From ae541252472a54e78a57aba76be65384c8e23076 Mon Sep 17 00:00:00 2001
From: nbv <nbv@opencascade.com>
Date: Fri, 12 Aug 2016 22:08:50 +0300
Subject: [PATCH] 0027766: Incorrect section curves between attached cylinders

2d-tolerance has been bounded above (earlier it was too big for precise computation).

Creation of the test case for this issue.
Adjusting some test cases according to their new behavior.

Adjusting test case according to its new behavior.
---
 .../IntPatch_ImpImpIntersection_2.gxx         |  7 +++--
 tests/bugs/modalg_6/bug27310_2                |  2 +-
 tests/bugs/modalg_6/bug27761                  | 17 ++++++++---
 tests/bugs/modalg_6/bug27766                  | 30 +++++++++++++++++++
 4 files changed, 49 insertions(+), 7 deletions(-)
 create mode 100644 tests/bugs/modalg_6/bug27766

diff --git a/src/IntPatch/IntPatch_ImpImpIntersection_2.gxx b/src/IntPatch/IntPatch_ImpImpIntersection_2.gxx
index f94f8096d2..b1d3dfcbfd 100644
--- a/src/IntPatch/IntPatch_ImpImpIntersection_2.gxx
+++ b/src/IntPatch/IntPatch_ImpImpIntersection_2.gxx
@@ -177,8 +177,11 @@ void IntPatch_ImpImpIntersection::Perform(const Handle(Adaptor3d_HSurface)&  S1,
           aBox2.Add(gp_Pnt2d(aU2f, S2->FirstVParameter()));
           aBox2.Add(gp_Pnt2d(aU2l, S2->LastVParameter()));
 
-          const Standard_Real a2DTol = Min( S1->UResolution(TolTang),
-                                              S2->UResolution(TolTang));
+          // Resolution is too big if the cylinder radius is
+          // too small. Therefore, we shall bounde its value above. 
+          // Here, we use simple constant.
+          const Standard_Real a2DTol = Min(1.0e-4, Min( S1->UResolution(TolTang),
+                                              S2->UResolution(TolTang)));
 
           Standard_Boolean isReversed = ((aU2l - aU2f) < (aU1l - aU1f));
 
diff --git a/tests/bugs/modalg_6/bug27310_2 b/tests/bugs/modalg_6/bug27310_2
index 30e5754f8d..fe5faee133 100644
--- a/tests/bugs/modalg_6/bug27310_2
+++ b/tests/bugs/modalg_6/bug27310_2
@@ -6,7 +6,7 @@ puts ""
 # Huge tolerance obtained in the result of intersection of two cylindrical faces
 #################################################
 
-set ExpTol 7.7015195151142059e-006
+set ExpTol 0.00027580830315682321
 set GoodNbCurv 2
 
 restore [locate_data_file OCC496a.brep] a 
diff --git a/tests/bugs/modalg_6/bug27761 b/tests/bugs/modalg_6/bug27761
index 68222063ea..4b5c54f866 100644
--- a/tests/bugs/modalg_6/bug27761
+++ b/tests/bugs/modalg_6/bug27761
@@ -1,6 +1,3 @@
-puts "TODO OCC27766 ALL: Error : The command is not valid. The length is 0."
-puts "TODO OCC27766 ALL: Error : The length of result shape is"
-
 puts "========"
 puts "OCC27761"
 puts "========"
@@ -16,4 +13,16 @@ bsection result c1 c2
 
 checkshape result
 # approximate theoretical length of the result
-checkprops result -l 0.00201518
\ No newline at end of file
+checkprops result -l 0.00192624
+
+regexp {nb alone Vertices : ([-0-9.+eE]+)} [checksection result] full nbv
+if { $nbv != 0 } { puts "Error : Section is incorrect" }
+
+smallview
+don result
+fit
+clear
+disp c1 c2
+disp result
+
+checkview -screenshot -2d -path ${imagedir}/${test_image}.png
diff --git a/tests/bugs/modalg_6/bug27766 b/tests/bugs/modalg_6/bug27766
new file mode 100644
index 0000000000..d992b88ed2
--- /dev/null
+++ b/tests/bugs/modalg_6/bug27766
@@ -0,0 +1,30 @@
+puts "========"
+puts "OCC27766"
+puts "========"
+puts ""
+#################################################
+# Incorrect section curves between attached cylinders
+#################################################
+
+set ExpTol 1.0e-7
+set GoodNbCurv 5
+
+restore [locate_data_file bug27761_c1.brep] c1
+restore [locate_data_file bug27761_c2.brep] c2
+
+set log [bopcurves c1 c2 -2d]
+
+regexp {Tolerance Reached=+([-0-9.+eE]+)\n+([-0-9.+eE]+)} ${log} full Toler NbCurv
+
+if {${NbCurv} != ${GoodNbCurv}} {
+  puts "Error: Number of curves is bad!"
+}
+
+checkreal TolReached $Toler $ExpTol 0.0 0.1
+
+smallview
+don c_*
+fit
+disp c1 c2
+
+checkview -screenshot -2d -path ${imagedir}/${test_image}.png