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/*
* box.c - This file contains the functions for dealing with boxes.
*
* $Id: box.c,v 1.23 2012/10/17 04:25:57 johns Exp $
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define TACHYON_INTERNAL 1
#include "tachyon.h"
#include "macros.h"
#include "box.h"
#include "vector.h"
#include "intersect.h"
int box_bbox(void * obj, vector * min, vector * max) {
box * b = (box *) obj;
*min = b->min;
*max = b->max;
return 1;
}
static object_methods box_methods = {
(void (*)(const void *, void *))(box_intersect),
(void (*)(const void *, const void *, const void *, void *))(box_normal),
box_bbox,
free
};
box * newbox(void * tex, vector min, vector max) {
box * b;
b=(box *) malloc(sizeof(box));
memset(b, 0, sizeof(box));
b->methods = &box_methods;
b->tex = tex;
b->min = min;
b->max = max;
return b;
}
void box_intersect(const box * bx, ray * ry) {
flt a, tx1, tx2, ty1, ty2, tz1, tz2;
flt tnear, tfar;
tnear= -FHUGE;
tfar= FHUGE;
if (ry->d.x == 0.0) {
if ((ry->o.x < bx->min.x) || (ry->o.x > bx->max.x)) return;
}
else {
tx1 = (bx->min.x - ry->o.x) / ry->d.x;
tx2 = (bx->max.x - ry->o.x) / ry->d.x;
if (tx1 > tx2) { a=tx1; tx1=tx2; tx2=a; }
if (tx1 > tnear) tnear=tx1;
if (tx2 < tfar) tfar=tx2;
}
if (tnear > tfar) return;
if (tfar < 0.0) return;
if (ry->d.y == 0.0) {
if ((ry->o.y < bx->min.y) || (ry->o.y > bx->max.y)) return;
}
else {
ty1 = (bx->min.y - ry->o.y) / ry->d.y;
ty2 = (bx->max.y - ry->o.y) / ry->d.y;
if (ty1 > ty2) { a=ty1; ty1=ty2; ty2=a; }
if (ty1 > tnear) tnear=ty1;
if (ty2 < tfar) tfar=ty2;
}
if (tnear > tfar) return;
if (tfar < 0.0) return;
if (ry->d.z == 0.0) {
if ((ry->o.z < bx->min.z) || (ry->o.z > bx->max.z)) return;
}
else {
tz1 = (bx->min.z - ry->o.z) / ry->d.z;
tz2 = (bx->max.z - ry->o.z) / ry->d.z;
if (tz1 > tz2) { a=tz1; tz1=tz2; tz2=a; }
if (tz1 > tnear) tnear=tz1;
if (tz2 < tfar) tfar=tz2;
}
if (tnear > tfar) return;
if (tfar < 0.0) return;
ry->add_intersection(tnear, (const object *) bx, ry);
ry->add_intersection(tfar, (object *) bx, ry);
}
void box_normal(const box * bx, const vector * pnt, const ray * incident, vector * N) {
vector a, b, c;
flt t;
c.x=(bx->max.x + bx->min.x) / 2.0;
c.y=(bx->max.y + bx->min.y) / 2.0;
c.z=(bx->max.z + bx->min.z) / 2.0;
VSub((vector *) pnt, &c, N);
b=(*N);
a.x=FABS(N->x);
a.y=FABS(N->y);
a.z=FABS(N->z);
N->x=0.0; N->y=0.0; N->z=0.0;
t=MYMAX(a.x, MYMAX(a.y, a.z));
if (t==a.x) N->x=b.x;
if (t==a.y) N->y=b.y;
if (t==a.z) N->z=b.z;
VNorm(N);
/* Flip surface normal to point toward the viewer if necessary */
if (VDot(N, &(incident->d)) > 0.0) {
N->x=-N->x;
N->y=-N->y;
N->z=-N->z;
}
}
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