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deps/g3dlite/include/G3D/ConvexPolyhedron.h

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+/**
+  @file ConvexPolyhedron.h
+  
+  @maintainer Morgan McGuire, http://graphics.cs.williams.edu
+
+  @created 2001-11-11
+  @edited  2006-04-10
+ 
+  Copyright 2000-2006, Morgan McGuire.
+  All rights reserved.
+ */
+
+#ifndef G3D_CONVEXPOLYHEDRON_H
+#define G3D_CONVEXPOLYHEDRON_H
+
+#include "G3D/platform.h"
+#include "G3D/Vector3.h"
+#include "G3D/Vector2.h"
+#include "G3D/CoordinateFrame.h"
+#include "G3D/Plane.h"
+#include "G3D/Line.h"
+#include "G3D/Array.h"
+
+namespace G3D {
+
+class DirectedEdge {
+public:
+    Vector3 start;
+    Vector3 stop;
+};
+
+class ConvexPolygon {
+private:
+
+    friend class ConvexPolyhedron;
+
+    Array<Vector3>            _vertex;
+
+public:
+
+    ConvexPolygon() {}
+    ConvexPolygon(const Vector3& v0, const Vector3& v1, const Vector3& v2);
+    ConvexPolygon(const Array<Vector3>& __vertex);
+    virtual ~ConvexPolygon() {}
+
+    /**
+     Counter clockwise winding order.  
+     */
+    inline const Vector3& vertex(int i) const {
+        return _vertex[i];
+    }
+    
+    inline void setVertex(int i, const Vector3& v) {
+        _vertex[i] = v;
+    }
+    
+    /**
+       Zero vertices indicates an empty polygon (zero area).
+    */
+    inline int numVertices() const {
+        return _vertex.size();
+    }
+    
+    inline void setNumVertices(int n) {
+        _vertex.resize(n);
+    }
+    
+    /**
+       O(n) in the number of edges
+    */
+    bool isEmpty() const;
+
+    /**
+       Cuts the polygon at the plane. If the polygon is entirely above or below
+       the plane, one of the returned polygons will be empty.
+     
+       @param above The part of the polygon above (on the side the
+              normal points to or in the plane) the plane
+       @param below The part of the polygon below the plane.
+       @param newEdge  If a new edge was introduced, this is that edge (on the above portion; the below portion is the opposite winding.
+    */
+    void cut(const Plane& plane, ConvexPolygon &above, ConvexPolygon &below, DirectedEdge& newEdge);
+    void cut(const Plane& plane, ConvexPolygon &above, ConvexPolygon &below);
+
+    /**
+       When a cut plane grazes a vertex in the polygon, two near-identical vertices may be created.
+       The closeness of these two points can cause a number of problems, such as ConvexPolygon::normal() 
+       returning an infinite vector.  It should be noted, however, that not all applications are 
+       sensitive to near-identical vertices.
+       
+       removeDuplicateVertices() detects and eliminates redundant vertices.
+    */
+    void removeDuplicateVertices();
+    
+    /**
+     O(n) in the number of edges
+     */
+    float getArea() const;
+
+    inline Vector3 normal() const {
+        debugAssert(_vertex.length() >= 3);
+        return (_vertex[1] - _vertex[0]).cross(_vertex[2] - _vertex[0]).direction();
+    }
+
+    /**
+     Returns the same polygon with inverse winding.
+     */
+    ConvexPolygon inverse() const;
+};
+
+
+
+class ConvexPolyhedron {
+public:
+    /**
+     Zero faces indicates an empty polyhedron
+     */
+    Array<ConvexPolygon> face;
+    
+    ConvexPolyhedron() {}
+    ConvexPolyhedron(const Array<ConvexPolygon>& _face);
+
+    /**
+     O(n) in the number of edges
+     */
+    bool isEmpty() const;
+
+    /**
+     O(n) in the number of edges
+     */
+    float getVolume() const;
+
+    /**
+       Cuts the polyhedron at the plane. If the polyhedron is entirely above or below
+       the plane, one of the returned polyhedra will be empty.
+     
+       @param above The part of the polyhedron above (on the side the
+              normal points to or in the plane) the plane
+       @param below The part of the polyhedron below the plane.
+     */
+    void cut(const Plane& plane, ConvexPolyhedron &above, ConvexPolyhedron &below);
+};
+
+/**
+
+    */
+class ConvexPolygon2D {
+private:
+
+    Array<Vector2>          m_vertex;
+
+public:
+
+    ConvexPolygon2D() {}
+
+    /** 
+     Points are counter-clockwise in a Y = down, X = right coordinate
+     system.
+
+     @param reverse If true, the points are reversed (i.e. winding direction is changed)
+     before the polygon is created.
+     */
+    ConvexPolygon2D(const Array<Vector2>& pts, bool reverse = false);
+
+    inline int numVertices() const {
+        return m_vertex.size();
+    }
+
+    inline const Vector2& vertex(int index) const {
+        debugAssert((index >= 0) && (index <= m_vertex.size()));
+        return m_vertex[index];
+    }
+
+    /** @param reverseWinding If true, the winding direction of the polygon is reversed for this test.*/
+    bool contains(const Vector2& p, bool reverseWinding = false) const;
+};
+
+
+} // namespace
+#endif