src/common/fvect.c

#ifndef lint
static const char       RCSid[] = "$Id: fvect.c,v 2.17 2012/11/22 06:07:17 greg Exp $";
#endif
/*
 *  fvect.c - routines for floating-point vector calculations
 */

#include "copyright.h"

#include  <math.h>
#include  "fvect.h"


double
fdot(                           /* return the dot product of two vectors */
const FVECT v1,
const FVECT v2
)
{
        return(DOT(v1,v2));
}


double
dist2(                          /* return square of distance between points */
const FVECT p1,
const FVECT p2
)
{
        FVECT  delta;

        VSUB(delta, p2, p1);

        return(DOT(delta, delta));
}


double
dist2line(                      /* return square of distance to line */
const FVECT p,          /* the point */
const FVECT ep1,
const FVECT ep2         /* points on the line */
)
{
        double  d, d1, d2;

        d = dist2(ep1, ep2);
        d1 = dist2(ep1, p);
        d2 = d + d1 - dist2(ep2, p);

        return(d1 - 0.25*d2*d2/d);
}


double
dist2lseg(                      /* return square of distance to line segment */
const FVECT p,          /* the point */
const FVECT ep1,
const FVECT ep2         /* the end points */
)
{
        double  d, d1, d2;

        d = dist2(ep1, ep2);
        d1 = dist2(ep1, p);
        d2 = dist2(ep2, p);

        if (d2 > d1) {                  /* check if past endpoints */
                if (d2 - d1 > d)
                        return(d1);
        } else {
                if (d1 - d2 > d)
                        return(d2);
        }
        d2 = d + d1 - d2;

        return(d1 - 0.25*d2*d2/d);      /* distance to line */
}


void
fcross(                         /* vres = v1 X v2 */
FVECT vres,
const FVECT v1,
const FVECT v2
)
{
        VCROSS(vres, v1, v2);
}


void
fvsum(                          /* vres = v0 + f*v1 */
FVECT vres,
const FVECT v0,
const FVECT v1,
double f
)
{
        VSUM(vres, v0, v1, f);
}


double
normalize(                      /* normalize a vector, return old magnitude */
FVECT  v
)
{
        double  len, d;
        
        d = DOT(v, v);
        
        if (d == 0.0)
                return(0.0);
        
        if ((d <= 1.0+FTINY) & (d >= 1.0-FTINY)) {
                len = 0.5 + 0.5*d;      /* first order approximation */
                d = 2.0 - len;
        } else {
                len = sqrt(d);
                d = 1.0/len;
        }
        v[0] *= d;
        v[1] *= d;
        v[2] *= d;

        return(len);
}


int
closestapproach(                        /* closest approach of two rays */
RREAL t[2],             /* returned distances along each ray */
const FVECT rorg0,              /* first origin */
const FVECT rdir0,              /* first direction (normalized) */
const FVECT rorg1,              /* second origin */
const FVECT rdir1               /* second direction (normalized) */
)
{
        double  dotprod = DOT(rdir0, rdir1);
        double  denom = 1. - dotprod*dotprod;
        double  o1o2_d1;
        FVECT   o0o1;

        if (denom <= FTINY) {           /* check if lines are parallel */
                t[0] = t[1] = 0.0;
                return(0);
        }
        VSUB(o0o1, rorg0, rorg1);
        o1o2_d1 = DOT(o0o1, rdir1);
        t[0] = (o1o2_d1*dotprod - DOT(o0o1,rdir0)) / denom;
        t[1] = o1o2_d1 + t[0]*dotprod;
        return(1);
}


void
spinvector(                             /* rotate vector around normal */
FVECT vres,             /* returned vector (same magnitude as vorig) */
const FVECT vorig,              /* original vector */
const FVECT vnorm,              /* normalized vector for rotation */
double theta            /* right-hand radians */
)
{
        double  sint, cost, normprod;
        FVECT  vperp;
        int  i;
        
        if (theta == 0.0) {
                if (vres != vorig)
                        VCOPY(vres, vorig);
                return;
        }
        cost = cos(theta);
        sint = sin(theta);
        normprod = DOT(vorig, vnorm)*(1.-cost);
        VCROSS(vperp, vnorm, vorig);
        for (i = 0; i < 3; i++)
                vres[i] = vorig[i]*cost + vnorm[i]*normprod + vperp[i]*sint;
}

double
geodesic(               /* rotate vector on great circle towards target */
FVECT vres,             /* returned vector (same magnitude as vorig) */
const FVECT vorig,      /* original vector */
const FVECT vtarg,      /* vector we are rotating towards */
double t,               /* amount along arc directed towards vtarg */
int meas                /* distance measure (radians, absolute, relative) */
)
{
        FVECT   normtarg;
        double  volen, dotprod, sintr, cost;
        int     i;

