FreeWRL / FreeX3D 4.3.0
curve.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 * curve.c++
37 *
38 */
39
40#include "glimports.h"
41#include "myassert.h"
42#include "mystdio.h"
43#include "mymath.h"
44#include "curve.h"
45#include "mapdesc.h"
46#include "types.h"
47#include "quilt.h"
48#include "nurbsconsts.h"
49
50/*--------------------------------------------------------------------------
51 * Curve::Curve - copy curve from quilt and transform control points
52 *--------------------------------------------------------------------------
53 */
54
55Curve::Curve( Quilt_ptr geo, REAL pta, REAL ptb, Curve *c )
56{
57 mapdesc = geo->mapdesc;
58 next = c;
59 needsSampling = mapdesc->isRangeSampling() ? 1 : 0;
60 cullval = mapdesc->isCulling() ? CULL_ACCEPT : CULL_TRIVIAL_ACCEPT;
61 order = geo->qspec[0].order;
62 stride = MAXCOORDS;
63
64 REAL *ps = geo->cpts;
65 Quiltspec_ptr qs = geo->qspec;
66 ps += qs->offset;
67 ps += qs->index * qs->order * qs->stride;
68
69 if( needsSampling )
70 mapdesc->xformSampling( ps, qs->order, qs->stride, spts, stride );
71
72 if( cullval == CULL_ACCEPT )
73 mapdesc->xformCulling( ps, qs->order, qs->stride, cpts, stride );
74
75 /* set untrimmed curve range */
76 range[0] = qs->breakpoints[qs->index];
77 range[1] = qs->breakpoints[qs->index+1];
78 range[2] = range[1] - range[0];
79
80 if( range[0] != pta ) {
81 Curve lower( *this, pta, 0 );
82 lower.next = next;
83 *this = lower;
84 }
85 if( range[1] != ptb ) {
86 Curve lower( *this, ptb, 0 );
87 }
88}
89
90/*--------------------------------------------------------------------------
91 * Curve::Curve - subdivide a curve along an isoparametric line
92 *--------------------------------------------------------------------------
93 */
94
95Curve::Curve( Curve& upper, REAL value, Curve *c )
96{
97 Curve &lower = *this;
98
99 lower.next = c;
100 lower.mapdesc = upper.mapdesc;
101 lower.needsSampling = upper.needsSampling;
102 lower.order = upper.order;
103 lower.stride = upper.stride;
104 lower.cullval = upper.cullval;
105
106 REAL d = (value - upper.range[0]) / upper.range[2];
107
108 if( needsSampling )
109 mapdesc->subdivide( upper.spts, lower.spts, d, upper.stride, upper.order );
110
111 if( cullval == CULL_ACCEPT )
112 mapdesc->subdivide( upper.cpts, lower.cpts, d, upper.stride, upper.order );
113
114 lower.range[0] = upper.range[0];
115 lower.range[1] = value;
116 lower.range[2] = value - upper.range[0];
117 upper.range[0] = value;
118 upper.range[2] = upper.range[1] - value;
119}
120
121
122/*--------------------------------------------------------------------------
123 * Curve::clamp - clamp the sampling rate to a given maximum
124 *--------------------------------------------------------------------------
125 */
126
127void
128Curve::clamp( void )
129{
130 if( stepsize < minstepsize )
131 stepsize = mapdesc->clampfactor * minstepsize;
132}
133
134void
135Curve::setstepsize( REAL max )
136{
137 stepsize = ( max >= 1.0 ) ? (range[2] / max) : range[2];
138 minstepsize = stepsize;
139}
140
141void
142Curve::getstepsize( void )
143{
144 minstepsize= 0;
145
146 if( mapdesc->isConstantSampling() ) {
147 // fixed number of samples per patch in each direction
148 // maxrate is number of s samples per patch
149 setstepsize( mapdesc->maxrate );
150 } else if( mapdesc->isDomainSampling() ) {
151 // maxrate is number of s samples per unit s length of domain
152 setstepsize( mapdesc->maxrate * range[2] );
153 } else {
154 // upper bound on path length between sample points
155
156 assert( order <= MAXORDER );
157
158 /* points have been transformed, therefore they are homogeneous */
159 REAL tmp[MAXORDER][MAXCOORDS];
160 const int tstride = sizeof(tmp[0]) / sizeof(REAL);
161 int val = mapdesc->project( spts, stride, &tmp[0][0], tstride, order );
162
163 if( val == 0 ) {
164 // control points cross infinity, therefore derivatives are undefined
165 setstepsize( mapdesc->maxrate );
166 } else {
167 REAL t = mapdesc->getProperty( N_PIXEL_TOLERANCE );
168 if( mapdesc->isParametricDistanceSampling() ) {
169 REAL d = mapdesc->calcPartialVelocity( &tmp[0][0], tstride, order, 2, range[2] );
170 stepsize = (d > 0.0) ? sqrtf( 8.0 * t / d ) : range[2];
171 minstepsize = ( mapdesc->maxrate > 0.0 ) ? (range[2] / mapdesc->maxrate) : 0.0;
172 } else if( mapdesc->isPathLengthSampling() ) {
173 // t is upper bound on path (arc) length
174 REAL d = mapdesc->calcPartialVelocity( &tmp[0][0], tstride, order, 1, range[2] );
175 stepsize = ( d > 0.0 ) ? (t / d) : range[2];
176 minstepsize = ( mapdesc->maxrate > 0.0 ) ? (range[2] / mapdesc->maxrate) : 0.0;
177 } else {
178 // control points cross infinity, therefore partials are undefined
179 setstepsize( mapdesc->maxrate );
180 }
181 }
182 }
183}
184
185int
186Curve::needsSamplingSubdivision( void )
187{
188 return ( stepsize < minstepsize ) ? 1 : 0;
189}
190
191int
192Curve::cullCheck( void )
193{
194 if( cullval == CULL_ACCEPT )
195 cullval = mapdesc->cullCheck( cpts, order, stride );
196 return cullval;
197}
198
Definition curve.h:46