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engines/sword25/math/polygon.h

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+/* 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;
+
+/**
+	@brief Eine Polygonklasse.
+*/
+class Polygon : public Persistable {
+public:
+	/**
+	 * Creates an object of type #BS_Polygon, containing 0 Vertecies.
+	 *
+	 * With the method Init(), Vertices can be added in later
+	 */
+	Polygon();
+
+	/**
+	 * Copy constructor
+	 */
+	Polygon(const Polygon &other);
+
+	/**
+	 * Creates a polygon using persisted data
+	 */
+	Polygon(InputPersistenceBlock &reader);
+
+	/**
+	 * Creaes an object of type #BS_Polygon, and assigns Vertices to it
+	 * @param VertexCount       The number of vertices being passed
+	 * @param Vertecies         An array of BS_Vertex objects representing the vertices in the polygon.
+	 * @remark                  The Vertecies that define a polygon must not have any self-intersections.
+	 * If the polygon does have self-intersections, then an empty polygon object is created.
+	 */
+	Polygon(int vertexCount_, const Vertex *vertices_);
+
+	/**
+	 * Deletes the BS_Polygon object
+	 */
+	~Polygon() override;
+
+	/**
+	 * Initializes the BS_Polygon with a list of Vertecies.
+	 *
+	 * The Vertices need to define a polygon must not have self-intersections.
+	 * If a polygon already has verticies, this will re-initialize it with the new list.
+	 *
+	 * @param VertexCount       The number of vertices being passed
+	 * @param Vertecies         An array of BS_Vertex objects representing the vertices in the polygon.
+	 * @return                  Returns false if the Vertecies have self-intersections. In this case,
+	 * the object is not initialized.
+	 */
+	bool init(int vertexCount_, const Vertex *vertices_);
+
+	//
+	// ** Exploratory methods **
+	//
+
+	/**
+	 * Checks whether the Vertecies of the polygon are arranged in a clockwise direction.
+	 * @return                  Returns true if the Vertecies of the polygon are arranged clockwise or co-planar.
+	 * Returns false if the Vertecies of the polygon are arrange counter-clockwise.
+	 * @remark                  This method only returns a meaningful result if the polygon has at least three Vertecies.
+	 */
+	bool isCW() const;
+
+	/**
+	 * Checks whether the Vertices of the polygon are arranged in a counter-clockwise direction.
+	 * @return                  Returns true if the Vertecies of the polygon are arranged counter-clockwise.
+	 * Returns false if the Vertecies of the polygon are arranged clockwise or co-planar.
+	 * @remark                  This method only returns a meaningful result if the polygon has at least three Vertecies.
+	 */
+	bool isCCW() const;
+
+	/**
+	 * Checks whether a point is inside the polygon
+	 * @param Vertex            A Vertex with the co-ordinates of the point to be tested.
+	 * @param BorderBelongsToPolygon    Specifies whether the edge of the polygon should be considered
+	 * @return                  Returns true if the point is inside the polygon, false if it is outside.
+	 */
+	bool isPointInPolygon(const Vertex &vertex, bool borderBelongsToPolygon = true) const;
+
+	/**
+	 * Checks whether a point is inside the polygon
+	 * @param X                 The X position of the point
+	 * @param Y                 The Y position of the point
+	 * @param BorderBelongsToPolygon    Specifies whether the edge of the polygon should be considered
+	 * @return                  Returns true if the point is inside the polygon, false if it is outside.
+	 */
+	bool isPointInPolygon(int x, int y, bool borderBelongsToPolygon = true) const;
+
+	/**
+	 * Returns the focus/centroid of the polygon
+	 */
+	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
+	//
+
+	/**
+	 * Ensures that the Vertecies of the polygon are arranged in a clockwise direction
+	 */
+	void ensureCWOrder();
+
+	/**
+	 * Ensures that the Vertecies of the polygon are arranged in a counter-clockwise direction
+	 */
+	void ensureCCWOrder();
+
+	/**
+	 * Reverses the Vertecies order.
+	 */
+	void reverseVertexOrder();
+
+	/**
+	 * Moves the polygon.
+	 * @param Delta             The vertex around the polygon to be moved.
+	 */
+	void operator+=(const Vertex &delta);
+
+	//
+	//------------------
+	//
+
+	/// Specifies the number of Vertecies in the Vertecies array.
+	int32 vertexCount;
+	/// COntains the Vertecies of the polygon
+	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;
+
+	/**
+	 * Computes the centroid of the polygon.
+	 */
+	Vertex computeCentroid() const;
+
+	/**
+	 * Determines how the Vertecies of the polygon are arranged.
+	 * @return                  Returns true if the Vertecies are arranged in a clockwise
+	 * direction, otherwise false.
+	 */
+	bool computeIsCW() const;
+
+	/**
+	 * Calculates the cross product of three Vertecies
+	 * @param V1                The first Vertex
+	 * @param V2                The second Vertex
+	 * @param V3                The third Vertex
+	 * @return                  Returns the cross-product of the three vertecies
+	 * @todo                    This method would be better as a method of the BS_Vertex class
+	 */
+	int crossProduct(const Vertex &v1, const Vertex &v2, const Vertex &v3) const;
+
+	/**
+	 * Checks whether the polygon is self-intersecting
+	 * @return                  Returns true if the polygon is self-intersecting.
+	 * Returns false if the polygon is not self-intersecting.
+	 */
+	bool checkForSelfIntersection() const;
+
+	/**
+	 * Find the vertex of the polygon that is located below the right-most point,
+	 * and returns it's index in the vertex array.
+	 * @return                  Returns the index of the vertex at the bottom-right of the polygon.
+	 * Returns -1 if the vertex list is empty.
+	 */
+	int findLRVertexIndex() const;
+
+	bool isLineInCone(int startVertexIndex, const Vertex &endVertex, bool includeEdges) const;
+};
+
+} // End of namespace Sword25
+
+#endif