// SONIC ROBO BLAST 2
//-----------------------------------------------------------------------------
// Copyright (C) 1993-1996 by id Software, Inc.
// Copyright (C) 1998-2000 by DooM Legacy Team.
// Copyright (C) 1999-2018 by Sonic Team Junior.
//
// This program is free software distributed under the
// terms of the GNU General Public License, version 2.
// See the 'LICENSE' file for more details.
//-----------------------------------------------------------------------------
/// \file  r_bsp.c
/// \brief BSP traversal, handling of LineSegs for rendering

#include "doomdef.h"
#include "g_game.h"

#include "r_fps.h"
#include "r_local.h"
#include "r_state.h"
#include "r_portal.h" // Add seg portals
#include "r_splats.h"

#include "p_local.h" // camera
#include "p_slopes.h"
#include "z_zone.h" // Check R_Prep3DFloors

#include "qs22j.h"

seg_t  *curline = NULL;
side_t *sidedef = NULL;
line_t *linedef = NULL;
sector_t *frontsector = NULL;
sector_t *backsector = NULL;

// very ugly realloc() of drawsegs at run-time, I upped it to 512
// instead of 256.. and someone managed to send me a level with
// 896 drawsegs! So too bad here's a limit removal a-la-Boom
drawseg_t *curdrawsegs = NULL; /**< This is used to handle multiple lists for masked drawsegs. */
drawseg_t *drawsegs = NULL;
drawseg_t *ds_p = NULL;

// indicates doors closed wrt automap bugfix:
INT32 doorclosed = 0;

// A wall was drawn covering the whole screen, which means we
// can block off the BSP across that seg.
boolean g_walloffscreen = false;

boolean R_NoEncore(sector_t *sector, boolean ceiling)
{
	const INT32 invspecial = GETSECSPECIAL(sector->special, 2);
	boolean invertencore = (invspecial == 12 || invspecial == 15); // keeping this incase its used

#if 0 // perfect implementation
	const INT32 sprnspecial = GETSECSPECIAL(sector->special, 3);
	if (sprnspecial != 1 && sprnspecial != 3 // spring panel
#else // optimised, see #define GETSECSPECIAL(i,j) ((i >> ((j-1)*4))&15)
	if ((!(sector->special & (1<<8)) || (sector->special & ((4|8)<<8))) // spring panel
#endif
		&& GETSECSPECIAL(sector->special, 4) != 6) // sneaker panel
	{
		return invertencore;
	}

	if (invertencore)
	{
		return false;
	}

	if (ceiling)
	{
		return ((boolean)(sector->flags & SF_FLIPSPECIAL_CEILING));
	}

	return ((boolean)(sector->flags & SF_FLIPSPECIAL_FLOOR));
}

//
// R_ClearDrawSegs
//
void R_ClearDrawSegs(void)
{
	ds_p = drawsegs;
}

// CPhipps -
// Instead of clipsegs, let's try using an array with one entry for each column,
// indicating whether it's blocked by a solid wall yet or not.
UINT8 *solidcol = NULL;

void R_AllocClipSegMemory(void)
{
	solidcol = static_cast<UINT8*>(Z_Realloc(solidcol, sizeof(*solidcol) * viewwidth, PU_STATIC, NULL));
}

namespace
{

enum class ClipType
{
	// Does handle solid walls,
	//  e.g. single sided LineDefs (middle texture)
	//  that entirely block the view.
	kSolid,
	kSolidDontRender,

	// Clips the given range of columns, but does not include it in the clip list.
	// Does handle windows, e.g. LineDefs with upper and lower texture.
	kPass,
};

// CPhipps -
// R_ClipWallSegment
//
// Replaces the old R_Clip*WallSegment functions. It draws bits of walls in those
// columns which aren't solid, and updates the solidcol[] array appropriately
template <ClipType Type>
static void R_ClipWallSegment(int first, int last)
{
	while (first < last)
	{
		UINT8 *p;

		if (solidcol[first])
		{
			p = static_cast<UINT8*>(memchr(solidcol+first, 0, last-first));
			if (!p)
				return; // All solid

			first = p - solidcol;
		}
		else
		{
			p = static_cast<UINT8*>(memchr(solidcol+first, 1, last-first));

			int to;
			if (!p)
				to = last;
			else
				to = p - solidcol;

			if constexpr (Type != ClipType::kSolidDontRender)
			{
				R_StoreWallRange(first, to-1);
			}

			if constexpr (Type != ClipType::kPass)
			{
				memset(solidcol+first, 1, to-first);
			}

			first = to;
		}
	}
}

}; // namespace

//
// R_ClearClipSegs
//
void R_ClearClipSegs(void)
{
	memset(solidcol, 0, viewwidth);
}

void R_PortalClearClipSegs(INT32 start, INT32 end)
{
	R_ClearClipSegs();

	if (start > 0)
		memset(solidcol, 1, start);

	if (end < viewwidth)
		memset(solidcol + end, 1, viewwidth - end);
}

//
// If player's view height is underneath fake floor, lower the
// drawn ceiling to be just under the floor height, and replace
// the drawn floor and ceiling textures, and light level, with
// the control sector's.
//
// Similar for ceiling, only reflected.
//
sector_t *R_FakeFlat(sector_t *sec, sector_t *tempsec, INT32 *floorlightlevel,
	INT32 *ceilinglightlevel, boolean back)
{
	if (floorlightlevel)
		*floorlightlevel = sec->floorlightsec == -1 ?
			sec->lightlevel : sectors[sec->floorlightsec].lightlevel;

	if (ceilinglightlevel)
		*ceilinglightlevel = sec->ceilinglightsec == -1 ?
			sec->lightlevel : sectors[sec->ceilinglightsec].lightlevel;

