对任意平面的镜像

st788796

http://379910987.blog.163.com/blog/static/33523797201011306586296/?suggestedreading&wumii
对任意平面的镜像  

数学基础

如果向量n为平面P的单位法向量，即有:

则实体关于该平面的变换矩阵为：

AutoCAD环境下的实现

下面是测试代码，我们用三个点构建一个平面，平面的Normal返回一个Vector3d对象，该对象是该平面的单位法向量。

using System; using Autodesk.AutoCAD.Runtime; using Autodesk.AutoCAD.Geometry; using Autodesk.AutoCAD.ApplicationServices; using Autodesk.AutoCAD.DatabaseServices; using Autodesk.AutoCAD.EditorInput; namespace CADTest {     public class Class1     {         #region实体镜像         [CommandMethod("MP")]//Mirror Entity         public void MirrorEntity()         { Database db = Application.DocumentManager.MdiActiveDocument.Database; Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;             //对称平面 Plane mp = new Plane(new Point3d(1, 0, 0), new Point3d(0, 1, 0), new Point3d(0, 0, 1));             double x = mp.Normal.X;             double y = mp.Normal.Y; double z = mp.Normal.Z; double[] dm = new double[16];             dm[0] = 1 - 2 * x * x; dm[5] = 1 - 2 * y * y;             dm[10] = 1 - 2 * z * z;             dm[15]=1;             dm[1] = dm[4] = -2*x * y;             dm[2] = dm[8] = -2*x * z;             dm[6] = dm[9] = -2*y * z; Matrix3d Tm = new Matrix3d(dm); using (Transaction trans = db.TransactionManager.StartTransaction())             { BlockTable bt = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForRead); BlockTableRecord btr = (BlockTableRecord)trans.GetObject(db.CurrentSpaceId, OpenMode.ForWrite); Solid3d sld = new Solid3d();                 sld.SetDatabaseDefaults();                 sld.CreateBox(100, 150, 200);                 sld.ColorIndex = 1;//red                 btr.AppendEntity(sld);                 trans.AddNewlyCreatedDBObject(sld, true); Solid3d sldClone = sld.Clone() as Solid3d;                 sldClone.ColorIndex = 3;//green                 sldClone.TransformBy(Tm);                 btr.AppendEntity(sldClone);                 trans.AddNewlyCreatedDBObject(sldClone, true);                 trans.Commit();             }         }         #endregion     } }

ScmTools

不错的例子

csharp

Mark
1 new plan (p1,p2,p3)
2 new Matrix3d (new Double[16])
3 clone transformby