FreeWRL / FreeX3D 4.3.0
knotvector.cc
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 knotlist = 0;
65}
66
67Knotvector::~Knotvector( void )
68{
69 if( knotlist ) delete[] knotlist;
70}
71
72int Knotvector::validate( void )
73{
74 /* kindex is used as an array index so subtract one first,
75 * this propagates throughout the code so study carefully */
76 long kindex = knotcount-1;
77
78 if( order < 1 || order > MAXORDER ) {
79 // spline order un-supported
80 return( 1 );
81 }
82
83 if( knotcount < (2 * order) ) {
84 // too few knots
85 return( 2 );
86 }
87
88 if( identical( knotlist[kindex-(order-1)], knotlist[order-1]) ) {
89 // valid knot range is empty
90 return( 3 );
91 }
92
93 for( long i = 0; i < kindex; i++)
94 if( knotlist[i] > knotlist[i+1] ) {
95 // decreasing knot sequence
96 return( 4 );
97 }
98
99 /* check for valid multiplicity */
100
101 /* kindex is currently the index of the last knot.
102 * In the next loop it is decremented to ignore the last knot
103 * and the loop stops when kindex is 2 so as to ignore the first
104 * knot as well. These knots are not used in computing
105 * knot multiplicities.
106 */
107
108 long multi = 1;
109 for( ; kindex >= 1; kindex-- ) {
110 if( knotlist[kindex] - knotlist[kindex-1] < TOLERANCE ) {
111 multi++;
112 continue;
113 }
114 if ( multi > order ) {
115 // knot multiplicity greater than order of spline
116 return( 5 );
117 }
118 multi = 1;
119 }
120
121 if ( multi > order ) {
122 // knot multiplicity greater than order of spline
123 return( 5 );
124 }
125
126 return 0;
127}
128
129void Knotvector::show( const char *msg )
130{
131#ifndef NDEBUG
132 _glu_dprintf( "%s\n", msg );
133 _glu_dprintf( "order = %ld, count = %ld\n", order, knotcount );
134
135 for( int i=0; i<knotcount; i++ )
136 _glu_dprintf( "knot[%d] = %g\n", i, knotlist[i] );
137#endif
138}
139