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root/Development/ray/src/common/fvect.c
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Comparing ray/src/common/fvect.c (file contents):
Revision 1.1 by greg, Thu Feb 2 10:34:32 1989 UTC vs.
Revision 2.3 by greg, Fri Dec 10 09:53:30 1993 UTC

# Line 10 | Line 10 | static char SCCSid[] = "$SunId$ LBL";
10   *     8/14/85
11   */
12  
13 + #include  <math.h>
14   #include  "fvect.h"
15  
15 – #define  FTINY          1e-7
16  
17 –
17   double
18   fdot(v1, v2)                    /* return the dot product of two vectors */
19   register FVECT  v1, v2;
# Line 83 | Line 82 | register FVECT  vres, v1, v2;
82   }
83  
84  
85 + fvsum(vres, v0, v1, f)          /* vres = v0 + f*v1 */
86 + FVECT  vres, v0, v1;
87 + double  f;
88 + {
89 +        vres[0] = v0[0] + f*v1[0];
90 +        vres[1] = v0[1] + f*v1[1];
91 +        vres[2] = v0[2] + f*v1[2];
92 + }
93 +
94 +
95   double
96   normalize(v)                    /* normalize a vector, return old magnitude */
97   register FVECT  v;
# Line 91 | Line 100 | register FVECT  v;
100          
101          len = DOT(v, v);
102          
103 <        if (len <= FTINY*FTINY)
103 >        if (len <= 0.0)
104                  return(0.0);
105          
106 <        if (len >= (1.0-FTINY)*(1.0-FTINY) &&
107 <                        len <= (1.0+FTINY)*(1.0+FTINY))
108 <                return(1.0);
106 >        if (len <= 1.0+FTINY && len >= 1.0-FTINY)
107 >                len = 0.5 + 0.5*len;    /* first order approximation */
108 >        else
109 >                len = sqrt(len);
110  
101 –        len = sqrt(len);
111          v[0] /= len;
112          v[1] /= len;
113          v[2] /= len;
114 +
115          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 +        double  sint, cost, normprod;
124 +        FVECT  vperp;
125 +        register int  i;
126 +        
127 +        if (theta == 0.0) {
128 +                if (vres != vorig)
129 +                        VCOPY(vres, vorig);
130 +                return;
131 +        }
132 +        cost = cos(theta);
133 +        sint = sin(theta);
134 +        normprod = DOT(vorig, vnorm)*(1.-cost);
135 +        fcross(vperp, vnorm, vorig);
136 +        for (i = 0; i < 3; i++)
137 +                vres[i] = vorig[i]*cost + vnorm[i]*normprod + vperp[i]*sint;
138   }

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