about summary refs log tree commit diff
path: root/generator/ppmforge.c
blob: 114f7f1835aa2995e498aa6b56de5a3db3bd472c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
/*

        Fractal forgery generator for the PPM toolkit

    Originally  designed  and  implemented  in December of 1989 by
    John Walker as a stand-alone program for the  Sun  and  MS-DOS
    under  Turbo C.  Adapted in September of 1991 for use with Jef
        Poskanzer's raster toolkit.

    References cited in the comments are:

        Foley, J. D., and Van Dam, A., Fundamentals of Interactive
        Computer  Graphics,  Reading,  Massachusetts:  Addison
        Wesley, 1984.

        Peitgen, H.-O., and Saupe, D. eds., The Science Of Fractal
        Images, New York: Springer Verlag, 1988.

        Press, W. H., Flannery, B. P., Teukolsky, S. A., Vetterling,
        W. T., Numerical Recipes In C, New Rochelle: Cambridge
        University Press, 1988.

    Author:
        John Walker
        http://www.fourmilab.ch/

    Permission  to  use, copy, modify, and distribute this software and
    its documentation  for  any  purpose  and  without  fee  is  hereby
    granted,  without any conditions or restrictions.  This software is
    provided "as is" without express or implied warranty.

*/

#define _XOPEN_SOURCE 500  /* get M_PI in math.h */

#include <math.h>
#include <assert.h>

#include "pm_c_util.h"
#include "ppm.h"
#include "mallocvar.h"
#include "shhopt.h"

static double const hugeVal = 1e50;

/* Definitions used to address real and imaginary parts in a two-dimensional
   array of complex numbers as stored by fourn(). */

#define Real(v, x, y)  v[1 + (((x) * meshsize) + (y)) * 2]
#define Imag(v, x, y)  v[2 + (((x) * meshsize) + (y)) * 2]

/* Coordinate indices within arrays. */

typedef struct {
    double x;
    double y;
    double z;
} Vector;

/* Definition for obtaining random numbers. */

#define nrand 4               /* Gauss() sample count */
#define Cast(low, high) ((low)+(((high)-(low)) * ((rand() & 0x7FFF) / arand)))

/*  Local variables  */

static double arand, gaussadd, gaussfac; /* Gaussian random parameters */
static double fracdim;            /* Fractal dimension */
static double powscale;           /* Power law scaling exponent */
static int meshsize = 256;        /* FFT mesh size */
static double inclangle, hourangle;   /* Star position relative to planet */
static bool inclspec = FALSE;      /* No inclination specified yet */
static bool hourspec = FALSE;      /* No hour specified yet */
static double icelevel;           /* Ice cap threshold */
static double glaciers;           /* Glacier level */
static int starfraction;          /* Star fraction */
static int starcolor;            /* Star color saturation */


struct CmdlineInfo {
    unsigned int clouds;
    unsigned int night;
    float        dimension;
    float        hourAngle;
    unsigned int hourSpec;
    float        inclAngle;
    unsigned int inclinationSpec;
    unsigned int meshSize;
    unsigned int meshSpec;
    float        power;
    float        glaciers;
    float        ice;
    int          saturation;
    unsigned int seed;
    int          stars;
    unsigned int starsSpec;
    unsigned int width;
    unsigned int height;
};



static void
parseCommandLine(int argc, const char **argv,
                 struct CmdlineInfo * const cmdlineP) {
/*----------------------------------------------------------------------------
  Convert program invocation arguments (argc,argv) into a format the
  program can use easily, struct cmdlineInfo.  Validate arguments along
  the way and exit program with message if invalid.

  Note that some string information we return as *cmdlineP is in the storage
  argv[] points to.
-----------------------------------------------------------------------------*/
    optEntry * option_def;
        /* Instructions to OptParseOptions3 on how to parse our options.
         */
    optStruct3 opt;

    unsigned int option_def_index;

    unsigned int dimensionSpec, seedSpec,
        meshSpec, powerSpec, glaciersSpec, iceSpec, saturationSpec,
        starsSpec, widthSpec, heightSpec;
    float hour;
    float inclination;
    unsigned int mesh;