	// if (sec->midmap != -1)
	//	mapnum = sec->midmap;
	// In original colormap code, this block did not run if sec->midmap was set
	if (!sec->extra_colormap && sec->heightsec != -1)
	{
		const sector_t *s = &sectors[sec->heightsec];
		mobj_t *pviewmobj = viewplayer->mo;
		INT32 heightsec;
		boolean underwater;
		camera_t *thiscam = &camera[R_GetViewNumber()];

		if (thiscam->chase)
			heightsec = thiscam->subsector->sector->heightsec;
		else if (viewmobj)
			heightsec = pviewmobj->subsector->sector->heightsec;
		else
			return sec;

		underwater = (heightsec != -1 && viewz <= sectors[heightsec].floorheight);

		// Replace sector being drawn, with a copy to be hacked
		*tempsec = *sec;

		// Replace floor and ceiling height with other sector's heights.
		tempsec->floorheight = s->floorheight;
		tempsec->ceilingheight = s->ceilingheight;

		if ((underwater && (tempsec->  floorheight = sec->floorheight,
			tempsec->ceilingheight = s->floorheight - 1, !back)) || viewz <= s->floorheight)
		{ // head-below-floor hack
			tempsec->floorpic = s->floorpic;
			tempsec->floor_xoffs = s->floor_xoffs;
			tempsec->floor_yoffs = s->floor_yoffs;
			tempsec->floorpic_angle = s->floorpic_angle;

			if (underwater)
			{
				if (s->ceilingpic == skyflatnum)
				{
					tempsec->floorheight = tempsec->ceilingheight+1;
					tempsec->ceilingpic = tempsec->floorpic;
					tempsec->ceiling_xoffs = tempsec->floor_xoffs;
					tempsec->ceiling_yoffs = tempsec->floor_yoffs;
					tempsec->ceilingpic_angle = tempsec->floorpic_angle;
				}
				else
				{
					tempsec->ceilingpic = s->ceilingpic;
					tempsec->ceiling_xoffs = s->ceiling_xoffs;
					tempsec->ceiling_yoffs = s->ceiling_yoffs;
					tempsec->ceilingpic_angle = s->ceilingpic_angle;
				}
			}

			tempsec->lightlevel = s->lightlevel;

			if (floorlightlevel)
				*floorlightlevel = s->floorlightsec == -1 ? s->lightlevel
					: sectors[s->floorlightsec].lightlevel;

			if (ceilinglightlevel)
				*ceilinglightlevel = s->ceilinglightsec == -1 ? s->lightlevel
					: sectors[s->ceilinglightsec].lightlevel;
		}
		else if (heightsec != -1 && viewz >= sectors[heightsec].ceilingheight
			&& sec->ceilingheight > s->ceilingheight)
		{ // Above-ceiling hack
			tempsec->ceilingheight = s->ceilingheight;
			tempsec->floorheight = s->ceilingheight + 1;

			tempsec->floorpic = tempsec->ceilingpic = s->ceilingpic;
			tempsec->floor_xoffs = tempsec->ceiling_xoffs = s->ceiling_xoffs;
			tempsec->floor_yoffs = tempsec->ceiling_yoffs = s->ceiling_yoffs;
			tempsec->floorpic_angle = tempsec->ceilingpic_angle = s->ceilingpic_angle;

			if (s->floorpic == skyflatnum) // SKYFIX?
			{
				tempsec->ceilingheight = tempsec->floorheight-1;
				tempsec->floorpic = tempsec->ceilingpic;
				tempsec->floor_xoffs = tempsec->ceiling_xoffs;
				tempsec->floor_yoffs = tempsec->ceiling_yoffs;
				tempsec->floorpic_angle = tempsec->ceilingpic_angle;
			}
			else
			{
				tempsec->ceilingheight = sec->ceilingheight;
				tempsec->floorpic = s->floorpic;
				tempsec->floor_xoffs = s->floor_xoffs;
				tempsec->floor_yoffs = s->floor_yoffs;
				tempsec->floorpic_angle = s->floorpic_angle;
			}

			tempsec->lightlevel = s->lightlevel;

			if (floorlightlevel)
				*floorlightlevel = s->floorlightsec == -1 ? s->lightlevel :
			sectors[s->floorlightsec].lightlevel;

			if (ceilinglightlevel)
				*ceilinglightlevel = s->ceilinglightsec == -1 ? s->lightlevel :
			sectors[s->ceilinglightsec].lightlevel;
		}
		sec = tempsec;
	}

	return sec;
}

boolean R_IsEmptyLine(seg_t *line, const sector_t *front, const sector_t *back)
{
	return (!line->sidedef->midtexture && !line->polyseg
	&& ((!front->ffloors && !back->ffloors) || front->tag == back->tag)
	&& (memcmp(front, back, (offsetof(sector_t, extra_colormap) + sizeof(extracolormap_t *))) == 0));
}

//
// R_AddLine
// Clips the given segment and adds any visible pieces to the line list.
//
static void R_AddLine(seg_t *line)
{
	INT32 x1, x2;
	angle_t angle1, angle2, span, tspan;
	static sector_t tempsec;
	boolean bothfloorssky   = false;

	g_portal = NULL;

