Merge pull request #1 from rena0157/develop

Adding Area for Polylines with Arcs

Author: rena0157

src/DxfLibrary/GeoMath/BasicGeometry.cs

@@ -13,6 +13,9 @@ namespace DxfLibrary.GeoMath
     /// </summary>
     public static class BasicGeometry
     {
+        /// <summary>
+        /// The Tolerance for floating point numbers in this library.
+        /// </summary>
         public static double Tolerance = 1E-10;
 
         /// <summary>
@@ -49,7 +52,7 @@ public static double TrapzArea(GeoLine line)
         /// <param name="radius">The radius of the circle</param>
         /// <param name="angle">The angle that the segment occupies in Radians</param>
         /// <returns>The Area of the segment</returns>
-        public static double CircleSegmentArea(double radius, double angle) => Math.Pow(radius, 2) * (angle - Math.Sin(angle));
+        public static double CircleSegmentArea(double radius, double angle) => Math.Pow(radius, 2) * 0.5 * (angle - Math.Sin(angle));
 
         #region Unit Conversion
 

src/DxfLibrary/GeoMath/Vector.cs

@@ -30,6 +30,16 @@ public Vector(GeoPoint origin, GeoPoint destination)
             Destination = destination;
         }
 
+        /// <summary>
+        /// Constructor that creates a vector with its tail at the origin
+        /// and the destination given by a <see cref="GeoPoint">.
+        /// </summary>
+        /// <param name="destination">The GeoPoint for the destination</param>
+        public Vector(GeoPoint destination) : this(new GeoPoint(0,0), destination)
+        {
+
+        }
+
         #endregion
 
         #region Public Properties
@@ -94,6 +104,72 @@ public Vector Translate(GeoPoint origin)
              new GeoPoint(origin.X + X, origin.Y + Y, origin.Z + Z));
         }
 
+        /// <summary>
+        /// Dot product of the vector and another vector
+        /// </summary>
+        /// <param name="other">The other vector to dot with</param>
+        /// <returns>Returns: The result of the dot product</returns>
+        public double Dot(Vector other) => X * other.X + Y * other.Y + Z * other.Z;
+
+        /// <summary>
+        /// The Cross Product of this vector and another vector.
+        /// Note that this returns a new vector where this origin is the same
+        /// as this vector.
+        /// </summary>
+        /// <param name="v2">The other vector that is being crossed</param>
+        /// <returns>Returns: A new vector</returns>
+        public Vector Cross(Vector v2) => new Vector(Origin, 
+            new GeoPoint(Origin.X + Y*v2.Z - v2.Y*Z,
+            Origin.Y + v2.X*Z - X*v2.Z,
+            Origin.Z + (X*v2.Y - v2.X*Y)));
+
+        #endregion
+
+        #region Overrides
+
+        /// <summary>
+        /// Overloaded operator + for the vector type
+        /// </summary>
+        /// <param name="a">The first vector</param>
+        /// <param name="b">The second vector</param>
+        /// <returns>Returns a new vector which is the addition of the two vectors</returns>
+        public static Vector operator +(Vector a, Vector b)
+        {
+            return new Vector(new GeoPoint(a.Origin.X + b.Origin.X, a.Origin.Y + b.Origin.Y, a.Origin.Z + b.Origin.Z),
+                new GeoPoint(a.Destination.X + b.Destination.X,
+                a.Destination.Y + b.Destination.Y, a.Destination.Z + b.Destination.Z));
+        }
+
+        /// <summary>
+        /// Equals override for the vector type
+        /// </summary>
+        /// <param name="obj">The object that you are comparing</param>
+        /// <returns>Returns true if the vector is equal to another vector</returns>
+        public override bool Equals(object obj)
+        {
+            var vector = obj as Vector;
+
+            if (vector == null)
+                return false;
+
+            return Origin.Equals(vector.Origin) && 
+                Destination.Equals(vector.Destination);
+        }
+
+        /// <summary>
+        /// Override for the GetHashCode Type
+        /// </summary>
+        /// <returns>Returns: an int which is the hash code for the vector</returns>
+        public override int GetHashCode()
+        {
+            int hash = 983251653;
+
+            hash = (hash * 817504243) + Origin.GetHashCode();
+            hash = (hash * 817504243) + Destination.GetHashCode();
+
+            return hash;
+        }
+
         #endregion
 