    MALLOCARRAY_NOFAIL(option_def, 100);

    option_def_index = 0;
    OPTENT3(0, "clouds",      OPT_FLAG, NULL, &cmdlineP->clouds, 0);
    OPTENT3(0, "night",       OPT_FLAG, NULL, &cmdlineP->night, 0);
    OPTENT3(0, "dimension",   OPT_FLOAT, &cmdlineP->dimension,
            &dimensionSpec, 0);
    OPTENT3(0, "hour",        OPT_FLOAT, &hour,
            &cmdlineP->hourSpec, 0);
    OPTENT3(0, "inclination", OPT_FLOAT, &inclination,
            &cmdlineP->inclinationSpec, 0);
    OPTENT3(0, "tilt",        OPT_FLOAT, &inclination,
            &cmdlineP->inclinationSpec, 0);
    OPTENT3(0, "mesh",        OPT_UINT, &mesh,
            &meshSpec, 0);
    OPTENT3(0, "power",       OPT_FLOAT, &cmdlineP->power,
            &powerSpec, 0);
    OPTENT3(0, "glaciers",    OPT_FLOAT, &cmdlineP->glaciers,
            &glaciersSpec, 0);
    OPTENT3(0, "ice",         OPT_FLOAT, &cmdlineP->ice,
            &iceSpec, 0);
    OPTENT3(0, "saturation",  OPT_INT,   &cmdlineP->saturation,
            &saturationSpec, 0);
    OPTENT3(0, "seed",        OPT_UINT,  &cmdlineP->seed,
            &seedSpec, 0);
    OPTENT3(0, "stars",       OPT_INT,   &cmdlineP->stars,
            &starsSpec, 0);
    OPTENT3(0, "width",       OPT_UINT,  &cmdlineP->width,
            &widthSpec, 0);
    OPTENT3(0, "xsize",       OPT_UINT,  &cmdlineP->width,
            &widthSpec, 0);
    OPTENT3(0, "height",      OPT_UINT,  &cmdlineP->height,
            &heightSpec, 0);
    OPTENT3(0, "ysize",       OPT_UINT,  &cmdlineP->height,
            &heightSpec, 0);

    opt.opt_table = option_def;
    opt.short_allowed = FALSE;  /* We have no short (old-fashioned) options */
    opt.allowNegNum = FALSE;  /* We have no parms that are negative numbers */

    pm_optParseOptions3(&argc, (char **)argv, opt, sizeof(opt), 0);
        /* Uses and sets argc, argv, and some of *cmdlineP and others. */

    if (dimensionSpec) {
        if (cmdlineP->dimension <= 0.0)
            pm_error("-dimension must be greater than zero.  "
                     "You specified %f", cmdlineP->dimension);
    } else
        cmdlineP->dimension = cmdlineP->clouds ? 2.15 : 2.4;

    if (cmdlineP->hourSpec)
        cmdlineP->hourAngle = (M_PI / 12.0) * (hour + 12.0);

    if (cmdlineP->inclinationSpec)
        cmdlineP->inclAngle = (M_PI / 180.0) * inclination;

    if (meshSpec) {
        unsigned int i;
        if (mesh < 2)
            pm_error("-mesh value must be at least 2.  "
                     "You specified %u", mesh);
        /* Force FFT mesh to the next larger power of 2. */
        for (i = 2; i < mesh; i <<= 1);
        cmdlineP->meshSize = i;
    } else
        cmdlineP->meshSize = 256;

    if (powerSpec) {
        if (cmdlineP->power <= 0.0)
            pm_error("-power must be greater than zero.  "
                     "You specified %f", cmdlineP->power);
    } else
        cmdlineP->power = cmdlineP->clouds ? 0.75 : 1.2;

    if (iceSpec) {
        if (cmdlineP->ice <= 0.0)
            pm_error("-ice must be greater than zero.  "
                     "You specified %f", cmdlineP->ice);
    } else
        cmdlineP->ice = 0.4;

    if (glaciersSpec) {
        if (cmdlineP->glaciers <= 0.0)
            pm_error("-glaciers must be greater than 0.  "
                     "You specified %f", cmdlineP->glaciers);
    } else
        cmdlineP->glaciers = 0.75;

    if (!starsSpec)
        cmdlineP->stars = 100;

    if (!saturationSpec)
        cmdlineP->saturation = 125;

    if (!seedSpec)
        cmdlineP->seed = pm_randseed();

    if (!widthSpec)
        cmdlineP->width = 256;

    if (!heightSpec)
        cmdlineP->height = 256;

    if (argc-1 > 0)
        pm_error("There are no non-option arguments.  "
                 "You specified %u", argc-1);

    free(option_def);
}



static void
fourn(float *     const data,
      const int * const nn,
      int         const ndim,
      int         const isign) {
/*----------------------------------------------------------------------------
    Multi-dimensional fast Fourier transform

    Arguments:

       data       A  one-dimensional  array  of  floats  (NOTE!!!   NOT
              DOUBLES!!), indexed from one (NOTE!!!   NOT  ZERO!!),
              containing  pairs of numbers representing the complex
              valued samples.  The Fourier transformed results  are
              returned in the same array.

       nn         An  array specifying the edge size in each dimension.
              THIS ARRAY IS INDEXED FROM  ONE,  AND  ALL  THE  EDGE
              SIZES MUST BE POWERS OF TWO!!!

       ndim       Number of dimensions of FFT to perform.  Set to 2 for
              two dimensional FFT.

       isign      If 1, a Fourier transform is done; if -1 the  inverse
              transformation is performed.