	// big room fix
	angle1 = R_PointToAngle64(line->v1->x, line->v1->y);
	angle2 = R_PointToAngle64(line->v2->x, line->v2->y);

	curline = line;

	// Clip to view edges.
	span = angle1 - angle2;

	// Back side? i.e. backface culling?
	if (span >= ANGLE_180)
		return;

	// Global angle needed by segcalc.
	rw_angle1 = angle1;
	angle1 -= viewangle;
	angle2 -= viewangle;

	tspan = angle1 + clipangle;
	if (tspan > doubleclipangle)
	{
		tspan -= doubleclipangle;

		// Totally off the left edge?
		if (tspan >= span)
			return;

		angle1 = clipangle;
	}

	tspan = clipangle - angle2;
	if (tspan > doubleclipangle)
	{
		tspan -= doubleclipangle;

		// Totally off the left edge?
		if (tspan >= span)
			return;

		angle2 = -(signed)clipangle;
	}

	// The seg is in the view range, but not necessarily visible.
	angle1 = (angle1+ANGLE_90)>>ANGLETOFINESHIFT;
	angle2 = (angle2+ANGLE_90)>>ANGLETOFINESHIFT;

	// killough 1/31/98: Here is where "slime trails" can SOMETIMES occur:
	x1 = viewangletox[angle1];
	x2 = viewangletox[angle2];

	// Does not cross a pixel?
	if (x1 >= x2)       // killough 1/31/98 -- change == to >= for robustness
		return;

	backsector = line->backsector;

	// Portal line
	if (line->linedef->special == PORTALSPECIAL && line->side == 0)
	{
		if (portalrender < cv_maxportals.value)
		{
			// Find the other side!
			INT32 line2 = P_FindSpecialLineFromTag(PORTALSPECIAL, line->linedef->tag, -1);

			if (line->linedef == &lines[line2])
				line2 = P_FindSpecialLineFromTag(PORTALSPECIAL, line->linedef->tag, line2);

			if (line2 >= 0) // found it!
			{
				Portal_Add2Lines(line->linedef-lines, line2, x1, x2); // Remember the lines for later rendering
				//return; // Don't fill in that space now!
				goto clipsolid;
			}
		}
		// Recursed TOO FAR (viewing a portal within a portal)
		// So uhhh, render it as a normal wall instead or something ???
	}

	// Single sided line?
	if (!backsector)
		goto clipsolid;

	backsector = R_FakeFlat(backsector, &tempsec, NULL, NULL, true);

	doorclosed = 0;

	// likewise, but for floors and upper textures
	if (backsector->floorpic == skyflatnum && frontsector->floorpic == skyflatnum)
		bothfloorssky = true;

	fixed_t frontf1,frontf2, frontc1, frontc2; // front floor/ceiling ends
	fixed_t backf1, backf2, backc1, backc2; // back floor ceiling ends

	// Closed door.
	if (frontsector->f_slope || frontsector->c_slope || backsector->f_slope || backsector->c_slope)
	{
#define SLOPEPARAMS(slope, end1, end2, normalheight) \
	end1 = P_GetZAt(slope, line->v1->x, line->v1->y, normalheight); \
	end2 = P_GetZAt(slope, line->v2->x, line->v2->y, normalheight);

		SLOPEPARAMS(frontsector->f_slope, frontf1, frontf2, frontsector->floorheight)
		SLOPEPARAMS(frontsector->c_slope, frontc1, frontc2, frontsector->ceilingheight)
		SLOPEPARAMS( backsector->f_slope, backf1,  backf2,  backsector->floorheight)
		SLOPEPARAMS( backsector->c_slope, backc1,  backc2,  backsector->ceilingheight)
#undef SLOPEPARAMS
	}
	else
	{
		frontf1 = frontf2 = frontsector->floorheight;
		frontc1 = frontc2 = frontsector->ceilingheight;
		backf1 = backf2 = backsector->floorheight;
		backc1 = backc2 = backsector->ceilingheight;
	}

	if (viewsector != backsector && viewsector != frontsector)
	{
		// here we're talking about a CEILING lower than a floor. ...yeah we don't even need to bother.
		const boolean ceillow = (backc1 <= frontf1 && backc2 <= frontf2);

		// this tries to fix some skyboxes drawing a black void as a midtexture lel
		if (ceillow && (!bothfloorssky && backsector->ceilingpic == skyflatnum && frontsector->ceilingpic != skyflatnum) // double sided with back ceiling sky but not front ceiling sky
			&& !line->sidedef->midtexture && !line->sidedef->bottomtexture && !line->sidedef->toptexture && !line->polyseg) // effectively empty
		{
			goto clippass;
		}

		doorclosed = ceillow
		|| (backf1 >= frontc1 && backf2 >= frontc2)
		// Check for automap fix. Store in doorclosed for r_segs.c
		|| (backc1 <= backf1 && backc2 <= backf2
		&& ((backc1 >= frontc1 && backc2 >= frontc2) || curline->sidedef->toptexture)
		&& ((backf1 <= frontf1 && backf2 >= frontf2) || curline->sidedef->bottomtexture)
		&& (backsector->ceilingpic != skyflatnum || frontsector->ceilingpic != skyflatnum));

		if (doorclosed)
			goto clipsolid;
	}

	// Window.
	if (backc1 != frontc1 || backc2 != frontc2
		|| backf1 != frontf1 || backf2 != frontf2)
	{
		goto clippass;
	}

	// Reject empty lines used for triggers and special events.
	// Identical floor and ceiling on both sides, identical light levels on both sides,
	// and no middle texture.

