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INTERSEC.C
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C/C++ Source or Header
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1991-07-18
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4KB
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174 lines
/*
* intersect.c
*
* Copyright (C) 1989, 1991, Craig E. Kolb
* All rights reserved.
*
* This software may be freely copied, modified, and redistributed
* provided that this copyright notice is preserved on all copies.
*
* You may not distribute this software, in whole or in part, as part of
* any commercial product without the express consent of the authors.
*
* There is no warranty or other guarantee of fitness of this software
* for any purpose. It is provided solely "as is".
*
* $Id: intersect.c,v 4.0 91/07/17 14:38:37 kolb Exp Locker: kolb $
*
* $Log: intersect.c,v $
* Revision 4.0 91/07/17 14:38:37 kolb
* Initial version.
*
*/
#include "geom.h"
static void AddToHitList();
/*
* Number of bounding volume tests.
* External modules have read access via IntersectStats().
*/
static unsigned long BVTests;
/*
* Intersect object & ray. Return distance from "pos" along "ray" to
* intersection point. Return value <= 0 indicates no intersection.
*/
int
intersect(obj, ray, hitlist, mindist, maxdist)
Geom *obj; /* Geom to be tested. */
Ray *ray; /* Ray origin, direction. */
HitList *hitlist; /* Intersection path */
Float mindist, *maxdist;
{
Ray newray;
Vector vtmp;
Trans *curtrans;
Float distfact, nmindist, nmaxdist;
/*
* Check ray/bounding volume intersection, if required.
*/
if (obj->methods->checkbounds) {
VecAddScaled(ray->pos, mindist, ray->dir, &vtmp);
if (OutOfBounds(&vtmp, obj->bounds)) {
nmaxdist = *maxdist;
BVTests++;
if (!BoundsIntersect(ray, obj->bounds, mindist,
&nmaxdist))
return FALSE;
}
}
newray = *ray;
nmindist = mindist;
nmaxdist = *maxdist;
/*
* Transform the ray if necessary.
*/
if (obj->trans != (Trans *)0) {
/*
* If object's idea of the current time is wrong,
* update the transformations.
*/
if (obj->animtrans && !equal(obj->timenow, ray->time)) {
TransResolveAssoc(obj->trans);
}
/*
* Transforming the ray can change the distance between
* the ray origin and the point of intersection.
* We save the amount the ray is "stretched" and later
* divide the computed distance by this amount.
*/
distfact = 1.;
for (curtrans = obj->transtail; curtrans;
curtrans = curtrans->prev)
distfact *= RayTransform(&newray, &curtrans->itrans);
nmindist *= distfact;
nmaxdist *= distfact;
}
/*
* Geom has been updated to current time.
*/
obj->timenow = ray->time;
/*
* Call correct intersection routine.
*/
if (IsAggregate(obj)) {
/*
* Aggregate
*/
if (!(*obj->methods->intersect)
(obj->obj, &newray, hitlist, nmindist, &nmaxdist))
return FALSE;
} else {
/*
* Primitive
*/
if (!(*obj->methods->intersect)
(obj->obj, &newray, nmindist, &nmaxdist))
return FALSE;
hitlist->nodes = 0;
}
/*
* Had a hit -- add ray, distance and object to tail of hitlist.
*/
AddToHitList(hitlist, &newray, nmindist, nmaxdist, obj);
/*
* Set dist to distance to intersection point from the origin
* of the untransformed ray.
*/
if (obj->trans != (Trans *)0)
*maxdist = nmaxdist / distfact;
else
*maxdist = nmaxdist;
return TRUE;
}
static void
AddToHitList(hitlist, ray, mind, dist, obj)
HitList *hitlist;
Ray *ray;
Float mind, dist;
Geom *obj;
{
HitNode *np;
Trans *list;
np = &hitlist->data[hitlist->nodes++];
np->ray = *ray;
np->obj = obj;
np->mindist = mind;
np->dist = dist;
np->enter = 0;
if (obj->trans) {
/*
* Compute total transformation, forward and inverse,
* for this object, and store in hitlist for use later.
*/
TransCopy(obj->trans, &np->trans);
for (list = obj->trans->next; list; list = list->next)
TransCompose(&np->trans, list, &np->trans);
np->dotrans = TRUE;
} else
np->dotrans = FALSE;
}
/*
* Return intersection statistics.
* Currently, this is limited to the # of bounding volume test performed.
*/
void
IntersectStats(bvtests)
unsigned long *bvtests;
{
*bvtests = BVTests;
}