src/rt/noise3.c

/* Copyright (c) 1988 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  noise3.c - noise functions for random textures.
 *
 *     Credit for the smooth algorithm goes to Ken Perlin.
 *     (ref. SIGGRAPH Vol 19, No 3, pp 287-96)
 *
 *     4/15/86
 *     5/19/88  Added fractal noise function
 */


#define  A              0
#define  B              1
#define  C              2
#define  D              3

#define  rand3a(x,y,z)  frand(67*(x)+59*(y)+71*(z))
#define  rand3b(x,y,z)  frand(73*(x)+79*(y)+83*(z))
#define  rand3c(x,y,z)  frand(89*(x)+97*(y)+101*(z))
#define  rand3d(x,y,z)  frand(103*(x)+107*(y)+109*(z))

#define  hermite(p0,p1,r0,r1,t)  (      p0*((2.0*t-3.0)*t*t+1.0) + \
                                        p1*(-2.0*t+3.0)*t*t + \
                                        r0*((t-2.0)*t+1.0)*t + \
                                        r1*(t-1.0)*t*t )

static char  *noise_name[4] = {"noise3a", "noise3b", "noise3c", "noise3"};
static char  fnoise_name[] = "fnoise3";
static char  hermite_name[] = "hermite";

double  *noise3(), fnoise3(), argument(), frand();

static long  xlim[3][2];
static double  xarg[3];

#define  EPSILON        .0001           /* error allowed in fractal */

#define  frand3(x,y,z)  frand(17*(x)+23*(y)+29*(z))


static double
l_noise3(nam)                   /* compute a noise function */
register char  *nam;
{
        register int  i;
        double  x[3];
                                        /* get point */
        x[0] = argument(1);
        x[1] = argument(2);
        x[2] = argument(3);
                                        /* make appropriate call */
        if (nam == fnoise_name)
                return(fnoise3(x));
        i = 4;
        while (i--)
                if (nam == noise_name[i])
                        return(noise3(x)[i]);
        eputs("Bad call to l_noise3()!\n");
        quit(1);
}


double
l_hermite()                     /* library call for hermite interpolation */
{
        double  t;
        
        t = argument(5);
        return( hermite(argument(1), argument(2),
                        argument(3), argument(4), t) );
}


setnoisefuncs()                 /* add noise functions to library */
{
        register int  i;

        funset(hermite_name, 5, ':', l_hermite);
        funset(fnoise_name, 3, ':', l_noise3);
        i = 4;
        while (i--)
                funset(noise_name[i], 3, ':', l_noise3);
}


double *
noise3(xnew)                    /* compute the noise function */
register double  xnew[3];
{
        extern double  floor();
        static double  x[3] = {-100000.0, -100000.0, -100000.0};
        static double  f[4];

        if (x[0]==xnew[0] && x[1]==xnew[1] && x[2]==xnew[2])
                return(f);
        x[0] = xnew[0]; x[1] = xnew[1]; x[2] = xnew[2];
        xlim[0][0] = floor(x[0]); xlim[0][1] = xlim[0][0] + 1;
        xlim[1][0] = floor(x[1]); xlim[1][1] = xlim[1][0] + 1;
        xlim[2][0] = floor(x[2]); xlim[2][1] = xlim[2][0] + 1;
        xarg[0] = x[0] - xlim[0][0];
        xarg[1] = x[1] - xlim[1][0];
        xarg[2] = x[2] - xlim[2][0];
        interpolate(f, 0, 3);
        return(f);
}


static
interpolate(f, i, n)
double  f[4];
register int  i, n;
{
        double  f0[4], f1[4];

