//**************************************************************************
//**
//** r_plane.c : Heretic 2 : Raven Software, Corp.
//**
//** $RCSfile: r_plane.c,v $
//** $Revision: 1.5 $
//** $Date: 95/07/13 15:17:12 $
//** $Author: cjr $
//**
//**************************************************************************

// HEADER FILES ------------------------------------------------------------

#include "h2def.h"
#include "r_local.h"

// MACROS ------------------------------------------------------------------

// TYPES -------------------------------------------------------------------

// EXTERNAL FUNCTION PROTOTYPES --------------------------------------------

// PUBLIC FUNCTION PROTOTYPES ----------------------------------------------

// PRIVATE FUNCTION PROTOTYPES ---------------------------------------------

// EXTERNAL DATA DECLARATIONS ----------------------------------------------

extern fixed_t Sky1ScrollDelta;
extern fixed_t Sky2ScrollDelta;

// PUBLIC DATA DEFINITIONS -------------------------------------------------

int Sky1Texture;
int Sky2Texture;
fixed_t Sky1ColumnOffset;
fixed_t Sky2ColumnOffset;
int skyflatnum;
int skytexturemid;
fixed_t skyiscale;
boolean DoubleSky;
planefunction_t floorfunc, ceilingfunc;

// Opening
visplane_t visplanes[MAXVISPLANES], *lastvisplane;
visplane_t *floorplane, *ceilingplane;
short openings[MAXOPENINGS], *lastopening;

// Clip values are the solid pixel bounding the range.
// floorclip start out SCREENHEIGHT
// ceilingclip starts out -1
short floorclip[SCREENWIDTH];
short ceilingclip[SCREENWIDTH];

// spanstart holds the start of a plane span, initialized to 0
int spanstart[SCREENHEIGHT];
int spanstop[SCREENHEIGHT];

// Texture mapping
lighttable_t **planezlight;
fixed_t planeheight;
fixed_t yslope[SCREENHEIGHT];
fixed_t distscale[SCREENWIDTH];
fixed_t basexscale, baseyscale;
fixed_t cachedheight[SCREENHEIGHT];
fixed_t cacheddistance[SCREENHEIGHT];
fixed_t cachedxstep[SCREENHEIGHT];
fixed_t cachedystep[SCREENHEIGHT];

// PRIVATE DATA DEFINITIONS ------------------------------------------------

// CODE --------------------------------------------------------------------

//==========================================================================
//
// R_InitSky
//
// Called at level load.
//
//==========================================================================

void R_InitSky(int map)
{
	Sky1Texture = P_GetMapSky1Texture(map);
	Sky2Texture = P_GetMapSky2Texture(map);
	Sky1ScrollDelta = P_GetMapSky1ScrollDelta(map);
	Sky2ScrollDelta = P_GetMapSky2ScrollDelta(map);
	Sky1ColumnOffset = 0;
	Sky2ColumnOffset = 0;
	DoubleSky = P_GetMapDoubleSky(map);
}

//==========================================================================
//
// R_InitSkyMap
//
// Called whenever the view size changes.
//
//==========================================================================

void R_InitSkyMap(void)
{
	skyflatnum = R_FlatNumForName("F_SKY");
	skytexturemid = 200*FRACUNIT;
	skyiscale = FRACUNIT;
}

//==========================================================================
//
// R_InitPlanes
//
// Called at game startup.
//
//==========================================================================

void R_InitPlanes(void)
{
}

//==========================================================================
//
// R_MapPlane
//
// Globals used: planeheight, ds_source, basexscale, baseyscale,
// viewx, viewy.
//
//==========================================================================

void R_MapPlane(int y, int x1, int x2)
{
	angle_t angle;
	fixed_t distance, length;
	unsigned index;

