2
* SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
3
* Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
5
* Permission is hereby granted, free of charge, to any person obtaining a
6
* copy of this software and associated documentation files (the "Software"),
7
* to deal in the Software without restriction, including without limitation
8
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
9
* and/or sell copies of the Software, and to permit persons to whom the
10
* Software is furnished to do so, subject to the following conditions:
12
* The above copyright notice including the dates of first publication and
13
* either this permission notice or a reference to
14
* http://oss.sgi.com/projects/FreeB/
15
* shall be included in all copies or substantial portions of the Software.
17
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20
* SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
21
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
22
* OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
25
* Except as contained in this notice, the name of Silicon Graphics, Inc.
26
* shall not be used in advertising or otherwise to promote the sale, use or
27
* other dealings in this Software without prior written authorization from
28
* Silicon Graphics, Inc.
31
** Author: Eric Veach, July 1994.
40
typedef struct GLUESmesh GLUESmesh;
42
typedef struct GLUESvertex GLUESvertex;
43
typedef struct GLUESface GLUESface;
44
typedef struct GLUEShalfEdge GLUEShalfEdge;
46
typedef struct ActiveRegion ActiveRegion; /* Internal data */
48
/* The mesh structure is similar in spirit, notation, and operations
49
* to the "quad-edge" structure (see L. Guibas and J. Stolfi, Primitives
50
* for the manipulation of general subdivisions and the computation of
51
* Voronoi diagrams, ACM Transactions on Graphics, 4(2):74-123, April 1985).
52
* For a simplified description, see the course notes for CS348a,
53
* "Mathematical Foundations of Computer Graphics", available at the
54
* Stanford bookstore (and taught during the fall quarter).
55
* The implementation also borrows a tiny subset of the graph-based approach
56
* use in Mantyla's Geometric Work Bench (see M. Mantyla, An Introduction
57
* to Sold Modeling, Computer Science Press, Rockville, Maryland, 1988).
59
* The fundamental data structure is the "half-edge". Two half-edges
60
* go together to make an edge, but they point in opposite directions.
61
* Each half-edge has a pointer to its mate (the "symmetric" half-edge Sym),
62
* its origin vertex (Org), the face on its left side (Lface), and the
63
* adjacent half-edges in the CCW direction around the origin vertex
64
* (Onext) and around the left face (Lnext). There is also a "next"
65
* pointer for the global edge list (see below).
67
* The notation used for mesh navigation:
68
* Sym = the mate of a half-edge (same edge, but opposite direction)
69
* Onext = edge CCW around origin vertex (keep same origin)
70
* Dnext = edge CCW around destination vertex (keep same dest)
71
* Lnext = edge CCW around left face (dest becomes new origin)
72
* Rnext = edge CCW around right face (origin becomes new dest)
74
* "prev" means to substitute CW for CCW in the definitions above.
76
* The mesh keeps global lists of all vertices, faces, and edges,
77
* stored as doubly-linked circular lists with a dummy header node.
78
* The mesh stores pointers to these dummy headers (vHead, fHead, eHead).
80
* The circular edge list is special; since half-edges always occur
81
* in pairs (e and e->Sym), each half-edge stores a pointer in only
82
* one direction. Starting at eHead and following the e->next pointers
83
* will visit each *edge* once (ie. e or e->Sym, but not both).
84
* e->Sym stores a pointer in the opposite direction, thus it is
85
* always true that e->Sym->next->Sym->next == e.
87
* Each vertex has a pointer to next and previous vertices in the
88
* circular list, and a pointer to a half-edge with this vertex as
89
* the origin (NULL if this is the dummy header). There is also a
90
* field "data" for client data.
92
* Each face has a pointer to the next and previous faces in the
93
* circular list, and a pointer to a half-edge with this face as
94
* the left face (NULL if this is the dummy header). There is also
95
* a field "data" for client data.
