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Diffstat (limited to 'generator/pgmcrater.c')
| -rw-r--r-- | generator/pgmcrater.c | 423 |
1 files changed, 0 insertions, 423 deletions
diff --git a/generator/pgmcrater.c b/generator/pgmcrater.c deleted file mode 100644 index 25b7b817..00000000 --- a/generator/pgmcrater.c +++ /dev/null @@ -1,423 +0,0 @@ -/* - - Fractal cratering - - Designed and implemented in November of 1989 by: - - John Walker - Autodesk SA - Avenue des Champs-Montants 14b - CH-2074 MARIN - Switzerland - Usenet: kelvin@Autodesk.com - Fax: 038/33 88 15 - Voice: 038/33 76 33 - - The algorithm used to determine crater size is as described on - pages 31 and 32 of: - - Peitgen, H.-O., and Saupe, D. eds., The Science Of Fractal - Images, New York: Springer Verlag, 1988. - - The mathematical technique used to calculate crater radii that - obey the proper area law distribution from a uniformly distributed - pseudorandom sequence was developed by Rudy Rucker. - - 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. - - PLUGWARE! - - If you like this kind of stuff, you may also enjoy "James Gleick's - Chaos--The Software" for MS-DOS, available for $59.95 from your - local software store or directly from Autodesk, Inc., Attn: Science - Series, 2320 Marinship Way, Sausalito, CA 94965, USA. Telephone: - (800) 688-2344 toll-free or, outside the U.S. (415) 332-2344 Ext - 4886. Fax: (415) 289-4718. "Chaos--The Software" includes a more - comprehensive fractal forgery generator which creates - three-dimensional landscapes as well as clouds and planets, plus - five more modules which explore other aspects of Chaos. The user - guide of more than 200 pages includes an introduction by James - Gleick and detailed explanations by Rudy Rucker of the mathematics - and algorithms used by each program. - -*/ - -/* Modifications by Arjen Bax, 2001-06-21: Remove black vertical line at right - * edge. Make craters wrap around the image (enables tiling of image). - */ - -#define _XOPEN_SOURCE /* get M_PI in math.h */ - -#include <assert.h> -#include <math.h> - -#include "pm_c_util.h" -#include "pgm.h" -#include "mallocvar.h" -#include "shhopt.h" - - -struct CmdlineInfo { - /* All the information the user supplied in the command line, - in a form easy for the program to use. - */ - unsigned int number; - unsigned int height; - unsigned int width; - float gamma; - unsigned int randomseed; - unsigned int randomseedSpec; -}; - - - -static void -parseCommandLine(int argc, const char ** const argv, - struct CmdlineInfo * const cmdlineP) { -/*---------------------------------------------------------------------------- - Note that the file spec array we return is stored in the storage that - was passed to us as the argv array. ------------------------------------------------------------------------------*/ - optEntry * option_def; - /* Instructions to OptParseOptions3 on how to parse our options. - */ - optStruct3 opt; - unsigned int option_def_index; - - unsigned int numberSpec, heightSpec, widthSpec, gammaSpec; - - MALLOCARRAY_NOFAIL(option_def, 100); - - option_def_index = 0; /* incremented by OPTENT3 */ - OPTENT3(0, "number", OPT_UINT, &cmdlineP->number, - &numberSpec, 0); - OPTENT3(0, "height", OPT_UINT, &cmdlineP->height, - &heightSpec, 0); - OPTENT3(0, "ysize", OPT_UINT, &cmdlineP->height, - &heightSpec, 0); - OPTENT3(0, "width", OPT_UINT, &cmdlineP->width, - &widthSpec, 0); - OPTENT3(0, "xsize", OPT_UINT, &cmdlineP->width, - &widthSpec, 0); - OPTENT3(0, "gamma", OPT_FLOAT, &cmdlineP->gamma, - &gammaSpec, 