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/*
* bounds.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".
*
* $Id$
*
* $Log$
*/
#include "object.h"
/*
* Check for intersection between bounding box and the given ray.
* If there is an intersection between mindist and *maxdist along
* the ray, *maxdist is replaced with the distance to the point of
* intersection, and TRUE is returned. Otherwise, FALSE is returned.
*
* If this routine is used to check for intersection with a volume
* rather than a "hollow" box, one should first determine if
* (ray->pos + mindist * ray->dir) is inside the bounding volume, and
* call BoundsIntersect() only if it is not.
*/
int
BoundsIntersect(ray, bounds, mindist, maxdist)
Ray *ray;
Float bounds[2][3], mindist, *maxdist;
{
Float t, tmin, tmax;
Float dir, pos;
tmax = *maxdist;
tmin = mindist;
dir = ray->dir.x;
pos = ray->pos.x;
if (dir < 0) {
t = (bounds[LOW][X] - pos) / dir;
if (t < tmin)
return FALSE;
if (t <= tmax)
tmax = t;
t = (bounds[HIGH][X] - pos) / dir;
if (t >= tmin) {
if (t > tmax)
return FALSE;
tmin = t;
}
} else if (dir > 0.) {
t = (bounds[HIGH][X] - pos) / dir;
if (t < tmin)
return FALSE;
if (t <= tmax)
tmax = t;
t = (bounds[LOW][X] - pos) / dir;
if (t >= tmin) {
if (t > tmax)
return FALSE;
tmin = t;
}
} else if (pos < bounds[LOW][X] || pos > bounds[HIGH][X])
return FALSE;
dir = ray->dir.y;
pos = ray->pos.y;
if (dir < 0) {
t = (bounds[LOW][Y] - pos) / dir;
if (t < tmin)
return FALSE;
if (t <= tmax)
tmax = t;
t = (bounds[HIGH][Y] - pos) / dir;
if (t >= tmin) {
if (t > tmax)
return FALSE;
tmin = t;
}
} else if (dir > 0.) {
t = (bounds[HIGH][Y] - pos) / dir;
if (t < tmin)
return FALSE;
if (t <= tmax)
tmax = t;
t = (bounds[LOW][Y] - pos) / dir;
if (t >= tmin) {
if (t > tmax)
return FALSE;
tmin = t;
}
} else if (pos < bounds[LOW][Y] || pos > bounds[HIGH][Y])
return FALSE;
dir = ray->dir.z;
pos = ray->pos.z;
if (dir < 0) {
t = (bounds[LOW][Z] - pos) / dir;
if (t < tmin)
return FALSE;
if (t <= tmax)
tmax = t;
t = (bounds[HIGH][Z] - pos) / dir;
if (t >= tmin) {
if (t > tmax)
return FALSE;
tmin = t;
}
} else if (dir > 0.) {
t = (bounds[HIGH][Z] - pos) / dir;
if (t < tmin)
return FALSE;
if (t <= tmax)
tmax = t;
t = (bounds[LOW][Z] - pos) / dir;
if (t >= tmin) {
if (t > tmax)
return FALSE;
tmin = t;
}
} else if (pos < bounds[LOW][Z] || pos > bounds[HIGH][Z])
return FALSE;
if (tmin == mindist) {
if (tmax < *maxdist) {
*maxdist = tmax;
return TRUE;
}
} else {
if (tmin < *maxdist) {
*maxdist = tmin;
return TRUE;
}
}
return FALSE; /* hit, but not closer than maxdist */
}
/*
* Transform an object's bounding box by the given transformation
* matrix.
*/
void
BoundsTransform(trans, objbounds)
Matrix *trans;
Float objbounds[2][3];
{
Vector tmp;
Float bounds[2][3];
int x, y, z;
/*
* Can't (and shouldn't) do anything with unbounded objects.
*/
if (objbounds[LOW][X] > objbounds[HIGH][X])
return;
BoundsInit(bounds);
/*
* Find bounding box of transformed corners of bounding box.
*/
for (x = 0 ; x < 2; x++) {
for (y = 0; y < 2; y++) {
for (z = 0; z < 2; z++) {
tmp.x = objbounds[x][X];
tmp.y = objbounds[y][Y];
tmp.z = objbounds[z][Z];
PointTransform(&tmp, trans);
if (tmp.x < bounds[LOW][X])
bounds[LOW][X] = tmp.x;
if (tmp.x > bounds[HIGH][X])
bounds[HIGH][X] = tmp.x;
if (tmp.y < bounds[LOW][Y])
bounds[LOW][Y] = tmp.y;
if (tmp.y > bounds[HIGH][Y])
bounds[HIGH][Y] = tmp.y;
if (tmp.z < bounds[LOW][Z])
bounds[LOW][Z] = tmp.z;
if (tmp.z > bounds[HIGH][Z])
bounds[HIGH][Z] = tmp.z;
}
}
}
BoundsCopy(bounds, objbounds);
}
void
BoundsInit(bounds)
Float bounds[2][3];
{
bounds[LOW][X] = bounds[LOW][Y] = bounds[LOW][Z] = FAR_AWAY;
bounds[HIGH][X] = bounds[HIGH][Y] = bounds[HIGH][Z] = -FAR_AWAY;
}
void
BoundsCopy(from, into)
Float into[2][3], from[2][3];
{
into[LOW][X] = from[LOW][X];
into[LOW][Y] = from[LOW][Y];
into[LOW][Z] = from[LOW][Z];
into[HIGH][X] = from[HIGH][X];
into[HIGH][Y] = from[HIGH][Y];
into[HIGH][Z] = from[HIGH][Z];
}
#define SetIfLess(a, b) (a = ((a) < (b) ? (a) : (b)))
#define SetIfGreater(a, b) (a = ((a) > (b) ? (a) : (b)))
/*
* Find bounding box of the union of two bounding boxes.
*/
void
BoundsEnlarge(old, new)
Float old[2][3], new[2][3];
{
SetIfLess(old[LOW][X], new[LOW][X]);
SetIfLess(old[LOW][Y], new[LOW][Y]);
SetIfLess(old[LOW][Z], new[LOW][Z]);
SetIfGreater(old[HIGH][X], new[HIGH][X]);
SetIfGreater(old[HIGH][Y], new[HIGH][Y]);
SetIfGreater(old[HIGH][Z], new[HIGH][Z]);
}
void
BoundsPrint(box, fp)
Float box[2][3];
FILE *fp;
{
fprintf(fp,"\tX: %f to %f\n",box[LOW][X], box[HIGH][X]);
fprintf(fp,"\tY: %f to %f\n",box[LOW][Y], box[HIGH][Y]);
fprintf(fp,"\tZ: %f to %f\n",box[LOW][Z], box[HIGH][Z]);
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.