#ifdef RANGECHECK
	if(x2 < x1 || x1 < 0 || x2 >= viewwidth || (unsigned)y > viewheight)
	{
		I_Error("R_MapPlane: %i, %i at %i", x1, x2, y);
	}
#endif

	if(planeheight != cachedheight[y])
	{
		cachedheight[y] = planeheight;
		distance = cacheddistance[y] = FixedMul(planeheight, yslope[y]);
		ds_xstep = cachedxstep[y] = FixedMul(distance, basexscale);
		ds_ystep = cachedystep[y] = FixedMul(distance, baseyscale);
	}
	else
	{
		distance = cacheddistance[y];
		ds_xstep = cachedxstep[y];
		ds_ystep = cachedystep[y];
	}
	
	length = FixedMul(distance, distscale[x1]);
	angle = (viewangle+xtoviewangle[x1])>>ANGLETOFINESHIFT;
	ds_xfrac = viewx+FixedMul(finecosine[angle], length);
	ds_yfrac = -viewy-FixedMul(finesine[angle], length);

	if(fixedcolormap)
	{
		ds_colormap = fixedcolormap;
	}
	else
	{
		index = distance >> LIGHTZSHIFT;
		if(index >= MAXLIGHTZ )
		{
			index = MAXLIGHTZ-1;
		}
		ds_colormap = planezlight[index];
	}

	ds_y = y;
	ds_x1 = x1;
	ds_x2 = x2;

	spanfunc(); // High or low detail
}

//==========================================================================
//
// R_ClearPlanes
//
// Called at the beginning of each frame.
//
//==========================================================================

void R_ClearPlanes(void)
{
	int i;
	angle_t angle;

	// Opening / clipping determination
	for(i = 0; i < viewwidth; i++)
	{
		floorclip[i] = viewheight;
		ceilingclip[i] = -1;
	}

	lastvisplane = visplanes;
	lastopening = openings;

	// Texture calculation
	memset(cachedheight, 0, sizeof(cachedheight));	
	angle = (viewangle-ANG90)>>ANGLETOFINESHIFT; // left to right mapping
	// Scale will be unit scale at SCREENWIDTH/2 distance
	basexscale = FixedDiv(finecosine[angle], centerxfrac);
	baseyscale = -FixedDiv(finesine[angle], centerxfrac);
}

//==========================================================================
//
// R_FindPlane
//
//==========================================================================

visplane_t *R_FindPlane(fixed_t height, int picnum,
	int lightlevel, int special)
{
	visplane_t *check;

	if(special < 150)
	{ // Don't let low specials affect search
		special = 0;
	}

	if(picnum == skyflatnum)
	{ // All skies map together
		height = 0;
		lightlevel = 0;
	}

	for(check = visplanes; check < lastvisplane; check++)
	{
		if(height == check->height
		&& picnum == check->picnum
		&& lightlevel == check->lightlevel
		&& special == check->special)
			break;
	}

	if(check < lastvisplane)
	{
		return(check);
	}

	if(lastvisplane-visplanes == MAXVISPLANES)
	{
		I_Error("R_FindPlane: no more visplanes");
	}

	lastvisplane++;
	check->height = height;
	check->picnum = picnum;
	check->lightlevel = lightlevel;
	check->special = special;
	check->minx = SCREENWIDTH;
	check->maxx = -1;
	memset(check->top, 0xff, sizeof(check->top));
	return(check);
}

//==========================================================================
//
// R_CheckPlane
//
//==========================================================================

visplane_t *R_CheckPlane(visplane_t *pl, int start, int stop)
{
	int intrl, intrh;
	int unionl, unionh;
	int x;

	if(start < pl->minx)
	{
		intrl = pl->minx;
		unionl = start;
	}
	else
	{
		unionl = pl->minx;
		intrl = start;
	}
	if(stop > pl->maxx)
	{
		intrh = pl->maxx;
		unionh = stop;
	}
	else
	{
		unionh = pl->maxx;
		intrh = stop;
	}

	for(x = intrl; x <= intrh; x++)
	{
		if(pl->top[x] != 0xff)
		{
			break;
		}
	}

	if(x > intrh)
	{
		pl->minx = unionl;
		pl->maxx = unionh;
		return pl; // use the same visplane
	}

