(globalpicnum);

	xnice = (pow2long[picsiz[globalpicnum]&15] == tsizx);
	if (xnice) tsizx--;
	ynice = (pow2long[picsiz[globalpicnum]>>4] == tsizy);