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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* fvect.c - routines for floating-point vector calculations |
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*/ |
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|
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#include "copyright.h" |
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|
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#include <math.h> |
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#include "fvect.h" |
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|
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|
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double |
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fdot(v1, v2) /* return the dot product of two vectors */ |
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register FVECT v1, v2; |
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{ |
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return(DOT(v1,v2)); |
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} |
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|
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|
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double |
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dist2(p1, p2) /* return square of distance between points */ |
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register FVECT p1, p2; |
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{ |
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FVECT delta; |
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|
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delta[0] = p2[0] - p1[0]; |
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delta[1] = p2[1] - p1[1]; |
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delta[2] = p2[2] - p1[2]; |
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|
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return(DOT(delta, delta)); |
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} |
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|
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|
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double |
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dist2line(p, ep1, ep2) /* return square of distance to line */ |
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FVECT p; /* the point */ |
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FVECT ep1, ep2; /* points on the line */ |
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{ |
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register double d, d1, d2; |
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|
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d = dist2(ep1, ep2); |
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d1 = dist2(ep1, p); |
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d2 = d + d1 - dist2(ep2, p); |
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|
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return(d1 - 0.25*d2*d2/d); |
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} |
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|
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|
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double |
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dist2lseg(p, ep1, ep2) /* return square of distance to line segment */ |
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FVECT p; /* the point */ |
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FVECT ep1, ep2; /* the end points */ |
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{ |
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register double d, d1, d2; |
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|
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d = dist2(ep1, ep2); |
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d1 = dist2(ep1, p); |
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d2 = dist2(ep2, p); |
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|
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if (d2 > d1) { /* check if past endpoints */ |
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if (d2 - d1 > d) |
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return(d1); |
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} else { |
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if (d1 - d2 > d) |
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return(d2); |
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} |
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d2 = d + d1 - d2; |
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|
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return(d1 - 0.25*d2*d2/d); /* distance to line */ |
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} |
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|
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|
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void |
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fcross(vres, v1, v2) /* vres = v1 X v2 */ |
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register FVECT vres, v1, v2; |
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{ |
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vres[0] = v1[1]*v2[2] - v1[2]*v2[1]; |
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vres[1] = v1[2]*v2[0] - v1[0]*v2[2]; |
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vres[2] = v1[0]*v2[1] - v1[1]*v2[0]; |
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} |
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|
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|
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void |
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fvsum(vres, v0, v1, f) /* vres = v0 + f*v1 */ |
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register FVECT vres, v0, v1; |
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register double f; |
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{ |
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vres[0] = v0[0] + f*v1[0]; |
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vres[1] = v0[1] + f*v1[1]; |
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vres[2] = v0[2] + f*v1[2]; |
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} |
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|
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|
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double |
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normalize(v) /* normalize a vector, return old magnitude */ |
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register FVECT v; |
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{ |
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register double len, d; |
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|
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d = DOT(v, v); |
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|
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if (d <= 0.0) |
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return(0.0); |
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|
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if (d <= 1.0+FTINY && d >= 1.0-FTINY) |
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len = 0.5 + 0.5*d; /* first order approximation */ |
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else |
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len = sqrt(d); |
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|
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v[0] *= d = 1.0/len; |
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v[1] *= d; |
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v[2] *= d; |
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|
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return(len); |
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} |
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|
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|
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void |
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spinvector(vres, vorig, vnorm, theta) /* rotate vector around normal */ |
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FVECT vres, vorig, vnorm; |
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double theta; |
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{ |
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double sint, cost, normprod; |
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FVECT vperp; |
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register int i; |
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|
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if (theta == 0.0) { |
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if (vres != vorig) |
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VCOPY(vres, vorig); |
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return; |
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} |
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cost = cos(theta); |
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sint = sin(theta); |
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normprod = DOT(vorig, vnorm)*(1.-cost); |
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fcross(vperp, vnorm, vorig); |
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for (i = 0; i < 3; i++) |
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vres[i] = vorig[i]*cost + vnorm[i]*normprod + vperp[i]*sint; |
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} |
