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* 8/14/85 |
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*/ |
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|
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+ |
#include <math.h> |
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#include "fvect.h" |
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|
| 15 |
– |
#define FTINY 1e-7 |
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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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|
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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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+ |
|
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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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len = DOT(v, v); |
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|
| 103 |
< |
if (len <= FTINY*FTINY) |
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> |
if (len <= 0.0) |
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return(0.0); |
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|
| 106 |
+ |
/****** problematic |
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|
if (len >= (1.0-FTINY)*(1.0-FTINY) && |
| 108 |
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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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|
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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); |
| 117 |
+ |
} |
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+ |
|
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+ |
|
| 120 |
+ |
spinvector(vres, vorig, vnorm, theta) /* rotate vector around normal */ |
| 121 |
+ |
FVECT vres, vorig, vnorm; |
| 122 |
+ |
double theta; |
| 123 |
+ |
{ |
| 124 |
+ |
double sint, cost, normprod; |
| 125 |
+ |
FVECT vperp; |
| 126 |
+ |
register int i; |
| 127 |
+ |
|
| 128 |
+ |
if (theta == 0.0) { |
| 129 |
+ |
if (vres != vorig) |
| 130 |
+ |
VCOPY(vres, vorig); |
| 131 |
+ |
return; |
| 132 |
+ |
} |
| 133 |
+ |
cost = cos(theta); |
| 134 |
+ |
sint = sin(theta); |
| 135 |
+ |
normprod = DOT(vorig, vnorm)*(1.-cost); |
| 136 |
+ |
fcross(vperp, vnorm, vorig); |
| 137 |
+ |
for (i = 0; i < 3; i++) |
| 138 |
+ |
vres[i] = vorig[i]*cost + vnorm[i]*normprod + vperp[i]*sint; |
| 139 |
|
} |
