reactos/dll/win32/glu32/libnurbs/nurbtess/partitionY.h

   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 ** $Date$ $Revision: 1.1 $
  35 */
  36 /*
  37  *partitionY.h:
  38  *partition a polygon into a Y-monotone polygon:
  39  * A polygon is Y-monotone if the boundary can be split into two polygon chains
  40  *A and B such that each chain is Y-monotonic that is the intersection of any
  41  *horizontal line intersects each chain has at most one connected componenets
  42  * (empty, single point or a single line).
  43  *
  44  * A vertex is a cusp if both its ajacent vertices are either at or above v,
  45  *or both at or below v. In addition, at least one of the ajacent verteces is
  46  *strictly below or above v.
  47  * A vertex is a relex vertex if the internals angle is strictly greater than
  48  *180. In other words, if the the signed area is negative:
  49  *(x1, y1), (x2, y2), (x3, y3) are the three vertices along a polygon, the
  50  *order is such that left hand side is inside the polygon. Then (x2,y2) is
  51  *reflex if:
  52  *  (x2-x1, y2-y1) cross (x3-x1, y3-y1) <0.
  53  *A vertex is an interior cusp if it is a cusp and a reflex.
  54  *A vertex is an exterior cusp if it is a cusp but not a reflex.
  55  *
  56  * $Header: /cygdrive/c/RCVS/CVS/ReactOS/reactos/lib/glu32/libnurbs/nurbtess/partitionY.h,v 1.1 2004/02/02 16:39:13 navaraf Exp $
  57  */
  58
  59 #ifndef _PARTITIONY_H
  60 #define _PARTITIONY_H
  61
  62 #include "directedLine.h"
  63
  64 /*whether an edge is below a vertex*/
  65 Int isBelow(directedLine *v, directedLine *e);
  66
  67 /*whether an edge is above a vertex*/
  68 Int isAbove(directedLine *v, directedLine *e);
  69
  70 /*not-cusp,
  71  *inerior cusp
  72  *exterior cusp
  73  */
  74 Int cuspType(directedLine *v);
  75
  76 /*used in trapezoidalization*/
  77 typedef struct sweepRange{
  78   directedLine *left;
  79   Int leftType; /*either a vertex (leftType=0) or an edge (leftType =1) */
  80   directedLine *right;
  81   Int rightType; /*either a vertex (rightType=0) or an edge (rightType =1) */
  82 } sweepRange;
  83
  84 sweepRange* sweepRangeMake(directedLine* left, Int leftType,
  85                            directedLine* right, Int rightType);
  86
  87 void sweepRangeDelete(sweepRange* range);
  88 Int sweepRangeEqual(sweepRange* sr1, sweepRange* sr2);
  89
  90 /*given a set of simple polygons where the interior
  91  *is decided by left-hand principle,
  92  *return a range (sight) for each vertex. This is called
  93  *Trapezoidalization.
  94  */
  95 void sweepY(Int nVertices, directedLine **sortedVerteces, sweepRange** ret_ranges);
  96
  97
  98 directedLine* partitionY(directedLine *polygons, sampledLine **retSampledLines);
  99
 100 void findDiagonals(Int total_num_edges, directedLine** sortedVertices, sweepRange** ranges, Int& num_diagonals, directedLine** diagonal_vertices);
 101
 102 directedLine** DBGfindDiagonals(directedLine *polygons, Int& num_diagonals);
 103
 104 #endif