d_polyse.c

quake1 dos源代码最新版本

	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);

#if	id386
	a_sstepxfrac = r_sstepx << 16;
	a_tstepxfrac = r_tstepx << 16;
#else
	a_sstepxfrac = r_sstepx & 0xFFFF;
	a_tstepxfrac = r_tstepx & 0xFFFF;
#endif

	a_ststepxwhole = skinwidth * (r_tstepx >> 16) + (r_sstepx >> 16);
}

#endif	// !id386


#if 0
byte gelmap[256];
void InitGel (byte *palette)
{
	int		i;
	int		r;

	for (i=0 ; i<256 ; i++)
	{
//		r = (palette[i*3]>>4);
		r = (palette[i*3] + palette[i*3+1] + palette[i*3+2])/(16*3);
		gelmap[i] = /* 64 */ 0 + r;
	}
}
#endif


#if	!id386

/*
================
D_PolysetDrawSpans8
================
*/
void D_PolysetDrawSpans8 (spanpackage_t *pspanpackage)
{
	int		lcount;
	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 = 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)
				{
					*lpdest = ((byte *)acolormap)[*lptex + (llight & 0xFF00)];
// gel mapping					*lpdest = gelmap[*lpdest];
					*lpz = lzi >> 16;
				}
				lpdest++;
				lzi += r_zistepx;
				lpz++;
				llight += r_lstepx;
				lptex += a_ststepxwhole;
				lsfrac += a_sstepxfrac;
				lptex += lsfrac >> 16;
				lsfrac &= 0xFFFF;
				ltfrac += a_tstepxfrac;
				if (ltfrac & 0x10000)
				{
					lptex += r_affinetridesc.skinwidth;
					ltfrac &= 0xFFFF;
				}
			} while (--lcount);
		}

		pspanpackage++;
	} while (pspanpackage->count != -999999);
}
#endif	// !id386


/*
================
D_PolysetFillSpans8
================
*/
void D_PolysetFillSpans8 (spanpackage_t *pspanpackage)
{
	int				color;

// FIXME: do z buffering

	color = d_aflatcolor++;

	while (1)
	{
		int		lcount;
		byte	*lpdest;

		lcount = pspanpackage->count;

		if (lcount == -1)
			return;

		if (lcount)
		{
			lpdest = pspanpackage->pdest;

			do
			{
				*lpdest++ = color;
			} while (--lcount);
		}

		pspanpackage++;
	}
}

/*
================
D_RasterizeAliasPolySmooth
================
*/
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];

//
// 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
//

//
// scan out the top (and possibly only) part of the left edge
//
	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;
#if	id386
	d_sfrac = (plefttop[2] & 0xFFFF) << 16;
	d_tfrac = (plefttop[3] & 0xFFFF) << 16;
#else
	d_sfrac = plefttop[2] & 0xFFFF;
	d_tfrac = plefttop[3] & 0xFFFF;
#endif
	d_light = plefttop[4];
	d_zi = plefttop[5];

	d_pdest = (byte *)d_viewbuffer +
			ystart * screenwidth + plefttop[0];
	d_pz = d_pzbuffer + ystart * d_zwidth + plefttop[0];

	if (initialleftheight == 1)
	{
		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++;
	}
	else
	{
		D_PolysetSetUpForLineScan(plefttop[0], plefttop[1],
							  pleftbottom[0], pleftbottom[1]);

	#if	id386
		d_pzbasestep = (d_zwidth + ubasestep) << 1;
		d_pzextrastep = d_pzbasestep + 2;
	#else
		d_pzbasestep = d_zwidth + ubasestep;
		d_pzextrastep = d_pzbasestep + 1;
	#endif

		d_pdestbasestep = screenwidth + ubasestep;
		d_pdestextrastep = d_pdestbasestep + 1;

	// TODO: can reuse partial expressions here

	// 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;
	#if	id386
		d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) << 16;
		d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) << 16;
	#else
		d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) & 0xFFFF;
		d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) & 0xFFFF;
	#endif
		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;
	#if	id386
		d_sfracextrastep = (r_sstepy + r_sstepx*d_countextrastep) << 16;
		d_tfracextrastep = (r_tstepy + r_tstepx*d_countextrastep) << 16;
	#else
		d_sfracextrastep = (r_sstepy + r_sstepx*d_countextrastep) & 0xFFFF;
		d_tfracextrastep = (r_tstepy + r_tstepx*d_countextrastep) & 0xFFFF;
	#endif
		d_lightextrastep = d_lightbasestep + working_lstepx;
		d_ziextrastep = d_zibasestep + r_zistepx;

