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root/radiance/ray/src/rt/rayinit.cal
Revision: 1.3
Committed: Wed Oct 9 11:36:45 1991 UTC (32 years, 6 months ago) by greg
Branch: MAIN
Changes since 1.2: +10 -0 lines
Log Message:
added normally distributed random variable nrand(x)

File Contents

# User Rev Content
1 greg 1.1 { SCCSid "$SunId$ LBL" }
2    
3     {
4     Initialization file for Radiance.
5    
6     The following are predefined:
7    
8     Dx, Dy, Dz - ray direction
9     Nx, Ny, Nz - surface normal
10     Px, Py, Pz - intersection point
11     T - distance from start
12     Rdot - ray dot product
13     S - world scale
14     Tx, Ty, Tz - world origin
15     Ix, Iy, Iz - world i unit vector
16     Jx, Jy, Jz - world j unit vector
17     Kx, Ky, Kz - world k unit vector
18     arg(n) - real arguments, arg(0) is count
19    
20     For brdf functions, the following are also available:
21    
22     NxP, NyP, NzP - perturbed surface normal
23     RdotP - perturbed ray dot product
24     CrP, CgP, CbP - perturbed material color
25    
26     Library functions:
27    
28     if(a, b, c) - if a positive, return b, else c
29    
30     select(N, a1, a2, ..) - return aN
31    
32     sqrt(x) - square root function
33    
34     sin(x), cos(x), tan(x),
35     asin(x), acos(x),
36     atan(x), atan2(y,x) - standard trig functions
37    
38     floor(x), ceil(x) - g.l.b. & l.u.b.
39    
40     exp(x), log(x), log10(x) - exponent and log functions
41    
42     erf(z), erfc(z) - error functions
43    
44     rand(x) - pseudo-random function (0 to 1)
45    
46     hermite(p0,p1,r0,r1,t) - 1-dimensional hermite polynomial
47    
48     noise3(x,y,z), noise3a(x,y,z),
49     noise3b(x,y,z), noise3c(x,y,z) - noise function with gradient (-1 to 1)
50    
51     fnoise3(x,y,z) - fractal noise function (-1 to 1)
52     }
53    
54     { Backward compatibility }
55     AC = arg(0);
56     A1 = arg(1); A2 = arg(2); A3 = arg(3); A4 = arg(4); A5 = arg(5);
57     A6 = arg(6); A7 = arg(7); A8 = arg(8); A9 = arg(9); A10 = arg(10);
58    
59     { Forward compatibility (?) }
60     D(i) = select(i, Dx, Dy, Dz);
61     N(i) = select(i, Nx, Ny, Nz);
62     P(i) = select(i, Px, Py, Pz);
63     noise3d(i,x,y,z) = select(i, noise3a(x,y,z), noise3b(x,y,z), noise3c(x,y,z));
64    
65     { More robust versions of library functions }
66     bound(a,x,b) : if(a-x, a, if(x-b, b, x));
67     Acos(x) : acos(bound(-1,x,1));
68     Asin(x) : asin(bound(-1,x,1));
69     Exp(x) : if(-x-60, 0, exp(x));
70     Sqrt(x) : if(x, sqrt(x), 0);
71    
72     { Useful constants }
73     PI : 3.14159265358979323846;
74     DEGREE : PI/180;
75     FTINY : 1e-7;
76    
77     { Useful functions }
78     and(a,b) : if( a, b, a );
79     or(a,b) : if( a, a, b );
80     not(a) : if( a, -1, 1 );
81     abs(x) : if( x, x, -x );
82     sgn(x) : if( x, 1, if(-x, -1, 0) );
83     sq(x) : x*x;
84     max(a,b) : if( a-b, a, b );
85     min(a,b) : if( a-b, b, a );
86     inside(a,x,b) : and(x-a,b-x);
87     frac(x) : x - floor(x);
88     mod(n,d) : n - floor(n/d)*d;
89     tri(n,d) : abs( d - mod(n-d,2*d) );
90     linterp(t,p0,p1) : (1-t)*p0 + t*p1;
91    
92     noop(v) = v;
93     clip(v) = bound(0,v,1);
94     noneg(v) = max(0,v);
95     red(r,g,b) = r;
96     green(r,g,b) = g;
97     blue(r,g,b) = b;
98     grey(r,g,b) = .3*r + .59*g + .11*b;
99     clip_r(r,g,b) = bound(0,r,1);
100     clip_g(r,g,b) = bound(0,g,1);
101     clip_b(r,g,b) = bound(0,b,1);
102     clipgrey(r,g,b) = bound(0,grey(r,g,b),1);
103    
104     dot(v1,v2) : v1(1)*v2(1) + v1(2)*v2(2) + v1(3)*v2(3);
105     cross(i,v1,v2) : select(i, v1(2)*v2(3) - v1(3)*v2(2),
106     v1(3)*v2(1) - v1(1)*v2(3),
107     v1(1)*v2(2) - v1(2)*v2(1));
108    
109     fade(near_val,far_val,dist) = far_val +
110     if (16-dist, (near_val-far_val)/(1+dist*dist), 0);
111    
112     bezier(p1, p2, p3, p4, t) = p1 * (1+t*(-3+t*(3-t))) +
113     p2 * 3*t*(1+t*(-2+t)) +
114     p3 * 3*t*t*(1-t) +
115     p4 * t*t*t ;
116    
117     bspline(pp, p0, p1, pn, t) = pp * (1/6+t*(-.5+t*(.5-1/6*t))) +
118     p0 * (2/3+t*t*(-1+.5*t)) +
119     p1 * (1/6+t*(.5+t*(.5-.5*t))) +
120     pn * (1/6*t*t*t) ;
121    
122     turbulence(x,y,z,s) = if( s-1.01, 0, abs(noise3(x/s,y/s,z/s)*s) +
123     turbulence(x,y,z,2*s) );
124     turbulencea(x,y,z,s) = if( s-1.01, 0,
125     sgn(noise3(x/s,y/s,z/s))*noise3a(x/s,y/s,z/s) +
126     turbulencea(x,y,z,2*s) );
127     turbulenceb(x,y,z,s) = if( s-1.01, 0,
128     sgn(noise3(x/s,y/s,z/s))*noise3b(x/s,y/s,z/s) +
129     turbulenceb(x,y,z,2*s) );
130     turbulencec(x,y,z,s) = if( s-1.01, 0,
131     sgn(noise3(x/s,y/s,z/s))*noise3c(x/s,y/s,z/s) +
132     turbulencec(x,y,z,2*s) );
133 greg 1.2
134 greg 1.3 { Normal distribution from uniform range (0,1) }
135    
136     un2`private(t) : t - (2.515517+t*(.802853+t*.010328))/
137     (1+t*(1.432788+t*(.189269+t*.001308))) ;
138     un1`private(p) : un2`private(sqrt(log(1/p/p))) ;
139    
140     unif2norm(p) : if( .5-p, un1`private(p), -un1`private(1-p) ) ;
141    
142     nrand(x) = unif2norm(rand(x));
143    
144 greg 1.2 { Local (u,v) coordinates for planar surfaces }
145     crosslen`private = Nx*Nx + Ny*Ny;
146     { U is distance from origin in XY-plane }
147     U = if( crosslen`private - FTINY,
148     (Py*Nx - Px*Ny)/crosslen`private,
149     Px);
150     { V is defined so that N = U x V }
151     V = if( crosslen`private - FTINY,
152     Pz - Nz*(Px*Nx + Py*Ny)/crosslen`private,
153     Py);