中点拉伸约束成只能拉伸成曲线的垂足方向.

src/DatabaseServices/Extrude.ts

@@ -514,8 +514,24 @@ export class ExtureSolid extends Entity
 
         let localVec = vec.clone().applyMatrix4(this.OCSInv.setPosition(cZeroVec));
 
-        dragType === DragPointType.Grip ?
-            this.ContourCurve.MoveGripPoints(indexList, localVec) :
+        if (dragType === DragPointType.Grip)
+        {
+            if (this.ContourCurve instanceof Polyline
+                && indexList.length === 1
+                && indexList[0] % 2 === 1)
+            {
+                let param = indexList[0] / 2;
+                if (this.ContourCurve.GetBuilgeAt(Math.floor(param)) === 0)
+                {
+                    let der = this.ContourCurve.GetFistDeriv(param).normalize();
+                    [der.x, der.y] = [der.y, -der.x];
+                    let d = localVec.dot(der);
+                    localVec.copy(der).multiplyScalar(d);
+                }
+            }
+            this.ContourCurve.MoveGripPoints(indexList, localVec);
+        }
+        else
             this.ContourCurve.MoveStretchPoints(indexList, localVec);
     }