        if (n == 0) {
                f[A] = rand3a(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
                f[B] = rand3b(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
                f[C] = rand3c(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
                f[D] = rand3d(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
        } else {
                n--;
                interpolate(f0, i, n);
                interpolate(f1, i | 1<<n, n);
                f[A] = (1.0-xarg[n])*f0[A] + xarg[n]*f1[A];
                f[B] = (1.0-xarg[n])*f0[B] + xarg[n]*f1[B];
                f[C] = (1.0-xarg[n])*f0[C] + xarg[n]*f1[C];
                f[D] = hermite(f0[D], f1[D], f0[n], f1[n], xarg[n]);
        }
}


double
frand(s)                        /* get random number from seed */
register long  s;
{
        s = s<<13 ^ s;
        return(1.0-((s*(s*s*15731+789221)+1376312589)&0x7fffffff)/1073741824.0);
}


double
fnoise3(p)                      /* compute fractal noise function */
double  p[3];
{
        double  floor();
        long  t[3], v[3], beg[3];
        double  fval[8], fc;
        int  branch;
        register long  s;
        register int  i, j;
                                                /* get starting cube */
        s = (long)(1.0/EPSILON);
        for (i = 0; i < 3; i++) {
                t[i] = s*p[i];
                beg[i] = s*floor(p[i]);
        }
        for (j = 0; j < 8; j++) {
                for (i = 0; i < 3; i++) {
                        v[i] = beg[i];
                        if (j & 1<<i)
                                v[i] += s;
                }
                fval[j] = frand3(v[0],v[1],v[2]);
        }
                                                /* compute fractal */
        for ( ; ; ) {
                fc = 0.0;
                for (j = 0; j < 8; j++)
                        fc += fval[j];
                fc *= 0.125;
                if ((s >>= 1) == 0)
                        return(fc);             /* close enough */
                branch = 0;
                for (i = 0; i < 3; i++) {       /* do center */
                        v[i] = beg[i] + s;
                        if (t[i] > v[i]) {
                                branch |= 1<<i;
                        }
                }
                fc += s*EPSILON*frand3(v[0],v[1],v[2]);
                fval[~branch & 7] = fc;
                for (i = 0; i < 3; i++) {       /* do faces */
                        if (branch & 1<<i)
                                v[i] += s;
                        else
                                v[i] -= s;
                        fc = 0.0;
                        for (j = 0; j < 8; j++)
                                if (~(j^branch) & 1<<i)
                                        fc += fval[j];
                        fc = 0.25*fc + s*EPSILON*frand3(v[0],v[1],v[2]);
                        fval[~(branch^1<<i) & 7] = fc;
                        v[i] = beg[i] + s;
                }
                for (i = 0; i < 3; i++) {       /* do edges */
                        j = (i+1)%3;
                        if (branch & 1<<j)
                                v[j] += s;
                        else
                                v[j] -= s;
                        j = (i+2)%3;
                        if (branch & 1<<j)
                                v[j] += s;
                        else
