!2673 修复:太小的圆弧建模报错

src/Add-on/ArcBoard/ArcBoardBuild.ts

@@ -117,13 +117,16 @@ export class ArcBoardBuild
         let path = ArcBoardBuild.OffsetPolyline(this._SweepPath, -this._board.Thickness);
         if (this._FaceDir === FaceDirection.Back)
         {
-            this._SweepPath1 = this._SweepPath;
+            this._SweepPath1 = ArcBoardBuild.OffsetPolyline(path, this._board.Thickness);
             this._SweepPath2 = path;
 
-            this._SweepCurves1 = this._SweepPath.Explode();
+            this._SweepCurves1 = this._SweepPath1.Explode();
             this._SweepCurves2 = this._SweepCurves1.map(c =>
             {
-                return c.GetOffsetCurves(-this._board.Thickness)[0];
+                let offsetC = c.GetOffsetCurves(-this._board.Thickness)[0];
+                if (!offsetC)
+                    offsetC = new Line(c.StartPoint, c.StartPoint);
+                return offsetC;
             });
         }
         else
@@ -131,10 +134,13 @@ export class ArcBoardBuild
             this._SweepPath1 = path;
             this._SweepPath2 = ArcBoardBuild.OffsetPolyline(this._SweepPath1, this._board.Thickness);
 
-            this._SweepCurves1 = path.Explode();
+            this._SweepCurves1 = this._SweepPath1.Explode();
             this._SweepCurves2 = this._SweepCurves1.map(c =>
             {
-                return c.GetOffsetCurves(this._board.Thickness)[0];
+                let offsetC = c.GetOffsetCurves(this._board.Thickness)[0];
+                if (!offsetC)
+                    offsetC = new Line(c.StartPoint, c.StartPoint);
+                return offsetC;
             });
         }
 
@@ -283,7 +289,7 @@ export class ArcBoardBuild
             let co2 = this._SweepCurves2[i + 1];
 
             //避免多余槽
-            if (equalv2(co1.EndPoint, co2.StartPoint, 0.1)) continue;
+            if (co1.Length < 0.1 || co2.Length < 0.1 || equalv2(co1.EndPoint, co2.StartPoint, 0.1)) continue;
 
             let p = co1.IntersectWith(co2, IntersectOption.ExtendNone, 0.1);
             if (p.length === 1)