0); - OPTENT3(0, "randomseed", OPT_UINT, &cmdlineP->randomseed, - &cmdlineP->randomseedSpec, 0); - - opt.opt_table = option_def; - opt.short_allowed = FALSE; /* We have no short (old-fashioned) options */ - opt.allowNegNum = FALSE; /* We may have 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 (argc-1 > 0) - pm_error("There are no non-option arguments. You specified %u", - argc-1); - - if (!numberSpec) - cmdlineP->number = 50000; - - if (cmdlineP->number == 0) - pm_error("-number must be positive"); - - if (!heightSpec) - cmdlineP->height = 256; - - if (cmdlineP->height == 0) - pm_error("-height must be positive"); - - if (!widthSpec) - cmdlineP->width = 256; - - if (cmdlineP->width == 0) - pm_error("-width must be positive"); - - if (!gammaSpec) - cmdlineP->gamma = 1.0; - - if (cmdlineP->gamma <= 0.0) - pm_error("gamma correction must be greater than 0"); - - free(option_def); -} - - - -/* Definitions for obtaining random numbers. */ - -/* Display parameters */ - -#define SCRX screenxsize /* Screen width */ -#define SCRY screenysize /* Screen height */ -#define SCRGAMMA 1.0 /* Display gamma */ - -#define RGBQuant 255 - - -static double const ImageGamma = 0.5; /* Inherent gamma of mapped image */ - -static double const arand = 32767.0; /* Random number parameters */ - -static double const CdepthPower = 1.5; /* Crater depth power factor */ - -static double DepthBias; /* sqrt(.5) */ - -static int const slopemin = -52; -static int const slopemax = 52; - - -static double const -Cast(double const low, - double const high) { - - return low + (high - low) * ((rand() & 0x7FFF) / arand); -} - - - -static int -modulo(int const t, - int const n) { - - int m; - - assert(n > 0); - - m = t % n; - - while (m < 0) { - m += n; - } - - return m; -} - - - -#define Auxadr(x, y) &aux[modulo(y, screenysize)*screenxsize+modulo(x, screenxsize)] - - - -static void -generateScreenImage(const unsigned short * const aux, - unsigned int const screenxsize, - unsigned int const screenysize, - unsigned char * const slopemap) { - - unsigned int row; - gray * pixrow; - - pgm_writepgminit(stdout, screenxsize, screenysize, RGBQuant, FALSE); - pixrow = pgm_allocrow(screenxsize); - - for (row = 0; row < screenysize; ++row) { - unsigned int col; - - for (col = 0; col < screenxsize; ++col) { - int j; - j = *Auxadr(col+1, row) - *Auxadr(col, row); - j = MIN(MAX(slopemin, j), slopemax); - pixrow[col] = slopemap[j - slopemin]; - } - pgm_writepgmrow(stdout, pixrow, screenxsize, RGBQuant, FALSE); - } - pm_close(stdout); - pgm_freerow(pixrow); - -} - - - -static void -gencraters(struct CmdlineInfo const cmdline) { -/*---------------------------------------------------------------------------- - Generate cratered terrain ------------------------------------------------------------------------------*/ - unsigned int const screenxsize = cmdline.width; /* screen X size */ - unsigned int const screenysize = cmdline.height; /* screen Y size */ - double const dgamma = cmdline.gamma; /* display gamma */ - unsigned int const ncraters = cmdline.number; /* num craters to gen */ - - int i, j; - unsigned int l; - unsigned short * aux; - unsigned char * slopemap; /* Slope to pixel map */ - - /* Acquire the elevation array and initialize it to mean - surface elevation. */ - - MALLOCARRAY(aux, SCRX * SCRY); - if (aux == NULL) - pm_error("out of memory allocating elevation array"); - - /* Acquire the elevation buffer and initialize to mean - initial elevation. */ - - for (i = 0; i < SCRY; i++) { - unsigned short *zax = aux + (((long) SCRX) * i); - - for (j = 0; j < SCRX; j++) { - *zax++ = 