         #region UnitVectors

src/DxfLibrary/Geometry/Bulge.cs

@@ -41,7 +41,7 @@ public Bulge(double bulgeValue)
         /// <summary>
         /// The Angle of the Bulge in Degrees
         /// </summary>
-        public double AngleDeg => Rad2Deg(Angle);
+        public double AngleDeg => BasicGeometry.Rad2Deg(Angle);
 
         /// <summary>
         /// Distance from the Chord line to the highest point of the arc,
@@ -61,12 +61,5 @@ public double Sagitta(GeoPoint p0, GeoPoint p1)
         /// <returns>The Radius of the Arc</returns>
         public double Radius(GeoPoint p0, GeoPoint p1)
             => BasicGeometry.Distance(p0, p1) * 0.5 * (Math.Pow(Value, 2) + 1) / (2 * Value);
-
-        /// <summary>
-        /// Converter for rads to degs
-        /// </summary>
-        /// <param name="val">Val in radians</param>
-        /// <returns>The value in degrees</returns>
-        private double Rad2Deg(double val) => val * (180 / Math.PI);
     }
 }

src/DxfLibrary/Geometry/GeoLine.cs

@@ -69,6 +69,12 @@ public GeoLine(GeoPoint p0, GeoPoint p1, Bulge bulge)
         /// </summary>
         public Bulge Bulge {get;}
 
+        /// <summary>
+        /// Returns True if the line has a bulge, and false
+        /// if the file does not have a bulge
+        /// </summary>
+        public bool HasBulge => !(BasicGeometry.DoubleCompare(Bulge.Value, 0));
+
         /// <summary>
         /// The Length of the Line.
         /// </summary>
@@ -85,7 +91,8 @@ public GeoLine(GeoPoint p0, GeoPoint p1, Bulge bulge)
         /// <summary>
         /// Area of the Segment. The Area of the segment
         /// Is the area of a trapizoid that is bounded by the two points of the
-        /// line.
+        /// line. Note that if the segment is an arc then the area is the area
+        /// bounded by that arc.
         /// </summary>
         public double Area => CalcArea();
 
@@ -101,8 +108,13 @@ public double Radius
         /// If the bulge is zero then the angle will return 
         /// positive infinity
         /// </summary>
+        /// <remarks>
+        /// If there is no arc then the segment is a line and
+        /// will then have an angle of PI (180 degrees). This angle will be returned 
+        /// in radians.
+        /// </remarks>
         public double Angle
-            => Bulge.Value != 0 ? Bulge.Angle : double.PositiveInfinity;
+            => Bulge.Value != 0 ? Bulge.Angle : Math.PI;
 
         #endregion
 
@@ -111,7 +123,7 @@ public double Angle
         /// <summary>
         /// Override of the ToString Method
         /// </summary>
-        /// <returns></returns>
+        /// <returns>Returns: The Lines points and coordinates</returns>
         public override string ToString()
         {
             return $"P0({Point0.X}, {Point0.Y}, {Point0.Z}), P1({Point1.X}, {Point1.Y}, {Point1.Z})";
@@ -120,7 +132,10 @@ public override string ToString()
         /// <summary>
         /// Convert this entity to a vector
         /// </summary>
-        /// <returns>A new vector</returns>
+        /// <returns>
+        /// Returns: A new vector that has the origin and destination
+        /// the same as this lines point 0 and point 1
+        /// </returns>
         public Vector ToVector() => new Vector(Point0, Point1);
 
         #endregion
@@ -130,7 +145,12 @@ public override string ToString()
         /// <summary>
         /// Calculate the length of the Segment.
         /// </summary>
-        /// <returns>The length of the line</returns>
+        /// <remarks>
+        /// If the bulge value is 0: Returns the length of the line segment
+        /// 
+        /// If the bulge value is not 0: Returns the arc length of the arc segment
+        /// </remarks>
+        /// <returns>The length of the segment</returns>
         private double CalcLength()
         {
             // If the line has no bulge then calculate the straight length
@@ -155,11 +175,9 @@ private double CalcArea()
 
             // If the bulge value is not equal to 0 then return the 
             // Area of the circle segment
-            return BasicGeometry.CircleSegmentArea(Bulge.Radius(Point0, Point1), Bulge.Angle);
+            return Math.Abs(BasicGeometry.CircleSegmentArea(Bulge.Radius(Point0, Point1), Bulge.Angle));
         }
 
