internal class ArcToPolyLine { /// <summary> /// Converts the arc in a Polyline2D. /// </summary> /// <param name="precision">Number of divisions.</param> /// <returns>A new instance of <see cref="Polyline2D">Polyline2D</see> that represents the arc.</returns> public Polyline2D ToPolyline2D(int precision) { IEnumerable<Vector2> vertexes = this.PolygonalVertexes(precision); Vector3 ocsCenter = MathHelper.Transform(this.center, this.Normal, CoordinateSystem.World, CoordinateSystem.Object); Polyline2D poly = new Polyline2D { Layer = (Layer)this.Layer.Clone(), Linetype = (Linetype)this.Linetype.Clone(), Color = (AciColor)this.Color.Clone(), Lineweight = this.Lineweight, Transparency = (Transparency)this.Transparency.Clone(), LinetypeScale = this.LinetypeScale, Normal = this.Normal, Elevation = ocsCenter.Z, Thickness = this.Thickness, IsClosed = false }; foreach (Vector2 v in vertexes) { poly.Vertexes.Add(new Polyline2DVertex(v.X + ocsCenter.X, v.Y + ocsCenter.Y)); } return poly; } /// <summary> /// Transforms a point between coordinate systems. /// </summary> /// <param name="point">Point to transform.</param> /// <param name="zAxis">Object normal vector.</param> /// <param name="from">Point coordinate system.</param> /// <param name="to">Coordinate system of the transformed point.</param> /// <returns>Transformed point.</returns> public static Vector3 Transform(Vector3 point, Vector3 zAxis, CoordinateSystem from, CoordinateSystem to) { Matrix3 trans = ArbitraryAxis(zAxis); switch (from) { case CoordinateSystem.World when to == CoordinateSystem.Object: trans = trans.Transpose(); return trans * point; case CoordinateSystem.Object when to == CoordinateSystem.World: return trans * point; default: return point; } } /// <summary> /// Gets the rotation matrix from the normal vector (extrusion direction) of an entity. /// </summary> /// <param name="zAxis">Normal vector.</param> /// <returns>Rotation matrix.</returns> public static Matrix3 ArbitraryAxis(Vector3 zAxis) { zAxis.Normalize(); if (zAxis.Equals(Vector3.UnitZ)) { return Matrix3.Identity; } Vector3 wY = Vector3.UnitY; Vector3 wZ = Vector3.UnitZ; Vector3 aX; if ((Math.Abs(zAxis.X) < 1 / 64.0) && (Math.Abs(zAxis.Y) < 1 / 64.0)) { aX = Vector3.CrossProduct(wY, zAxis); } else { aX = Vector3.CrossProduct(wZ, zAxis); } aX.Normalize(); Vector3 aY = Vector3.CrossProduct(zAxis, aX); aY.Normalize(); return new Matrix3(aX.X, aY.X, zAxis.X, aX.Y, aY.Y, zAxis.Y, aX.Z, aY.Z, zAxis.Z); } }