32767; - } - } - - /* Every time we go around this loop we plop another crater - on the surface. */ - - for (l = 0; l < ncraters; l++) { - double g; - int cx = Cast(0.0, ((double) SCRX - 1)), - cy = Cast(0.0, ((double) SCRY - 1)), - gx, gy, x, y; - unsigned int amptot = 0, axelev; - unsigned int npatch = 0; - - - /* Phase 1. Compute the mean elevation of the impact - area. We assume the impact area is a - fraction of the total crater size. */ - - /* Thanks, Rudy, for this equation that maps the uniformly - distributed numbers from Cast into an area-law - distribution as observed on cratered bodies. */ - - g = sqrt(1 / (M_PI * (1 - Cast(0, 0.9999)))); - - /* If the crater is tiny, handle it specially. */ - - if (g < 3) { - - /* Set pixel to the average of its Moore neighbourhood. */ - - for (y = cy - 1; y <= cy + 1; y++) { - for (x = cx - 1; x <= cx + 1; x++) { - amptot += *Auxadr(x, y); - npatch++; - } - } - axelev = amptot / npatch; - - /* Perturb the mean elevation by a small random factor. */ - - x = (g >= 1) ? ((rand() >> 8) & 3) - 1 : 0; - *Auxadr(cx, cy) = axelev + x; - - /* Jam repaint sizes to correct patch. */ - - gx = 1; - gy = 0; - - } else { - - /* Regular crater. Generate an impact feature of the - correct size and shape. */ - - /* Determine mean elevation around the impact area. */ - - gx = MAX(2, (g / 3)); - gy = MAX(2, g / 3); - - for (y = cy - gy; y <= cy + gy; y++) { - for (x = cx-gx; x <= cx + gx; x++) { - amptot += *Auxadr(x,y); - npatch++; - } - } - axelev = amptot / npatch; - - gy = MAX(2, g); - g = gy; - gx = MAX(2, g); - - for (y = cy - gy; y <= cy + gy; y++) { - double dy = (cy - y) / (double) gy, - dysq = dy * dy; - - for (x = cx - gx; x <= cx + gx; x++) { - double dx = ((cx - x) / (double) gx), - cd = (dx * dx) + dysq, - cd2 = cd * 2.25, - tcz = DepthBias - sqrt(fabs(1 - cd2)), - cz = MAX((cd2 > 1) ? 0.0 : -10, tcz), - roll, iroll; - unsigned short av; - - cz *= pow(g, CdepthPower); - if (dy == 0 && dx == 0 && ((int) cz) == 0) { - cz = cz < 0 ? -1 : 1; - } - -#define rollmin 0.9 - roll = (((1 / (1 - MIN(rollmin, cd))) / - (1 / (1 - rollmin))) - (1 - rollmin)) / rollmin; - iroll = 1 - roll; - - av = (axelev + cz) * iroll + (*Auxadr(x,y) + cz) * roll; - av = MAX(1000, MIN(64000, av)); - *Auxadr(x,y) = av; - } - } - } - if ((l % 5000) == 4999) { - pm_message( "%u craters generated of %u (%u%% done)", - l + 1, ncraters, ((l + 1) * 100) / ncraters); - } - } - - i = MAX((slopemax - slopemin) + 1, 1); - MALLOCARRAY(slopemap, i); - if (slopemap == NULL) - pm_error("out of memory allocating slope map"); - - for (i = slopemin; i <= slopemax; i++) { - - /* Confused? OK, we're using the left-to-right slope to - calculate a shade based on the sine of the angle with - respect to the vertical (light incident from the left). - Then, with one exponentiation, we account for both the - inherent gamma of the image (ad-hoc), and the - user-specified display gamma, using the identity: - - (x^y)^z = (x^(y*z)) */ - - slopemap[i - slopemin] = i > 0 ? - (128 + 127.0 * - pow(sin((M_PI / 2) * i / slopemax), - dgamma * ImageGamma)) : - (128 - 127.0 * - pow(sin((M_PI / 2) * i / slopemin), - dgamma * ImageGamma)); - } - - generateScreenImage(aux, screenxsize, screenysize, slopemap); - - free((char *) slopemap); - free((char *) aux); -} - - - -int -main(int argc, const char ** argv) { - - struct CmdlineInfo cmdline; - - pm_proginit(&argc, argv); - - parseCommandLine(argc, argv, &cmdline); - - srand(cmdline.randomseedSpec ? cmdline.randomseed : pm_randseed()); - - DepthBias = sqrt(0.5); - - gencraters(cmdline); - - exit(0); -} - - - |