        This  function  is essentially as given in Press et al., "Numerical
        Recipes In C", Section 12.11, pp.  467-470.
-----------------------------------------------------------------------------*/
    int i1, i2, i3;
    int i2rev, i3rev, ip1, ip2, ip3, ifp1, ifp2;
    int ibit, idim, k1, k2, n, nprev, nrem, ntot;
    float tempi, tempr;
    double theta, wi, wpi, wpr, wr, wtemp;

#define SWAP(a,b) tempr=(a); (a) = (b); (b) = tempr

    ntot = 1;
    for (idim = 1; idim <= ndim; idim++)
        ntot *= nn[idim];
    nprev = 1;
    for (idim = ndim; idim >= 1; idim--) {
        n = nn[idim];
        nrem = ntot / (n * nprev);
        ip1 = nprev << 1;
        ip2 = ip1 * n;
        ip3 = ip2 * nrem;
        i2rev = 1;
        for (i2 = 1; i2 <= ip2; i2 += ip1) {
            if (i2 < i2rev) {
                for (i1 = i2; i1 <= i2 + ip1 - 2; i1 += 2) {
                    for (i3 = i1; i3 <= ip3; i3 += ip2) {
                        i3rev = i2rev + i3 - i2;
                        SWAP(data[i3], data[i3rev]);
                        SWAP(data[i3 + 1], data[i3rev + 1]);
                    }
                }
            }
            ibit = ip2 >> 1;
            while (ibit >= ip1 && i2rev > ibit) {
                i2rev -= ibit;
                ibit >>= 1;
            }
            i2rev += ibit;
        }
        ifp1 = ip1;
        while (ifp1 < ip2) {
            ifp2 = ifp1 << 1;
            theta = isign * (M_PI * 2) / (ifp2 / ip1);
            wtemp = sin(0.5 * theta);
            wpr = -2.0 * wtemp * wtemp;
            wpi = sin(theta);
            wr = 1.0;
            wi = 0.0;
            for (i3 = 1; i3 <= ifp1; i3 += ip1) {
                for (i1 = i3; i1 <= i3 + ip1 - 2; i1 += 2) {
                    for (i2 = i1; i2 <= ip3; i2 += ifp2) {
                        k1 = i2;
                        k2 = k1 + ifp1;
                        tempr = wr * data[k2] - wi * data[k2 + 1];
                        tempi = wr * data[k2 + 1] + wi * data[k2];
                        data[k2] = data[k1] - tempr;
                        data[k2 + 1] = data[k1 + 1] - tempi;
                        data[k1] += tempr;
                        data[k1 + 1] += tempi;
                    }
                }
                wr = (wtemp = wr) * wpr - wi * wpi + wr;
                wi = wi * wpr + wtemp * wpi + wi;
            }
            ifp1 = ifp2;
        }
        nprev *= n;
    }
}
#undef SWAP



static void
initgauss(unsigned int const seed) {
/*----------------------------------------------------------------------------
  Initialize random number generators.

  As given in Peitgen & Saupe, page 77.
-----------------------------------------------------------------------------*/
    /* Range of random generator */
    arand = pow(2.0, 15.0) - 1.0;
    gaussadd = sqrt(3.0 * nrand);
    gaussfac = 2 * gaussadd / (nrand * arand);
    srand(seed);
}



static double
gauss() {
/*----------------------------------------------------------------------------
  A Gaussian random number.

  As given in Peitgen & Saupe, page 77.
-----------------------------------------------------------------------------*/
    int i;
    double sum;

    for (i = 1, sum = 0.0; i <= nrand; ++i) {
        sum += (rand() & 0x7FFF);
    }
    return gaussfac * sum - gaussadd;
}



static void
spectralsynth(float **     const x,
              unsigned int const n,
              double        const h) {
/*----------------------------------------------------------------------------
  Spectrally synthesized fractal motion in two dimensions.

  This algorithm is given under the name SpectralSynthesisFM2D on page 108 of
  Peitgen & Saupe.
-----------------------------------------------------------------------------*/
    unsigned bl;
    int i, j, i0, j0, nsize[3];
    double rad, phase, rcos, rsin;
    float *a;

    bl = ((((unsigned long) n) * n) + 1) * 2 * sizeof(float);
    a = (float *) calloc(bl, 1);
    if (a == (float *) 0) {
        pm_error("Cannot allocate %d x %d result array (% d bytes).",
                 n, n, bl);
    }
    *x = a;

