godot/thirdparty/misc/polypartition.h
2021-01-12 13:46:16 -05:00

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C++

/*************************************************************************/
/* Copyright (c) 2011-2021 Ivan Fratric and contributors. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
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/* distribute, sublicense, 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 and this permission notice 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.*/
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/*************************************************************************/
#ifndef POLYPARTITION_H
#define POLYPARTITION_H
#include "core/math/vector2.h"
#include "core/templates/list.h"
#include "core/templates/set.h"
typedef double tppl_float;
enum TPPLOrientation {
TPPL_ORIENTATION_CW = -1,
TPPL_ORIENTATION_NONE = 0,
TPPL_ORIENTATION_CCW = 1,
};
enum TPPLVertexType {
TPPL_VERTEXTYPE_REGULAR = 0,
TPPL_VERTEXTYPE_START = 1,
TPPL_VERTEXTYPE_END = 2,
TPPL_VERTEXTYPE_SPLIT = 3,
TPPL_VERTEXTYPE_MERGE = 4,
};
// 2D point structure.
typedef Vector2 TPPLPoint;
// Polygon implemented as an array of points with a "hole" flag.
class TPPLPoly {
protected:
TPPLPoint *points;
long numpoints;
bool hole;
public:
// Constructors and destructors.
TPPLPoly();
~TPPLPoly();
TPPLPoly(const TPPLPoly &src);
TPPLPoly &operator=(const TPPLPoly &src);
// Getters and setters.
long GetNumPoints() const {
return numpoints;
}
bool IsHole() const {
return hole;
}
void SetHole(bool hole) {
this->hole = hole;
}
TPPLPoint &GetPoint(long i) {
return points[i];
}
const TPPLPoint &GetPoint(long i) const {
return points[i];
}
TPPLPoint *GetPoints() {
return points;
}
TPPLPoint &operator[](int i) {
return points[i];
}
const TPPLPoint &operator[](int i) const {
return points[i];
}
// Clears the polygon points.
void Clear();
// Inits the polygon with numpoints vertices.
void Init(long numpoints);
// Creates a triangle with points p1, p2, and p3.
void Triangle(TPPLPoint &p1, TPPLPoint &p2, TPPLPoint &p3);
// Inverts the orfer of vertices.
void Invert();
// Returns the orientation of the polygon.
// Possible values:
// TPPL_ORIENTATION_CCW: Polygon vertices are in counter-clockwise order.
// TPPL_ORIENTATION_CW: Polygon vertices are in clockwise order.
// TPPL_ORIENTATION_NONE: The polygon has no (measurable) area.
TPPLOrientation GetOrientation() const;
// Sets the polygon orientation.
// Possible values:
// TPPL_ORIENTATION_CCW: Sets vertices in counter-clockwise order.
// TPPL_ORIENTATION_CW: Sets vertices in clockwise order.
// TPPL_ORIENTATION_NONE: Reverses the orientation of the vertices if there
// is one, otherwise does nothing (if orientation is already NONE).
void SetOrientation(TPPLOrientation orientation);
// Checks whether a polygon is valid or not.
inline bool Valid() const { return this->numpoints >= 3; }
};
#ifdef TPPL_ALLOCATOR
typedef List<TPPLPoly, TPPL_ALLOCATOR(TPPLPoly)> TPPLPolyList;
#else
typedef List<TPPLPoly> TPPLPolyList;
#endif
class TPPLPartition {
protected:
struct PartitionVertex {
bool isActive;
bool isConvex;
bool isEar;
TPPLPoint p;
tppl_float angle;
PartitionVertex *previous;
PartitionVertex *next;
PartitionVertex();
};
struct MonotoneVertex {
TPPLPoint p;
long previous;
long next;
};
class VertexSorter {
MonotoneVertex *vertices;
public:
VertexSorter(MonotoneVertex *v) :
vertices(v) {}
bool operator()(long index1, long index2);
};
struct Diagonal {
long index1;
long index2;
};
#ifdef TPPL_ALLOCATOR
typedef List<Diagonal, TPPL_ALLOCATOR(Diagonal)> DiagonalList;
#else
typedef List<Diagonal> DiagonalList;
#endif
// Dynamic programming state for minimum-weight triangulation.
