// world.c -- world query functions

#include "quakedef.h"

/*

entities never clip against themselves, or their owner

line of sight checks trace->crosscontent, but bullets don't

*/


typedef struct {
    vec3_t boxmins, boxmaxs;	// enclose the test object along entire move
    float *mins, *maxs;		// size of the moving object
    vec3_t mins2, maxs2;	// size when clipping against mosnters
    float *start, *end;
    trace_t trace;
    int type;
    edict_t *passedict;
} moveclip_t;


int SV_HullPointContents(hull_t * hull, int num, vec3_t p);

/*
===============================================================================

HULL BOXES

===============================================================================
*/


static hull_t box_hull;
static dclipnode_t box_clipnodes[6];
static mplane_t box_planes[6];

/*
===================
SV_InitBoxHull

Set up the planes and clipnodes so that the six floats of a bounding box
can just be stored out and get a proper hull_t structure.
===================
*/
void SV_InitBoxHull(void)
{
    int i;
    int side;

    box_hull.clipnodes = box_clipnodes;
    box_hull.planes = box_planes;
    box_hull.firstclipnode = 0;
    box_hull.lastclipnode = 5;

    for (i = 0; i < 6; i++) {
	box_clipnodes[i].planenum = i;

	side = i & 1;

	box_clipnodes[i].children[side] = CONTENTS_EMPTY;
	if (i != 5)
	    box_clipnodes[i].children[side ^ 1] = i + 1;
	else
	    box_clipnodes[i].children[side ^ 1] = CONTENTS_SOLID;

	box_planes[i].type = i >> 1;
	box_planes[i].normal[i >> 1] = 1;
    }

}


/*
===================
SV_HullForBox

To keep everything totally uniform, bounding boxes are turned into small
BSP trees instead of being compared directly.
===================
*/
hull_t *SV_HullForBox(vec3_t mins, vec3_t maxs)
{
    box_planes[0].dist = maxs[0];
    box_planes[1].dist = mins[0];
    box_planes[2].dist = maxs[1];
    box_planes[3].dist = mins[1];
    box_planes[4].dist = maxs[2];
    box_planes[5].dist = mins[2];

    return &box_hull;
}



/*
================
SV_HullForEntity

Returns a hull that can be used for testing or clipping an object of mins/maxs
size.
Offset is filled in to contain the adjustment that must be added to the
testing object's origin to get a point to use with the returned hull.
================
*/
hull_t *SV_HullForEntity(edict_t * ent, vec3_t mins, vec3_t maxs,
			 vec3_t offset)
{
    model_t *model;
    vec3_t size;
    vec3_t hullmins, hullmaxs;
    hull_t *hull;

// decide which clipping hull to use, based on the size
    if (ent->v.solid == SOLID_BSP) {	// explicit hulls in the BSP model
	if (ent->v.movetype != MOVETYPE_PUSH)
	    Sys_Error("SOLID_BSP without MOVETYPE_PUSH");

	model = sv.models[(int) ent->v.modelindex];

	if (!model || model->type != mod_brush)
	    Sys_Error("MOVETYPE_PUSH with a non bsp model");

	VectorSubtract(maxs, mins, size);
	if (size[0] < 3)
	    hull = &model->hulls[0];
	else if (size[0] <= 32)
	    hull = &model->hulls[1];
	else
	    hull = &model->hulls[2];

// calculate an offset value to center the origin
	VectorSubtract(hull->clip_mins, mins, offset);
	VectorAdd(offset, ent->v.origin, offset);
    } else {			// create a temp hull from bounding box sizes

	VectorSubtract(ent->v.mins, maxs, hullmins);
	VectorSubtract(ent->v.maxs, mins, hullmaxs);
	hull = SV_HullForBox(hullmins, hullmaxs);

	VectorCopy(ent->v.origin, offset);
    }


    return hull;
}

/*
===============================================================================

ENTITY AREA CHECKING

===============================================================================
*/

typedef struct areanode_s {
    int axis;			// -1 = leaf node
    float dist;
    struct areanode_s *children[2];
    link_t trigger_edicts;
    link_t solid_edicts;
} areanode_t;

#define	AREA_DEPTH	4
#define	AREA_NODES	32

static areanode_t sv_areanodes[AREA_NODES];
static int sv_numareanodes;

/*
===============
SV_CreateAreaNode

===============
*/
areanode_t *SV_CreateAreaNode(int depth, vec3_t mins, vec3_t maxs)
{
    areanode_t *anode;
    vec3_t size;
    vec3_t mins1, maxs1, mins2, maxs2;

    anode = &sv_areanodes[sv_numareanodes];
    sv_numareanodes++;

