knotvector.cc revision f220fa62 
1/*
2** License Applicability. Except to the extent portions of this file are
3** made subject to an alternative license as permitted in the SGI Free
4** Software License B, Version 1.1 (the "License"), the contents of this
5** file are subject only to the provisions of the License. You may not use
6** this file except in compliance with the License. You may obtain a copy
7** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
8** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
9**
10** http://oss.sgi.com/projects/FreeB
11**
12** Note that, as provided in the License, the Software is distributed on an
13** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
14** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
15** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
16** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
17**
18** Original Code. The Original Code is: OpenGL Sample Implementation,
19** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
20** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
21** Copyright in any portions created by third parties is as indicated
22** elsewhere herein. All Rights Reserved.
23**
24** Additional Notice Provisions: The application programming interfaces
25** established by SGI in conjunction with the Original Code are The
26** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
27** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
28** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
29** Window System(R) (Version 1.3), released October 19, 1998. This software
30** was created using the OpenGL(R) version 1.2.1 Sample Implementation
31** published by SGI, but has not been independently verified as being
32** compliant with the OpenGL(R) version 1.2.1 Specification.
33*/
34
35/*
36 * knotvector.c++
37 *
38 */
39
40#include "glimports.h"
41#include "mystdio.h"
42#include "myassert.h"
43#include "knotvector.h"
44#include "defines.h"
45
46#ifdef __WATCOMC__
47#pragma warning 726 10
48#endif
49
50void Knotvector::init( long _knotcount, long _stride, long _order, INREAL *_knotlist )
51{
52    knotcount = _knotcount;
53    stride = _stride;
54    order = _order;
55    knotlist = new Knot[_knotcount];
56    assert( knotlist != 0 );
57
58    for( int i = 0; i != _knotcount; i++ )
59	knotlist[i] = (Knot) _knotlist[i];
60}
61
62Knotvector::Knotvector( void )
63{
64    knotcount = 0;
65    stride = 0;
66    order = 0;
67    knotlist = 0;
68}
69
70Knotvector::~Knotvector( void )
71{
72    if( knotlist ) delete[] knotlist;
73}
74
75int Knotvector::validate( void )
76{
77   /* kindex is used as an array index so subtract one first,
78     * this propagates throughout the code so study carefully */
79    long	kindex = knotcount-1;
80
81    if( order < 1 || order > MAXORDER ) {
82	// spline order un-supported
83	return( 1 );
84    }
85
86    if( knotcount < (2 * order) ) {
87	// too few knots
88	return( 2 );
89    }
90
91    if( identical( knotlist[kindex-(order-1)], knotlist[order-1]) ) {
92	// valid knot range is empty
93	return( 3 );
94    }
95
96    for( long i = 0; i < kindex; i++)
97	if( knotlist[i] > knotlist[i+1] ) {
98	    // decreasing knot sequence
99	    return( 4 );
100	}
101
102    /* check for valid multiplicity */
103
104    /*	kindex is currently the index of the last knot.
105     *	In the next loop  it is decremented to ignore the last knot
106     *	and the loop stops when kindex	is 2 so as to ignore the first
107     *	knot as well.  These knots are not used in computing
108     *	knot multiplicities.
109     */
110
111    long multi = 1;
112    for( ; kindex >= 1; kindex-- ) {
113	if( knotlist[kindex] - knotlist[kindex-1] < TOLERANCE ) {
114	    multi++;
115	    continue;
116	}
117	if ( multi > order ) {
118	    // knot multiplicity greater than order of spline
119	    return( 5 );
120	}
121	multi = 1;
122    }
123
124    if ( multi > order ) {
125	// knot multiplicity greater than order of spline
126	return( 5 );
127    }
128
129    return 0;
130}
131
132void Knotvector::show( const char *msg )
133{
134#ifndef NDEBUG
135    _glu_dprintf( "%s\n", msg );
136    _glu_dprintf( "order = %ld, count = %ld\n", order, knotcount );
137
138    for( int i=0; i<knotcount; i++ )
139	_glu_dprintf( "knot[%d] = %g\n", i, knotlist[i] );
140#endif
141}
142
143