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 * hull.c++
37 *
38 */
39
40#include "glimports.h"
41#include "myassert.h"
42#include "mystdio.h"
43#include "hull.h"
44#include "gridvertex.h"
45#include "gridtrimvertex.h"
46#include "gridline.h"
47#include "trimline.h"
48#include "uarray.h"
49#include "trimregion.h"
50
51Hull::Hull( void )
52{}
53
54Hull::~Hull( void )
55{}
56
57/*----------------------------------------------------------------------
58 * Hull:init - this routine does the initialization needed before any
59 *	 	calls to nextupper or nextlower can be made.
60 *----------------------------------------------------------------------
61 */
62void
63Hull::init( void )
64{
65    TrimVertex *lfirst = left.first();
66    TrimVertex *llast = left.last();
67    if( lfirst->param[0] <= llast->param[0] ) {
68	fakeleft.init( left.first() );
69	upper.left = &fakeleft;
70	lower.left = &left;
71    } else {
72	fakeleft.init( left.last() );
73	lower.left = &fakeleft;
74 	upper.left = &left;
75    }
76    upper.left->last();
77    lower.left->first();
78
79    if( top.ustart <= top.uend ) {
80	upper.line = &top;
81	upper.index = top.ustart;
82    } else
83	upper.line = 0;
84
85    if( bot.ustart <= bot.uend ) {
86	lower.line = &bot;
87	lower.index = bot.ustart;
88    } else
89	lower.line = 0;
90
91    TrimVertex *rfirst = right.first();
92    TrimVertex *rlast = right.last();
93    if( rfirst->param[0] <= rlast->param[0] ) {
94	fakeright.init( right.last() );
95	lower.right = &fakeright;
96	upper.right = &right;
97    } else {
98	fakeright.init( right.first() );
99	upper.right = &fakeright;
100	lower.right = &right;
101    }
102    upper.right->first();
103    lower.right->last();
104}
105
106/*----------------------------------------------------------------------
107 * nextupper - find next vertex on upper hull of trim region.
108 *		 - if vertex is on trim curve, set vtop point to
109 *		   that vertex.  if vertex is on grid, set vtop to
110 *		   point to temporary area and stuff coordinants into
111 *		   temporary vertex.  Also, place grid coords in temporary
112 *		   grid vertex.
113 *----------------------------------------------------------------------
114 */
115GridTrimVertex *
116Hull::nextupper( GridTrimVertex *gv )
117{
118    if( upper.left ) {
119	gv->set( upper.left->prev() );
120	if( gv->isTrimVert() ) return gv;
121	upper.left = 0;
122    }
123
124    if( upper.line ) {
125	assert( upper.index <= upper.line->uend );
126	gv->set( uarray.uarray[upper.index], upper.line->vval );
127	gv->set( upper.index, upper.line->vindex );
128	if( upper.index++ == upper.line->uend ) upper.line = 0;
129	return gv;
130    }
131
132    if( upper.right ) {
133	gv->set( upper.right->next() );
134	if( gv->isTrimVert() ) return gv;
135	upper.right = 0;
136    }
137
138    return 0;
139}
140
141GridTrimVertex *
142Hull::nextlower( GridTrimVertex *gv )
143{
144    if( lower.left ) {
145	gv->set( lower.left->next() );
146	if( gv->isTrimVert() ) return gv;
147	lower.left = 0;
148    }
149
150    if( lower.line ) {
151	gv->set( uarray.uarray[lower.index], lower.line->vval );
152	gv->set( lower.index, lower.line->vindex );
153	if( lower.index++ == lower.line->uend ) lower.line = 0;
154	return gv;
155    }
156
157    if( lower.right ) {
158	gv->set( lower.right->prev() );
159	if( gv->isTrimVert() ) return gv;
160	lower.right = 0;
161    }
162
163    return 0;
164}
165
166