        VCOPY(normtarg, vtarg);         /* in case vtarg==vres */
        if (vres != vorig)
                VCOPY(vres, vorig);
        if (t == 0.0)
                return(VLEN(vres));     /* no rotation requested */
        if ((volen = normalize(vres)) == 0.0)
                return(0.0);
        if (normalize(normtarg) == 0.0)
                return(0.0);            /* target vector is zero */
        dotprod = DOT(vres, normtarg);
                                        /* check for colinear */
        if (dotprod >= 1.0-FTINY*FTINY) {
                if (meas != GEOD_REL)
                        return(0.0);
                vres[0] *= volen; vres[1] *= volen; vres[2] *= volen;
                return(volen);
        }
        if (dotprod <= -1.0+FTINY*FTINY)
                return(0.0);
        if (meas == GEOD_ABS)
                t /= volen;
        else if (meas == GEOD_REL)
                t *= acos(dotprod);
        cost = cos(t);
        sintr = sin(t) / sqrt(1. - dotprod*dotprod);
        for (i = 0; i < 3; i++)
                vres[i] = volen*( cost*vres[i] +
                                  sintr*(normtarg[i] - dotprod*vres[i]) );

        return(volen);                  /* return vector length */
}
Revision:	2.18
Committed:	Wed Apr 3 00:22:12 2013 UTC (11 years, 1 month ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.17:	+5 -11 lines
Log Message:	Added more use of macros
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.18	static const char RCSid[] = "$Id: fvect.c,v 2.17 2012/11/22 06:07:17 greg Exp $";
3	greg	1.1	#endif
4	greg	2.6	/*
5			* fvect.c - routines for floating-point vector calculations
6			*/
7	greg	1.1
8	greg	2.7	#include "copyright.h"
9	greg	1.1
10	greg	2.2	#include <math.h>
11	greg	1.1	#include "fvect.h"
12
13
14			double
15	greg	2.8	fdot( /* return the dot product of two vectors */
16	greg	2.13	const FVECT v1,
17			const FVECT v2
18	greg	2.8	)
19	greg	1.1	{
20			return(DOT(v1,v2));
21			}
22
23
24			double
25	greg	2.8	dist2( /* return square of distance between points */
26	greg	2.13	const FVECT p1,
27			const FVECT p2
28	greg	2.8	)
29	greg	1.1	{
30	gwlarson	2.4	FVECT delta;
31	greg	1.1
32	greg	2.18	VSUB(delta, p2, p1);
33	gwlarson	2.5
34	greg	1.1	return(DOT(delta, delta));
35			}
36
37
38			double
39	greg	2.8	dist2line( /* return square of distance to line */
40	greg	2.13	const FVECT p, /* the point */
41			const FVECT ep1,
42			const FVECT ep2 /* points on the line */
43	greg	2.8	)
44	greg	1.1	{
45	greg	2.11	double d, d1, d2;
46	greg	1.1
47			d = dist2(ep1, ep2);
48			d1 = dist2(ep1, p);
49	gwlarson	2.5	d2 = d + d1 - dist2(ep2, p);
50	greg	1.1
51	gwlarson	2.5	return(d1 - 0.25d2d2/d);
52	greg	1.1	}
53
54
55			double
56	greg	2.8	dist2lseg( /* return square of distance to line segment */
57	greg	2.13	const FVECT p, /* the point */
58			const FVECT ep1,
59			const FVECT ep2 /* the end points */
60	greg	2.8	)
61	greg	1.1	{
62	greg	2.11	double d, d1, d2;
63	greg	1.1
64			d = dist2(ep1, ep2);
65			d1 = dist2(ep1, p);
66			d2 = dist2(ep2, p);
67
68			if (d2 > d1) { /* check if past endpoints */
69			if (d2 - d1 > d)
70			return(d1);
71			} else {
72			if (d1 - d2 > d)
73			return(d2);
74			}
75	gwlarson	2.5	d2 = d + d1 - d2;
76	greg	1.1
77	gwlarson	2.5	return(d1 - 0.25d2d2/d); /* distance to line */
78	greg	1.1	}
79
80
81	greg	2.6	void
82	greg	2.8	fcross( /* vres = v1 X v2 */
83	greg	2.11	FVECT vres,
84	greg	2.13	const FVECT v1,
85			const FVECT v2
86	greg	2.8	)
87	greg	1.1	{
88	greg	2.18	VCROSS(vres, v1, v2);
89	greg	1.1	}
90
91
92	greg	2.6	void
93	greg	2.8	fvsum( /* vres = v0 + fv1 /
94	greg	2.11	FVECT vres,
95	greg	2.13	const FVECT v0,
96			const FVECT v1,
97	greg	2.11	double f
98	greg	2.8	)
99	greg	1.4	{
100	greg	2.18	VSUM(vres, v0, v1, f);
101	greg	1.4	}
102
103
104	greg	1.1	double
