0025063: Visualization - 2D objects are not displayed at some camera positions

Minimum thresolds introduced to zfit operation and to camera SetDistance() method.

Test case for issue CR25063

src/Graphic3d/Graphic3d_Camera.cxx

@@ -36,6 +36,9 @@ namespace
 
   // atomic state counter
   static volatile Standard_Integer THE_STATE_COUNTER = 0;
+
+  // minimum camera distance
+  static const Standard_Real MIN_DISTANCE = Pow (0.1, ShortRealDigits() - 2);
 };
 
 // =======================================================================
@@ -165,7 +168,9 @@ void Graphic3d_Camera::SetDistance (const Standard_Real theDistance)
 {
   gp_Vec aCenter2Eye (Direction());
   aCenter2Eye.Reverse();
-  aCenter2Eye.Scale (theDistance);
+
+  // Camera should have non-zero distance.
+  aCenter2Eye.Scale (Max (theDistance, MIN_DISTANCE));
   SetEye (Center().Translated (aCenter2Eye));
 }
 

src/OpenGl/OpenGl_BVHTreeSelector.cxx

@@ -163,6 +163,10 @@ Standard_ShortReal OpenGl_BVHTreeSelector::SignedPlanePointDistance (const OpenG
   const Standard_ShortReal aNormLength = std::sqrt (theNormal.x() * theNormal.x()
                                                   + theNormal.y() * theNormal.y()
                                                   + theNormal.z() * theNormal.z());
+
+  if (aNormLength < FLT_EPSILON)
+    return 0.0f;
+
   const Standard_ShortReal anInvNormLength = 1.0f / aNormLength;
   const Standard_ShortReal aD  = theNormal.w() * anInvNormLength;
   const Standard_ShortReal anA = theNormal.x() * anInvNormLength;

src/V3d/V3d_View.cxx

@@ -1665,13 +1665,13 @@ void V3d_View::ZFitAll (const Standard_Real theScaleFactor)
   // ShortReal precision factor used to add meaningful tolerance to
   // ZNear, ZFar values in order to avoid equality after type conversion
   // to ShortReal matrices type.
-  const Standard_Real aPrecision = 1.0 / Pow (10.0, ShortRealDigits() - 1);
+  const Standard_Real aPrecision = Pow (0.1, ShortRealDigits() - 2);
 
   // Compute enlarged or shrank near and far z ranges
   Standard_Real aZNear = aMidDepth - aHalfDepth * theScaleFactor;
   Standard_Real aZFar  = aMidDepth + aHalfDepth * theScaleFactor;
-  aZNear              -= Abs (aZNear) * aPrecision;
-  aZFar               += Abs (aZFar)  * aPrecision;
+  aZNear              -= aPrecision * 0.5;
+  aZFar               += aPrecision * 0.5;
 
   if (!myCamera->IsOrthographic())
   {
@@ -3329,7 +3329,7 @@ Standard_Boolean V3d_View::FitMinMax (const Handle(Graphic3d_Camera)& theCamera,
   gp_Trsf aCenterTrsf;
   aCenterTrsf.SetTranslation (theCamera->Center(), aNewCenter);
   theCamera->Transform (aCenterTrsf);
-  theCamera->SetDistance (Max (aMatchDistance[5] + aMatchDistance[4], Precision::Confusion()));
+  theCamera->SetDistance (aMatchDistance[5] + aMatchDistance[4]);
 
   // Bounding box collapses to a point or thin line going in depth of the screen
   if (aViewSizeXv < theResolution && aViewSizeYv < theResolution)

tests/bugs/vis/bug25063

@@ -0,0 +1,14 @@
+puts "==========="
+puts "OCC25063"
+puts "==========="
+puts ""
+##########################################################################
+# Visualization - 2D objects are not displayed at some camera positions
+##########################################################################
+
+vinit
+vtop
+vline 1 -90 -90 130 90 90 130
+vfit
+
+set only_screen 1