    ClearLink(&anode->trigger_edicts);
    ClearLink(&anode->solid_edicts);

    if (depth == AREA_DEPTH) {
	anode->axis = -1;
	anode->children[0] = anode->children[1] = NULL;
	return anode;
    }

    VectorSubtract(maxs, mins, size);
    if (size[0] > size[1])
	anode->axis = 0;
    else
	anode->axis = 1;

    anode->dist = 0.5 * (maxs[anode->axis] + mins[anode->axis]);
    VectorCopy(mins, mins1);
    VectorCopy(mins, mins2);
    VectorCopy(maxs, maxs1);
    VectorCopy(maxs, maxs2);

    maxs1[anode->axis] = mins2[anode->axis] = anode->dist;

    anode->children[0] = SV_CreateAreaNode(depth + 1, mins2, maxs2);
    anode->children[1] = SV_CreateAreaNode(depth + 1, mins1, maxs1);

    return anode;
}

/*
===============
SV_ClearWorld

===============
*/
void SV_ClearWorld(void)
{
    SV_InitBoxHull();

    memset(sv_areanodes, 0, sizeof(sv_areanodes));
    sv_numareanodes = 0;
    SV_CreateAreaNode(0, sv.worldmodel->mins, sv.worldmodel->maxs);
}


/*
===============
SV_UnlinkEdict

===============
*/
void SV_UnlinkEdict(edict_t * ent)
{
    if (!ent->area.prev)
	return;			// not linked in anywhere
    RemoveLink(&ent->area);
    ent->area.prev = ent->area.next = NULL;
}


/*
====================
SV_TouchLinks
====================
*/
void SV_TouchLinks(edict_t * ent, areanode_t * node)
{
    link_t *l, *next;
    edict_t *touch;
    int old_self, old_other;

// touch linked edicts
    for (l = node->trigger_edicts.next; l != &node->trigger_edicts;
	 l = next) {
	next = l->next;
	touch = EDICT_FROM_AREA(l);
	if (touch == ent)
	    continue;
	if (!touch->v.touch || touch->v.solid != SOLID_TRIGGER)
	    continue;
	if (ent->v.absmin[0] > touch->v.absmax[0]
	    || ent->v.absmin[1] > touch->v.absmax[1]
	    || ent->v.absmin[2] > touch->v.absmax[2]
	    || ent->v.absmax[0] < touch->v.absmin[0]
	    || ent->v.absmax[1] < touch->v.absmin[1]
	    || ent->v.absmax[2] < touch->v.absmin[2])
	    continue;

	old_self = pr_global_struct->self;
	old_other = pr_global_struct->other;

	pr_global_struct->self = EDICT_TO_PROG(touch);
	pr_global_struct->other = EDICT_TO_PROG(ent);
	pr_global_struct->time = sv.time;
	PR_ExecuteProgram(touch->v.touch);

	pr_global_struct->self = old_self;
	pr_global_struct->other = old_other;
    }

// recurse down both sides
    if (node->axis == -1)
	return;

    if (ent->v.absmax[node->axis] > node->dist)
	SV_TouchLinks(ent, node->children[0]);
    if (ent->v.absmin[node->axis] < node->dist)
	SV_TouchLinks(ent, node->children[1]);
}


/*
===============
SV_FindTouchedLeafs

===============
*/
void SV_FindTouchedLeafs(edict_t * ent, mnode_t * node)
{
    mplane_t *splitplane;
    mleaf_t *leaf;
    int sides;
    int leafnum;

    if (node->contents == CONTENTS_SOLID)
	return;

// add an efrag if the node is a leaf

    if (node->contents < 0) {
	if (ent->num_leafs == MAX_ENT_LEAFS)
	    return;

	leaf = (mleaf_t *) node;
	leafnum = leaf - sv.worldmodel->leafs - 1;

	ent->leafnums[ent->num_leafs] = leafnum;
	ent->num_leafs++;
	return;
    }
// NODE_MIXED

    splitplane = node->plane;
    sides = BOX_ON_PLANE_SIDE(ent->v.absmin, ent->v.absmax, splitplane);

// recurse down the contacted sides
    if (sides & 1)
	SV_FindTouchedLeafs(ent, node->children[0]);

    if (sides & 2)
	SV_FindTouchedLeafs(ent, node->children[1]);
}

/*
===============
SV_LinkEdict

===============
*/
void SV_LinkEdict(edict_t * ent, qboolean touch_triggers)
{
    areanode_t *node;

    if (ent->area.prev)
	SV_UnlinkEdict(ent);	// unlink from old position

    if (ent == sv.edicts)
	return;			// don't add the world

    if (ent->free)
	return;

