src/px/pf2.c

#ifndef lint
static const char       RCSid[] = "$Id: pf2.c,v 2.6 2003/02/22 02:07:27 greg Exp $";
#endif
/*
 *  pf2.c - routines used by pfilt.
 */

#include  <stdio.h>
#include  <stdlib.h>
#include  <math.h>

#include  "rterror.h"
#include  "random.h"
#include  "color.h"
#include  "pfilt.h"

#define  PI             3.14159265359
#define  FTINY          (1e-6)

#define  AVGLVL         0.5     /* target mean brightness */

double  avgbrt;                 /* average picture brightness */
long    npix;                   /* # pixels in average */

typedef struct  hotpix {        /* structure for avgbrt pixels */
        struct hotpix  *next;   /* next in list */
        COLOR  val;             /* pixel color */
        short  x, y;            /* pixel position */
        float  slope;           /* random slope for diffraction */
}  HOTPIX;

HOTPIX  *head;                  /* head of avgbrt pixel list */

double  sprdfact;               /* computed spread factor */

static void starpoint(COLOR  fcol, int  x, int  y, HOTPIX        *hp);


extern void
pass1init(void)                 /* prepare for first pass */
{
        avgbrt = 0.0;
        npix = 0;
        head = NULL;
}


extern void
pass1default(void)                      /* for single pass */
{
        avgbrt = AVGLVL;
        npix = 1;
        head = NULL;
}


extern void
pass1scan(              /* process first pass scanline */
        register COLOR  *scan,
        int  y
)
{
        double  cbrt;
        register int  x;
        register HOTPIX  *hp;

        for (x = 0; x < xres; x++) {
        
                cbrt = (*ourbright)(scan[x]);

                if (cbrt <= 0)
                        continue;

                if (avghot || cbrt < hotlvl) {
                        avgbrt += cbrt;
                        npix++;
                }
                if (npts && cbrt >= hotlvl) {
                        hp = (HOTPIX *)malloc(sizeof(HOTPIX));
                        if (hp == NULL) {
                                fprintf(stderr, "%s: out of memory\n",
                                                progname);
                                quit(1);
                        }
                        copycolor(hp->val, scan[x]);
                        hp->x = x;
                        hp->y = y;
                        hp->slope = tan(PI*(0.5-(random()%npts+0.5)/npts));
                        hp->next = head;
                        head = hp;
                }
        }
}


extern void
pass2init(void)                 /* prepare for final pass */
{
        if (!npix) {
                fprintf(stderr, "%s: picture too dark or too bright\n",
                                progname);
                quit(1);
        }
        avgbrt /= (double)npix;

        scalecolor(exposure,  AVGLVL/avgbrt);
        
        sprdfact = spread / (hotlvl * (*ourbright)(exposure))
                        * ((double)xres*xres + (double)yres*yres) / 4.0;
}


extern void
pass2scan(              /* process final pass scanline */
        register COLOR  *scan,
        int  y
)
{
        int  xmin, xmax;
        register int  x;
        register HOTPIX  *hp;
        
        for (hp = head; hp != NULL; hp = hp->next) {
                if (hp->slope > FTINY) {
                        xmin = (y - hp->y - 0.5)/hp->slope + hp->x;
                        xmax = (y - hp->y + 0.5)/hp->slope + hp->x;
                } else if (hp->slope < -FTINY) {
                        xmin = (y - hp->y + 0.5)/hp->slope + hp->x;
                        xmax = (y - hp->y - 0.5)/hp->slope + hp->x;
                } else if (y == hp->y) {
                        xmin = 0;
                        xmax = xres-1;
                } else {
                        xmin = 1;
                        xmax = 0;
                }
                if (xmin < 0)
                        xmin = 0;
                if (xmax >= xres)
                        xmax = xres-1;
                for (x = xmin; x <= xmax; x++)
                        starpoint(scan[x], x, y, hp);
        }
        for (x = 0; x < xres; x++)
                multcolor(scan[x], exposure);
}


static void
starpoint(              /* pixel is on the star's point */
        COLOR  fcol,
        int  x,
        int  y,
        register HOTPIX  *hp
)
{
        COLOR  ctmp;
        double  d2;
        
