cad.net 投影三维图元到某个平面上+求图元交点

投影三维图元到某个平面上

如果遇到复杂的三维图元,要先进行消隐hide命令,但是我还没研究好这个命令.

红色(1号色)是三维的,黄色(2号色)投影下来的,它是曲线,因为曲线是直线的父类.可以依照曲率转换为自己喜欢的直线或者多段线,圆弧等等.

命令

[CommandMethod("test_ty", CommandFlags.Modal | CommandFlags.Session | CommandFlags.Redraw)]
public static void JJ_testty()
{
    Database db = HostApplicationServices.WorkingDatabase;//当前的数据库
    Editor ed = Acap.DocumentManager.MdiActiveDocument.Editor;
    ed.WriteMessage("
****{惊惊连盒}测试,投影三维图元到某个平面上");

    using (Acap.DocumentManager.MdiActiveDocument.LockDocument())//锁文档 CommandFlags.Session
    {
        db.Action(tr =>
        {
            //三维的线 
            var entity = new Line(Point3d.Origin, new Point3d(1, 1, 1));//var entity = EntityAdd.AddLineToEntity(Point3d.Origin, new Point3d(1, 1, 1));
            entity.ColorIndex = 1;
            var lineId = tr.AddEntityToMsPs(db, entity);

            var ids = new List<ObjectId>() { lineId };
            var cus = tr.Entitys2Plane(ids);
            foreach (var item in cus)
            {
                item.ColorIndex = 2;
                tr.AddEntityToMsPs(db, item);
            }
        });
    }
}

投影平面

/// <summary>
/// 投影平面
/// </summary> 
/// <param name="tr">事务</param>
/// <param name="ids">图元</param>
/// <param name="normal">投影方向</param>
/// <returns>投影到某个平面的图元</returns>
public static List<Curve> Entitys2Plane(this Transaction tr,
    IEnumerable<ObjectId> ids, Vector3d? normal = null)
{
    var ls = new List<Curve>();
    if (normal == null)
    {
        normal = Vector3d.ZAxis;//绕Z轴,也就是XY平面
    }
    var plane = new Plane(Point3d.Origin, normal.Value);
    foreach (var sobject in ids)
    {
        if (sobject.IsOk())
        {
            var curve = sobject.ToEntity(tr) as Curve;
            if (curve == null)
                continue;
            Curve pCurve = null;
            try
            {
                pCurve = curve.GetOrthoProjectedCurve(plane);
            }
            catch
            { }
            if (pCurve == null)
                continue; 
            ls.Add(pCurve);
        }
    }
    return ls;
}

/// <summary>
/// 将图形添加到数据库的当前空间中
/// </summary>
/// <param name="db">图形数据库</param>
/// <param name="ent">图形对象</param>
/// <returns>图形的ObjectId</returns>
public static ObjectId AddEntityToMsPs(this Transaction tr, Database db, Entity ent)
{
    ObjectId entId;
    //在位编辑的时候自动加到块内了,而不是模型空间,因为会把临时的数据拷贝回去块表记录上面
    //出现eLockViolation 是因 CommandFlags.Session | CommandFlags.Redraw 又没有锁文档
    var btRec = tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite) as BlockTableRecord;
    //加图元到块表记录,设定返回值
    entId = btRec.AppendEntity(ent);
    //更新数据
    tr.AddNewlyCreatedDBObject(ent, true);
    btRec.DowngradeOpen();
    btRec.Dispose();
    return entId;
}

求直线交点

在 数学篇 求两条直线的交点,说明过程 中有一个纯数学的解决方法.
那么cad的图元上面也有一个:Entity.IntersectWith函数.
但是展示这个函数前需要先说明一下,这个函数遇到两个坐标值特别大的图元会计算不出来,
例如两条spl样条曲线会计算不出来,而特大的坐标的直线却可以计算,原因可能是内部求导函数的问题.

Acad2008复现问题的方法是:画pline,设置坐标:(内存长度) (1e15,1e15) ~ (2e15,2e15)~ (3e15,3e15)
然后在这个范围上画spl,你会发现画得断断续续的...甚至卡死你的cad

而当你求不出交点的时候要注意是否小数点后数字过多!
如果遇到不妨将两条spl平移回原点附近再进行求交.

#if !HC2020
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;
using Acap = Autodesk.AutoCAD.ApplicationServices.Application;
#else
using GrxCAD.DatabaseServices;
using GrxCAD.EditorInput;
using GrxCAD.Geometry;
using GrxCAD.ApplicationServices;
using GrxCAD.DatabaseServices.Filters;
using GrxCAD.Runtime;
using Acap = GrxCAD.ApplicationServices.Application;
#endif

#if AC2008 || AC2010 || AC2012
using Autodesk.AutoCAD.Interop;
#endif

namespace JoinBox
{
    public class Intersection
    {
        [CommandMethod("IntersectionTest")]
        public void IntersectionTest()
        {
            var ed = Acap.DocumentManager.MdiActiveDocument.Editor;
            var db = HostApplicationServices.WorkingDatabase;
            ed.WriteMessage("
求空间两曲线交点");

            var per = ed.GetEntity("
选择第一条曲线(可以选择line,因为父类是曲线):");
            if (per.Status != PromptStatus.OK) { return; }
            ObjectId id1 = per.ObjectId;

            per = ed.GetEntity("
选择第二条曲线(可以选择line,因为父类是曲线):");
            if (per.Status != PromptStatus.OK) { return; }
            ObjectId id2 = per.ObjectId;

            db.Action(tr =>
            {
                var cur1 = id1.ToEntity(tr) as Curve;
                var cur2 = id2.ToEntity(tr) as Curve;

                var ints = new Point3dCollection();

               //plane是投影面
                cur1.IntersectWith(cur2, Intersect.OnBothOperands, new Plane(), ints, 0, 0); //得出的所有交点在c1曲线上
                if (ints.Count == 0)
                {
                    ed.WriteMessage($"
无交点或图元交点过大(小数点过多)");
                }
                else
                {
                    foreach (Point3d pt in ints)
                    {
                        ed.WriteMessage($"
第一条曲线与第二条曲线交点:{pt}");
                    }
                }

                ed.WriteMessage("
================================================");
                ints.Clear();

                cur2.IntersectWith(cur1, Intersect.OnBothOperands, new Plane(), ints, 0, 0); //得出的所有交点在c2曲线上
                if (ints.Count == 0)
                {
                    ed.WriteMessage($"
无交点或图元交点过大(小数点过多)");
                }
                else
                {
                    foreach (Point3d pt in ints)
                    {
                        ed.WriteMessage($"
第二条曲线与第条曲线一交点:{pt}");
                    }
                }
            });
        }
    }
}

(完)