// set the abs box
    VectorAdd(ent->v.origin, ent->v.mins, ent->v.absmin);
    VectorAdd(ent->v.origin, ent->v.maxs, ent->v.absmax);

//
// to make items easier to pick up and allow them to be grabbed off
// of shelves, the abs sizes are expanded
//
    if ((int) ent->v.flags & FL_ITEM) {
	ent->v.absmin[0] -= 15;
	ent->v.absmin[1] -= 15;
	ent->v.absmax[0] += 15;
	ent->v.absmax[1] += 15;
    } else {			// because movement is clipped an epsilon away from an actual edge,
	// we must fully check even when bounding boxes don't quite touch
	ent->v.absmin[0] -= 1;
	ent->v.absmin[1] -= 1;
	ent->v.absmin[2] -= 1;
	ent->v.absmax[0] += 1;
	ent->v.absmax[1] += 1;
	ent->v.absmax[2] += 1;
    }

// link to PVS leafs
    ent->num_leafs = 0;
    if (ent->v.modelindex)
	SV_FindTouchedLeafs(ent, sv.worldmodel->nodes);

    if (ent->v.solid == SOLID_NOT)
	return;

// find the first node that the ent's box crosses
    node = sv_areanodes;
    while (1) {
	if (node->axis == -1)
	    break;
	if (ent->v.absmin[node->axis] > node->dist)
	    node = node->children[0];
	else if (ent->v.absmax[node->axis] < node->dist)
	    node = node->children[1];
	else
	    break;		// crosses the node
    }

// link it in   

    if (ent->v.solid == SOLID_TRIGGER)
	InsertLinkBefore(&ent->area, &node->trigger_edicts);
    else
	InsertLinkBefore(&ent->area, &node->solid_edicts);

// if touch_triggers, touch all entities at this node and decend for more
    if (touch_triggers)
	SV_TouchLinks(ent, sv_areanodes);
}



/*
===============================================================================

POINT TESTING IN HULLS

===============================================================================
*/

/*
==================
SV_HullPointContents

==================
*/
int SV_HullPointContents(hull_t * hull, int num, vec3_t p)
{
    float d;
    dclipnode_t *node;
    mplane_t *plane;

    while (num >= 0) {
	if (num < hull->firstclipnode || num > hull->lastclipnode)
	    Sys_Error("SV_HullPointContents: bad node number");

	node = hull->clipnodes + num;
	plane = hull->planes + node->planenum;

	if (plane->type < 3)
	    d = p[plane->type] - plane->dist;
	else
	    d = DotProduct(plane->normal, p) - plane->dist;
	if (d < 0)
	    num = node->children[1];
	else
	    num = node->children[0];
    }

    return num;
}

/*
==================
SV_PointContents

==================
*/
int SV_PointContents(vec3_t p)
{
    return SV_HullPointContents(&sv.worldmodel->hulls[0], 0, p);
}

//===========================================================================

/*
============
SV_TestEntityPosition

A small wrapper around SV_BoxInSolidEntity that never clips against the
supplied entity.
============
*/
edict_t *SV_TestEntityPosition(edict_t * ent)
{
    trace_t trace;

    trace =
	SV_Move(ent->v.origin, ent->v.mins, ent->v.maxs, ent->v.origin, 0,
		ent);

    if (trace.startsolid)
	return sv.edicts;

    return NULL;
}


/*
===============================================================================

LINE TESTING IN HULLS

===============================================================================
*/

// 1/32 epsilon to keep floating point happy
#define	DIST_EPSILON	(0.03125)

/*
==================
SV_RecursiveHullCheck

==================
*/
qboolean SV_RecursiveHullCheck(hull_t * hull, int num, float p1f,
			       float p2f, vec3_t p1, vec3_t p2,
			       trace_t * trace)
{
    dclipnode_t *node;
    mplane_t *plane;
    float t1, t2;
    float frac;
    int i;
    vec3_t mid;
    int side;
    float midf;

// check for empty
    if (num < 0) {
	if (num != CONTENTS_SOLID) {
	    trace->allsolid = false;
	    if (num == CONTENTS_EMPTY)
		trace->inopen = true;
	    else
		trace->inwater = true;
	} else
	    trace->startsolid = true;
	return true;		// empty
    }

    if (num < hull->firstclipnode || num > hull->lastclipnode)
	Sys_Error("SV_RecursiveHullCheck: bad node number");

