1 /* 2 * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008) 3 * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved. 4 * 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: 11 * 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. 16 * 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 23 * SOFTWARE. 24 * 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. 29 */ 30 /* 31 *partitionY.h: 32 *partition a polygon into a Y-monotone polygon: 33 * A polygon is Y-monotone if the boundary can be split into two polygon chains 34 *A and B such that each chain is Y-monotonic that is the intersection of any 35 *horizontal line intersects each chain has at most one connected componenets 36 * (empty, single point or a single line). 37 * 38 * A vertex is a cusp if both its ajacent vertices are either at or above v, 39 *or both at or below v. In addition, at least one of the ajacent verteces is 40 *strictly below or above v. 41 * A vertex is a relex vertex if the internals angle is strictly greater than 42 *180. In other words, if the signed area is negative: 43 *(x1, y1), (x2, y2), (x3, y3) are the three vertices along a polygon, the 44 *order is such that left hand side is inside the polygon. Then (x2,y2) is 45 *reflex if: 46 * (x2-x1, y2-y1) cross (x3-x1, y3-y1) <0. 47 *A vertex is an interior cusp if it is a cusp and a reflex. 48 *A vertex is an exterior cusp if it is a cusp but not a reflex. 49 * 50 */ 51 52 #ifndef _PARTITIONY_H 53 #define _PARTITIONY_H 54 55 #include "directedLine.h" 56 57 /*whether an edge is below a vertex*/ 58 Int isBelow(directedLine *v, directedLine *e); 59 60 /*whether an edge is above a vertex*/ 61 Int isAbove(directedLine *v, directedLine *e); 62 63 /*not-cusp, 64 *inerior cusp 65 *exterior cusp 66 */ 67 Int cuspType(directedLine *v); 68 69 /*used in trapezoidalization*/ 70 typedef struct sweepRange{ 71 directedLine *left; 72 Int leftType; /*either a vertex (leftType=0) or an edge (leftType =1) */ 73 directedLine *right; 74 Int rightType; /*either a vertex (rightType=0) or an edge (rightType =1) */ 75 } sweepRange; 76 77 sweepRange* sweepRangeMake(directedLine* left, Int leftType, 78 directedLine* right, Int rightType); 79 80 void sweepRangeDelete(sweepRange* range); 81 Int sweepRangeEqual(sweepRange* sr1, sweepRange* sr2); 82 83 /*given a set of simple polygons where the interior 84 *is decided by left-hand principle, 85 *return a range (sight) for each vertex. This is called 86 *Trapezoidalization. 87 */ 88 void sweepY(Int nVertices, directedLine **sortedVerteces, sweepRange** ret_ranges); 89 90 91 directedLine* partitionY(directedLine *polygons, sampledLine **retSampledLines); 92 93 void findDiagonals(Int total_num_edges, directedLine** sortedVertices, sweepRange** ranges, Int& num_diagonals, directedLine** diagonal_vertices); 94 95 directedLine** DBGfindDiagonals(directedLine *polygons, Int& num_diagonals); 96 97 #endif 98