    for (i = 0; i <= n / 2; i++) {
        for (j = 0; j <= n / 2; j++) {
            phase = 2 * M_PI * ((rand() & 0x7FFF) / arand);
            if (i != 0 || j != 0) {
                rad = pow((double) (i * i + j * j), -(h + 1) / 2) * gauss();
            } else {
                rad = 0;
            }
            rcos = rad * cos(phase);
            rsin = rad * sin(phase);
            Real(a, i, j) = rcos;
            Imag(a, i, j) = rsin;
            i0 = (i == 0) ? 0 : n - i;
            j0 = (j == 0) ? 0 : n - j;
            Real(a, i0, j0) = rcos;
            Imag(a, i0, j0) = - rsin;
        }
    }
    Imag(a, n / 2, 0) = 0;
    Imag(a, 0, n / 2) = 0;
    Imag(a, n / 2, n / 2) = 0;
    for (i = 1; i <= n / 2 - 1; i++) {
        for (j = 1; j <= n / 2 - 1; j++) {
            phase = 2 * M_PI * ((rand() & 0x7FFF) / arand);
            rad = pow((double) (i * i + j * j), -(h + 1) / 2) * gauss();
            rcos = rad * cos(phase);
            rsin = rad * sin(phase);
            Real(a, i, n - j) = rcos;
            Imag(a, i, n - j) = rsin;
            Real(a, n - i, j) = rcos;
            Imag(a, n - i, j) = - rsin;
        }
    }

    nsize[0] = 0;
    nsize[1] = nsize[2] = n;          /* Dimension of frequency domain array */
    fourn(a, nsize, 2, -1);       /* Take inverse 2D Fourier transform */
}



static void
temprgb(double   const temp,
        double * const r,
        double * const g,
        double * const b) {
/*----------------------------------------------------------------------------
  Calculate the relative R, G, and B components for a black body emitting
  light at a given temperature.  We solve the Planck radiation equation
  directly for the R, G, and B wavelengths defined for the CIE 1931 Standard
  Colorimetric Observer.  The color temperature is specified in kelvins.
-----------------------------------------------------------------------------*/
    double const c1 = 3.7403e10;
    double const c2 = 14384.0;
    double er, eg, eb, es;

/* Lambda is the wavelength in microns: 5500 angstroms is 0.55 microns. */

#define Planck(lambda)  ((c1 * pow((double) lambda, -5.0)) /  \
                         (pow(M_E, c2 / (lambda * temp)) - 1))

        er = Planck(0.7000);
        eg = Planck(0.5461);
        eb = Planck(0.4358);
#undef Planck

        es = 1.0 / MAX(er, MAX(eg, eb));

        *r = er * es;
        *g = eg * es;
        *b = eb * es;
}



static void
etoile(pixel * const pix) {
/*----------------------------------------------------------------------------
    Set a pixel in the starry sky.
-----------------------------------------------------------------------------*/
    if ((rand() % 1000) < starfraction) {
#define StarQuality 0.5       /* Brightness distribution exponent */
#define StarIntensity   8         /* Brightness scale factor */
#define StarTintExp 0.5       /* Tint distribution exponent */
        double v = StarIntensity * pow(1 / (1 - Cast(0, 0.9999)),
                                       (double) StarQuality),
            temp,
            r, g, b;

        if (v > 255) {
            v = 255;
        }

        /* We make a special case for star color  of zero in order to
           prevent  floating  point  roundoff  which  would  otherwise
           result  in  more  than  256 star colors.  We can guarantee
           that if you specify no star color, you never get more than
           256 shades in the image. */

        if (starcolor == 0) {
            int vi = v;

            PPM_ASSIGN(*pix, vi, vi, vi);
        } else {
            temp = 5500 + starcolor *
                pow(1 / (1 - Cast(0, 0.9999)), StarTintExp) *
                ((rand() & 7) ? -1 : 1);
            /* Constrain temperature to a reasonable value: >= 2600K
               (S Cephei/R Andromedae), <= 28,000 (Spica). */
            temp = MAX(2600, MIN(28000, temp));
            temprgb(temp, &r, &g, &b);
            PPM_ASSIGN(*pix, (int) (r * v + 0.499),
                       (int) (g * v + 0.499),
                       (int) (b * v + 0.499));
        }
    } else {
        PPM_ASSIGN(*pix, 0, 0, 0);
    }
}



static double
uprj(unsigned int const a,
     unsigned int const size) {

    return (double)a/(size-1);
}



static double
atSat(double const x,
      double const y,
      double const dsat) {

    return x*(1.0-dsat) + y*dsat;
}



static unsigned char *
makeCp(float *      const a,
       unsigned int const n,
       pixval       const maxval) {