	// Make a new visplane
	lastvisplane->height = pl->height;
	lastvisplane->picnum = pl->picnum;
	lastvisplane->lightlevel = pl->lightlevel;
	lastvisplane->special = pl->special;
	pl = lastvisplane++;
	pl->minx = start;
	pl->maxx = stop;
	memset(pl->top, 0xff, sizeof(pl->top));

	return pl;
}

//==========================================================================
//
// R_MakeSpans
//
//==========================================================================

void R_MakeSpans(int x, int t1, int b1, int t2, int b2)
{
	while(t1 < t2 && t1 <= b1)
	{
		R_MapPlane(t1, spanstart[t1], x-1);
		t1++;
	}
	while(b1 > b2 && b1 >= t1)
	{
		R_MapPlane(b1, spanstart[b1], x-1);
		b1--;
	}
	while(t2 < t1 && t2 <= b2)
	{
		spanstart[t2] = x;
		t2++;
	}
	while(b2 > b1 && b2 >= t2)
	{
		spanstart[b2] = x;
		b2--;
	}
}

//==========================================================================
//
// R_DrawPlanes
//
//==========================================================================

#define SKYTEXTUREMIDSHIFTED 200

void R_DrawPlanes(void)
{
	visplane_t *pl;
	int light;
	int x, stop;
	int angle;
	byte *tempSource;
	byte *source;
	byte *source2;
	byte *dest;
	int count;
	int offset;
	int skyTexture;
	int offset2;
	int skyTexture2;
	int scrollOffset;

	extern byte *ylookup[MAXHEIGHT];
	extern int columnofs[MAXWIDTH];

#ifdef RANGECHECK
	if(ds_p-drawsegs > MAXDRAWSEGS)
	{
		I_Error("R_DrawPlanes: drawsegs overflow (%i)", ds_p-drawsegs);
	}
	if(lastvisplane-visplanes > MAXVISPLANES)
	{
		I_Error("R_DrawPlanes: visplane overflow (%i)",
			lastvisplane-visplanes);
	}
	if(lastopening-openings > MAXOPENINGS)
	{
		I_Error("R_DrawPlanes: opening overflow (%i)",
			lastopening-openings);
	}
#endif