105	greg	2.8	normalize( /* normalize a vector, return old magnitude */
106	greg	2.11	FVECT v
107	greg	2.8	)
108	greg	1.1	{
109	greg	2.11	double len, d;
110	greg	1.1
111	gwlarson	2.5	d = DOT(v, v);
112	greg	1.1
113	greg	2.10	if (d == 0.0)
114	greg	1.1	return(0.0);
115
116	greg	2.15	if ((d <= 1.0+FTINY) & (d >= 1.0-FTINY)) {
117	gwlarson	2.5	len = 0.5 + 0.5d; / first order approximation */
118	greg	2.12	d = 2.0 - len;
119			} else {
120	gwlarson	2.5	len = sqrt(d);
121	greg	2.12	d = 1.0/len;
122			}
123			v[0] *= d;
124	gwlarson	2.5	v[1] *= d;
125			v[2] *= d;
126	greg	2.3
127	greg	1.1	return(len);
128			}
129	greg	1.5
130
131	greg	2.8	int
132			closestapproach( /* closest approach of two rays */
133			RREAL t[2], /* returned distances along each ray */
134	greg	2.13	const FVECT rorg0, /* first origin */
135			const FVECT rdir0, /* first direction (normalized) */
136			const FVECT rorg1, /* second origin */
137			const FVECT rdir1 /* second direction (normalized) */
138	greg	2.8	)
139			{
140			double dotprod = DOT(rdir0, rdir1);
141			double denom = 1. - dotprod*dotprod;
142			double o1o2_d1;
143			FVECT o0o1;
144
145			if (denom <= FTINY) { /* check if lines are parallel */
146			t[0] = t[1] = 0.0;
147			return(0);
148			}
149			VSUB(o0o1, rorg0, rorg1);
150			o1o2_d1 = DOT(o0o1, rdir1);
151			t[0] = (o1o2_d1*dotprod - DOT(o0o1,rdir0)) / denom;
152			t[1] = o1o2_d1 + t[0]*dotprod;
153			return(1);
154			}
155
156
157	greg	2.6	void
158	greg	2.8	spinvector( /* rotate vector around normal */
159	greg	2.15	FVECT vres, /* returned vector (same magnitude as vorig) */
160	greg	2.13	const FVECT vorig, /* original vector */
161			const FVECT vnorm, /* normalized vector for rotation */
162	greg	2.14	double theta /* right-hand radians */
163	greg	2.8	)
164	greg	1.5	{
165	greg	1.6	double sint, cost, normprod;
166	greg	1.5	FVECT vperp;
167	greg	2.11	int i;
168	greg	1.5
169			if (theta == 0.0) {
170	greg	1.6	if (vres != vorig)
171			VCOPY(vres, vorig);
172	greg	1.5	return;
173			}
174	greg	1.6	cost = cos(theta);
175	greg	1.5	sint = sin(theta);
176	greg	1.6	normprod = DOT(vorig, vnorm)*(1.-cost);
177	greg	2.18	VCROSS(vperp, vnorm, vorig);
178	greg	1.5	for (i = 0; i < 3; i++)
179	greg	1.6	vres[i] = vorig[i]cost + vnorm[i]normprod + vperp[i]*sint;
180	greg	1.5	}
181	greg	2.15
182			double
183			geodesic( /* rotate vector on great circle towards target */
184			FVECT vres, /* returned vector (same magnitude as vorig) */
185			const FVECT vorig, /* original vector */
186			const FVECT vtarg, /* vector we are rotating towards */
187			double t, /* amount along arc directed towards vtarg */
188			int meas /* distance measure (radians, absolute, relative) */
189			)
190			{
191			FVECT normtarg;
192	greg	2.17	double volen, dotprod, sintr, cost;
193	greg	2.15	int i;
194
195	greg	2.16	VCOPY(normtarg, vtarg); /* in case vtarg==vres */
196	greg	2.15	if (vres != vorig)
197			VCOPY(vres, vorig);
198			if (t == 0.0)
199			return(VLEN(vres)); /* no rotation requested */
200			if ((volen = normalize(vres)) == 0.0)
201			return(0.0);
202			if (normalize(normtarg) == 0.0)
203			return(0.0); /* target vector is zero */
204			dotprod = DOT(vres, normtarg);
205			/* check for colinear */
206			if (dotprod >= 1.0-FTINY*FTINY) {
207			if (meas != GEOD_REL)
208			return(0.0);
209			vres[0] = volen; vres[1] = volen; vres[2] *= volen;
210			return(volen);
211			}
212			if (dotprod <= -1.0+FTINY*FTINY)
213			return(0.0);
214			if (meas == GEOD_ABS)
215			t /= volen;
216			else if (meas == GEOD_REL)
217			t *= acos(dotprod);
218			cost = cos(t);
219	greg	2.17	sintr = sin(t) / sqrt(1. - dotprod*dotprod);
220	greg	2.15	for (i = 0; i < 3; i++)
221			vres[i] = volen( costvres[i] +
222	greg	2.17	sintr(normtarg[i] - dotprodvres[i]) );
223	greg	2.15
224			return(volen); /* return vector length */
225			}