	if (R_IsEmptyLine(line, frontsector, backsector))
		return;

clippass:
	g_walloffscreen = false;
	R_ClipWallSegment<ClipType::kPass>(x1, x2);

	if (g_walloffscreen)
		R_ClipWallSegment<ClipType::kSolidDontRender>(x1, x2);
	return;

clipsolid:
	g_walloffscreen = false;
	R_ClipWallSegment<ClipType::kSolid>(x1, x2);
}

//
// R_CheckBBox
// Checks BSP node/subtree bounding box.
// Returns true if some part of the bbox might be visible.
//
//   | 0 | 1 | 2
// --+---+---+---
// 0 | 0 | 1 | 2
// 1 | 4 | 5 | 6
// 2 | 8 | 9 | A
const INT32 checkcoord[12][4] =
{
	{3, 0, 2, 1},
	{3, 0, 2, 0},
	{3, 1, 2, 0},
	{0}, // UNUSED
	{2, 0, 2, 1},
	{0}, // UNUSED
	{3, 1, 3, 0},
	{0}, // UNUSED
	{2, 0, 3, 1},
	{2, 1, 3, 1},
	{2, 1, 3, 0}
};

static boolean R_CheckBBox(const fixed_t *bspcoord)
{
	angle_t angle1, angle2;
	INT32 sx1, sx2;
	const INT32* check;

	// Find the corners of the box
	// that define the edges from current viewpoint.
	const INT32 boxpos = (viewx <= bspcoord[BOXLEFT]   ? 0 :
						  viewx <  bspcoord[BOXRIGHT]  ? 1 : 2) +
						 (viewy >= bspcoord[BOXTOP]    ? 0 :
						  viewy >  bspcoord[BOXBOTTOM] ? 4 : 8);

	if (boxpos == 5)
		return true;

	check = checkcoord[boxpos];

	// big room fix
	angle1 = R_PointToAngle64(bspcoord[check[0]], bspcoord[check[1]]) - viewangle;
	angle2 = R_PointToAngle64(bspcoord[check[2]], bspcoord[check[3]]) - viewangle;

	// cph - replaced old code, which was unclear and badly commented
	// Much more efficient code now
	if ((signed)angle1 < (signed)angle2) /* it's "behind" us */
	{
		/* Either angle1 or angle2 is behind us, so it doesn't matter if we
		 * change it to the corect sign
		 */
		if ((angle1 >= ANGLE_180) && (angle1 < ANGLE_270))
			angle1 = ANGLE_180-1;
		else
			angle2 = ANGLE_180;
	}

	if ((signed)angle2 >= (signed)clipangle)  return false;                // Both off left edge
	if ((signed)angle1 <= -(signed)clipangle) return false;                // Both off right edge
	if ((signed)angle1 >= (signed)clipangle)  angle1 = clipangle;          // Clip at left edge
	if ((signed)angle2 <= -(signed)clipangle) angle2 = -(signed)clipangle; // Clip at right edge

	// Find the first clippost that touches the source post (adjacent pixels are touching).
	angle1 = (angle1+ANGLE_90)>>ANGLETOFINESHIFT;
	angle2 = (angle2+ANGLE_90)>>ANGLETOFINESHIFT;
	sx1 = viewangletox[angle1];
	sx2 = viewangletox[angle2];

	// Does not cross a pixel.
	if (sx1 >= sx2)
		return false;

	if (!memchr(solidcol+sx1, 0, sx2-sx1))
	{
		// All columns it covers are already solidly covered
		return false;
	}

	return true;
}

size_t numpolys;        // number of polyobjects in current subsector
size_t num_po_ptrs;     // number of polyobject pointers allocated
polyobj_t **po_ptrs;    // temp ptr array to sort polyobject pointers

//
// R_PolyobjCompare
//
// Callback for qsort that compares the z distance of two polyobjects.
// Returns the difference such that the closer polyobject will be
// sorted first.
//
static int R_PolyobjCompare(const void *p1, const void *p2)
{
	const polyobj_t *po1 = *(const polyobj_t * const *)p1;
	const polyobj_t *po2 = *(const polyobj_t * const *)p2;

	return po1->zdist - po2->zdist;
}

//
// R_SortPolyObjects
//
// haleyjd 03/03/06: Here's the REAL meat of Eternity's polyobject system.
// Hexen just figured this was impossible, but as mentioned in polyobj.c,
// it is perfectly doable within the confines of the BSP tree. Polyobjects
// must be sorted to draw in DOOM's front-to-back order within individual
// subsectors. This is a modified version of R_SortVisSprites.
//
void R_SortPolyObjects(subsector_t *sub)
{
	if (numpolys)
	{
		polyobj_t *po;
		INT32 i = 0;

		// allocate twice the number needed to minimize allocations
		if (num_po_ptrs < numpolys*2)
		{
			// use free instead realloc since faster (thanks Lee ^_^)
			free(po_ptrs);
			po_ptrs = static_cast<polyobj_t**>(malloc((num_po_ptrs = numpolys*2)* sizeof(*po_ptrs)));
		}

		po = sub->polyList;

		while (po)
		{
			po->zdist = R_PointToDist2(viewx, viewy,
				po->centerPt.x, po->centerPt.y);
			po_ptrs[i++] = po;
			po = (polyobj_t *)(po->link.next);
		}

		// the polyobjects are NOT in any particular order, so use qsort
		// 03/10/06: only bother if there are actually polys to sort
		if (numpolys >= 2)
		{
			qs22j(po_ptrs, numpolys, sizeof(polyobj_t *), R_PolyobjCompare);
		}
	}
}

