| /* |
| * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008) |
| * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved. |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a |
| * copy of this software and associated documentation files (the "Software"), |
| * to deal in the Software without restriction, including without limitation |
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| * and/or sell copies of the Software, and to permit persons to whom the |
| * Software is furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice including the dates of first publication and |
| * either this permission notice or a reference to |
| * http://oss.sgi.com/projects/FreeB/ |
| * shall be included in all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
| * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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| * SOFTWARE. |
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| * Except as contained in this notice, the name of Silicon Graphics, Inc. |
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| * Silicon Graphics, Inc. |
| */ |
| /* |
| *partitionY.h: |
| *partition a polygon into a Y-monotone polygon: |
| * A polygon is Y-monotone if the boundary can be split into two polygon chains |
| *A and B such that each chain is Y-monotonic that is the intersection of any |
| *horizontal line intersects each chain has at most one connected componenets |
| * (empty, single point or a single line). |
| * |
| * A vertex is a cusp if both its ajacent vertices are either at or above v, |
| *or both at or below v. In addition, at least one of the ajacent verteces is |
| *strictly below or above v. |
| * A vertex is a relex vertex if the internals angle is strictly greater than |
| *180. In other words, if the the signed area is negative: |
| *(x1, y1), (x2, y2), (x3, y3) are the three vertices along a polygon, the |
| *order is such that left hand side is inside the polygon. Then (x2,y2) is |
| *reflex if: |
| * (x2-x1, y2-y1) cross (x3-x1, y3-y1) <0. |
| *A vertex is an interior cusp if it is a cusp and a reflex. |
| *A vertex is an exterior cusp if it is a cusp but not a reflex. |
| * |
| * $Header: /cvs/bao-parsec/pkgs/libs/mesa/src/src/glu/sgi/libnurbs/nurbtess/partitionY.h,v 1.1.1.1 2012/03/29 17:22:17 uid42307 Exp $ |
| */ |
| |
| #ifndef _PARTITIONY_H |
| #define _PARTITIONY_H |
| |
| #include "directedLine.h" |
| |
| /*whether an edge is below a vertex*/ |
| Int isBelow(directedLine *v, directedLine *e); |
| |
| /*whether an edge is above a vertex*/ |
| Int isAbove(directedLine *v, directedLine *e); |
| |
| /*not-cusp, |
| *inerior cusp |
| *exterior cusp |
| */ |
| Int cuspType(directedLine *v); |
| |
| /*used in trapezoidalization*/ |
| typedef struct sweepRange{ |
| directedLine *left; |
| Int leftType; /*either a vertex (leftType=0) or an edge (leftType =1) */ |
| directedLine *right; |
| Int rightType; /*either a vertex (rightType=0) or an edge (rightType =1) */ |
| } sweepRange; |
| |
| sweepRange* sweepRangeMake(directedLine* left, Int leftType, |
| directedLine* right, Int rightType); |
| |
| void sweepRangeDelete(sweepRange* range); |
| Int sweepRangeEqual(sweepRange* sr1, sweepRange* sr2); |
| |
| /*given a set of simple polygons where the interior |
| *is decided by left-hand principle, |
| *return a range (sight) for each vertex. This is called |
| *Trapezoidalization. |
| */ |
| void sweepY(Int nVertices, directedLine **sortedVerteces, sweepRange** ret_ranges); |
| |
| |
| directedLine* partitionY(directedLine *polygons, sampledLine **retSampledLines); |
| |
| void findDiagonals(Int total_num_edges, directedLine** sortedVertices, sweepRange** ranges, Int& num_diagonals, directedLine** diagonal_vertices); |
| |
| directedLine** DBGfindDiagonals(directedLine *polygons, Int& num_diagonals); |
| |
| #endif |