12 |
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|
13 |
|
#include "fvect.h" |
14 |
|
|
15 |
– |
#define FTINY 1e-7 |
15 |
|
|
17 |
– |
|
16 |
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double |
17 |
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fdot(v1, v2) /* return the dot product of two vectors */ |
18 |
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register FVECT v1, v2; |
113 |
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v[1] /= len; |
114 |
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v[2] /= len; |
115 |
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return(len); |
116 |
+ |
} |
117 |
+ |
|
118 |
+ |
|
119 |
+ |
spinvector(vres, vorig, vnorm, theta) /* rotate vector around normal */ |
120 |
+ |
FVECT vres, vorig, vnorm; |
121 |
+ |
double theta; |
122 |
+ |
{ |
123 |
+ |
extern double cos(), sin(); |
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 |
|
} |