//
// R_PolysegCompare
//
// Callback for qsort to sort the segs of a polyobject. Returns such that the
// closer one is sorted first. I sure hope this doesn't break anything. -Red
//
static int R_PolysegCompare(const void *p1, const void *p2)
{
	const seg_t *seg1 = *(const seg_t * const *)p1;
	const seg_t *seg2 = *(const seg_t * const *)p2;
	fixed_t dist1v1, dist1v2, dist2v1, dist2v2;

	// TODO might be a better way to get distance?
#define pdist(x, y) (FixedMul(R_PointToDist(x, y), FINECOSINE((R_PointToAngle(x, y)-viewangle)>>ANGLETOFINESHIFT))+0xFFFFFFF)
#define vxdist(v) pdist(v->x, v->y)

	dist1v1 = vxdist(seg1->v1);
	dist1v2 = vxdist(seg1->v2);
	dist2v1 = vxdist(seg2->v1);
	dist2v2 = vxdist(seg2->v2);

	if (std::min(dist1v1, dist1v2) != std::min(dist2v1, dist2v2))
		return std::min(dist1v1, dist1v2) - std::min(dist2v1, dist2v2);

	{ // That didn't work, so now let's try this.......
		fixed_t delta1, delta2, x1, y1, x2, y2;
		vertex_t *near1, *near2, *far1, *far2; // wherever you are~

		delta1 = R_PointToDist2(seg1->v1->x, seg1->v1->y, seg1->v2->x, seg1->v2->y);
		delta2 = R_PointToDist2(seg2->v1->x, seg2->v1->y, seg2->v2->x, seg2->v2->y);

		delta1 = FixedDiv(128<<FRACBITS, delta1);
		delta2 = FixedDiv(128<<FRACBITS, delta2);

		if (dist1v1 < dist1v2)
		{
			near1 = seg1->v1;
			far1 = seg1->v2;
		}
		else
		{
			near1 = seg1->v2;
			far1 = seg1->v1;
		}

		if (dist2v1 < dist2v2)
		{
			near2 = seg2->v1;
			far2 = seg2->v2;
		}
		else
		{
			near2 = seg2->v2;
			far2 = seg2->v1;
		}

		x1 = near1->x + FixedMul(far1->x-near1->x, delta1);
		y1 = near1->y + FixedMul(far1->y-near1->y, delta1);

		x2 = near2->x + FixedMul(far2->x-near2->x, delta2);
		y2 = near2->y + FixedMul(far2->y-near2->y, delta2);

		return pdist(x1, y1)-pdist(x2, y2);
	}
#undef vxdist
#undef pdist
}

//
// R_AddPolyObjects
//
// haleyjd 02/19/06
// Adds all segs in all polyobjects in the given subsector.
//
static void R_AddPolyObjects(subsector_t *sub)
{
	polyobj_t *po = sub->polyList;
	size_t i, j;

	numpolys = 0;

	// count polyobjects
	while (po)
	{
		++numpolys;
		po = (polyobj_t *)(po->link.next);
	}

	g_portal = NULL;

	// for render stats
	ps_numpolyobjects.value.i += numpolys;

	// sort polyobjects
	R_SortPolyObjects(sub);

	// render polyobjects
	for (i = 0; i < numpolys; ++i)
	{
		qs22j(po_ptrs[i]->segs, po_ptrs[i]->segCount, sizeof(seg_t *), R_PolysegCompare);

		for (j = 0; j < po_ptrs[i]->segCount; ++j)
		{
			seg_t *seg = po_ptrs[i]->segs[j];

			if (!(seg->polyseg->flags & POF_RENDERSIDES))
				continue;

			R_AddLine(seg);
		}
	}
}

//
// R_Subsector
// Determine floor/ceiling planes.
// Add sprites of things in sector.
// Draw one or more line segments.
//

drawseg_t *firstseg;

static void R_Subsector(size_t num)
{
	INT32 count, floorlightlevel, ceilinglightlevel, light;
	seg_t *line;
	subsector_t *sub;
	static sector_t tempsec; // Deep water hack
	extracolormap_t *floorcolormap;
	extracolormap_t *ceilingcolormap;
	fixed_t floorcenterz, ceilingcenterz;
	ffloor_t *rover;

	// subsectors added at run-time
	if (num >= numsubsectors)
	{
#ifdef RANGECHECK
		I_Error("R_Subsector: ss %s with numss = %s\n", sizeu1(num), sizeu2(numsubsectors));
#else
		return;
#endif
	}

	sub = &subsectors[num];
	frontsector = sub->sector;
	count = sub->numlines;
	line = &segs[sub->firstline];

	// Deep water/fake ceiling effect.
	frontsector = R_FakeFlat(frontsector, &tempsec, &floorlightlevel, &ceilinglightlevel, false);

	floorcolormap = ceilingcolormap = frontsector->extra_colormap;

	floorcenterz   = P_GetSectorFloorZAt(frontsector, frontsector->soundorg.x, frontsector->soundorg.y);
	ceilingcenterz = P_GetSectorCeilingZAt(frontsector, frontsector->soundorg.x, frontsector->soundorg.y);

