From 3551d209732b6f7bc098181a12653775f059abe4 Mon Sep 17 00:00:00 2001
From: ifv <ifv@opencascade.com>
Date: Tue, 21 Feb 2017 17:38:52 +0300
Subject: [PATCH] 0028458: Some faces are missing when loading a specific CAD.
 This is a regression from OCCT 7.0 and Express Mesh 7.0.

Function ACos and ASin are modified to avoid exception when argument is +-(1. + Epsilon(1.)) because of "numerical noise"

Conflicts:
	src/Standard/Standard_Real.cxx
---
 src/Standard/Standard_Real.cxx | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/Standard/Standard_Real.cxx b/src/Standard/Standard_Real.cxx
index b587af4f82..7c03f07d0a 100644
--- a/src/Standard/Standard_Real.cxx
+++ b/src/Standard/Standard_Real.cxx
@@ -20,6 +20,8 @@
 #include <Standard_Stream.hxx>
 #include <Standard_OStream.hxx>
 
+static const Standard_Real ACosLimit = 1. + Epsilon(1.);
+
 // ------------------------------------------------------------------
 // Hascode : Computes a hascoding value for a given real
 // ------------------------------------------------------------------
@@ -44,9 +46,17 @@ Standard_Integer HashCode(const Standard_Real me, const Standard_Integer Upper)
 //-------------------------------------------------------------------
 Standard_Real ACos (const Standard_Real Value) 
 { 
-  if ( (Value < -1.) || (Value > 1.) ){
+  if ((Value < -ACosLimit) || (Value > ACosLimit)){
     Standard_RangeError::Raise();
   } 
+  else if (Value > 1.)
+  {
+    return 0.; //acos(1.)
+  }
+  else if (Value < -1.)
+  {
+    return M_PI; //acos(-1.)
+  }
   return acos(Value); 
 }
 
@@ -94,9 +104,17 @@ Standard_Real ACosApprox (const Standard_Real Value)
 //-------------------------------------------------------------------
 Standard_Real ASin (const Standard_Real Value) 
 { 
-  if ( Value < -1 || Value > 1 ){
+  if ((Value < -ACosLimit) || (Value > ACosLimit)){
     Standard_RangeError::Raise();
   }
+  else if (Value > 1.)
+  {
+    return M_PI_2; //asin(1.)
+  }
+  else if (Value < -1.)
+  {
+    return -M_PI_2; //asin(-1.)
+  }
   return asin(Value); 
 }
 
-- 
2.39.5