    /* Prescale the grid points into intensities. */

    unsigned char * cp;
    unsigned char * ap;

    if (UINT_MAX / n < n)
        pm_error("arithmetic overflow squaring %u", n);
    cp = malloc(n * n);
    if (cp == NULL)
        pm_error("Unable to allocate %u bytes for cp array", n);

    ap = cp;
    {
        unsigned int i;
        for (i = 0; i < n; i++) {
            unsigned int j;
            for (j = 0; j < n; j++)
                *ap++ = ((double)maxval * (Real(a, i, j) + 1.0)) / 2.0;
        }
    }
    return cp;
}



static void
createPlanetStuff(bool             const clouds,
                  float *          const a,
                  unsigned int     const n,
                  double **        const uP,
                  double **        const u1P,
                  unsigned int **  const bxfP,
                  unsigned int **  const bxcP,
                  unsigned char ** const cpP,
                  Vector *         const sunvecP,
                  unsigned int     const cols,
                  pixval           const maxval) {

    double *u, *u1;
    unsigned int *bxf, *bxc;
    unsigned char * cp;
    double shang, siang;
    bool flipped;

    /* Compute incident light direction vector. */

    shang = hourspec ? hourangle : Cast(0, 2 * M_PI);
    siang = inclspec ? inclangle : Cast(-M_PI * 0.12, M_PI * 0.12);

    sunvecP->x = sin(shang) * cos(siang);
    sunvecP->y = sin(siang);
    sunvecP->z = cos(shang) * cos(siang);  /* initial value */

    /* Allow only 25% of random pictures to be crescents */

    if (!hourspec && ((rand() % 100) < 75)) {
        flipped = (sunvecP->z < 0);
        sunvecP->z = fabs(sunvecP->z);
    } else
        flipped = FALSE;

    if (!clouds) {
        pm_message(
            "        -inclination %.0f -hour %d -ice %.2f -glaciers %.2f",
            (siang * (180.0 / M_PI)),
            (int) (((shang * (12.0 / M_PI)) + 12 +
                    (flipped ? 12 : 0)) + 0.5) % 24,
            icelevel,
            glaciers);
        pm_message("        -stars %d -saturation %d.",
                   starfraction, starcolor);
    }

    cp = makeCp(a, n, maxval);

    /* Fill the screen from the computed  intensity  grid  by  mapping
       screen  points onto the grid, then calculating each pixel value
       by bilinear interpolation from  the  surrounding  grid  points.
       (N.b. the pictures would undoubtedly look better when generated
       with small grids if  a  more  well-behaved  interpolation  were
       used.)

       Also compute the line-level interpolation parameters that
       caller will need every time around his inner loop.
    */

    MALLOCARRAY(u,   cols);
    MALLOCARRAY(u1,  cols);
    MALLOCARRAY(bxf, cols);
    MALLOCARRAY(bxc, cols);

    if (u == NULL || u1 == NULL || bxf == NULL || bxc == NULL)
        pm_error("Cannot allocate %u element interpolation tables.", cols);
    {
        unsigned int j;
        for (j = 0; j < cols; j++) {
            double const bx = (n - 1) * uprj(j, cols);

            bxf[j] = floor(bx);
            bxc[j] = MIN(bxf[j] + 1, n - 1);
            u[j] = bx - bxf[j];
            u1[j] = 1 - u[j];
        }
    }
    *uP   = u;  *u1P  = u1;
    *bxfP = bxf; *bxcP = bxc;
    *cpP  = cp;
}



static void
generateStarrySkyRow(pixel *      const pixels,
                     unsigned int const cols) {
/*----------------------------------------------------------------------------
  Generate a starry sky.  Note  that no FFT is performed;
  the output is  generated  directly  from  a  power  law
  mapping  of  a  pseudorandom sequence into intensities.
-----------------------------------------------------------------------------*/
    unsigned int j;

    for (j = 0; j < cols; j++)
        etoile(pixels + j);
}



static void
generateCloudRow(pixel *         const pixels,
                 unsigned int    const cols,
                 double          const t,
                 double          const t1,
                 double *        const u,
                 double *        const u1,
                 unsigned char * const cp,
                 unsigned int *  const bxc,
                 unsigned int *  const bxf,
                 int             const byc,
                 int             const byf,
                 pixval          const maxval) {

    /* Render the FFT output as clouds. */

    unsigned int col;

    for (col = 0; col < cols; ++col) {
        double r;
        pixval w;

        r = 0.0;  /* initial value */
        /* Note that where t1 and t are zero, the cp[] element
           referenced below does not exist.
        */
        if (t1 > 0.0)
            r += t1 * u1[col] * cp[byf + bxf[col]] +
                t1 * u[col]  * cp[byf + bxc[col]];
        if (t > 0.0)
            r += t * u1[col] * cp[byc + bxf[col]] +
                t * u[col]  * cp[byc + bxc[col]];

        w = (r > 127.0) ? (maxval * ((r - 127.0) / 128.0)) : 0;

