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#include "fvect.h" |
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#define FTINY 1e-7 |
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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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fvsum(vres, v0, v1, f) /* vres = v0 + f*v1 */ |
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FVECT vres, v0, v1; |
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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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double |
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normalize(v) /* normalize a vector, return old magnitude */ |
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register FVECT v; |
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len = DOT(v, v); |
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if (len <= FTINY*FTINY) |
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if (len <= 0.0) |
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return(0.0); |
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/****** problematic |
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if (len >= (1.0-FTINY)*(1.0-FTINY) && |
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len <= (1.0+FTINY)*(1.0+FTINY)) |
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return(1.0); |
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******/ |
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len = sqrt(len); |
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v[0] /= len; |
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v[1] /= len; |
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v[2] /= len; |
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return(len); |
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} |
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|
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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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extern double cos(), sin(); |
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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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} |