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 */
37 
38 #include <stdlib.h>
39 //#include <stdio.h>
40 
41 #include "partitionX.h"
42 
43 #define CONCAVITY_ZERO 1.0e-6 //this number is used to test whether a vertex is concave (refelx)
44                               //or not. The test needs to compute the area of the three adjacent
45                               //vertices to see if the are is positive or negative.
46 
47 Int isCuspX(directedLine *v)
48 {
49   //if v->prev <= v && v->next <= v
50   //|| v->prev >= v && v->next >= v
51   Real* T = v->head();
52   Real* P = v->getPrev()->head();
53   Real* N = v->getNext()->head();
54   if(
55      (compV2InX(T,P) != -1 &&
56       compV2InX(T,N) != -1
57       ) ||
58      (compV2InX(T,P) != 1 &&
59       compV2InX(T,N) != 1
60       )
61      )
62     return 1;
63   else
64     return 0;
65 }
66 
67 Int isReflexX(directedLine* v)
68 {
69   Real* A = v->getPrev()->head();
70   Real* B = v->head();
71   Real* C = v->tail();
72   Real Bx,By, Cx, Cy;
73   //scale them in case they are too small
74   Bx = 10*(B[0] - A[0]);
75   By = 10*(B[1] - A[1]);
76   Cx = 10*(C[0] - A[0]);
77   Cy = 10*(C[1] - A[1]);
78 
79   if(Bx*Cy - Cx*By < -CONCAVITY_ZERO) return 1;
80   else return 0;
81 }
82 
83 
84 /*return
85  *0: not-cusp
86  *1: interior cusp
87  *2: exterior cusp
88  */
89 Int cuspTypeX(directedLine *v)
90 {
91   if(! isCuspX(v)) return 0;
92   else
93     {
94 //printf("isCusp,%f,%f\n", v->head()[0], v->head()[1]);
95       if(isReflexX(v))
96 	{
97 //	  printf("isReflex\n");
98 	  return 1;
99 	}
100       else
101 	{
102 //	  printf("not isReflex\n");
103 	  return 2;
104 	}
105     }
106 }
107 
108 Int numInteriorCuspsX(directedLine *polygon)
109 {
110   directedLine *temp;
111   int ret = 0;
112   if(cuspTypeX(polygon) == 1)
113     ret++;
114   for(temp = polygon->getNext(); temp != polygon; temp = temp->getNext())
115     if(cuspTypeX(temp) == 1)
116       ret++;
117   return ret;
118 }
119 
120 
121 void findInteriorCuspsX(directedLine *polygon, Int& ret_n_interior_cusps,
122 			directedLine** ret_interior_cusps)
123 {
124   directedLine *temp;
125   ret_n_interior_cusps = 0;
126   if(cuspTypeX(polygon) == 1)
127     {
128       ret_interior_cusps[ret_n_interior_cusps++] = polygon;
129     }
130   for(temp = polygon->getNext(); temp != polygon; temp = temp->getNext())
131     if(cuspTypeX(temp) == 1)
132       {
133 	ret_interior_cusps[ret_n_interior_cusps++] = temp;
134       }
135 }
136 
137 directedLine* findDiagonal_singleCuspX(directedLine* cusp)
138 {
139   directedLine* temp;
140   Int is_minimal = ((compV2InX(cusp->head(), cusp->tail()) == -1)? 1:0);
141 
142   if(is_minimal)
143     for(temp = cusp->getNext(); temp != cusp; temp = temp->getNext())
144       {
145 	if(compV2InX(cusp->head(), temp->head()) == 1)
146 	  {
147 	    return temp;
148 	  }
149       }
150   else //is maxmal
151     for(temp = cusp->getNext(); temp != cusp; temp = temp->getNext())
152       {
153 	if(compV2InX(cusp->head(), temp->head()) == -1)
154 	  {
155 	    return temp;
156 	  }
157       }
158   return NULL;
159 }
160 
161 
162 
163