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greg |
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/* Copyright (c) 1986 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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/* |
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* pf2.c - routines used by pfilt. |
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* |
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* 10/3/85 |
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*/ |
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#include <stdio.h> |
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#include "random.h" |
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#include "color.h" |
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#define PI 3.14159265359 |
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#define FTINY (1e-6) |
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extern int nrows, ncols; /* number of rows and columns for output */ |
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extern int xres, yres; /* x and y resolution */ |
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extern int avghot; /* true means average in avgbrt spots */ |
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extern double hotlvl; /* brightness considered "hot" */ |
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extern int npts; /* # of points for stars */ |
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extern double spread; /* spread for star points */ |
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extern char *progname; |
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extern COLOR exposure; /* exposure for frame */ |
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#define AVGLVL 0.5 /* target mean brightness */ |
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double avgbrt; /* average picture brightness */ |
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typedef struct hotpix { /* structure for avgbrt pixels */ |
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struct hotpix *next; /* next in list */ |
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COLOR val; /* pixel color */ |
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short x, y; /* pixel position */ |
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float slope; /* random slope for diffraction */ |
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} HOTPIX; |
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HOTPIX *head; /* head of avgbrt pixel list */ |
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double sprdfact; /* computed spread factor */ |
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pass1init() /* prepare for first pass */ |
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{ |
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avgbrt = 0.0; |
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head = NULL; |
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} |
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pass1default() /* for single pass */ |
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{ |
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avgbrt = AVGLVL * xres * yres; |
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head = NULL; |
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} |
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pass1scan(scan, y) /* process first pass scanline */ |
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register COLOR *scan; |
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int y; |
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{ |
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extern char *malloc(); |
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extern double tan(), sqrt(); |
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double cbrt; |
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register int x; |
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register HOTPIX *hp; |
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for (x = 0; x < xres; x++) { |
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cbrt = bright(scan[x]); |
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if (avghot || cbrt < hotlvl) |
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avgbrt += cbrt; |
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if (npts && cbrt >= hotlvl) { |
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hp = (HOTPIX *)malloc(sizeof(HOTPIX)); |
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if (hp == NULL) { |
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fprintf(stderr, "%s: out of memory\n", |
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progname); |
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quit(1); |
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} |
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copycolor(hp->val, scan[x]); |
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hp->x = x; |
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hp->y = y; |
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hp->slope = tan(PI*(0.5-(random()%npts+0.5)/npts)); |
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hp->next = head; |
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head = hp; |
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} |
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} |
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} |
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pass2init() /* prepare for final pass */ |
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{ |
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avgbrt /= (double)xres * yres; |
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if (avgbrt <= FTINY) { |
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fprintf(stderr, "%s: picture too dark\n", progname); |
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quit(1); |
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} |
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scalecolor(exposure, AVGLVL/avgbrt); |
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sprdfact = spread / (hotlvl * bright(exposure)) |
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* ((double)xres*xres + (double)yres*yres) / 4.0; |
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} |
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pass2scan(scan, y) /* process final pass scanline */ |
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register COLOR *scan; |
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int y; |
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{ |
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int xmin, xmax; |
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register int x; |
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register HOTPIX *hp; |
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for (hp = head; hp != NULL; hp = hp->next) { |
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if (hp->slope > FTINY) { |
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xmin = (y - hp->y - 0.5)/hp->slope + hp->x; |
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xmax = (y - hp->y + 0.5)/hp->slope + hp->x; |
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} else if (hp->slope < -FTINY) { |
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xmin = (y - hp->y + 0.5)/hp->slope + hp->x; |
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xmax = (y - hp->y - 0.5)/hp->slope + hp->x; |
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} else if (y == hp->y) { |
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xmin = 0; |
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xmax = xres-1; |
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} else { |
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xmin = 1; |
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xmax = 0; |
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} |
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if (xmin < 0) |
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xmin = 0; |
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if (xmax >= xres) |
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xmax = xres-1; |
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for (x = xmin; x <= xmax; x++) |
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starpoint(scan[x], x, y, hp); |
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} |
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for (x = 0; x < xres; x++) |
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multcolor(scan[x], exposure); |
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} |
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starpoint(fcol, x, y, hp) /* pixel is on the star's point */ |
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COLOR fcol; |
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int x, y; |
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register HOTPIX *hp; |
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{ |
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COLOR ctmp; |
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double d2; |
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d2 = (double)(x - hp->x)*(x - hp->x) + (double)(y - hp->y)*(y - hp->y); |
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if (d2 > sprdfact) { |
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d2 = sprdfact / d2; |
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if (d2 < FTINY) |
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return; |
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copycolor(ctmp, hp->val); |
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scalecolor(ctmp, d2); |
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addcolor(fcol, ctmp); |
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} else if (d2 > FTINY) { |
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addcolor(fcol, hp->val); |
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} |
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} |