//
// find the point distances
//
    node = hull->clipnodes + num;
    plane = hull->planes + node->planenum;

    if (plane->type < 3) {
	t1 = p1[plane->type] - plane->dist;
	t2 = p2[plane->type] - plane->dist;
    } else {
	t1 = DotProduct(plane->normal, p1) - plane->dist;
	t2 = DotProduct(plane->normal, p2) - plane->dist;
    }

#if 1
    if (t1 >= 0 && t2 >= 0)
	return SV_RecursiveHullCheck(hull, node->children[0], p1f, p2f, p1,
				     p2, trace);
    if (t1 < 0 && t2 < 0)
	return SV_RecursiveHullCheck(hull, node->children[1], p1f, p2f, p1,
				     p2, trace);
#else
    if ((t1 >= DIST_EPSILON && t2 >= DIST_EPSILON) || (t2 > t1 && t1 >= 0))
	return SV_RecursiveHullCheck(hull, node->children[0], p1f, p2f, p1,
				     p2, trace);
    if ((t1 <= -DIST_EPSILON && t2 <= -DIST_EPSILON)
	|| (t2 < t1 && t1 <= 0))
	return SV_RecursiveHullCheck(hull, node->children[1], p1f, p2f, p1,
				     p2, trace);
#endif

// put the crosspoint DIST_EPSILON pixels on the near side
    if (t1 < 0)
	frac = (t1 + DIST_EPSILON) / (t1 - t2);
    else
	frac = (t1 - DIST_EPSILON) / (t1 - t2);
    if (frac < 0)
	frac = 0;
    if (frac > 1)
	frac = 1;

    midf = p1f + (p2f - p1f) * frac;
    for (i = 0; i < 3; i++)
	mid[i] = p1[i] + frac * (p2[i] - p1[i]);

    side = (t1 < 0);

// move up to the node
    if (!SV_RecursiveHullCheck
	(hull, node->children[side], p1f, midf, p1, mid, trace))
	return false;

#ifdef PARANOID
    if (SV_HullPointContents(sv_hullmodel, mid, node->children[side])
	== CONTENTS_SOLID) {
	Con_Printf("mid PointInHullSolid\n");
	return false;
    }
#endif

    if (SV_HullPointContents(hull, node->children[side ^ 1], mid)
	!= CONTENTS_SOLID)
// go past the node
	return SV_RecursiveHullCheck(hull, node->children[side ^ 1], midf,
				     p2f, mid, p2, trace);

    if (trace->allsolid)
	return false;		// never got out of the solid area

//==================
// the other side of the node is solid, this is the impact point
//==================
    if (!side) {
	VectorCopy(plane->normal, trace->plane.normal);
	trace->plane.dist = plane->dist;
    } else {
	VectorSubtract(vec3_origin, plane->normal, trace->plane.normal);
	trace->plane.dist = -plane->dist;
    }

    while (SV_HullPointContents(hull, hull->firstclipnode, mid)
	   == CONTENTS_SOLID) {	// shouldn't really happen, but does occasionally
	frac -= 0.1;
	if (frac < 0) {
	    trace->fraction = midf;
	    VectorCopy(mid, trace->endpos);
	    Con_Printf("backup past 0\n");
	    return false;
	}
	midf = p1f + (p2f - p1f) * frac;
	for (i = 0; i < 3; i++)
	    mid[i] = p1[i] + frac * (p2[i] - p1[i]);
    }

    trace->fraction = midf;
    VectorCopy(mid, trace->endpos);

    return false;
}


/*
==================
SV_ClipMoveToEntity

Handles selection or creation of a clipping hull, and offseting (and
eventually rotation) of the end points
==================
*/
trace_t SV_ClipMoveToEntity(edict_t * ent, vec3_t start, vec3_t mins,
			    vec3_t maxs, vec3_t end)
{
    trace_t trace;
    vec3_t offset;
    vec3_t start_l, end_l;
    hull_t *hull;

// fill in a default trace
    memset(&trace, 0, sizeof(trace_t));
    trace.fraction = 1;
    trace.allsolid = true;
    VectorCopy(end, trace.endpos);

// get the clipping hull
    hull = SV_HullForEntity(ent, mins, maxs, offset);

    VectorSubtract(start, offset, start_l);
    VectorSubtract(end, offset, end_l);

// trace a line through the apropriate clipping hull
    SV_RecursiveHullCheck(hull, hull->firstclipnode, 0, 1, start_l, end_l,
			  &trace);

// fix trace up by the offset
    if (trace.fraction != 1)
	VectorAdd(trace.endpos, offset, trace.endpos);

// did we clip the move?
    if (trace.fraction < 1 || trace.startsolid)
	trace.ent = ent;

    return trace;
}

//===========================================================================

/*
====================
SV_ClipToLinks

Mins and maxs enclose the entire area swept by the move
====================
*/
void SV_ClipToLinks(areanode_t * node, moveclip_t * clip)
{
    link_t *l, *next;
    edict_t *touch;
    trace_t trace;

