From: aml <aml@opencascade.com>
Date: Thu, 5 May 2016 10:55:20 +0000 (+0300)
Subject: 0027467: Modeling Algorithms - class Extrema_ExtCC2d does not find extremum between... 
X-Git-Tag: V7_0_winwerth~60
X-Git-Url: http://git.dev.opencascade.org/gitweb/?p=occt.git;a=commitdiff_plain;h=15a954deb57ec441aab4a941464cb75d95983677

0027467: Modeling Algorithms - class Extrema_ExtCC2d does not find extremum between two intersecting lines

Line / line analytic treatment is added for 2d case.
Test case is added.
---

diff --git a/src/Extrema/Extrema_ExtElC2d.cxx b/src/Extrema/Extrema_ExtElC2d.cxx
index ae22e42f67..1c237e8c7f 100644
--- a/src/Extrema/Extrema_ExtElC2d.cxx
+++ b/src/Extrema/Extrema_ExtElC2d.cxx
@@ -36,9 +36,13 @@
 Extrema_ExtElC2d::Extrema_ExtElC2d () { myDone = Standard_False; }
 //=============================================================================
 
-Extrema_ExtElC2d::Extrema_ExtElC2d (const gp_Lin2d& C1, 
-				    const gp_Lin2d& C2,
-				    const Standard_Real)
+//=======================================================================
+//function : Extrema_ExtElC2d
+//purpose  :
+//=======================================================================
+Extrema_ExtElC2d::Extrema_ExtElC2d (const gp_Lin2d& C1,
+                                    const gp_Lin2d& C2,
+                                    const Standard_Real)
 /*-----------------------------------------------------------------------------
 Function:
    Find min distance between 2 straight lines.
@@ -57,15 +61,37 @@ Method:
   myIsPar = Standard_False;
   myNbExt = 0;
 
-  gp_Dir2d D1 = C1.Direction();
-  gp_Dir2d D2 = C2.Direction();
-  if (D1.IsParallel(D2, Precision::Angular())) {
+  gp_Vec2d D1(C1.Direction());
+  gp_Vec2d D2(C2.Direction());
+  if (D1.IsParallel(D2, Precision::Angular()))
+  {
     myIsPar = Standard_True;
     mySqDist[0] = C2.SquareDistance(C1.Location());
   }
-  else {
-    myNbExt = 0;
+  else
+  {
+    // Vector from P1 to P2 (P2 - P1).
+    gp_Vec2d aP1P2(C1.Location(), C2.Location());
+
+    // Solve linear system using Cramer's rule:
+    // D1.X * t1 + D2.X * (-t2)  = P2.X - P1.X
+    // D1.Y * t1 + D2.Y * (-t2)  = P2.Y - P1.Y
+
+    // There is no division by zero since lines are not parallel.
+    Standard_Real aDelim = 1 / (D1^D2);
+
+    Standard_Real aParam1 = (aP1P2 ^ D2) * aDelim;
+    Standard_Real aParam2 = -(D1 ^ aP1P2) * aDelim; // -1.0 coefficient before t2.
+
+    gp_Pnt2d P1 = ElCLib::Value(aParam1, C1);
+    gp_Pnt2d P2 = ElCLib::Value(aParam2, C2);
+
+    mySqDist[myNbExt] = 0.0;
+    myPoint[myNbExt][0] = Extrema_POnCurv2d(aParam1,P1);
+    myPoint[myNbExt][1] = Extrema_POnCurv2d(aParam2,P2);
+    myNbExt = 1;
   }
+
   myDone = Standard_True;
 }
 //=============================================================================
diff --git a/tests/bugs/moddata_3/bug27467 b/tests/bugs/moddata_3/bug27467
new file mode 100644
index 0000000000..b6ccf7c908
--- /dev/null
+++ b/tests/bugs/moddata_3/bug27467
@@ -0,0 +1,28 @@
+puts "============"
+puts "OCC27467"
+puts "============"
+puts ""
+#########################################################################
+# Modeling Algorithms - class Extrema_ExtCC2d does not find extremum between two intersecting lines
+# Analytical solver can not work on 2 lines.
+#########################################################################
+
+line l1 0 0 0 -1
+trim l1 l1 0 23
+
+line l2 1 -9.5 -1 -0
+trim l2 l2 0 2
+set info [2dextrema l1 l2]
+
+# Number of solutions check. 
+# There should be only one solution - intersection point.
+if {[llength $info] != 4} {
+  ERROR: Incorrect number of solutions.
+}
+
+# Check distance.
+regexp "dist 1: +(\[-0-9.+eE\]+)" $info full aDist
+set absTol 1.0e-9
+set relTol 0.001
+set aDist_Exp 0.0
+checkreal "Distance value check" $aDist $aDist_Exp $absTol $relTol