	// Check and prep all 3D floors. Set the sector floor/ceiling light levels and colormaps.
	if (frontsector->ffloors)
	{
		boolean anyMoved = frontsector->moved;

		if (anyMoved == false)
		{
			for (rover = frontsector->ffloors; rover; rover = rover->next)
			{
				if (!(rover->flags & FF_EXISTS) || !(rover->flags & FF_RENDERPLANES))
					continue;

				const sector_t *controlSec = &sectors[rover->secnum];

				if (controlSec->moved != true)
					continue;

				anyMoved = true;
				break;
			}
		}

		if (anyMoved == true)
		{
			frontsector->numlights = sub->sector->numlights = 0;
			R_Prep3DFloors(frontsector, ceilingcenterz);
			sub->sector->lightlist = frontsector->lightlist;
			sub->sector->numlights = frontsector->numlights;
			sub->sector->moved = frontsector->moved = false;
		}

		light = R_GetPlaneLight(frontsector, floorcenterz, false);
		if (frontsector->floorlightsec == -1)
			floorlightlevel = *frontsector->lightlist[light].lightlevel;
		floorcolormap = frontsector->lightlist[light].extra_colormap;
		light = R_GetPlaneLight(frontsector, ceilingcenterz, false);
		if (frontsector->ceilinglightsec == -1)
			ceilinglightlevel = *frontsector->lightlist[light].lightlevel;
		ceilingcolormap = frontsector->lightlist[light].extra_colormap;
	}

	sub->sector->extra_colormap = frontsector->extra_colormap;

	if (P_GetSectorFloorZAt(frontsector, viewx, viewy) < viewz
		|| frontsector->floorpic == skyflatnum
		|| (frontsector->heightsec != -1 && sectors[frontsector->heightsec].ceilingpic == skyflatnum))
	{
		floorplane = R_FindPlane(frontsector->floorheight, frontsector->floorpic, floorlightlevel,
			frontsector->floor_xoffs, frontsector->floor_yoffs, frontsector->floorpic_angle, floorcolormap, NULL
			, NULL
			, frontsector->f_slope
			, R_NoEncore(frontsector, false), false, frontsector);
	}
	else
		floorplane = NULL;

	if (P_GetSectorCeilingZAt(frontsector, viewx, viewy) > viewz
		|| frontsector->ceilingpic == skyflatnum
		|| (frontsector->heightsec != -1 && sectors[frontsector->heightsec].floorpic == skyflatnum))
	{
		ceilingplane = R_FindPlane(frontsector->ceilingheight, frontsector->ceilingpic,
			ceilinglightlevel, frontsector->ceiling_xoffs, frontsector->ceiling_yoffs, frontsector->ceilingpic_angle,
			ceilingcolormap, NULL
			, NULL
			, frontsector->c_slope
			, R_NoEncore(frontsector, true), true, frontsector);
	}
	else
		ceilingplane = NULL;

	numffloors = 0;
	visffloor[numffloors].slope = NULL;
	visffloor[numffloors].plane = NULL;
	visffloor[numffloors].polyobj = NULL;

	if (frontsector->ffloors)
	{
		fixed_t heightcheck, planecenterz;

		for (rover = frontsector->ffloors; rover && numffloors < MAXFFLOORS; rover = rover->next)
		{
			if (!(rover->flags & FF_EXISTS) || !(rover->flags & FF_RENDERPLANES) || !(rover->flags & FF_RENDERALL))
				continue;

			if (frontsector->cullheight)
			{
				if (R_DoCulling(frontsector->cullheight, viewsector->cullheight, viewz, *rover->bottomheight, *rover->topheight))
				{
					rover->norender = leveltime;
					continue;
				}
			}

			visffloor[numffloors].plane = NULL;
			visffloor[numffloors].polyobj = NULL;

			heightcheck  = P_GetFFloorBottomZAt(rover, viewx, viewy);
			planecenterz = P_GetFFloorBottomZAt(rover, frontsector->soundorg.x, frontsector->soundorg.y);

			if (planecenterz <= ceilingcenterz
				&& planecenterz >= floorcenterz
				&& ((viewz < heightcheck && !(rover->flags & FF_INVERTPLANES))
				|| (viewz > heightcheck && (rover->flags & FF_BOTHPLANES))))
			{
				light = R_GetPlaneLight(frontsector, planecenterz,
					viewz < heightcheck);

				visffloor[numffloors].plane = R_FindPlane(
					*rover->bottomheight, *rover->bottompic,
					*frontsector->lightlist[light].lightlevel,
					*rover->bottomxoffs, *rover->bottomyoffs, *rover->bottomangle,
					frontsector->lightlist[light].extra_colormap, rover
					, NULL
					, *rover->b_slope
					, R_NoEncore(rover->master->frontsector, true), true, frontsector
				);

				visffloor[numffloors].slope = *rover->b_slope;

				// Tell the renderer this sector has slopes in it.
				if (visffloor[numffloors].slope)
					frontsector->hasslope = true;

				visffloor[numffloors].height = heightcheck;
				visffloor[numffloors].ffloor = rover;
				numffloors++;
			}

			if (numffloors >= MAXFFLOORS)
				break;

			visffloor[numffloors].plane = NULL;
			visffloor[numffloors].polyobj = NULL;

			heightcheck  = P_GetFFloorTopZAt(rover, viewx, viewy);
			planecenterz = P_GetFFloorTopZAt(rover, frontsector->soundorg.x, frontsector->soundorg.y);

			if (planecenterz >= floorcenterz
				&& planecenterz <= ceilingcenterz
				&& ((viewz > heightcheck && !(rover->flags & FF_INVERTPLANES))
				|| (viewz < heightcheck && (rover->flags & FF_BOTHPLANES))))
			{
				light = R_GetPlaneLight(frontsector, planecenterz, viewz < heightcheck);

				visffloor[numffloors].plane = R_FindPlane(
					*rover->topheight, *rover->toppic,
					*frontsector->lightlist[light].lightlevel,
					*rover->topxoffs, *rover->topyoffs, *rover->topangle,
					frontsector->lightlist[light].extra_colormap, rover
					, NULL
					, *rover->t_slope
					, R_NoEncore(rover->master->frontsector, false), false, frontsector
				);

				visffloor[numffloors].slope = *rover->t_slope;