	for(pl = visplanes; pl < lastvisplane; pl++)
	{
		if(pl->minx > pl->maxx)
		{
			continue;
		}
		if(pl->picnum == skyflatnum)
		{ // Sky flat
			if(DoubleSky)
			{ // Render 2 layers, sky 1 in front
				offset = Sky1ColumnOffset>>16;
				skyTexture = texturetranslation[Sky1Texture];
				offset2 = Sky2ColumnOffset>>16;
				skyTexture2 = texturetranslation[Sky2Texture];
				for(x = pl->minx; x <= pl->maxx; x++)
				{
					dc_yl = pl->top[x];
					dc_yh = pl->bottom[x];
					if(dc_yl <= dc_yh)
					{
						count = dc_yh-dc_yl;
						if(count < 0)
						{
							return;
						}
						angle = (viewangle+xtoviewangle[x])
							>>ANGLETOSKYSHIFT;
						source = R_GetColumn(skyTexture, angle+offset)
							+SKYTEXTUREMIDSHIFTED+(dc_yl-centery);
						source2 = R_GetColumn(skyTexture2, angle+offset2)
							+SKYTEXTUREMIDSHIFTED+(dc_yl-centery);
						dest = ylookup[dc_yl]+columnofs[x];
						do
						{
							if(*source)
							{
								*dest = *source++;
								source2++;
							}
							else
							{
								*dest = *source2++;
								source++;
							}
							dest += SCREENWIDTH;
						} while(count--);
					}
				}
				continue; // Next visplane
			}
			else
			{ // Render single layer
				if(pl->special == 200)
				{ // Use sky 2
					offset = Sky2ColumnOffset>>16;
					skyTexture = texturetranslation[Sky2Texture];
				}
				else
				{ // Use sky 1
					offset = Sky1ColumnOffset>>16;
					skyTexture = texturetranslation[Sky1Texture];
				}
				for(x = pl->minx; x <= pl->maxx; x++)
				{
					dc_yl = pl->top[x];
					dc_yh = pl->bottom[x];
					if(dc_yl <= dc_yh)
					{
						count = dc_yh-dc_yl;
						if(count < 0)
						{
							return;
						}
						angle = (viewangle+xtoviewangle[x])
							>>ANGLETOSKYSHIFT;
						source = R_GetColumn(skyTexture, angle+offset)
							+SKYTEXTUREMIDSHIFTED+(dc_yl-centery);
						dest = ylookup[dc_yl]+columnofs[x];
						do
						{
							*dest = *source++;
							dest += SCREENWIDTH;
						} while(count--);
					}
				}
				continue; // Next visplane
			}
		}
		// Regular flat
		tempSource = W_CacheLumpNum(firstflat+
			flattranslation[pl->picnum], PU_STATIC);
		scrollOffset = leveltime>>1&63;
		switch(pl->special)
		{ // Handle scrolling flats
			case 201: case 202: case 203: // Scroll_North_xxx
				ds_source = tempSource+((scrollOffset
					<<(pl->special-201)&63)<<6);
				break;
			case 204: case 205: case 206: // Scroll_East_xxx
				ds_source = tempSource+((63-scrollOffset)
					<<(pl->special-204)&63);
				break;
			case 207: case 208: case 209: // Scroll_South_xxx
				ds_source = tempSource+(((63-scrollOffset)
					<<(pl->special-207)&63)<<6);
				break;
			case 210: case 211: case 212: // Scroll_West_xxx
				ds_source = tempSource+(scrollOffset
					<<(pl->special-210)&63);
				break;
			case 213: case 214: case 215: // Scroll_NorthWest_xxx
				ds_source = tempSource+(scrollOffset
					<<(pl->special-213)&63)+((scrollOffset
					<<(pl->special-213)&63)<<6);
				break;
			case 216: case 217: case 218: // Scroll_NorthEast_xxx
				ds_source = tempSource+((63-scrollOffset)
					<<(pl->special-216)&63)+((scrollOffset
					<<(pl->special-216)&63)<<6);
				break;
			case 219: case 220: case 221: // Scroll_SouthEast_xxx
				ds_source = tempSource+((63-scrollOffset)
					<<(pl->special-219)&63)+(((63-scrollOffset)
					<<(pl->special-219)&63)<<6);
				break;
			case 222: case 223: case 224: // Scroll_SouthWest_xxx
				ds_source = tempSource+(scrollOffset
					<<(pl->special-222)&63)+(((63-scrollOffset)
					<<(pl->special-222)&63)<<6);
				break;
			default:
				ds_source = tempSource;
				break;
		}
		planeheight = abs(pl->height-viewz);
		light = (pl->lightlevel >> LIGHTSEGSHIFT)+extralight;
		if(light >= LIGHTLEVELS)
		{
			light = LIGHTLEVELS-1;
		}
		if(light < 0)
		{
			light = 0;
		}
		planezlight = zlight[light];

		pl->top[pl->maxx+1] = 0xff;
		pl->top[pl->minx-1] = 0xff;

		stop = pl->maxx+1;
		for(x = pl->minx; x <= stop; x++)
		{
			R_MakeSpans(x, pl->top[x-1], pl->bottom[x-1],
				pl->top[x], pl->bottom[x]);
		}
		Z_ChangeTag(tempSource, PU_CACHE);
	}
}