		D_PolysetScanLeftEdge (initialleftheight);
	}

//
// scan out the bottom part of the left edge, if it exists
//
	if (pedgetable->numleftedges == 2)
	{
		int		height;

		plefttop = pleftbottom;
		pleftbottom = pedgetable->pleftedgevert2;

		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_pdest = (byte *)d_viewbuffer + ystart * screenwidth + plefttop[0];
		d_pz = d_pzbuffer + ystart * d_zwidth + plefttop[0];

		if (height == 1)
		{
			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++;
		}
		else
		{
			D_PolysetSetUpForLineScan(plefttop[0], plefttop[1],
								  pleftbottom[0], pleftbottom[1]);

			d_pdestbasestep = screenwidth + ubasestep;
			d_pdestextrastep = d_pdestbasestep + 1;

	#if	id386
			d_pzbasestep = (d_zwidth + ubasestep) << 1;
			d_pzextrastep = d_pzbasestep + 2;
	#else
			d_pzbasestep = d_zwidth + ubasestep;
			d_pzextrastep = d_pzbasestep + 1;
	#endif

			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;
	#if	id386
			d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) << 16;
			d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) << 16;
	#else
			d_sfracbasestep = (r_sstepy + r_sstepx * ubasestep) & 0xFFFF;
			d_tfracbasestep = (r_tstepy + r_tstepx * ubasestep) & 0xFFFF;
	#endif
			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;
	#if	id386
			d_sfracextrastep = ((r_sstepy+r_sstepx*d_countextrastep) & 0xFFFF)<<16;
			d_tfracextrastep = ((r_tstepy+r_tstepx*d_countextrastep) & 0xFFFF)<<16;
	#else
			d_sfracextrastep = (r_sstepy+r_sstepx*d_countextrastep) & 0xFFFF;
			d_tfracextrastep = (r_tstepy+r_tstepx*d_countextrastep) & 0xFFFF;
	#endif
			d_lightextrastep = d_lightbasestep + working_lstepx;
			d_ziextrastep = d_zibasestep + r_zistepx;

			D_PolysetScanLeftEdge (height);
		}
	}

// 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_PolysetDrawSpans8 (a_spans);

// 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_PolysetDrawSpans8 (pstart);
	}
}


/*
================
D_PolysetSetEdgeTable
================
*/
void D_PolysetSetEdgeTable (void)
{
	int			edgetableindex;

	edgetableindex = 0;	// assume the vertices are already in
						//  top to bottom order

//
// 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];
}


#if 0

void D_PolysetRecursiveDrawLine (int *lp1, int *lp2)
{
	int		d;
	int		new[6];
	int 	ofs;

	d = lp2[0] - lp1[0];
	if (d < -1 || d > 1)
		goto split;
	d = lp2[1] - lp1[1];
	if (d < -1 || d > 1)
		goto split;

	return;	// line is completed

split:
// split this edge
	new[0] = (lp1[0] + lp2[0]) >> 1;
	new[1] = (lp1[1] + lp2[1]) >> 1;
	new[5] = (lp1[5] + lp2[5]) >> 1;
	new[2] = (lp1[2] + lp2[2]) >> 1;
	new[3] = (lp1[3] + lp2[3]) >> 1;
	new[4] = (lp1[4] + lp2[4]) >> 1;

// draw the point
	ofs = d_scantable[new[1]] + new[0];
	if (new[5] > d_pzbuffer[ofs])
	{
		int		pix;

		d_pzbuffer[ofs] = new[5];
		pix = skintable[new[3]>>16][new[2]>>16];
//		pix = ((byte *)acolormap)[pix + (new[4] & 0xFF00)];
		d_viewbuffer[ofs] = pix;
	}

// recursively continue
	D_PolysetRecursiveDrawLine (lp1, new);
	D_PolysetRecursiveDrawLine (new, lp2);
}

void D_PolysetRecursiveTriangle2 (int *lp1, int *lp2, int *lp3)
{
	int		d;
	int		new[4];

	d = lp2[0] - lp1[0];
	if (d < -1 || d > 1)
		goto split;
	d = lp2[1] - lp1[1];
	if (d < -1 || d > 1)
		goto split;
	return;

split:
// split this edge
	new[0] = (lp1[0] + lp2[0]) >> 1;
	new[1] = (lp1[1] + lp2[1]) >> 1;
	new[5] = (lp1[5] + lp2[5]) >> 1;
	new[2] = (lp1[2] + lp2[2]) >> 1;
	new[3] = (lp1[3] + lp2[3]) >> 1;
	new[4] = (lp1[4] + lp2[4]) >> 1;

	D_PolysetRecursiveDrawLine (new, lp3);

// recursively continue
	D_PolysetRecursiveTriangle (lp1, new, lp3);
	D_PolysetRecursiveTriangle (new, lp2, lp3);
}

#endif