97
* Note that what we call a "face" is really a loop; faces may consist
98
* of more than one loop (ie. not simply connected), but there is no
99
* record of this in the data structure. The mesh may consist of
100
* several disconnected regions, so it may not be possible to visit
101
* the entire mesh by starting at a half-edge and traversing the edge
104
* The mesh does NOT support isolated vertices; a vertex is deleted along
105
* with its last edge. Similarly when two faces are merged, one of the
106
* faces is deleted (see __gl_meshDelete below). For mesh operations,
107
* all face (loop) and vertex pointers must not be NULL. However, once
108
* mesh manipulation is finished, __gl_MeshZapFace can be used to delete
109
* faces of the mesh, one at a time. All external faces can be "zapped"
110
* before the mesh is returned to the client; then a NULL face indicates
111
* a region which is not part of the output polygon.
116
GLUESvertex* next; /* next vertex (never NULL) */
117
GLUESvertex* prev; /* previous vertex (never NULL) */
118
GLUEShalfEdge* anEdge; /* a half-edge with this origin */
119
void* data; /* client's data */
121
/* Internal data (keep hidden) */
122
double coords[3]; /* vertex location in 3D */
123
GLfloat s, t; /* projection onto the sweep plane */
124
long pqHandle; /* to allow deletion from priority queue */
129
GLUESface* next; /* next face (never NULL) */
130
GLUESface* prev; /* previous face (never NULL) */
131
GLUEShalfEdge* anEdge; /* a half edge with this left face */
132
void* data; /* room for client's data */
134
/* Internal data (keep hidden) */
135
GLUESface* trail; /* "stack" for conversion to strips */
136
GLboolean marked; /* flag for conversion to strips */
137
GLboolean inside; /* this face is in the polygon interior */
142
GLUEShalfEdge* next; /* doubly-linked list (prev==Sym->next) */
143
GLUEShalfEdge* Sym; /* same edge, opposite direction */
144
GLUEShalfEdge* Onext; /* next edge CCW around origin */
145
GLUEShalfEdge* Lnext; /* next edge CCW around left face */
146
GLUESvertex* Org; /* origin vertex (Overtex too long) */
147
GLUESface* Lface; /* left face */
149
/* Internal data (keep hidden) */
150
ActiveRegion* activeRegion; /* a region with this upper edge (sweep.c) */
151
int winding; /* change in winding number when crossing
152
from the right face to the left face */
155
#define Rface Sym->Lface
158
#define Oprev Sym->Lnext
159
#define Lprev Onext->Sym
160
#define Dprev Lnext->Sym
161
#define Rprev Sym->Onext
162
#define Dnext Rprev->Sym /* 3 pointers */
163
#define Rnext Oprev->Sym /* 3 pointers */
167
GLUESvertex vHead; /* dummy header for vertex list */
168
GLUESface fHead; /* dummy header for face list */
169
GLUEShalfEdge eHead; /* dummy header for edge list */
170
GLUEShalfEdge eHeadSym; /* and its symmetric counterpart */
173
/* The mesh operations below have three motivations: completeness,
174
* convenience, and efficiency. The basic mesh operations are MakeEdge,
175
* Splice, and Delete. All the other edge operations can be implemented
176
* in terms of these. The other operations are provided for convenience
179
* When a face is split or a vertex is added, they are inserted into the
180
* global list *before* the existing vertex or face (ie. e->Org or e->Lface).
181
* This makes it easier to process all vertices or faces in the global lists
182
* without worrying about processing the same data twice. As a convenience,
183
* when a face is split, the "inside" flag is copied from the old face.
184
* Other internal data (v->data, v->activeRegion, f->data, f->marked,
185
* f->trail, e->winding) is set to zero.
187
* ********************** Basic Edge Operations **************************
189
* __gl_meshMakeEdge( mesh ) creates one edge, two vertices, and a loop.
190
* The loop (face) consists of the two new half-edges.
192
* __gl_meshSplice( eOrg, eDst ) is the basic operation for changing the
193
* mesh connectivity and topology. It changes the mesh so that
194
* eOrg->Onext <- OLD(eDst->Onext)
195
* eDst->Onext <- OLD(eOrg->Onext)
196
* where OLD(...) means the value before the meshSplice operation.
