/*
Copyright (C) 1997-2001 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 "header/local.h"

static pixel_t	*r_turb_pbase, *r_turb_pdest;
static int	r_turb_s, r_turb_t, r_turb_sstep, r_turb_tstep;
int		*r_turb_turb;
static int	r_turb_spancount;

static void D_DrawTurbulent8Span (void);

byte	**warp_rowptr;
int	*warp_column;

/*
=============
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;
	pixel_t	*dest;
	int	*turb;
	byte	**row;

	static int	cached_width, cached_height;

	//
	// these are constant over resolutions, and can be saved
	//
	w = r_newrefdef.width;
	h = r_newrefdef.height;
	if (w != cached_width || h != cached_height)
	{
		cached_width = w;
		cached_height = h;
		for (v=0 ; v<h+AMP2*2 ; v++)
		{
			int v2;

			v2 = (int)((float)v/(h + AMP2 * 2) * r_refdef.vrect.height);
			warp_rowptr[v] = r_warpbuffer + (WARP_WIDTH * v2);
		}

		for (u=0 ; u<w+AMP2*2 ; u++)
		{
			int u2;

			u2 = (int)((float)u/(w + AMP2 * 2) * r_refdef.vrect.width);
			warp_column[u] = u2;
		}
	}

	turb = intsintable + ((int)(r_newrefdef.time*SPEED)&(CYCLE-1));
	dest = vid_buffer + r_newrefdef.y * vid.width + r_newrefdef.x;

	for (v=0 ; v<h ; v++, dest += vid.width)
	{
		int *col;

		col = warp_column + turb[v];
		row = warp_rowptr + v;
		for (u=0 ; u<w ; u++)
		{
			dest[u] = row[turb[u]][col[u]];
		}
	}
}

/*
=============
D_DrawTurbulent8Span
=============
*/
static void D_DrawTurbulent8Span (void)
{
	do
	{
		int sturb, tturb;
		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);
}

/*
=============
Turbulent8
=============
*/
void Turbulent8 (espan_t *pspan)
{
	int		snext, tnext;
	float	spancountminus1;
	float	sdivz16stepu, tdivz16stepu, zi16stepu;

	r_turb_turb = sintable + ((int)(r_newrefdef.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
	{
		int count;
		float sdivz, tdivz, zi, z, du, dv;

		r_turb_pdest = d_viewbuffer + (r_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);
}

//====================
//PGM
/*
=============
NonTurbulent8 - this is for drawing scrolling textures. they're warping water textures
	but the turbulence is automatically 0.
=============
*/
void NonTurbulent8 (espan_t *pspan)
{
	int snext, tnext;
	float spancountminus1;
	float sdivz16stepu, tdivz16stepu, zi16stepu;

	r_turb_turb = blanktable;

	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
	{
		int count;
		float sdivz, tdivz, zi, z, dv, du;

		r_turb_pdest = d_viewbuffer + (r_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);
}
//PGM
//====================

/*
=============
D_DrawSpans16

  FIXME: actually make this subdivide by 16 instead of 8!!!
=============
*/
void D_DrawSpans16 (espan_t *pspan)
{
	int spancount;
	unsigned char *pbase;
	int snext, tnext, sstep, tstep;
	float 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
	{
		pixel_t	*pdest;
		int		count, s, t;
		float	sdivz, tdivz, zi, z, du, dv;

		pdest = d_viewbuffer + (r_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);
}

/*
=============
D_DrawZSpans
=============
*/
void D_DrawZSpans (espan_t *pspan)
{
	int izistep;

	// 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
	{
		int		count;
		int		izi;
		zvalue_t	*pdest;
		float		zi;
		float		du, dv;

		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);

		while (count > 0)
		{
			*pdest++ = izi >> 16;
			izi += izistep;
			count--;
		}
	} while ((pspan = pspan->pnext) != NULL);
}