				// Tell the renderer this sector has slopes in it.
				if (visffloor[numffloors].slope)
					frontsector->hasslope = true;

				visffloor[numffloors].height = heightcheck;
				visffloor[numffloors].ffloor = rover;
				numffloors++;
			}
		}
	}

	// Polyobjects have planes, too!
	if (sub->polyList)
	{
		polyobj_t *po = sub->polyList;
		sector_t *polysec;

		while (po)
		{
			if (numffloors >= MAXFFLOORS)
				break;

			if (!(po->flags & POF_RENDERPLANES)) // Don't draw planes
			{
				po = (polyobj_t *)(po->link.next);
				continue;
			}

			polysec = po->lines[0]->backsector;
			visffloor[numffloors].plane = NULL;

			if (polysec->floorheight <= ceilingcenterz
				&& polysec->floorheight >= floorcenterz
				&& (viewz < polysec->floorheight))
			{
				light = R_GetPlaneLight(frontsector, polysec->floorheight, viewz < polysec->floorheight);
				visffloor[numffloors].plane = R_FindPlane(polysec->floorheight, polysec->floorpic,
					(light == -1 ? frontsector->lightlevel : *frontsector->lightlist[light].lightlevel), polysec->floor_xoffs, polysec->floor_yoffs,
					polysec->floorpic_angle-po->angle,
					(light == -1 ? frontsector->extra_colormap : frontsector->lightlist[light].extra_colormap), NULL, po
					,NULL // will ffloors be slopable eventually?
					, R_NoEncore(polysec, false), false, frontsector);

				visffloor[numffloors].height = polysec->floorheight;
				visffloor[numffloors].polyobj = po;
				visffloor[numffloors].slope = NULL;
//				visffloor[numffloors].ffloor = rover;
				po->visplane = visffloor[numffloors].plane;
				numffloors++;
			}

			if (numffloors >= MAXFFLOORS)
				break;

			visffloor[numffloors].plane = NULL;

			if (polysec->ceilingheight >= floorcenterz
				&& polysec->ceilingheight <= ceilingcenterz
				&& (viewz > polysec->ceilingheight))
			{
				light = R_GetPlaneLight(frontsector, polysec->floorheight, viewz < polysec->floorheight);
				visffloor[numffloors].plane = R_FindPlane(polysec->ceilingheight, polysec->ceilingpic,
					(light == -1 ? frontsector->lightlevel : *frontsector->lightlist[light].lightlevel), polysec->ceiling_xoffs, polysec->ceiling_yoffs, polysec->ceilingpic_angle-po->angle,
					(light == -1 ? frontsector->extra_colormap : frontsector->lightlist[light].extra_colormap), NULL, po
					,NULL // will ffloors be slopable eventually?
					, R_NoEncore(polysec, true), false, frontsector);

				visffloor[numffloors].polyobj = po;
				visffloor[numffloors].height = polysec->ceilingheight;
				visffloor[numffloors].slope = NULL;
//				visffloor[numffloors].ffloor = rover;
				po->visplane = visffloor[numffloors].plane;
				numffloors++;
			}

			po = (polyobj_t *)(po->link.next);
		}
	}

#ifdef FLOORSPLATS
	if (sub->splats)
		R_AddVisibleFloorSplats(sub);
#endif

   // killough 9/18/98: Fix underwater slowdown, by passing real sector
   // instead of fake one. Improve sprite lighting by basing sprite
   // lightlevels on floor & ceiling lightlevels in the surrounding area.
   //
   // 10/98 killough:
   //
   // NOTE: TeamTNT fixed this bug incorrectly, messing up sprite lighting!!!
   // That is part of the 242 effect!!!  If you simply pass sub->sector to
   // the old code you will not get correct lighting for underwater sprites!!!
   // Either you must pass the fake sector and handle validcount here, on the
   // real sector, or you must account for the lighting in some other way,
   // like passing it as an argument.
	R_AddSprites(sub->sector, (floorlightlevel+ceilinglightlevel)/2);

	firstseg = NULL;

	// haleyjd 02/19/06: draw polyobjects before static lines
	if (sub->polyList)
		R_AddPolyObjects(sub);

	while (count--)
	{
//		CONS_Debug(DBG_GAMELOGIC, "Adding normal line %d...(%d)\n", line->linedef-lines, leveltime);
		if (!line->polyseg) // ignore segs that belong to polyobjects
			R_AddLine(line);
		line++;
		curline = NULL; /* cph 2001/11/18 - must clear curline now we're done with it, so stuff doesn't try using it for other things */
	}
}

