varray.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 * varray.c++
37 *
38 */
39
40#include "glimports.h"
41#include "myassert.h"
42#include "mystdio.h"
43#include "varray.h"
44#include "arc.h"
45#include "simplemath.h"         // glu_abs()
46
47#define TINY 0.0001
48inline long sgn( REAL x )
49{
50    return (x < -TINY) ? -1 :  ((x > TINY) ? 1 : 0 );
51}
52
53
54Varray::Varray( void )
55{
56    int i;
57
58    varray = 0;
59    size = 0;
60    numquads = 0;
61
62    for (i = 0; i < 1000; i++) {
63        vval[i] = 0;
64        voffset[i] = 0;
65    }
66}
67
68Varray::~Varray( void )
69{
70    if( varray ) delete[] varray;
71}
72
73inline void
74Varray::update( Arc_ptr arc, long dir[2], REAL val )
75{
76    register long ds = sgn(arc->tail()[0] - arc->prev->tail()[0]);
77    register long dt = sgn(arc->tail()[1] - arc->prev->tail()[1]);
78
79    if( dir[0] != ds || dir[1] != dt ) {
80	dir[0] = ds;
81	dir[1] = dt;
82	append( val );
83    }
84}
85
86void
87Varray::grow( long guess )
88{
89    if( size < guess ) {
90	size = guess * 2;
91	if( varray ) delete[] varray;
92	varray = new REAL[size];
93	assert( varray != 0 );
94    }
95}
96
97long
98Varray::init( REAL delta, Arc_ptr toparc, Arc_ptr botarc )
99{
100    Arc_ptr left = toparc->next;
101    Arc_ptr right = toparc;
102    long ldir[2], rdir[2];
103
104    ldir[0] = sgn( left->tail()[0] - left->prev->tail()[0] );
105    ldir[1] = sgn( left->tail()[1] - left->prev->tail()[1] );
106    rdir[0] = sgn( right->tail()[0] - right->prev->tail()[0] );
107    rdir[1] = sgn( right->tail()[1] - right->prev->tail()[1] );
108
109    vval[0] = toparc->tail()[1];
110    numquads = 0;
111
112    while( 1 ) {
113	switch( sgn( left->tail()[1] - right->prev->tail()[1] ) ) {
114	case 1:
115	    left = left->next;
116	    update( left, ldir, left->prev->tail()[1] );
117	    break;
118	case -1:
119	    right = right->prev;
120	    update( right, rdir, right->tail()[1] );
121	    break;
122	case 0:
123	    if( glu_abs(left->tail()[1] - botarc->tail()[1]) < TINY) goto end;
124            if( glu_abs(left->tail()[0]-right->prev->tail()[0]) < TINY &&
125                glu_abs(left->tail()[1]-right->prev->tail()[1]) < TINY) goto end;
126	    left = left->next;
127	    break;
128 	}
129    }
130
131end:
132    append( botarc->tail()[1] );
133
134    grow( ((long) ((vval[0] - vval[numquads])/delta)) + numquads + 2 );
135
136    long i, index = 0;
137    for( i=0; i<numquads; i++ ) {
138	voffset[i] = index;
139        varray[index++] = vval[i];
140	REAL dist = vval[i] - vval[i+1];
141	if( dist > delta ) {
142	    long steps = ((long) (dist/delta)) +1;
143	    float deltav = - dist / (REAL) steps;
144	    for( long j=1; j<steps; j++ )
145		varray[index++] = vval[i] + j * deltav;
146	}
147    }
148    voffset[i] = index;
149    varray[index] = vval[i];
150    return index;
151}
152
153