-
-
         #endregion
     }
 }

src/DxfLibrary/Geometry/GeoPolyline.cs

@@ -3,18 +3,30 @@
 // Created on: 2019-01-13
 
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 
+using DxfLibrary.GeoMath;
+
 namespace DxfLibrary.Geometry
 {
-    public class GeoPolyline : GeoBase, IGeoLength, IGeoArea
+    /// <summary>
+    /// Class that represents a collection of Geolines
+    /// </summary>
+    public class GeoPolyline : GeoBase, IGeoLength, IGeoArea, IEnumerable<GeoLine>
     {
+        #region Private Members
+
         /// <summary>
         /// Private backing field for lines
         /// </summary>
         private List<GeoLine> _lines;
 
+        #endregion
+
+        #region Constructors
+
         /// <summary>
         /// Constructor for the GeoPolyline that takes in Lists of
         /// X, y and z coodinates
@@ -27,8 +39,12 @@ public GeoPolyline(List<double> x, List<double> y, List<double> bulges, bool isC
         {
             // If the numbers do not match then throw an error
             if (x.Count != y.Count || x.Count != bulges.Count)
-                throw new IndexOutOfRangeException();
+                throw new IndexOutOfRangeException("All coordinates must be the same size");
 
+            // If there are less than 2 points then the polyline cannot be defined
+            if (x.Count < 2)
+                throw new ArgumentException("Need more than two points to define a polyline");
+
             _lines = new List<GeoLine>();
 
             // Iterate through and create new lines
@@ -50,6 +66,12 @@ public GeoPolyline(List<double> x, List<double> y, List<double> bulges, bool isC
                 var bulge = new Bulge(bulges.Last());
                 _lines.Add(new GeoLine(point0, point1, bulge));
             }
+
+            // Determine the draw direction using the first and second
+            // line by converting them to vectors and crossing them.
+            if (_lines.Count > 1)
+                DrawDirection = _lines[0].ToVector()
+                    .Cross( _lines[1].ToVector() ).Z;
         }
 
         /// <summary>
@@ -62,6 +84,10 @@ public GeoPolyline(List<double> x, List<double> y, bool isClosed)
         {
         }
 
+        #endregion
+
+        #region Public Properties
+
         /// <summary>
         /// Get the total length of all the lines
         /// </summary>
@@ -70,6 +96,76 @@ public GeoPolyline(List<double> x, List<double> y, bool isClosed)
         /// <summary>
         /// Get the total area of all the lines
         /// </summary>
-        public double Area => _lines.Select(l => l.Area).Sum();
+        public double Area => CalcArea();
+
+        /// <summary>
+        /// The Draw direction of the polyline.
+        /// If the value is >0 then the draw direction is counterclockwise
+        /// If the value is less than 0 then the direction is clockwise
+        /// </summary>
+        public double DrawDirection {get;}
+
+        #endregion
+
+        #region Public Methods
+        
+        /// <summary>
+        /// Get the enumerator for the lines in the polyline
+        /// </summary>
+        /// <returns>Returns the Enumberator for the lines in the polyline</returns>
+        public IEnumerator<GeoLine> GetEnumerator()
+        {
+            return _lines.GetEnumerator();
+        }
+
+        /// <summary>
+        /// Gets the enumerator for the polyline class
+        /// </summary>
+        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+        
+        #endregion
+
+        #region Private Methods
+
+        private double CalcArea()
+        {
+            double sum = 0.0d;
+
+            // Need to iterate through the lines to caluclate the 
+            // Total area
+            foreach(var segment in  _lines)
+            {
+                // If the segment does not have a bulge then
+                // Add the area from the object to the sum
+                if (!segment.HasBulge)
+                {
+                    sum += segment.Area;
+                    continue;
+                }
+
+                // First add the area of the Trapizoid
+                if (DrawDirection > 0)
+                    sum += (new GeoLine(segment.Point0, segment.Point1).Area) * -1.0;
+
+                else if (DrawDirection < 0)
+                    sum += new GeoLine(segment.Point0, segment.Point1).Area;
+
+                // This value will determine if we are to add or subtract the segment area
+                var segmentAreaSwtich = DrawDirection * segment.Bulge.Value;
+
+                if (segmentAreaSwtich > 0)
+                    sum += segment.Area;
+
+                else if (segmentAreaSwtich < 0)
+                    sum -= segment.Area;
+                
+            }
+
+            return Math.Abs(sum);
+        }
+
+
+
+        #endregion
     }
 }