struct DPState {
bool visible;
tppl_float weight;
long bestvertex;
};
// Dynamic programming state for convex partitioning.
struct DPState2 {
bool visible;
long weight;
DiagonalList pairs;
};
// Edge that intersects the scanline.
struct ScanLineEdge {
mutable long index;
TPPLPoint p1;
TPPLPoint p2;
// Determines if the edge is to the left of another edge.
bool operator<(const ScanLineEdge &other) const;
bool IsConvex(const TPPLPoint &p1, const TPPLPoint &p2, const TPPLPoint &p3) const;
};
// Standard helper functions.
bool IsConvex(TPPLPoint &p1, TPPLPoint &p2, TPPLPoint &p3);
bool IsReflex(TPPLPoint &p1, TPPLPoint &p2, TPPLPoint &p3);
bool IsInside(TPPLPoint &p1, TPPLPoint &p2, TPPLPoint &p3, TPPLPoint &p);
bool InCone(TPPLPoint &p1, TPPLPoint &p2, TPPLPoint &p3, TPPLPoint &p);
bool InCone(PartitionVertex *v, TPPLPoint &p);
int Intersects(TPPLPoint &p11, TPPLPoint &p12, TPPLPoint &p21, TPPLPoint &p22);
TPPLPoint Normalize(const TPPLPoint &p);
tppl_float Distance(const TPPLPoint &p1, const TPPLPoint &p2);
// Helper functions for Triangulate_EC.
void UpdateVertexReflexity(PartitionVertex *v);
void UpdateVertex(PartitionVertex *v, PartitionVertex *vertices, long numvertices);
// Helper functions for ConvexPartition_OPT.
void UpdateState(long a, long b, long w, long i, long j, DPState2 **dpstates);
void TypeA(long i, long j, long k, PartitionVertex *vertices, DPState2 **dpstates);
void TypeB(long i, long j, long k, PartitionVertex *vertices, DPState2 **dpstates);
// Helper functions for MonotonePartition.
bool Below(TPPLPoint &p1, TPPLPoint &p2);
void AddDiagonal(MonotoneVertex *vertices, long *numvertices, long index1, long index2,
TPPLVertexType *vertextypes, Set<ScanLineEdge>::Element **edgeTreeIterators,
Set<ScanLineEdge> *edgeTree, long *helpers);
// Triangulates a monotone polygon, used in Triangulate_MONO.
int TriangulateMonotone(TPPLPoly *inPoly, TPPLPolyList *triangles);
public:
// Simple heuristic procedure for removing holes from a list of polygons.
// It works by creating a diagonal from the right-most hole vertex
// to some other visible vertex.
// Time complexity: O(h*(n^2)), h is the # of holes, n is the # of vertices.
// Space complexity: O(n)
// params:
// inpolys:
// A list of polygons that can contain holes.
// Vertices of all non-hole polys have to be in counter-clockwise order.
// Vertices of all hole polys have to be in clockwise order.
// outpolys:
// A list of polygons without holes.
// Returns 1 on success, 0 on failure.
int RemoveHoles(TPPLPolyList *inpolys, TPPLPolyList *outpolys);
// Triangulates a polygon by ear clipping.
// Time complexity: O(n^2), n is the number of vertices.
// Space complexity: O(n)
// params:
// poly:
// An input polygon to be triangulated.
// Vertices have to be in counter-clockwise order.
// triangles:
// A list of triangles (result).
// Returns 1 on success, 0 on failure.
int Triangulate_EC(TPPLPoly *poly, TPPLPolyList *triangles);
// Triangulates a list of polygons that may contain holes by ear clipping
// algorithm. It first calls RemoveHoles to get rid of the holes, and then
// calls Triangulate_EC for each resulting polygon.
// Time complexity: O(h*(n^2)), h is the # of holes, n is the # of vertices.
// Space complexity: O(n)
// params:
// inpolys:
// A list of polygons to be triangulated (can contain holes).
// Vertices of all non-hole polys have to be in counter-clockwise order.
// Vertices of all hole polys have to be in clockwise order.
// triangles:
// A list of triangles (result).