// touch linked edicts
    for (l = node->solid_edicts.next; l != &node->solid_edicts; l = next) {
	next = l->next;
	touch = EDICT_FROM_AREA(l);
	if (touch->v.solid == SOLID_NOT)
	    continue;
	if (touch == clip->passedict)
	    continue;
	if (touch->v.solid == SOLID_TRIGGER)
	    Sys_Error("Trigger in clipping list");

	if (clip->type == MOVE_NOMONSTERS && touch->v.solid != SOLID_BSP)
	    continue;

	if (clip->boxmins[0] > touch->v.absmax[0]
	    || clip->boxmins[1] > touch->v.absmax[1]
	    || clip->boxmins[2] > touch->v.absmax[2]
	    || clip->boxmaxs[0] < touch->v.absmin[0]
	    || clip->boxmaxs[1] < touch->v.absmin[1]
	    || clip->boxmaxs[2] < touch->v.absmin[2])
	    continue;

	if (clip->passedict && clip->passedict->v.size[0]
	    && !touch->v.size[0])
	    continue;		// points never interact

	// might intersect, so do an exact clip
	if (clip->trace.allsolid)
	    return;
	if (clip->passedict) {
	    if (PROG_TO_EDICT(touch->v.owner) == clip->passedict)
		continue;	// don't clip against own missiles
	    if (PROG_TO_EDICT(clip->passedict->v.owner) == touch)
		continue;	// don't clip against owner
	}

	if ((int) touch->v.flags & FL_MONSTER)
	    trace =
		SV_ClipMoveToEntity(touch, clip->start, clip->mins2,
				    clip->maxs2, clip->end);
	else
	    trace =
		SV_ClipMoveToEntity(touch, clip->start, clip->mins,
				    clip->maxs, clip->end);
	if (trace.allsolid || trace.startsolid
	    || trace.fraction < clip->trace.fraction) {
	    trace.ent = touch;
	    if (clip->trace.startsolid) {
		clip->trace = trace;
		clip->trace.startsolid = true;
	    } else
		clip->trace = trace;
	} else if (trace.startsolid)
	    clip->trace.startsolid = true;
    }

// recurse down both sides
    if (node->axis == -1)
	return;

    if (clip->boxmaxs[node->axis] > node->dist)
	SV_ClipToLinks(node->children[0], clip);
    if (clip->boxmins[node->axis] < node->dist)
	SV_ClipToLinks(node->children[1], clip);
}


/*
==================
SV_MoveBounds
==================
*/
void SV_MoveBounds(vec3_t start, vec3_t mins, vec3_t maxs, vec3_t end,
		   vec3_t boxmins, vec3_t boxmaxs)
{
#if 0
// debug to test against everything
    boxmins[0] = boxmins[1] = boxmins[2] = -9999;
    boxmaxs[0] = boxmaxs[1] = boxmaxs[2] = 9999;
#else
    int i;

    for (i = 0; i < 3; i++) {
	if (end[i] > start[i]) {
	    boxmins[i] = start[i] + mins[i] - 1;
	    boxmaxs[i] = end[i] + maxs[i] + 1;
	} else {
	    boxmins[i] = end[i] + mins[i] - 1;
	    boxmaxs[i] = start[i] + maxs[i] + 1;
	}
    }
#endif
}

/*
==================
SV_Move
==================
*/
trace_t SV_Move(vec3_t start, vec3_t mins, vec3_t maxs, vec3_t end,
		int type, edict_t * passedict)
{
    moveclip_t clip;
    int i;

    memset(&clip, 0, sizeof(moveclip_t));

// clip to world
    clip.trace = SV_ClipMoveToEntity(sv.edicts, start, mins, maxs, end);

    clip.start = start;
    clip.end = end;
    clip.mins = mins;
    clip.maxs = maxs;
    clip.type = type;
    clip.passedict = passedict;

    if (type == MOVE_MISSILE) {
	for (i = 0; i < 3; i++) {
	    clip.mins2[i] = -15;
	    clip.maxs2[i] = 15;
	}
    } else {
	VectorCopy(mins, clip.mins2);
	VectorCopy(maxs, clip.maxs2);
    }

// create the bounding box of the entire move
    SV_MoveBounds(start, clip.mins2, clip.maxs2, end, clip.boxmins,
		  clip.boxmaxs);

// clip to entities
    SV_ClipToLinks(sv_areanodes, &clip);

    return clip.trace;
}
