From ce48b00930ae801233d44228e5e1f5a193a5de82 Mon Sep 17 00:00:00 2001
From: nbv <nbv@opencascade.com>
Date: Wed, 18 Nov 2015 11:01:12 +0300
Subject: [PATCH] 0026884: Cylinder/Cylinder intersection algorithm throws an
 exception

Check, if cylinder axes are parallel is made more carefully.
This check is brought to conformity with check if axes are parallel (see constructor AxeOperator::AxeOperator(...) in IntAna_QuadQuadGeo.cxx file)

Test case for issue CR26884
---
 src/IntAna/IntAna_QuadQuadGeo.cxx             | 16 ++++-----
 .../IntPatch_ImpImpIntersection_4.gxx         |  8 ++++-
 tests/bugs/moddata_3/bug26884                 | 34 +++++++++++++++++++
 3 files changed, 49 insertions(+), 9 deletions(-)
 create mode 100644 tests/bugs/moddata_3/bug26884

diff --git a/src/IntAna/IntAna_QuadQuadGeo.cxx b/src/IntAna/IntAna_QuadQuadGeo.cxx
index eeeb586583..cd391957a9 100644
--- a/src/IntAna/IntAna_QuadQuadGeo.cxx
+++ b/src/IntAna/IntAna_QuadQuadGeo.cxx
@@ -125,8 +125,8 @@ class AxeOperator {
 //=======================================================================
 AxeOperator::AxeOperator(const gp_Ax1& A1,const gp_Ax1& A2) 
 {
-  myEPSILON_DISTANCE=0.00000000000001;
-  myEPSILON_AXES_PARA=0.000000000001;
+  myEPSILON_DISTANCE=1.0e-14;
+  myEPSILON_AXES_PARA=Precision::Angular();
   Axe1=A1; 
   Axe2=A2;
   //---------------------------------------------------------------------
@@ -275,12 +275,12 @@ IntAna_QuadQuadGeo::IntAna_QuadQuadGeo(void)
 //=======================================================================
 void IntAna_QuadQuadGeo::InitTolerances()
 {
-  myEPSILON_DISTANCE               = 0.00000000000001;
-  myEPSILON_ANGLE_CONE             = 0.000000000001;
-  myEPSILON_MINI_CIRCLE_RADIUS     = 0.000000001;
-  myEPSILON_CYLINDER_DELTA_RADIUS  = 0.0000000000001;
-  myEPSILON_CYLINDER_DELTA_DISTANCE= 0.0000001;
-  myEPSILON_AXES_PARA              = 0.000000000001;
+  myEPSILON_DISTANCE               = 1.0e-14;
+  myEPSILON_ANGLE_CONE             = Precision::Angular();
+  myEPSILON_MINI_CIRCLE_RADIUS     = 0.01*Precision::Confusion();
+  myEPSILON_CYLINDER_DELTA_RADIUS  = 1.0e-13;
+  myEPSILON_CYLINDER_DELTA_DISTANCE= Precision::Confusion();
+  myEPSILON_AXES_PARA              = Precision::Angular();
 }
 //=======================================================================
 //function : IntAna_QuadQuadGeo
diff --git a/src/IntPatch/IntPatch_ImpImpIntersection_4.gxx b/src/IntPatch/IntPatch_ImpImpIntersection_4.gxx
index 6b05437b7a..8673a17984 100644
--- a/src/IntPatch/IntPatch_ImpImpIntersection_4.gxx
+++ b/src/IntPatch/IntPatch_ImpImpIntersection_4.gxx
@@ -1022,7 +1022,13 @@ stCoeffsValue::stCoeffsValue( const gp_Cylinder& theCyl1,
     }
   }
 
-  if(Abs(aDetV1V2) < aNulValue)
+  // In point of fact, every determinant (aDelta1, aDelta2 and aDelta3) is
+  // cross-product between directions (i.e. sine of angle).
+  // If sine is too small then sine is (approx.) equal to angle itself.
+  // Therefore, in this case we should compare sine with angular tolerance. 
+  // This constant is used for check if axes are parallel (see constructor
+  // AxeOperator::AxeOperator(...) in IntAna_QuadQuadGeo.cxx file).
+  if(Abs(aDetV1V2) < Precision::Angular())
   {
     Standard_Failure::Raise("Error. Exception in divide by zerro (IntCyCyTrim)!!!!");
   }
diff --git a/tests/bugs/moddata_3/bug26884 b/tests/bugs/moddata_3/bug26884
new file mode 100644
index 0000000000..6bb33bb3d9
--- /dev/null
+++ b/tests/bugs/moddata_3/bug26884
@@ -0,0 +1,34 @@
+puts "================"
+puts "OCC26884"
+puts "================"
+puts ""
+##############################################################
+# Cylinder/Cylinder intersection algorithm throws an exception
+##############################################################
+
+set max_time 0.1
+
+restore [locate_data_file bug26884-f1.brep] f1
+restore [locate_data_file bug26884-f2.brep] f2
+
+dchrono cr reset
+dchrono cr start
+
+set info [bopcurves f1 f2 -2d]
+
+dchrono cr stop
+
+if {![regexp {has no 3d curves} $info] ||
+    ![regexp {has no 3d points} $info] } {
+  puts "Error: wrong output"
+}
+
+set logTime [dchrono cr show]
+
+regexp {CPU user time: ([-0-9.+eE]+) seconds} $logTime full z
+
+if { $z > ${max_time} } {
+    puts "Elapsed time ($z) is more than ${max_time} seconds - Error"
+} else {
+    puts "Elapsed time ($z) is less than ${max_time} seconds - OK"
+}
-- 
2.39.5