        d2 = (double)(x - hp->x)*(x - hp->x) + (double)(y - hp->y)*(y - hp->y);
        if (d2 > sprdfact) {
                d2 = sprdfact / d2;
                if (d2 < FTINY)
                        return;
                copycolor(ctmp, hp->val);
                scalecolor(ctmp, d2);
                addcolor(fcol, ctmp);
        } else if (d2 > FTINY) {
                addcolor(fcol, hp->val);
        }
}
Revision:	2.7
Committed:	Sun Mar 28 20:33:14 2004 UTC (20 years, 1 month ago) by schorsch
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad4R2P2, rad5R0, rad5R1, rad3R7P2, rad3R7P1, rad4R2, rad4R1, rad4R0, rad3R6, rad3R6P1, rad3R8, rad3R9, rad4R2P1
Changes since 2.6:	+28 -36 lines
Log Message:	Continued ANSIfication, and other fixes and clarifications.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	schorsch	2.7	static const char RCSid[] = "$Id: pf2.c,v 2.6 2003/02/22 02:07:27 greg Exp $";
3	greg	1.1	#endif
4			/*
5			* pf2.c - routines used by pfilt.
6			*/
7
8			#include <stdio.h>
9	greg	2.6	#include <stdlib.h>
10	greg	2.3	#include <math.h>
11
12	schorsch	2.7	#include "rterror.h"
13	greg	1.1	#include "random.h"
14			#include "color.h"
15	schorsch	2.7	#include "pfilt.h"
16	greg	1.1
17	greg	2.2	#define PI 3.14159265359
18			#define FTINY (1e-6)
19	greg	1.1
20	greg	2.2	#define AVGLVL 0.5 /* target mean brightness */
21	greg	1.1
22	greg	2.2	double avgbrt; /* average picture brightness */
23	greg	2.4	long npix; /* # pixels in average */
24	greg	1.1
25	greg	2.2	typedef struct hotpix { /* structure for avgbrt pixels */
26	greg	1.1	struct hotpix next; / next in list */
27			COLOR val; /* pixel color */
28			short x, y; /* pixel position */
29			float slope; /* random slope for diffraction */
30			} HOTPIX;
31
32	greg	2.2	HOTPIX head; / head of avgbrt pixel list */
33	greg	1.1
34	greg	2.2	double sprdfact; /* computed spread factor */
35	greg	1.1
36	schorsch	2.7	static void starpoint(COLOR fcol, int x, int y, HOTPIX *hp);
37
38	greg	1.1
39	schorsch	2.7	extern void
40			pass1init(void) /* prepare for first pass */
41	greg	1.1	{
42			avgbrt = 0.0;
43	greg	2.4	npix = 0;
44	greg	1.1	head = NULL;
45			}
46
47
48	schorsch	2.7	extern void
49			pass1default(void) /* for single pass */
50	greg	1.1	{
51	greg	2.4	avgbrt = AVGLVL;
52			npix = 1;
53	greg	1.1	head = NULL;
54			}
55
56
57	schorsch	2.7	extern void
58			pass1scan( /* process first pass scanline */
59			register COLOR *scan,
60			int y
61			)
62	greg	1.1	{
63	greg	2.2	double cbrt;
64	greg	1.1	register int x;
65	greg	2.2	register HOTPIX *hp;
66	greg	1.1
67			for (x = 0; x < xres; x++) {
68
69	greg	2.5	cbrt = (*ourbright)(scan[x]);
70	greg	1.1
71	greg	2.4	if (cbrt <= 0)
72			continue;
73
74			if (avghot \|\| cbrt < hotlvl) {
75	greg	1.1	avgbrt += cbrt;
76	greg	2.4	npix++;
77			}
78	greg	1.1	if (npts && cbrt >= hotlvl) {
79			hp = (HOTPIX *)malloc(sizeof(HOTPIX));
80			if (hp == NULL) {
81			fprintf(stderr, "%s: out of memory\n",
82			progname);
83			quit(1);
84			}
85			copycolor(hp->val, scan[x]);
86			hp->x = x;
87			hp->y = y;
88			hp->slope = tan(PI*(0.5-(random()%npts+0.5)/npts));
89			hp->next = head;
90			head = hp;
91			}
92			}
93			}
94
95
96	schorsch	2.7	extern void
97			pass2init(void) /* prepare for final pass */
98	greg	1.1	{
99	greg	2.4	if (!npix) {
100			fprintf(stderr, "%s: picture too dark or too bright\n",
101			progname);
102	greg	1.1	quit(1);
103			}
104	greg	2.4	avgbrt /= (double)npix;
105	greg	1.1
106			scalecolor(exposure, AVGLVL/avgbrt);
107
108	greg	2.5	sprdfact = spread / (hotlvl * (*ourbright)(exposure))
109	greg	1.1	* ((double)xresxres + (double)yresyres) / 4.0;
110			}
111
112
113	schorsch	2.7	extern void
114			pass2scan( /* process final pass scanline */
115			register COLOR *scan,
116			int y
117			)
118	greg	1.1	{
119			int xmin, xmax;
120			register int x;
121	greg	2.2	register HOTPIX *hp;
122	greg	1.1
123			for (hp = head; hp != NULL; hp = hp->next) {
124			if (hp->slope > FTINY) {
125			xmin = (y - hp->y - 0.5)/hp->slope + hp->x;
126			xmax = (y - hp->y + 0.5)/hp->slope + hp->x;
127			} else if (hp->slope < -FTINY) {
128			xmin = (y - hp->y + 0.5)/hp->slope + hp->x;
129			xmax = (y - hp->y - 0.5)/hp->slope + hp->x;
130			} else if (y == hp->y) {
131			xmin = 0;
132			xmax = xres-1;
133			} else {
134			xmin = 1;
135			xmax = 0;
136			}
137			if (xmin < 0)
138			xmin = 0;
139			if (xmax >= xres)
140			xmax = xres-1;
141			for (x = xmin; x <= xmax; x++)
142			starpoint(scan[x], x, y, hp);
143			}
144			for (x = 0; x < xres; x++)
145			multcolor(scan[x], exposure);
146			}
147
148
149	schorsch	2.7	static void
150			starpoint( /* pixel is on the star's point */
151			COLOR fcol,
152			int x,
153			int y,
154			register HOTPIX *hp
155			)
156	greg	1.1	{
157			COLOR ctmp;
158	greg	2.2	double d2;
159	greg	1.1
160			d2 = (double)(x - hp->x)(x - hp->x) + (double)(y - hp->y)(y - hp->y);
161			if (d2 > sprdfact) {
162			d2 = sprdfact / d2;
163			if (d2 < FTINY)
164			return;
165			copycolor(ctmp, hp->val);
166			scalecolor(ctmp, d2);
167			addcolor(fcol, ctmp);
168			} else if (d2 > FTINY) {
169			addcolor(fcol, hp->val);
170			}
171			}