From: akaftasev <akaftasev@opencascade.com>
Date: Wed, 2 Aug 2023 09:35:30 +0000 (+0100)
Subject: 0033418: Modeling Algorithms - BRepExtrema_DistShapeShape wrong arc ellipse - point... 
X-Git-Url: http://git.dev.opencascade.org/gitweb/?a=commitdiff_plain;h=refs%2Fheads%2FCR33418;p=occt.git

0033418: Modeling Algorithms - BRepExtrema_DistShapeShape wrong arc ellipse - point result

Wrong calculation of distance arises for ellipse with MajorRadius == MinorRadius when first or last parameter of trimmed ellipse more then 2*pi
This case should be calculated as circle
---

diff --git a/src/Extrema/Extrema_ExtPElC.cxx b/src/Extrema/Extrema_ExtPElC.cxx
index 53514f594b..ffa738deb4 100644
--- a/src/Extrema/Extrema_ExtPElC.cxx
+++ b/src/Extrema/Extrema_ExtPElC.cxx
@@ -217,6 +217,10 @@ Method:
      Then, (1) <=> (A*Cos-X,B*Sin-Y).(-A*Sin,B*Cos) = 0.
                     (B**2-A**2)*Cos*Sin - B*Y*Cos + A*X*Sin = 0.
      Use algorithm math_TrigonometricFunctionRoots to solve this equation.
+
+  Addition:
+    In case, when MajorRadius == MinorRadius calcualtion errors may occur
+    This case should be processed as Circle
 -----------------------------------------------------------------------------*/
 {
   myDone = Standard_False;
@@ -229,6 +233,12 @@ Method:
   gp_Vec Trsl = Axe.Multiplied(-(gp_Vec(O,P).Dot(Axe)));
   gp_Pnt Pp = P.Translated(Trsl);
 
+  if (Abs(C.MajorRadius() - C.MinorRadius() < Precision::Confusion()))
+  {
+    Perform(P, gp_Circ(gp_Ax2(O, C.Axis().Direction()), C.MajorRadius()), Tol, Uinf, Usup);
+    return;
+  }
+
 // 2- Calculation of solutions ...
 
   Standard_Integer NoSol, NbSol;
diff --git a/tests/bugs/modalg_8/bug33418 b/tests/bugs/modalg_8/bug33418
new file mode 100644
index 0000000000..d0ca280686
--- /dev/null
+++ b/tests/bugs/modalg_8/bug33418
@@ -0,0 +1,13 @@
+puts "================================================================="
+puts "0033418: Modeling Algorithms - BRepExtrema_DistShapeShape wrong arc ellipse - point result"
+puts "================================================================="
+puts ""
+
+ellipse el 0 0 0 0 1 0 1 1
+trim el el 4.71238898038 1.57079632679
+mkedge el el
+vertex v 0 0 1.5
+distmini d el v
+if {[dval d_val] > 0.5000001} {
+  puts "ERROR: Wrong distance calculation"
+}