//
// R_Prep3DFloors
//
// This function creates the lightlists that the given sector uses to light
// floors/ceilings/walls according to the 3D floors.
void R_Prep3DFloors(sector_t *sector, fixed_t secceilz)
{
	ffloor_t *rover;
	ffloor_t *best;
	fixed_t bestheight, maxheight;
	INT32 count, i;
	sector_t *sec;
	pslope_t *bestslope = NULL;
	fixed_t heighttest; // I think it's better to check the Z height at the sector's center
	                    // than assume unsloped heights are accurate indicators of order in sloped sectors. -Red

	count = 1;
	for (rover = sector->ffloors; rover; rover = rover->next)
	{
		if ((rover->flags & FF_EXISTS) && (!(rover->flags & FF_NOSHADE)
			|| (rover->flags & FF_CUTLEVEL) || (rover->flags & FF_CUTSPRITES)))
		{
			count++;
			if (rover->flags & FF_DOUBLESHADOW)
				count++;
		}
	}

	if (count != sector->numlights)
	{
		Z_Free(sector->lightlist);
		sector->lightlist = static_cast<lightlist_t*>(Z_Malloc(sizeof(*sector->lightlist) * count, PU_LEVEL, NULL));
		sector->numlights = count;
	}

	memset(sector->lightlist, 0, sizeof(lightlist_t) * count);

	heighttest = secceilz; // sector ceiling z

	sector->lightlist[0].height = heighttest + 1;
	sector->lightlist[0].slope = sector->c_slope;
	sector->lightlist[0].lightlevel = &sector->lightlevel;
	sector->lightlist[0].caster = NULL;
	sector->lightlist[0].extra_colormap = sector->extra_colormap;
	sector->lightlist[0].flags = 0;

	maxheight = INT32_MAX;
	for (i = 1; i < count; i++)
	{
		bestheight = INT32_MAX * -1;
		best = NULL;
		for (rover = sector->ffloors; rover; rover = rover->next)
		{
			rover->lastlight = 0;
			if (!(rover->flags & FF_EXISTS) || (rover->flags & FF_NOSHADE
				&& !(rover->flags & FF_CUTLEVEL) && !(rover->flags & FF_CUTSPRITES)))
				continue;

			heighttest = P_GetFFloorTopZAt(rover, sector->soundorg.x, sector->soundorg.y);

			if (heighttest > bestheight && heighttest < maxheight)
			{
				best = rover;
				bestheight = heighttest;
				bestslope = *rover->t_slope;
				continue;
			}

			if (rover->flags & FF_DOUBLESHADOW)
			{
				heighttest = P_GetFFloorBottomZAt(rover, sector->soundorg.x, sector->soundorg.y);

				if (heighttest > bestheight
					&& heighttest < maxheight)
				{
					best = rover;
					bestheight = heighttest;
					bestslope = *rover->b_slope;
					continue;
				}
			}
		}

		if (!best)
		{
			sector->numlights = i;
			return;
		}

		sector->lightlist[i].height = maxheight = bestheight;
		sector->lightlist[i].caster = best;
		sector->lightlist[i].flags = best->flags;
		sector->lightlist[i].slope = bestslope;
		sec = &sectors[best->secnum];

		if (best->flags & FF_NOSHADE)
		{
			sector->lightlist[i].lightlevel = sector->lightlist[i-1].lightlevel;
			sector->lightlist[i].extra_colormap = sector->lightlist[i-1].extra_colormap;
		}
		else if (best->flags & FF_COLORMAPONLY)
		{
			sector->lightlist[i].lightlevel = sector->lightlist[i-1].lightlevel;
			sector->lightlist[i].extra_colormap = sec->extra_colormap;
		}
		else
		{
			sector->lightlist[i].lightlevel = best->toplightlevel;
			sector->lightlist[i].extra_colormap = sec->extra_colormap;
		}

		if (best->flags & FF_DOUBLESHADOW)
		{
			heighttest = P_GetFFloorBottomZAt(best, sector->soundorg.x, sector->soundorg.y);

			if (bestheight == heighttest) ///TODO: do this in a more efficient way -Red
			{
				sector->lightlist[i].lightlevel = sector->lightlist[best->lastlight].lightlevel;
				sector->lightlist[i].extra_colormap =
					sector->lightlist[best->lastlight].extra_colormap;
			}
			else
				best->lastlight = i - 1;
		}
	}
}

INT32 R_GetPlaneLight(sector_t *sector, fixed_t planeheight, boolean underside)
{
	INT32 i;

	if (!underside)
	{
		for (i = 1; i < sector->numlights; i++)
			if (sector->lightlist[i].height <= planeheight)
				return i - 1;

		return sector->numlights - 1;
	}

	for (i = 1; i < sector->numlights; i++)
		if (sector->lightlist[i].height < planeheight)
			return i - 1;

	return sector->numlights - 1;
}

//
// RenderBSPNode
// Renders all subsectors below a given node,
//  traversing subtree recursively.
// Just call with BSP root.
//
// killough 5/2/98: reformatted, removed tail recursion

void R_RenderBSPNode(INT32 bspnum)
{
	const node_t *bsp;
	INT32 side;

	ps_numbspcalls.value.i++;

	while (!(bspnum & NF_SUBSECTOR))  // Found a subsector?
	{
		bsp = &nodes[bspnum];

		// Decide which side the view point is on.
		side = R_PointOnSideFast(viewx, viewy, bsp);
		// Recursively divide front space.
		R_RenderBSPNode(bsp->children[side]);

		// Possibly divide back space.
		if (!R_CheckBBox(bsp->bbox[side^1]))
			return;

		bspnum = bsp->children[side^1];
	}

	// PORTAL CULLING
	if (portalcullsector)
	{
		if (subsectors[bspnum & ~NF_SUBSECTOR].sector != portalcullsector)
			return;
		portalcullsector = NULL;
	}

	R_Subsector(bspnum == -1 ? 0 : bspnum & ~NF_SUBSECTOR);
}