198
* This can have two effects on the vertex structure:
199
* - if eOrg->Org != eDst->Org, the two vertices are merged together
200
* - if eOrg->Org == eDst->Org, the origin is split into two vertices
201
* In both cases, eDst->Org is changed and eOrg->Org is untouched.
203
* Similarly (and independently) for the face structure,
204
* - if eOrg->Lface == eDst->Lface, one loop is split into two
205
* - if eOrg->Lface != eDst->Lface, two distinct loops are joined into one
206
* In both cases, eDst->Lface is changed and eOrg->Lface is unaffected.
208
* __gl_meshDelete( eDel ) removes the edge eDel. There are several cases:
209
* if (eDel->Lface != eDel->Rface), we join two loops into one; the loop
210
* eDel->Lface is deleted. Otherwise, we are splitting one loop into two;
211
* the newly created loop will contain eDel->Dst. If the deletion of eDel
212
* would create isolated vertices, those are deleted as well.
214
* ********************** Other Edge Operations **************************
216
* __gl_meshAddEdgeVertex( eOrg ) creates a new edge eNew such that
217
* eNew == eOrg->Lnext, and eNew->Dst is a newly created vertex.
218
* eOrg and eNew will have the same left face.
220
* __gl_meshSplitEdge( eOrg ) splits eOrg into two edges eOrg and eNew,
221
* such that eNew == eOrg->Lnext. The new vertex is eOrg->Dst == eNew->Org.
222
* eOrg and eNew will have the same left face.
224
* __gl_meshConnect( eOrg, eDst ) creates a new edge from eOrg->Dst
225
* to eDst->Org, and returns the corresponding half-edge eNew.
226
* If eOrg->Lface == eDst->Lface, this splits one loop into two,
227
* and the newly created loop is eNew->Lface. Otherwise, two disjoint
228
* loops are merged into one, and the loop eDst->Lface is destroyed.
230
* ************************ Other Operations *****************************
232
* __gl_meshNewMesh() creates a new mesh with no edges, no vertices,
233
* and no loops (what we usually call a "face").
235
* __gl_meshUnion( mesh1, mesh2 ) forms the union of all structures in
236
* both meshes, and returns the new mesh (the old meshes are destroyed).
238
* __gl_meshDeleteMesh( mesh ) will free all storage for any valid mesh.
240
* __gl_meshZapFace( fZap ) destroys a face and removes it from the
241
* global face list. All edges of fZap will have a NULL pointer as their
242
* left face. Any edges which also have a NULL pointer as their right face
243
* are deleted entirely (along with any isolated vertices this produces).
244
* An entire mesh can be deleted by zapping its faces, one at a time,
245
* in any order. Zapped faces cannot be used in further mesh operations!
247
* __gl_meshCheckMesh( mesh ) checks a mesh for self-consistency.
250
GLUEShalfEdge* __gl_meshMakeEdge(GLUESmesh* mesh);
251
int __gl_meshSplice(GLUEShalfEdge* eOrg, GLUEShalfEdge* eDst);
252
int __gl_meshDelete(GLUEShalfEdge* eDel);
254
GLUEShalfEdge* __gl_meshAddEdgeVertex(GLUEShalfEdge* eOrg);
255
GLUEShalfEdge* __gl_meshSplitEdge(GLUEShalfEdge* eOrg);
256
GLUEShalfEdge* __gl_meshConnect(GLUEShalfEdge* eOrg, GLUEShalfEdge* eDst);
258
GLUESmesh* __gl_meshNewMesh(void);
259
GLUESmesh* __gl_meshUnion(GLUESmesh* mesh1, GLUESmesh* mesh2);
260
void __gl_meshDeleteMesh(GLUESmesh* mesh);
261
void __gl_meshZapFace(GLUESface* fZap);
264
#define __gl_meshCheckMesh(mesh)
266
void __gl_meshCheckMesh(GLUESmesh* mesh);
269
#endif /* __mesh_h_ */
added
removed
src/external/glues_stel/source/libtess/mesh.h
