polygon.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

/*
 * This code is based on Broken Sword 2.5 engine
 *
 * Copyright (c) Malte Thiesen, Daniel Queteschiner and Michael Elsdoerfer
 *
 * Licensed under GNU GPL v2
 *
 */

#ifndef SWORD25_POLYGON_H
#define SWORD25_POLYGON_H

// Includes
#include "sword25/kernel/common.h"
#include "sword25/kernel/persistable.h"
#include "sword25/math/vertex.h"

namespace Sword25 {

class Vertex;

class Polygon : public Persistable {
public:
    Polygon();

    Polygon(const Polygon &other);

    Polygon(InputPersistenceBlock &reader);

    Polygon(int vertexCount_, const Vertex *vertices_);

    ~Polygon() override;

    bool init(int vertexCount_, const Vertex *vertices_);

    //
    // ** Exploratory methods **
    //

    bool isCW() const;

    bool isCCW() const;

    bool isPointInPolygon(const Vertex &vertex, bool borderBelongsToPolygon = true) const;

    bool isPointInPolygon(int x, int y, bool borderBelongsToPolygon = true) const;

    Vertex getCentroid() const;

    // Edge belongs to the polygon
    // Polygon must be CW
    bool isLineInterior(const Vertex &a, const Vertex &b) const;
    // Edge does not belong to the polygon
    // Polygon must be CW
    bool isLineExterior(const Vertex &a, const Vertex &b) const;

    //
    // Manipulation methods
    //

    void ensureCWOrder();

    void ensureCCWOrder();

    void reverseVertexOrder();

    void operator+=(const Vertex &delta);

    //
    //------------------
    //

    int32 vertexCount;
    Vertex *vertices;

    bool persist(OutputPersistenceBlock &writer) override;
    bool unpersist(InputPersistenceBlock &reader) override;

    Polygon &operator=(const Polygon &p) {
        init(p.vertexCount, p.vertices);
        return *this;
    }

private:
    bool _isCW;
    Vertex _centroid;

    Vertex computeCentroid() const;

    bool computeIsCW() const;

    int crossProduct(const Vertex &v1, const Vertex &v2, const Vertex &v3) const;

    bool checkForSelfIntersection() const;

    int findLRVertexIndex() const;

    bool isLineInCone(int startVertexIndex, const Vertex &endVertex, bool includeEdges) const;
};

} // End of namespace Sword25

#endif