// Returns 1 on success, 0 on failure.
int Triangulate_EC(TPPLPolyList *inpolys, TPPLPolyList *triangles);
// Creates an optimal polygon triangulation in terms of minimal edge length.
// Time complexity: O(n^3), n is the number of vertices
// Space complexity: O(n^2)
// params:
// poly:
// An input polygon to be triangulated.
// Vertices have to be in counter-clockwise order.
// triangles:
// A list of triangles (result).
// Returns 1 on success, 0 on failure.
int Triangulate_OPT(TPPLPoly *poly, TPPLPolyList *triangles);
// Triangulates a polygon by first partitioning it into monotone polygons.
// Time complexity: O(n*log(n)), n is the number of vertices.
// Space complexity: O(n)
// params:
// poly:
// An input polygon to be triangulated.
// Vertices have to be in counter-clockwise order.
// triangles:
// A list of triangles (result).
// Returns 1 on success, 0 on failure.
int Triangulate_MONO(TPPLPoly *poly, TPPLPolyList *triangles);
// Triangulates a list of polygons by first
// partitioning them into monotone polygons.
// Time complexity: O(n*log(n)), n is the number of vertices.
// Space complexity: O(n)
// params:
// inpolys:
// A list of polygons to be triangulated (can contain holes).
// Vertices of all non-hole polys have to be in counter-clockwise order.
// Vertices of all hole polys have to be in clockwise order.
// triangles:
// A list of triangles (result).
// Returns 1 on success, 0 on failure.
int Triangulate_MONO(TPPLPolyList *inpolys, TPPLPolyList *triangles);
// Creates a monotone partition of a list of polygons that
// can contain holes. Triangulates a set of polygons by
// first partitioning them into monotone polygons.
// Time complexity: O(n*log(n)), n is the number of vertices.
// Space complexity: O(n)
// params:
// inpolys:
// A list of polygons to be triangulated (can contain holes).
// Vertices of all non-hole polys have to be in counter-clockwise order.
// Vertices of all hole polys have to be in clockwise order.
// monotonePolys:
// A list of monotone polygons (result).
// Returns 1 on success, 0 on failure.
int MonotonePartition(TPPLPolyList *inpolys, TPPLPolyList *monotonePolys);
// Partitions a polygon into convex polygons by using the
// Hertel-Mehlhorn algorithm. The algorithm gives at most four times
// the number of parts as the optimal algorithm, however, in practice
// it works much better than that and often gives optimal partition.
// It uses triangulation obtained by ear clipping as intermediate result.
// Time complexity O(n^2), n is the number of vertices.
// Space complexity: O(n)
// params:
// poly:
// An input polygon to be partitioned.
// Vertices have to be in counter-clockwise order.
// parts:
// Resulting list of convex polygons.
// Returns 1 on success, 0 on failure.
int ConvexPartition_HM(TPPLPoly *poly, TPPLPolyList *parts);
// Partitions a list of polygons into convex parts by using the
// Hertel-Mehlhorn algorithm. The algorithm gives at most four times
// the number of parts as the optimal algorithm, however, in practice
// it works much better than that and often gives optimal partition.
// It uses triangulation obtained by ear clipping as intermediate result.
// Time complexity O(n^2), n is the number of vertices.
// Space complexity: O(n)
// params:
// inpolys:
// An input list of polygons to be partitioned. Vertices of
// all non-hole polys have to be in counter-clockwise order.
// Vertices of all hole polys have to be in clockwise order.
// parts:
// Resulting list of convex polygons.
// Returns 1 on success, 0 on failure.
int ConvexPartition_HM(TPPLPolyList *inpolys, TPPLPolyList *parts);
// Optimal convex partitioning (in terms of number of resulting
// convex polygons) using the Keil-Snoeyink algorithm.
// For reference, see M. Keil, J. Snoeyink, "On the time bound for
// convex decomposition of simple polygons", 1998.
// Time complexity O(n^3), n is the number of vertices.
// Space complexity: O(n^3)
// params:
// poly:
// An input polygon to be partitioned.
// Vertices have to be in counter-clockwise order.
// parts:
// Resulting list of convex polygons.
// Returns 1 on success, 0 on failure.
int ConvexPartition_OPT(TPPLPoly *poly, TPPLPolyList *parts);
};
#endif