1 /*
2 * fbm.c
3 *
4 * Copyright (C) 1989, 1991, Craig E. Kolb
5 * All rights reserved.
6 *
7 * This software may be freely copied, modified, and redistributed
8 * provided that this copyright notice is preserved on all copies.
9 *
10 * You may not distribute this software, in whole or in part, as part of
11 * any commercial product without the express consent of the authors.
12 *
13 * There is no warranty or other guarantee of fitness of this software
14 * for any purpose. It is provided solely "as is".
15 *
16 * $Id: fbm.c,v 4.0 91/07/17 14:42:06 kolb Exp Locker: kolb $
17 *
18 * $Log: fbm.c,v $
19 * Revision 4.0 91/07/17 14:42:06 kolb
20 * Initial version.
21 *
22 */
23 #include "texture.h"
24 #include "fbm.h"
25
26 FBm *
FBmCreate(offset,scale,h,lambda,octaves,thresh,mapname)27 FBmCreate(offset, scale, h, lambda, octaves, thresh, mapname)
28 Float h, lambda, scale, offset, thresh;
29 int octaves;
30 char *mapname;
31 {
32 FBm *fbm;
33
34 fbm = (FBm *)Malloc(sizeof(FBm));
35
36 fbm->beta = 1. + 2*h;
37 fbm->omega = pow(lambda, -0.5*fbm->beta);
38 fbm->lambda = lambda;
39 fbm->scale = scale;
40 fbm->offset = offset;
41 fbm->thresh = thresh;
42 fbm->octaves = octaves;
43 if (mapname != (char *)NULL)
44 fbm->colormap = ColormapRead(mapname);
45 else
46 fbm->colormap = (Color *)NULL;
47 return fbm;
48 }
49
50 void
FBmApply(fbm,prim,ray,pos,norm,gnorm,surf)51 FBmApply(fbm, prim, ray, pos, norm, gnorm, surf)
52 FBm *fbm;
53 Geom *prim;
54 Ray *ray;
55 Vector *pos, *norm, *gnorm;
56 Surface *surf;
57 {
58 Float val;
59 int index;
60
61 val = fBm(pos, fbm->omega, fbm->lambda, fbm->octaves);
62 if (val < fbm->thresh)
63 val = fbm->offset;
64 else
65 val = fbm->offset + fbm->scale*(val - fbm->thresh);
66 if (fbm->colormap) {
67 index = 255. * val;
68 if (index > 255) index = 255;
69 if (index < 0) index = 0;
70 surf->diff.r *= fbm->colormap[index].r;
71 surf->diff.g *= fbm->colormap[index].g;
72 surf->diff.b *= fbm->colormap[index].b;
73 surf->amb.r *= fbm->colormap[index].r;
74 surf->amb.g *= fbm->colormap[index].g;
75 surf->amb.b *= fbm->colormap[index].b;
76 } else {
77 ColorScale(val, surf->diff, &surf->diff);
78 ColorScale(val, surf->amb, &surf->amb);
79 }
80 }
81