                                v[j] -= s;
                        fc = fval[branch & ~(1<<i)];
                        fc += fval[branch | 1<<i];
                        fc = 0.5*fc + s*EPSILON*frand3(v[0],v[1],v[2]);
                        fval[branch^1<<i] = fc;
                        j = (i+1)%3;
                        v[j] = beg[j] + s;
                        j = (i+2)%3;
                        v[j] = beg[j] + s;
                }
                for (i = 0; i < 3; i++)         /* new cube */
                        if (branch & 1<<i)
                                beg[i] += s;
        }
}
Revision:	1.5
Committed:	Fri May 24 14:23:33 1991 UTC (32 years, 11 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.4:	+36 -55 lines
Log Message:	changed noise3 initialization
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1988 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* noise3.c - noise functions for random textures.
9			*
10			* Credit for the smooth algorithm goes to Ken Perlin.
11			* (ref. SIGGRAPH Vol 19, No 3, pp 287-96)
12			*
13			* 4/15/86
14			* 5/19/88 Added fractal noise function
15			*/
16
17
18			#define A 0
19			#define B 1
20			#define C 2
21			#define D 3
22
23			#define rand3a(x,y,z) frand(67(x)+59(y)+71*(z))
24			#define rand3b(x,y,z) frand(73(x)+79(y)+83*(z))
25			#define rand3c(x,y,z) frand(89(x)+97(y)+101*(z))
26			#define rand3d(x,y,z) frand(103(x)+107(y)+109*(z))
27
28			#define hermite(p0,p1,r0,r1,t) ( p0((2.0t-3.0)tt+1.0) + \
29			p1(-2.0t+3.0)tt + \
30			r0((t-2.0)t+1.0)*t + \
31			r1(t-1.0)t*t )
32
33	greg	1.5	static char *noise_name[4] = {"noise3a", "noise3b", "noise3c", "noise3"};
34			static char fnoise_name[] = "fnoise3";
35			static char hermite_name[] = "hermite";
36	greg	1.1
37	greg	1.5	double *noise3(), fnoise3(), argument(), frand();
38
39	greg	1.1	static long xlim[3][2];
40			static double xarg[3];
41
42	greg	1.2	#define EPSILON .0001 /* error allowed in fractal */
43	greg	1.1
44	greg	1.3	#define frand3(x,y,z) frand(17(x)+23(y)+29*(z))
45	greg	1.1
46
47	greg	1.5	static double
48			l_noise3(nam) /* compute a noise function */
49			register char *nam;
50	greg	1.1	{
51	greg	1.5	register int i;
52			double x[3];
53			/* get point */
54			x[0] = argument(1);
55			x[1] = argument(2);
56			x[2] = argument(3);
57			/* make appropriate call */
58			if (nam == fnoise_name)
59			return(fnoise3(x));
60			i = 4;
61			while (i--)
62			if (nam == noise_name[i])
63			return(noise3(x)[i]);
64			eputs("Bad call to l_noise3()!\n");
65			quit(1);
66	greg	1.1	}
67
68
69			double
70	greg	1.5	l_hermite() /* library call for hermite interpolation */
71	greg	1.1	{
72	greg	1.5	double t;
73
74			t = argument(5);
75			return( hermite(argument(1), argument(2),
76			argument(3), argument(4), t) );
77	greg	1.1	}
78
79
80	greg	1.5	setnoisefuncs() /* add noise functions to library */
81	greg	1.1	{
82	greg	1.5	register int i;
83	greg	1.1
84	greg	1.5	funset(hermite_name, 5, ':', l_hermite);
85			funset(fnoise_name, 3, ':', l_noise3);
86			i = 4;
87			while (i--)
88			funset(noise_name[i], 3, ':', l_noise3);
89	greg	1.1	}
90
91
92			double *
93			noise3(xnew) /* compute the noise function */
94			register double xnew[3];
95			{
96			extern double floor();
97			static double x[3] = {-100000.0, -100000.0, -100000.0};
98			static double f[4];
99
100			if (x[0]==xnew[0] && x[1]==xnew[1] && x[2]==xnew[2])
101			return(f);