        PPM_ASSIGN(pixels[col], w, w, maxval);
    }
}



static void
makeLand(int *  const irP,
         int *  const igP,
         int *  const ibP,
         double const r) {
/*----------------------------------------------------------------------------
  Land area.  Look up color based on elevation from precomputed
  color map table.
-----------------------------------------------------------------------------*/
    static unsigned char pgnd[][3] = {
        {206, 205, 0}, {208, 207, 0}, {211, 208, 0},
        {214, 208, 0}, {217, 208, 0}, {220, 208, 0},
        {222, 207, 0}, {225, 205, 0}, {227, 204, 0},
        {229, 202, 0}, {231, 199, 0}, {232, 197, 0},
        {233, 194, 0}, {234, 191, 0}, {234, 188, 0},
        {233, 185, 0}, {232, 183, 0}, {231, 180, 0},
        {229, 178, 0}, {227, 176, 0}, {225, 174, 0},
        {223, 172, 0}, {221, 170, 0}, {219, 168, 0},
        {216, 166, 0}, {214, 164, 0}, {212, 162, 0},
        {210, 161, 0}, {207, 159, 0}, {205, 157, 0},
        {203, 156, 0}, {200, 154, 0}, {198, 152, 0},
        {195, 151, 0}, {193, 149, 0}, {190, 148, 0},
        {188, 147, 0}, {185, 145, 0}, {183, 144, 0},
        {180, 143, 0}, {177, 141, 0}, {175, 140, 0},
        {172, 139, 0}, {169, 138, 0}, {167, 137, 0},
        {164, 136, 0}, {161, 135, 0}, {158, 134, 0},
        {156, 133, 0}, {153, 132, 0}, {150, 132, 0},
        {147, 131, 0}, {145, 130, 0}, {142, 130, 0},
        {139, 129, 0}, {136, 128, 0}, {133, 128, 0},
        {130, 127, 0}, {127, 127, 0}, {125, 127, 0},
        {122, 127, 0}, {119, 127, 0}, {116, 127, 0},
        {113, 127, 0}, {110, 128, 0}, {107, 128, 0},
        {104, 128, 0}, {102, 127, 0}, { 99, 126, 0},
        { 97, 124, 0}, { 95, 122, 0}, { 93, 120, 0},
        { 92, 117, 0}, { 92, 114, 0}, { 92, 111, 0},
        { 93, 108, 0}, { 94, 106, 0}, { 96, 104, 0},
        { 98, 102, 0}, {100, 100, 0}, {103,  99, 0},
        {106,  99, 0}, {109,  99, 0}, {111, 100, 0},
        {114, 101, 0}, {117, 102, 0}, {120, 103, 0},
        {123, 102, 0}, {125, 102, 0}, {128, 100, 0},
        {130,  98, 0}, {132,  96, 0}, {133,  94, 0},
        {134,  91, 0}, {134,  88, 0}, {134,  85, 0},
        {133,  82, 0}, {131,  80, 0}, {129,  78, 0}
    };

    unsigned int const ix = ((r - 128) * (ARRAY_SIZE(pgnd) - 1)) / 127;

    *irP = pgnd[ix][0];
    *igP = pgnd[ix][1];
    *ibP = pgnd[ix][2];
}



static void
makeWater(int *  const irP,
          int *  const igP,
          int *  const ibP,
          double const r,
          pixval const maxval) {

    /* Water.  Generate clouds above water based on elevation.  */

    *irP = *igP = r > 64 ? (r - 64) * 4 : 0;
    *ibP = maxval;
}



static void
addIce(int *  const irP,
       int *  const igP,
       int *  const ibP,
       double const r,
       double const azimuth,
       double const icelevel,
       double const glaciers,
       pixval const maxval) {

    /* Generate polar ice caps. */

    double const icet = pow(fabs(sin(azimuth)), 1.0 / icelevel) - 0.5;
    double const ice = MAX(0.0,
                           (icet + glaciers * MAX(-0.5, (r - 128) / 128.0)));
    if  (ice > 0.125) {
        *irP = maxval;
        *igP = maxval;
        *ibP = maxval;
    }
}



static void
limbDarken(int *          const irP,
           int *          const igP,
           int *          const ibP,
           unsigned int   const col,
           unsigned int   const row,
           unsigned int   const cols,
           unsigned int   const rows,
           Vector         const sunvec,
           pixval         const maxval) {

    /* With Gcc 2.95.3 compiler optimization level > 1, I have seen this
       function confuse all the variables and ultimately generate a
       completely black image.  Adding an extra reference to 'rows' seems
       to put things back in order, and the assert() below does that.
       Take it out, and the problem comes back!  04.02.21.
    */

    /* Apply limb darkening by cosine rule. */

    double const atthick  = 1.03;
    double const atSatFac = 1.0;
    double const athfac   = sqrt(atthick * atthick - 1.0);
        /* Atmosphere thickness as a percentage of planet's diameter */

    double const dy = 2 * ((double)rows/2 - row) / rows;
    double const dysq = dy * dy;
    /* Note: we are in fact normalizing this horizontal position by the
       vertical size of the picture.  And we know rows >= cols.
    */
    double const dx   = 2 * ((double)cols/2 - col) / rows;
    double const dxsq = dx * dx;

    double const ds = MIN(1.0, sqrt(dxsq + dysq));

