GH C# Component tips_寸法線を記述します （Rhino5版）

DrawDimensionsForRhino5GH.cs

  private void RunScript(bool bake, string name, ref object A)
  {
    //Planeを適当に作成
    Point3d pt1 = new Point3d(200, 400, 0);
    Point3d pt2 = new Point3d(900, 600, 0);
    Point3d pt3 = new Point3d(1200, 800, 0);
    Plane plane = new Plane(pt1, pt2 - pt1, pt3 - pt1);

    //寸法の間隔を点でリストに追加
    List<Point2d> pts = new List<Point2d>();
    pts.Add(new Point2d(0, -150));
    pts.Add(new Point2d(1500, -150));
    pts.Add(new Point2d(2200.5, -150));
    pts.Add(new Point2d(3000, -150));

    //寸法の基準PlaneとListを入れると寸法が返ってくるメソッド。DimensionStyleも自動的に作成するためにnameも入れる。
    lnDims = GetLinearDimensions(plane, pts, -250, name);

    if(bake)
    {
      foreach(LinearDimension item in lnDims)
      {
        Rhino.DocObjects.Tables.ObjectTable oTable = Rhino.RhinoDoc.ActiveDoc.Objects;
        oTable.AddLinearDimension(item);
      }
    }
    //参考にPlaneの位置を出力で表示
    A = plane;
  }

  // <Custom additional code> 
  public List<LinearDimension> lnDims;
  public Color dimColor = Color.Green;

  //寸法を作成するメソッド
  public List<LinearDimension> GetLinearDimensions(
    Plane dimPlane, List<Point2d> extendLnEndPts, double offsetDimLn, string dimStyleName)
  {
    List<LinearDimension> lnDims = new List<LinearDimension>();
    LinearDimension lnDim;
    for(int i = 0; i < extendLnEndPts.Count - 1; i++)
    {
      lnDim = new LinearDimension(dimPlane, extendLnEndPts[i], extendLnEndPts[i + 1],
        new Point2d(extendLnEndPts[i].X, extendLnEndPts[i].Y + offsetDimLn));
      lnDim.DimensionStyleIndex = FindStyleIndexByName(dimStyleName);

      //距離がゼロの場合は寸法をリストに追加しない
      if(Math.Round(lnDim.DistanceBetweenArrowTips) != 0)
      {
        lnDims.Add(lnDim);
      }
    }
    return lnDims;
  }
  
  //参照元:http://www.grasshopper3d.com/forum/topics/how-to-add-dimensionstyle-to-the-lineardimension
  public int FindStyleIndexByName(string dimStyleName)
  {
    DimensionStyle dimStyle = doc.DimStyles.Find(dimStyleName, true);
    if(dimStyle == null)  //DimensionStyleに名前がなかった場合はStyleを新規作成してIndexを返す
    {
      int dimStyleIndex = doc.DimStyles.Add(dimStyleName, false);
      DimensionStyle newDimStyle = doc.DimStyles[dimStyleIndex];

      //DimensionStyleのプロパティについては下記説明とほぼ同じ単語なので参照
      //https://docs.mcneel.com/rhino/5/help/en-us/documentproperties/dimensions_styles.htm
      newDimStyle.LengthResolution = 2;
      newDimStyle.AngleResolution = 2;
      newDimStyle.TextHeight = 100;
      newDimStyle.TextGap = 20;
      newDimStyle.ExtensionLineExtension = 0;
      newDimStyle.ExtensionLineOffset = 10;
      newDimStyle.CenterMarkSize = 30;
      newDimStyle.ArrowType = DimensionStyleArrowType.Dot;
      newDimStyle.ArrowLength = 40;
      newDimStyle.LeaderArrowType = DimensionStyleArrowType.Dot;
      newDimStyle.LeaderArrowLength = 40;
      newDimStyle.TextAlignment = TextDisplayAlignment.AboveLine;
      newDimStyle.CommitChanges();

      return dimStyleIndex;
    }
    else  //DimensionStyleに名前があった場合はそのIndexを返す
    {
      return dimStyle.Index;
    }
  }
  
