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root/Development/ray/src/rt/noise3.c
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Comparing ray/src/rt/noise3.c (file contents):
Revision 1.6 by greg, Fri Aug 2 13:57:09 1991 UTC vs.
Revision 2.2 by greg, Fri Oct 2 16:18:50 1992 UTC

# Line 14 | Line 14 | static char SCCSid[] = "$SunId$ LBL";
14   *     5/19/88  Added fractal noise function
15   */
16  
17 + #include  <math.h>
18  
19   #define  A              0
20   #define  B              1
# Line 25 | Line 26 | static char SCCSid[] = "$SunId$ LBL";
26   #define  rand3c(x,y,z)  frand(89*(x)+97*(y)+101*(z))
27   #define  rand3d(x,y,z)  frand(103*(x)+107*(y)+109*(z))
28  
29 < #define  hermite(p0,p1,r0,r1,t)  (      p0*((2.0*t-3.0)*t*t+1.0) + \
30 <                                        p1*(-2.0*t+3.0)*t*t + \
31 <                                        r0*((t-2.0)*t+1.0)*t + \
32 <                                        r1*(t-1.0)*t*t )
29 > #define  hpoly1(t)      ((2.0*t-3.0)*t*t+1.0)
30 > #define  hpoly2(t)      (-2.0*t+3.0)*t*t
31 > #define  hpoly3(t)      ((t-2.0)*t+1.0)*t
32 > #define  hpoly4(t)      (t-1.0)*t*t
33  
34 + #define  hermite(p0,p1,r0,r1,t)  (      p0*hpoly1(t) + \
35 +                                        p1*hpoly2(t) + \
36 +                                        r0*hpoly3(t) + \
37 +                                        r1*hpoly4(t) )
38 +
39   static char  noise_name[4][8] = {"noise3a", "noise3b", "noise3c", "noise3"};
40   static char  fnoise_name[] = "fnoise3";
41   static char  hermite_name[] = "hermite";
# Line 94 | Line 100 | double *
100   noise3(xnew)                    /* compute the noise function */
101   register double  xnew[3];
102   {
97 –        extern double  floor();
103          static double  x[3] = {-100000.0, -100000.0, -100000.0};
104          static double  f[4];
105  
# Line 117 | Line 122 | interpolate(f, i, n)
122   double  f[4];
123   register int  i, n;
124   {
125 <        double  f0[4], f1[4];
125 >        double  f0[4], f1[4], hp1, hp2;
126  
127          if (n == 0) {
128                  f[A] = rand3a(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
# Line 128 | Line 133 | register int  i, n;
133                  n--;
134                  interpolate(f0, i, n);
135                  interpolate(f1, i | 1<<n, n);
136 <                f[A] = (1.0-xarg[n])*f0[A] + xarg[n]*f1[A];
137 <                f[B] = (1.0-xarg[n])*f0[B] + xarg[n]*f1[B];
138 <                f[C] = (1.0-xarg[n])*f0[C] + xarg[n]*f1[C];
139 <                f[D] = hermite(f0[D], f1[D], f0[n], f1[n], xarg[n]);
136 >                hp1 = hpoly1(xarg[n]); hp2 = hpoly2(xarg[n]);
137 >                f[A] = f0[A]*hp1 + f1[A]*hp2;
138 >                f[B] = f0[B]*hp1 + f1[B]*hp2;
139 >                f[C] = f0[C]*hp1 + f1[C]*hp2;
140 >                f[D] = f0[D]*hp1 + f1[D]*hp2 +
141 >                                f0[n]*hpoly3(xarg[n]) + f1[n]*hpoly4(xarg[n]);
142          }
143   }
144  
# Line 149 | Line 156 | double
156   fnoise3(p)                      /* compute fractal noise function */
157   double  p[3];
158   {
152 –        double  floor();
159          long  t[3], v[3], beg[3];
160          double  fval[8], fc;
161          int  branch;

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