/*
			===== IDBSP - id Software's BSP builder for DOOM ====
	DOS port (c) 1994 Ron Rossbach (ej070@cleveland.freenet.edu)

	File SAVEBLCK.C
		Implements functions which build the BLOCKMAP resource.

*/

#include "idbsp.h"
#define BLOCKSIZE       128

short   datalist[0x10000], *data_p;
float   orgx, orgy;
float   xl, xh, yl, yh;

/*
===============================================================================
=
= LineContact
=
===============================================================================
*/
boolean LineContact (worldline_t *wl)
{
	NXPoint         *p1, *p2, pt1, pt2;
	float           lxl, lxh, lyl, lyh;
	divline_t       ld;
	int             s1,s2;

	p1 = &wl->p1;
	p2 = &wl->p2;
	ld.pt.x = p1->x;
	ld.pt.y = p1->y;
	ld.dx = p2->x - p1->x;
	ld.dy = p2->y - p1->y;

	if (p1->x < p2->x)
		{
		lxl = p1->x;
		lxh = p2->x;
		}
	else
		{
		lxl = p2->x;
		lxh = p1->x;
		}
	if (p1->y < p2->y)
		{
		lyl = p1->y;
		lyh = p2->y;
		}
	else
		{
		lyl = p2->y;
		lyh = p1->y;
		}

	if (lxl >= xh || lxh < xl || lyl >= yh || lyh < yl)
		return false;   /* no bbox intersections */

	if ( ld.dy / ld.dx > 0)
		{       /* positive slope */
		pt1.x = xl;
		pt1.y = yh;
		pt2.x = xh;
		pt2.y = yl;
		}
	else
		{       /* negetive slope */
		pt1.x = xh;
		pt1.y = yh;
		pt2.x = xl;
		pt2.y = yl;
		}

	s1 = PointOnSide (&pt1, &ld);
	s2 = PointOnSide (&pt2, &ld);

	return s1 != s2;
}

/*
===============================================================================
=
= GenerateBlocklist
=
===============================================================================
*/
void GenerateBlockList(int x, int y)
{
	NXRect          r;
	worldline_t     *wl;
	int             count, i;

	*data_p++ = 0;          /* leave space for thing links */

	xl = orgx + x*BLOCKSIZE;
	xh = xl+BLOCKSIZE;
	yl = orgy + y*BLOCKSIZE;
	yh = yl+BLOCKSIZE;

	r.origin.x = xl;
	r.origin.y = yl;
	r.size.width = r.size.height = BLOCKSIZE;

	count = linestore_i->count;
	wl = linestore_i->data;

	for (i=0 ; i<count ; i++,wl++)
		{
		if (wl->p1.x == wl->p2.x)
			{       /* vertical */
			if (wl->p1.x < xl || wl->p1.x >= xh)
				continue;
			if (wl->p1.y < wl->p2.y)
				{
				if (wl->p1.y >= yh || wl->p2.y < yl)
					continue;
				}
			else
				{
				if (wl->p2.y >= yh || wl->p1.y < yl)
					continue;
				}
			*data_p++ = i;
			continue;
			}
		if (wl->p1.y == wl->p2.y)
			{       /* horizontal */
			if (wl->p1.y < yl || wl->p1.y >= yh)
				continue;
			if (wl->p1.x < wl->p2.x)
				{
				if (wl->p1.x >= xh || wl->p2.x < xl)
					continue;
				}
			else
				{
				if (wl->p2.x >= xh || wl->p1.x < xl)
					continue;
				}
			*data_p++ = i;
			continue;
			}
		/* diagonal */
		if (LineContact (wl) )
			*data_p++ = i;
		}

	*data_p++ = -1;         /* end of list marker */
}

/*
===============================================================================
=
= SaveBlocks
=
=	block lump holds:
=	orgx
=	orgy
=	blockwidth
=	blockheight
=	listoffset[blockwidth*blockheight]
=	lists
=				one short left blank for thing list
=				linedef numbers
=				-1 terminator
=
===============================================================================
*/
void SaveBlocks (void)
{
	int       blockwidth, blockheight;
	int       x,y, len;
	short   	*pointer_p;

	blockwidth = (worldbounds.size.width+BLOCKSIZE-1)/BLOCKSIZE;
	blockheight = (worldbounds.size.height+BLOCKSIZE-1)/BLOCKSIZE;
	orgx = worldbounds.origin.x;
	orgy = worldbounds.origin.y;

	pointer_p = datalist;
	*pointer_p++ = orgx;
	*pointer_p++ = orgy;
	*pointer_p++ = blockwidth;
	*pointer_p++ = blockheight;

	data_p = pointer_p + blockwidth*blockheight;

	for (y=0 ; y<blockheight ; y++)
		for (x=0 ; x<blockwidth ; x++)
			{
			len = data_p - datalist;
			*pointer_p++ = len;
			GenerateBlockList (x,y);
			}

	len = 2*(data_p-datalist);

	printf ("blockmap: (%i, %i) = %i\n",blockwidth, blockheight, len);
	addName("blockmap", datalist, len);
}