102			x[0] = xnew[0]; x[1] = xnew[1]; x[2] = xnew[2];
103			xlim[0][0] = floor(x[0]); xlim[0][1] = xlim[0][0] + 1;
104			xlim[1][0] = floor(x[1]); xlim[1][1] = xlim[1][0] + 1;
105			xlim[2][0] = floor(x[2]); xlim[2][1] = xlim[2][0] + 1;
106			xarg[0] = x[0] - xlim[0][0];
107			xarg[1] = x[1] - xlim[1][0];
108			xarg[2] = x[2] - xlim[2][0];
109			interpolate(f, 0, 3);
110			return(f);
111			}
112
113
114			static
115			interpolate(f, i, n)
116			double f[4];
117			register int i, n;
118			{
119			double f0[4], f1[4];
120
121			if (n == 0) {
122			f[A] = rand3a(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
123			f[B] = rand3b(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
124			f[C] = rand3c(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
125			f[D] = rand3d(xlim[0][i&1],xlim[1][i>>1&1],xlim[2][i>>2]);
126			} else {
127			n--;
128			interpolate(f0, i, n);
129			interpolate(f1, i \| 1<<n, n);
130			f[A] = (1.0-xarg[n])f0[A] + xarg[n]f1[A];
131			f[B] = (1.0-xarg[n])f0[B] + xarg[n]f1[B];
132			f[C] = (1.0-xarg[n])f0[C] + xarg[n]f1[C];
133			f[D] = hermite(f0[D], f1[D], f0[n], f1[n], xarg[n]);
134			}
135			}
136
137
138			double
139			frand(s) /* get random number from seed */
140			register long s;
141			{
142			s = s<<13 ^ s;
143			return(1.0-((s(ss*15731+789221)+1376312589)&0x7fffffff)/1073741824.0);
144			}
145
146
147			double
148			fnoise3(p) /* compute fractal noise function */
149	greg	1.3	double p[3];
150	greg	1.1	{
151			double floor();
152	greg	1.4	long t[3], v[3], beg[3];
153	greg	1.3	double fval[8], fc;
154			int branch;
155	greg	1.4	register long s;
156	greg	1.1	register int i, j;
157			/* get starting cube */
158	greg	1.3	s = (long)(1.0/EPSILON);
159			for (i = 0; i < 3; i++) {
160			t[i] = s*p[i];
161			beg[i] = s*floor(p[i]);
162			}
163	greg	1.1	for (j = 0; j < 8; j++) {
164			for (i = 0; i < 3; i++) {
165			v[i] = beg[i];
166			if (j & 1<<i)
167	greg	1.3	v[i] += s;
168	greg	1.1	}
169			fval[j] = frand3(v[0],v[1],v[2]);
170			}
171			/* compute fractal */
172			for ( ; ; ) {
173	greg	1.4	fc = 0.0;
174			for (j = 0; j < 8; j++)
175			fc += fval[j];
176			fc *= 0.125;
177			if ((s >>= 1) == 0)
178			return(fc); /* close enough */
179	greg	1.1	branch = 0;
180			for (i = 0; i < 3; i++) { /* do center */
181			v[i] = beg[i] + s;
182	greg	1.3	if (t[i] > v[i]) {
183	greg	1.1	branch \|= 1<<i;
184	greg	1.3	}
185	greg	1.1	}
186	greg	1.3	fc += sEPSILONfrand3(v[0],v[1],v[2]);
187	greg	1.1	fval[~branch & 7] = fc;
188			for (i = 0; i < 3; i++) { /* do faces */
189			if (branch & 1<<i)
190			v[i] += s;
191			else
192			v[i] -= s;
193			fc = 0.0;
194			for (j = 0; j < 8; j++)
195			if (~(j^branch) & 1<<i)
196			fc += fval[j];
197	greg	1.3	fc = 0.25fc + sEPSILON*frand3(v[0],v[1],v[2]);
198	greg	1.1	fval[~(branch^1<<i) & 7] = fc;
199			v[i] = beg[i] + s;
200			}
201			for (i = 0; i < 3; i++) { /* do edges */
202			j = (i+1)%3;
203			if (branch & 1<<j)
204			v[j] += s;
205			else
206			v[j] -= s;
207			j = (i+2)%3;
208			if (branch & 1<<j)
209			v[j] += s;
210			else
211			v[j] -= s;
212			fc = fval[branch & ~(1<<i)];
213			fc += fval[branch \| 1<<i];
214	greg	1.3	fc = 0.5fc + sEPSILON*frand3(v[0],v[1],v[2]);
215	greg	1.1	fval[branch^1<<i] = fc;
216			j = (i+1)%3;
217			v[j] = beg[j] + s;
218			j = (i+2)%3;
219			v[j] = beg[j] + s;
220			}
221			for (i = 0; i < 3; i++) /* new cube */
222			if (branch & 1<<i)
223			beg[i] += s;
224			}
225			}