src/glu/sgi/libnurbs/internals/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  * $Date: 2001/03/17 00:25:41 $ $Revision: 1.1 $
  39  * $Header: /home/krh/git/sync/mesa-cvs-repo/Mesa/src/glu/sgi/libnurbs/internals/knotvector.cc,v 1.1 2001/03/17 00:25:41 brianp Exp $
  40  */
  41
  42 #include "glimports.h"
  43 #include "mystdio.h"
  44 #include "myassert.h"
  45 #include "knotvector.h"
  46 #include "defines.h"
  47
  48
  49 void Knotvector::init( long _knotcount, long _stride, long _order, INREAL *_knotlist )
  50 {
  51     knotcount = _knotcount;
  52     stride = _stride;
  53     order = _order;
  54     knotlist = new Knot[_knotcount];
  55     assert( knotlist != 0 );
  56
  57     for( int i = 0; i != _knotcount; i++ )
  58         knotlist[i] = (Knot) _knotlist[i];
  59 }
  60
  61 Knotvector::Knotvector( void )
  62 {
  63     knotlist = 0;
  64 }
  65
  66 Knotvector::~Knotvector( void )
  67 {
  68     if( knotlist ) delete[] knotlist;
  69 }
  70
  71 int Knotvector::validate( void )
  72 {
  73    /* kindex is used as an array index so subtract one first,
  74      * this propagates throughout the code so study carefully */
  75     long        kindex = knotcount-1;
  76
  77     if( order < 1 || order > MAXORDER ) {
  78         // spline order un-supported
  79         return( 1 );
  80     }
  81
  82     if( knotcount < (2 * order) ) {
  83         // too few knots
  84         return( 2 );
  85     }
  86
  87     if( identical( knotlist[kindex-(order-1)], knotlist[order-1]) ) {
  88         // valid knot range is empty
  89         return( 3 );
  90     }
  91
  92     for( long i = 0; i < kindex; i++)
  93         if( knotlist[i] > knotlist[i+1] ) {
  94             // decreasing knot sequence
  95             return( 4 );
  96         }
  97
  98     /* check for valid multiplicity */
  99
 100     /*  kindex is currently the index of the last knot.
 101      *  In the next loop  it is decremented to ignore the last knot
 102      *  and the loop stops when kindex  is 2 so as to ignore the first
 103      *  knot as well.  These knots are not used in computing
 104      *  knot multiplicities.
 105      */
 106
 107     long multi = 1;
 108     for( ; kindex >= 1; kindex-- ) {
 109         if( knotlist[kindex] - knotlist[kindex-1] < TOLERANCE ) {
 110             multi++;
 111             continue;
 112         }
 113         if ( multi > order ) {
 114             // knot multiplicity greater than order of spline
 115             return( 5 );
 116         }
 117         multi = 1;
 118     }
 119
 120     if ( multi > order ) {
 121         // knot multiplicity greater than order of spline
 122         return( 5 );
 123     }
 124
 125     return 0;
 126 }
 127
 128 void Knotvector::show( char *msg )
 129 {
 130 #ifndef NDEBUG
 131     dprintf( "%s\n", msg );
 132     dprintf( "order = %ld, count = %ld\n", order, knotcount );
 133
 134     for( int i=0; i<knotcount; i++ )
 135         dprintf( "knot[%d] = %g\n", i, knotlist[i] );
 136 #endif
 137 }
 138