File: compact.c

package info (click to toggle)
gnuplot 3.7.1p1-4
  • links: PTS
  • area: main
  • in suites: potato
  • size: 5,808 kB
  • ctags: 4,418
  • sloc: ansic: 43,279; lisp: 661; makefile: 647; asm: 539; sh: 416; objc: 379; csh: 297; pascal: 194; perl: 138
file content (135 lines) | stat: -rw-r--r-- 4,291 bytes parent folder | download | duplicates (2)
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
/*
 * $Id: compact.c,v 1.2 1998/11/25 21:05:04 lhecking Exp $
 *
 */

/* GNUPLOT - compact.c */

/* contains routines to compress a vector stream without modifying it */

/*[
 * Copyright 1986 - 1993, 1998   Thomas Williams, Colin Kelley
 *
 * Permission to use, copy, and distribute this software and its
 * documentation for any purpose with or without fee is hereby granted,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.
 *
 * Permission to modify the software is granted, but not the right to
 * distribute the complete modified source code.  Modifications are to
 * be distributed as patches to the released version.  Permission to
 * distribute binaries produced by compiling modified sources is granted,
 * provided you
 *   1. distribute the corresponding source modifications from the
 *    released version in the form of a patch file along with the binaries,
 *   2. add special version identification to distinguish your version
 *    in addition to the base release version number,
 *   3. provide your name and address as the primary contact for the
 *    support of your modified version, and
 *   4. retain our contact information in regard to use of the base
 *    software.
 * Permission to distribute the released version of the source code along
 * with corresponding source modifications in the form of a patch file is
 * granted with same provisions 2 through 4 for binary distributions.
 *
 * This software is provided "as is" without express or implied warranty
 * to the extent permitted by applicable law.
]*/

#ifndef COMPACT

/* replaces runs of constant slope in the buffer with single vectors 
   returns the number of points eliminated */
int compact_slope(xp, yp, isa_move, sz, delta)
int xp[], yp[], isa_move[];
int *sz;
double delta;
{
    int dx, dy, old_size, new_index, i, start;
    float slope, old_slope;

    old_size = *sz;
    new_index = 0;
    start = 0;
    if (xp[1] != xp[0])
	old_slope = (float) (yp[1] - yp[0]) / (float) (xp[1] - xp[0]);
    else
	old_slope = (float) (yp[1] - yp[0]) / (float) (0.00001 + xp[1] - xp[0]);
    for (i = 2; i < old_size; i++) {
	dx = xp[i] - xp[i - 1];
	dy = yp[i] - yp[i - 1];
	if (dx != 0)
	    slope = (float) dy / (float) dx;
	else
	    slope = (float) dy / ((float) dx + 0.00001);
	if ((ABS(slope - old_slope) > delta) || (isa_move[i])) {
	    xp[new_index] = xp[start];
	    yp[new_index] = yp[start];
	    isa_move[new_index] = isa_move[start];
	    new_index++;
	    if (start != i - 1) {
		xp[new_index] = xp[i - 1];
		yp[new_index] = yp[i - 1];
		isa_move[new_index] = isa_move[i - 1];
		new_index++;
	    }
	    start = i;
	    /* this is the slope for the new run */
	    old_slope = slope;
	}
    }
    /* copy the last point into the new array */
    xp[new_index] = xp[old_size - 1];
    yp[new_index] = yp[old_size - 1];
    isa_move[new_index] = isa_move[old_size - 1];
    new_index++;
    *sz = new_index;
    return (old_size - *sz);
}

/* compacts the vector list by compressing runs of constant 
   dx&dy into one vector
   use this if floating point is too expensive!
   more naive than compact_slope; doesn't compact as much as possible
   returns the number of points eliminated */
int compact_int(xp, yp, isa_move, size)
int xp[], yp[], isa_move[], *size;
{
    int dx, dy, old_dx, old_dy, start, index, i, old_size;

    start = index = 0;
    old_dx = xp[1] - xp[0];
    old_dy = yp[1] - yp[0];
    for (i = 2; i < *size; i++) {
	dx = xp[i] - xp[i - 1];
	dy = yp[i] - yp[i - 1];
	if ((ABS(dx - old_dx) + ABS(dy - old_dy) != 0) || (isa_move[i])) {
	    /*  we've reached the end of a run */
	    xp[index] = xp[start];
	    yp[index] = yp[start];
	    isa_move[index] = isa_move[start];
	    index++;
	    if (start != i - 1) {
		xp[index] = xp[i - 1];
		yp[index] = yp[i - 1];
		isa_move[index] = isa_move[i - 1];
		index++;
	    }
	    start = i;
	    old_dx = dx;
	    old_dy = dy;
	}
    }				/* end for */
    /* include the last point */
    xp[index] = xp[*size - 1];
    yp[index] = yp[*size - 1];
    isa_move[index] = isa_move[*size - 1];
    index++;
    old_size = *size;
    *size = index;
    return (old_size - *size);
}
#endif

#define COMPACT