  //C#コンポーネント内で線とテキストを記述
  //Draw all wires and points in this method.
  public override void DrawViewportWires(IGH_PreviewArgs args)
  {
    /*
    DrawViewportWiresメソッドには寸法を直接表示する機能がないため、寸法の情報を利用して疑似寸法を描画する
    http://developer.rhino3d.com/api/RhinoCommon/html/T_Rhino_Display_DisplayPipeline.htm
    */
    foreach(LinearDimension item in lnDims)
    {
      Plane dimPln = item.Plane;
      Point3d tmpPt1 = dimPln.PointAt(item.Arrowhead1End.X, item.Arrowhead1End.Y);
      Point3d tmpPt2 = dimPln.PointAt(item.Arrowhead2End.X, item.Arrowhead2End.Y);
      Point3d tmpPt3 = dimPln.PointAt(item.ExtensionLine1End.X, item.ExtensionLine1End.Y);
      Point3d tmpPt4 = dimPln.PointAt(item.ExtensionLine2End.X, item.ExtensionLine2End.Y);
      Point3d tmpPt5 = dimPln.PointAt(item.TextPosition.X, item.TextPosition.Y);

      //args.Displayには様々なDrawメソッドがある
      args.Display.DrawLine(new Line(tmpPt1, tmpPt2), dimColor);  //寸法線
      args.Display.DrawLine(new Line(tmpPt1, tmpPt3), dimColor);  //寸法延長線1
      args.Display.DrawLine(new Line(tmpPt2, tmpPt4), dimColor);  //寸法延長線2

      string tmpTxt = Math.Round(new Line(tmpPt1, tmpPt2).Length, 1).ToString();
      dimPln = new Plane(tmpPt5, dimPln.XAxis, dimPln.YAxis);
      Rhino.Display.Text3d txt3d = new Rhino.Display.Text3d(tmpTxt, dimPln, 100);
      txt3d = TextJustification(txt3d, 8);
      args.Display.Draw3dText(txt3d, dimColor);
    }
  }
  
  //テキストの位置合わせを行う。完璧なものではないので参考まで。
  private Rhino.Display.Text3d TextJustification(
    Rhino.Display.Text3d txt3d, int justificationIndex)
  {
    /*
    1 - Top Left
    2 - Top Middle
    3 - Top Right
    4 - Middle Left
    5 - Middle Center
    6 - Middle Right
    7 - Bottom Left(default)
    8 - Bottom Center
    9 - Bottom Right
    */
    Point3d checkPt = new Point3d(0, 0, 0);
    Point3d basePt = new Point3d(0, 0, 0);

    double uFromTextPlane, vFromTextPlane;

    Rhino.Display.Text3d txt3dJustification = new Rhino.Display.Text3d("temp");

    Rectangle3d rect3d = new Rectangle3d(txt3d.TextPlane,
      txt3d.TextPlane.Origin, txt3d.BoundingBox.FurthestPoint(txt3d.TextPlane.Origin));

    switch(justificationIndex)
    {
      case 1:
        checkPt = rect3d.PointAt(0, 1);
        break;
      case 2:
        checkPt = rect3d.PointAt(0.5, 1);
        break;
      case 3:
        checkPt = rect3d.PointAt(1, 1);
        break;
      case 4:
        checkPt = rect3d.PointAt(0, 0.5);
        break;
      case 5:
        checkPt = rect3d.PointAt(0.5, 0.5);
        break;
      case 6:
        checkPt = rect3d.PointAt(1, 0.5);
        break;
      case 7:
        checkPt = rect3d.PointAt(0, 0);
        break;
      case 8:
        checkPt = rect3d.PointAt(0.5, 0);
        break;
      case 9:
        checkPt = rect3d.PointAt(1, 0);
        break;
    }

    txt3d.TextPlane.ClosestParameter(checkPt, out uFromTextPlane, out vFromTextPlane);
    basePt = txt3d.TextPlane.PointAt(-uFromTextPlane, -vFromTextPlane);
    txt3d.TextPlane = new Plane(basePt, txt3d.TextPlane.XAxis, txt3d.TextPlane.YAxis);
    txt3dJustification = txt3d;

    return txt3dJustification;
  }
  // </Custom additional code>