summaryrefslogtreecommitdiff
path: root/src/glu/sgi/libnurbs/internals/knotvector.cc
blob: 9eb5cbace948e05a232aebac74ca54e37a9033b9 (plain)
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
/*
** License Applicability. Except to the extent portions of this file are
** made subject to an alternative license as permitted in the SGI Free
** Software License B, Version 1.1 (the "License"), the contents of this
** file are subject only to the provisions of the License. You may not use
** this file except in compliance with the License. You may obtain a copy
** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
**
** http://oss.sgi.com/projects/FreeB
**
** Note that, as provided in the License, the Software is distributed on an
** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
**
** Original Code. The Original Code is: OpenGL Sample Implementation,
** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
** Copyright in any portions created by third parties is as indicated
** elsewhere herein. All Rights Reserved.
**
** Additional Notice Provisions: The application programming interfaces
** established by SGI in conjunction with the Original Code are The
** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
** Window System(R) (Version 1.3), released October 19, 1998. This software
** was created using the OpenGL(R) version 1.2.1 Sample Implementation
** published by SGI, but has not been independently verified as being
** compliant with the OpenGL(R) version 1.2.1 Specification.
*/

/*
 * knotvector.c++
 *
 */

#include "glimports.h"
#include "mystdio.h"
#include "myassert.h"
#include "knotvector.h"
#include "defines.h"

#ifdef __WATCOMC__
#pragma warning 726 10
#endif

void Knotvector::init( long _knotcount, long _stride, long _order, INREAL *_knotlist )
{
    knotcount = _knotcount;
    stride = _stride;
    order = _order;
    knotlist = new Knot[_knotcount];
    assert( knotlist != 0 );

    for( int i = 0; i != _knotcount; i++ )
	knotlist[i] = (Knot) _knotlist[i];
}

Knotvector::Knotvector( void )
{
    knotlist = 0;
}

Knotvector::~Knotvector( void )
{
    if( knotlist ) delete[] knotlist;
}

int Knotvector::validate( void )
{
   /* kindex is used as an array index so subtract one first,
     * this propagates throughout the code so study carefully */
    long	kindex = knotcount-1;

    if( order < 1 || order > MAXORDER ) {
	// spline order un-supported
	return( 1 );
    }

    if( knotcount < (2 * order) ) {
	// too few knots
	return( 2 );
    }

    if( identical( knotlist[kindex-(order-1)], knotlist[order-1]) ) {
	// valid knot range is empty
	return( 3 );
    }

    for( long i = 0; i < kindex; i++)
	if( knotlist[i] > knotlist[i+1] ) {
	    // decreasing knot sequence
	    return( 4 );
	}
        
    /* check for valid multiplicity */

    /*	kindex is currently the index of the last knot.
     *	In the next loop  it is decremented to ignore the last knot
     *	and the loop stops when kindex	is 2 so as to ignore the first
     *	knot as well.  These knots are not used in computing
     *	knot multiplicities.
     */

    long multi = 1;
    for( ; kindex >= 1; kindex-- ) {
	if( knotlist[kindex] - knotlist[kindex-1] < TOLERANCE ) {
	    multi++;
	    continue;
	}
	if ( multi > order ) {
	    // knot multiplicity greater than order of spline
	    return( 5 );
	}
	multi = 1;
    }

    if ( multi > order ) {
	// knot multiplicity greater than order of spline
	return( 5 );
    }

    return 0;
}

void Knotvector::show( const char *msg )
{
#ifndef NDEBUG
    _glu_dprintf( "%s\n", msg );
    _glu_dprintf( "order = %ld, count = %ld\n", order, knotcount );

    for( int i=0; i<knotcount; i++ )
	_glu_dprintf( "knot[%d] = %g\n", i, knotlist[i] );
#endif
}