    /* Calculate atmospheric absorption based on the thickness of
       atmosphere traversed by light on its way to the surface.
    */
    double const dsq = ds * ds;
    double const dsat = atSatFac * ((sqrt(atthick * atthick - dsq) -
                                     sqrt(1.0 * 1.0 - dsq)) / athfac);

    assert(rows >= cols);  /* An input requirement */

    *irP = atSat(*irP, maxval/2, dsat);
    *igP = atSat(*igP, maxval/2, dsat);
    *ibP = atSat(*ibP, maxval,   dsat);
    {
        double const PlanetAmbient = 0.05;

        double const sqomdysq = sqrt(1.0 - dysq);
        double const svx = sunvec.x;
        double const svy = sunvec.y * dy;
        double const svz = sunvec.z * sqomdysq;
        double const di =
            MAX(0, MIN(1.0, svx * dx + svy + svz * sqrt(1.0 - dxsq)));
        double const inx = PlanetAmbient * 1.0 + (1.0 - PlanetAmbient) * di;

        *irP *= inx;
        *igP *= inx;
        *ibP *= inx;
    }
}



static void
generatePlanetRow(pixel *         const pixelrow,
                  unsigned int    const row,
                  unsigned int    const rows,
                  unsigned int    const cols,
                  double          const t,
                  double          const t1,
                  double *        const u,
                  double *        const u1,
                  unsigned char * const cp,
                  unsigned int *  const bxc,
                  unsigned int *  const bxf,
                  int             const byc,
                  int             const byf,
                  Vector          const sunvec,
                  pixval          const maxval) {

    unsigned int const StarClose = 2;

    double const azimuth    = asin(((((double) row) / (rows - 1)) * 2) - 1);
    unsigned int const lcos = (rows / 2) * fabs(cos(azimuth));

    unsigned int col;

    for (col = 0; col < cols; ++col)
        PPM_ASSIGN(pixelrow[col], 0, 0, 0);

    for (col = cols/2 - lcos; col <= cols/2 + lcos; ++col) {
        double r;
        int ir, ig, ib;

        r = 0.0;   /* initial value */

        /* Note that where t1 and t are zero, the cp[] element
           referenced below does not exist.
        */
        if (t1 > 0.0)
            r += t1 * u1[col] * cp[byf + bxf[col]] +
                t1 * u[col]  * cp[byf + bxc[col]];
        if (t > 0.0)
            r += t * u1[col] * cp[byc + bxf[col]] +
                t * u[col]  * cp[byc + bxc[col]];

        if (r >= 128)
            makeLand(&ir, &ig, &ib, r);
        else
            makeWater(&ir, &ig, &ib, r, maxval);

        addIce(&ir, &ig, &ib, r, azimuth, icelevel, glaciers, maxval);

        limbDarken(&ir, &ig, &ib, col, row, cols, rows, sunvec, maxval);

        PPM_ASSIGN(pixelrow[col], ir, ig, ib);
    }

    /* Left stars */

    for (col = 0; (int)col < (int)(cols/2 - (lcos + StarClose)); ++col)
        etoile(&pixelrow[col]);

    /* Right stars */

    for (col = cols/2 + (lcos + StarClose); col < cols; ++col)
        etoile(&pixelrow[col]);
}



static void
genplanet(bool         const stars,
          bool         const clouds,
          float *      const a,
          unsigned int const cols,
          unsigned int const rows,
          unsigned int const n,
          unsigned int const rseed) {
/*----------------------------------------------------------------------------
  Generate planet from elevation array.

  If 'stars' is true, a is undefined.  Otherwise, it is defined.
-----------------------------------------------------------------------------*/
    pixval const maxval = PPM_MAXMAXVAL;

    unsigned char *cp;
    double *u, *u1;
    unsigned int *bxf, *bxc;

    pixel *pixelrow;
    unsigned int row;

    Vector sunvec;

    ppm_writeppminit(stdout, cols, rows, maxval, FALSE);

    if (stars) {
        pm_message("night: -seed %d -stars %d -saturation %d.",
                   rseed, starfraction, starcolor);
        cp = NULL;
        u = NULL; u1 = NULL;
        bxf = NULL; bxc = NULL;
    } else {
        pm_message("%s: -seed %d -dimension %.2f -power %.2f -mesh %d",
                   clouds ? "clouds" : "planet",
                   rseed, fracdim, powscale, meshsize);
        createPlanetStuff(clouds, a, n, &u, &u1, &bxf, &bxc, &cp, &sunvec,
                          cols, maxval);
    }

