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partitionY.h
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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*/
59 
60 /*whether an edge is above a vertex*/
62 
63 /*not-cusp,
64  *inerior cusp
65  *exterior cusp
66  */
68 
69 /*used in trapezoidalization*/
70 typedef struct sweepRange{
72  Int leftType; /*either a vertex (leftType=0) or an edge (leftType =1) */
74  Int rightType; /*either a vertex (rightType=0) or an edge (rightType =1) */
75 } sweepRange;
76 
78  directedLine* right, Int rightType);
79 
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
directedLine * right
Definition: partitionY.h:73
Int sweepRangeEqual(sweepRange *sr1, sweepRange *sr2)
Definition: partitionY.cc:167
Int leftType
Definition: partitionY.h:72
sweepRange * sweepRangeMake(directedLine *left, Int leftType, directedLine *right, Int rightType)
Definition: partitionY.cc:150
Int isBelow(directedLine *v, directedLine *e)
Definition: partitionY.cc:73
Int cuspType(directedLine *v)
Definition: partitionY.cc:142
Int rightType
Definition: partitionY.h:74
#define e
Definition: ke_i.h:82
Int isAbove(directedLine *v, directedLine *e)
Definition: partitionY.cc:89
GLint left
Definition: glext.h:7726
GLdouble GLdouble right
Definition: glext.h:10859
directedLine ** DBGfindDiagonals(directedLine *polygons, Int &num_diagonals)
Definition: partitionY.cc:426
directedLine * partitionY(directedLine *polygons, sampledLine **retSampledLines)
Definition: partitionY.cc:447
GLenum GLint * range
Definition: glext.h:7539
struct sweepRange sweepRange
void sweepY(Int nVertices, directedLine **sortedVerteces, sweepRange **ret_ranges)
Definition: partitionY.cc:722
const GLdouble * v
Definition: gl.h:2040
directedLine * left
Definition: partitionY.h:71
void findDiagonals(Int total_num_edges, directedLine **sortedVertices, sweepRange **ranges, Int &num_diagonals, directedLine **diagonal_vertices)
Definition: partitionY.cc:333
void sweepRangeDelete(sweepRange *range)
Definition: partitionY.cc:162
int Int
Definition: definitions.h:37