From eb1d06cb6f9517b362b878796c65256352a04f9b Mon Sep 17 00:00:00 2001
From: ChenX <maple6@vip.qq.com>
Date: Wed, 31 Jul 2019 11:58:56 +0800
Subject: [PATCH] =?UTF-8?q?fix=20#IXWMX=20=E4=BF=AE=E5=A4=8D=E7=9B=B4?=
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---
 src/Editor/GripDragServices.ts |  5 +++--
 src/Editor/SnapServices.ts     | 20 ++++++++++++++------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/src/Editor/GripDragServices.ts b/src/Editor/GripDragServices.ts
index 52d52a984..654d4ccf9 100644
--- a/src/Editor/GripDragServices.ts
+++ b/src/Editor/GripDragServices.ts
@@ -118,10 +118,11 @@ export class GripDragServices implements EditorService
             if (snapIndexMap[0].indexArr.length === 1)
             {
                 let i = snapIndexMap[0].indexArr[0];
+                let snapServices = this.ed.GetPointServices.snapServices;
                 if (i === 0)
-                    baseP = snapIndexMap[0].ent.EndPoint;
+                    snapServices.TanBasePoint = snapIndexMap[0].ent.EndPoint;
                 else if (i === 2)
-                    baseP = snapIndexMap[0].ent.StartPoint;
+                    snapServices.TanBasePoint = snapIndexMap[0].ent.StartPoint;
             }
         }
 
diff --git a/src/Editor/SnapServices.ts b/src/Editor/SnapServices.ts
index fcd4de6ef..d53ca32e9 100644
--- a/src/Editor/SnapServices.ts
+++ b/src/Editor/SnapServices.ts
@@ -79,6 +79,9 @@ export class SnapServices
     private m_IsZAxis = false;
     private m_SupportSnapPoints: SupportSnapPoint[] = [];//辅助捕捉点WCS
     private m_UCS: Matrix4;
+
+    /** 切线捕捉时使用的基点 */
+    TanBasePoint: Vector3;
     //开始捕捉
     Start(prompt: GetPointPrompt)
     {
@@ -98,7 +101,7 @@ export class SnapServices
                 Entitys: [],
             });
 
-            //当基点在圆上或者圆弧上的时候,支持切线捕捉
+            //#region 当基点在圆上或者圆弧上的时候,支持切线捕捉
             let sel = new SelectPick(app.Viewer, app.Viewer.WorldToScreen(prompt.BasePoint.clone()));
             sel.Select(app.Viewer.VisibleObjects, { filterTypes: [Circle, Arc] });
             let cirs = sel.SelectEntityList as (Circle | Arc)[];
@@ -117,6 +120,7 @@ export class SnapServices
                     Point: prompt.BasePoint.clone(),
                     Entitys: ents,
                 });
+            //#endregion
 
             this.UpdateCrossCursor();
             this.m_HasBasePoint = true;
@@ -135,6 +139,7 @@ export class SnapServices
             this.m_DelaySupportSnapId = undefined;
         }
 
+        this.TanBasePoint = undefined;
         this.m_SupportSnapPoints.length = 0;
         this.SnapPoint = undefined;
         this.m_SupportExtLinePts.length = 0;
@@ -221,13 +226,15 @@ export class SnapServices
 
         let selectEns = PointPick(vcsP, app.Viewer, { filterErase: true }, app.Viewer.VisibleObjects).map(GetEntity).filter(e => e !== undefined);
 
+        let viewXform = new Matrix3().setFromMatrix4(app.Viewer.Camera.matrix);
+
         //如果只有切线捕捉
         if (this.SnapModeEnable === ObjectSnapMode.Tan && !this.m_HasBasePoint)
             for (let e of selectEns)
             {
                 if (e instanceof Circle || e instanceof Arc)
                 {
-                    let sps = e.GetObjectSnapPoints(ObjectSnapMode.Nea, wcsP, baseP);
+                    let sps = e.GetObjectSnapPoints(ObjectSnapMode.Nea, wcsP, baseP, viewXform);
 
                     for (let p of sps)
                     {
@@ -241,9 +248,6 @@ export class SnapServices
                 }
             }
 
-
-        let viewXform = new Matrix3().setFromMatrix4(app.Viewer.Camera.matrix);
-
         //#region 实体点捕捉(端点,中点,圆心,垂点,切点)
         for (let mode of [
             ObjectSnapMode.End,
@@ -257,7 +261,11 @@ export class SnapServices
             if ((mode & this.SnapModeEnable) === 0)
                 continue;
 
-            let snapData = this.CalcClosestSnapPoint(selectEns, mode, wcsP, vcsP, baseP, viewXform);
+            let bp = baseP;
+            if (mode === ObjectSnapMode.Tan && this.TanBasePoint)
+                bp = this.TanBasePoint;
+
+            let snapData = this.CalcClosestSnapPoint(selectEns, mode, wcsP, vcsP, bp, viewXform);
 
             if (snapData.Point)
             {