    pixelrow = ppm_allocrow(cols);
    for (row = 0; row < rows; ++row) {
        if (stars)
            generateStarrySkyRow(pixelrow, cols);
        else {
            double const by = (n - 1) * uprj(row, rows);
            int    const byf = floor(by) * n;
            int    const byc = byf + n;
            double const t = by - floor(by);
            double const t1 = 1 - t;

            if (clouds)
                generateCloudRow(pixelrow, cols,
                                 t, t1, u, u1, cp, bxc, bxf, byc, byf,
                                 maxval);
            else
                generatePlanetRow(pixelrow, row, rows, cols,
                                  t, t1, u, u1, cp, bxc, bxf, byc, byf,
                                  sunvec,
                                  maxval);
        }
        ppm_writeppmrow(stdout, pixelrow, cols, maxval, FALSE);
    }
    pm_close(stdout);

    ppm_freerow(pixelrow);
    if (cp)  free(cp);
    if (u)   free(u);
    if (u1)  free(u1);
    if (bxf) free(bxf);
    if (bxc) free(bxc);
}



static void
applyPowerLawScaling(float * const a,
                     int     const meshsize,
                     double  const powscale) {

    /* Apply power law scaling if non-unity scale is requested. */

    if (powscale != 1.0) {
        unsigned int i;
        for (i = 0; i < meshsize; i++) {
            unsigned int j;
            for (j = 0; j < meshsize; j++) {
                double const r = Real(a, i, j);
                if (r > 0)
                    Real(a, i, j) = pow(r, powscale);
            }
        }
    }
}



static void
computeExtremeReal(const float * const a,
                   int           const meshsize,
                   double *      const rminP,
                   double *      const rmaxP) {

    /* Compute extrema for autoscaling. */

    double rmin, rmax;
    unsigned int i;

    rmin = hugeVal;
    rmax = -hugeVal;

    for (i = 0; i < meshsize; i++) {
        unsigned int j;
        for (j = 0; j < meshsize; j++) {
            double r = Real(a, i, j);

            rmin = MIN(rmin, r);
            rmax = MAX(rmax, r);
        }
    }
    *rminP = rmin;
    *rmaxP = rmax;
}



static void
replaceWithSpread(float * const a,
                  int     const meshsize) {
/*----------------------------------------------------------------------------
  Replace the real part of each element of the 'a' array with a
  measure of how far the real is from the middle; sort of a standard
  deviation.
-----------------------------------------------------------------------------*/
    double rmin, rmax;
    double rmean, rrange;
    unsigned int i;

    computeExtremeReal(a, meshsize, &rmin, &rmax);

    rmean = (rmin + rmax) / 2;
    rrange = (rmax - rmin) / 2;

    for (i = 0; i < meshsize; i++) {
        unsigned int j;
        for (j = 0; j < meshsize; j++) {
            Real(a, i, j) = (Real(a, i, j) - rmean) / rrange;
        }
    }
}



static bool
planet(unsigned int const cols,
       unsigned int const rows,
       bool         const stars,
       bool         const clouds,
       unsigned int const rseed) {
/*----------------------------------------------------------------------------
   Make a planet.
-----------------------------------------------------------------------------*/
    float * a;
    bool error;

    initgauss(rseed);

    if (stars) {
        a = NULL;
        error = FALSE;
    } else {
        spectralsynth(&a, meshsize, 3.0 - fracdim);
        if (a == NULL) {
            error = TRUE;
        } else {
            applyPowerLawScaling(a, meshsize, powscale);

            replaceWithSpread(a, meshsize);

            error = FALSE;
        }
    }
    if (!error)
        genplanet(stars, clouds, a, cols, rows, meshsize, rseed);

    if (a != NULL)
        free(a);

    return !error;
}



int
main(int argc, const char ** argv) {

    struct CmdlineInfo cmdline;
    bool success;

    unsigned int cols, rows;     /* Dimensions of our output image */

    pm_proginit(&argc, argv);

    parseCommandLine(argc, argv, &cmdline);

    fracdim      = cmdline.dimension;
    hourspec     = cmdline.hourSpec;
    hourangle    = cmdline.hourAngle;
    inclspec     = cmdline.inclinationSpec;
    inclangle    = cmdline.inclAngle;
    meshsize     = cmdline.meshSize;
    powscale     = cmdline.power;
    icelevel     = cmdline.ice;
    glaciers     = cmdline.glaciers;
    starfraction = cmdline.stars;
    starcolor    = cmdline.saturation;

    /* Force  screen to be at least  as wide as it is high.  Long,
       skinny screens  cause  crashes  because  picture  width  is
       calculated based on height.
    */

    cols = (MAX(cmdline.height, cmdline.width) + 1) & (~1);
    rows = cmdline.height;

    success = planet(cols, rows, cmdline.night, cmdline.clouds, cmdline.seed);

    exit(success ? 0 : 1);
}