0025071: Visualization - Inconsistent deflection values used by AIS_Shape

Fix misprint

Small correction for issue CR25071

src/AIS/AIS_Shape.cdl

@@ -291,10 +291,6 @@ uses
             aPresentation        : Presentation from Prs3d;
     	    ashape               : Shape from TopoDS) is static private;
 		
-    GetDeflection(myclass; aShape  : Shape from TopoDS;
-    	    	    	   aDrawer : Drawer from Prs3d)
-    	    	    	   returns Real from Standard;
-		
     DisplayBox(myclass; aPrs : Presentation from Prs3d;
 		       	aBox : Box from Bnd;
 		       	aDrawer : Drawer from Prs3d) is protected;

src/AIS/AIS_Shape.cxx

@@ -43,6 +43,7 @@
 #include <Graphic3d_MaterialAspect.hxx>
 #include <Graphic3d_SequenceOfGroup.hxx>
 
+#include <Prs3d.hxx>
 #include <Prs3d_Presentation.hxx>
 #include <Prs3d_Root.hxx>
 #include <Prs3d_ShadingAspect.hxx>
@@ -76,25 +77,6 @@
 
 static Standard_Boolean myFirstCompute;
 
-Standard_Real AIS_Shape::GetDeflection(const TopoDS_Shape& aShape,
-                                       const Handle(Prs3d_Drawer)& aDrawer)
-{
-  // WARNING: this same piece of code appears several times in Prs3d classes
-  Standard_Real aDeflection = aDrawer->MaximalChordialDeviation();
-  if (aDrawer->TypeOfDeflection() == Aspect_TOD_RELATIVE) {
-    Bnd_Box B;
-    BRepBndLib::Add(aShape, B, Standard_False);
-    if ( ! B.IsVoid() )
-    {
-      Standard_Real aXmin, aYmin, aZmin, aXmax, aYmax, aZmax;
-      B.Get(aXmin, aYmin, aZmin, aXmax, aYmax, aZmax);
-      aDeflection = Max( aXmax-aXmin, Max(aYmax-aYmin, aZmax-aZmin)) *
-                    aDrawer->DeviationCoefficient() * 4;
-    }
-  }
-  return aDeflection;
-}
-
 void AIS_Shape::DisplayBox(const Handle(Prs3d_Presentation)& aPrs,
                            const Bnd_Box& B,
                            const Handle(Prs3d_Drawer)& aDrawer)
@@ -435,7 +417,7 @@ void AIS_Shape::ComputeSelection(const Handle(SelectMgr_Selection)& aSelection,
 
 // POP protection against crash in low layers
 
-  Standard_Real aDeflection = GetDeflection(shape, myDrawer);
+  Standard_Real aDeflection = Prs3d::GetDeflection(shape, myDrawer);
   Standard_Boolean autoTriangulation = Standard_True;
   try {  
     OCC_CATCH_SIGNALS

src/Prs3d/Prs3d.cdl

@@ -16,19 +16,19 @@
 
 package Prs3d
 
-    	---Purpose: The Prs3d package provides the following services
+      ---Purpose: The Prs3d package provides the following services
-	-- -   a presentation object (the context for all
+  -- -   a presentation object (the context for all
-	--   modifications to the display, its presentation will be
+  --   modifications to the display, its presentation will be
-	--   displayed in every view of an active viewer)
+  --   displayed in every view of an active viewer)
-	-- -   an attribute manager governing how objects such
+  -- -   an attribute manager governing how objects such
-	--   as color, width, and type of line are displayed;
+  --   as color, width, and type of line are displayed;
-	--   these are generic objects, whereas those in
+  --   these are generic objects, whereas those in
-	--   StdPrs are specific geometries and topologies.
+  --   StdPrs are specific geometries and topologies.
-	-- -   generic   algorithms providing default settings for
+  -- -   generic   algorithms providing default settings for
-	--   objects such as points, curves, surfaces and shapes
+  --   objects such as points, curves, surfaces and shapes
-	-- -   a root object which provides the abstract
+  -- -   a root object which provides the abstract
-	--   framework for the DsgPrs definitions at work in
+  --   framework for the DsgPrs definitions at work in
-	--   display of dimensions, relations and trihedra.
+  --   display of dimensions, relations and trihedra.
     
 uses
   Graphic3d,
@@ -94,18 +94,18 @@ is
 
   class Presentation;
 
-	---Category: Aspect classes.
+  ---Category: Aspect classes.
 
   deferred class BasicAspect;	
   class PointAspect;
   class LineAspect;
-	class ShadingAspect;
+  class ShadingAspect;
-	class TextAspect;
+  class TextAspect;
   class IsoAspect;
   class ArrowAspect;
-	class PlaneAspect;
+  class PlaneAspect;
   class DimensionAspect;
-	class DatumAspect;
+  class DatumAspect;
   imported DimensionUnits;
 
   class Drawer;
@@ -118,15 +118,15 @@ is
 
   ---Category: Basis construction elements.
 
-	class Text;
+  class Text;
 
         ---Category: Class signatures.
 
-	class ShapeTool;
+  class ShapeTool;
 
   class Arrow;
-	---Purpose: draws an arrow at a given location, with respect
+  ---Purpose: draws an arrow at a given location, with respect
-	--          to a given direction. 
+  --          to a given direction.
 
   imported NListOfSequenceOfPnt; 
   imported NListIteratorListOfSequenceOfPnt;
@@ -134,8 +134,22 @@ is
   imported WFShape;
   
   MatchSegment(X,Y,Z: Length from Quantity;
-	            aDistance: Length from Quantity;
+              aDistance: Length from Quantity;
-		          p1,p2: Pnt from gp;
+              p1,p2: Pnt from gp;
               dist: out Length from Quantity)
-	returns Boolean from Standard;
+  returns Boolean from Standard;
+
+  GetDeflection (theShape  : Shape from TopoDS;
+                 theDrawer : Drawer from Prs3d)
+  returns Real from Standard;
+  ---Purpose: Computes the absolute deflection value depending on
+  -- the type of deflection in theDrawer:
+  -- <ul>
+  -- <li><b>Aspect_TOD_RELATIVE</b>: the absolute deflection is computed using the relative
+  --   deviation coefficient from theDrawer and the shape's bounding box;</li>
+  -- <li><b>Aspect_TOD_ABSOLUTE</b>: the maximal chordial deviation from theDrawer is returned.</li>
+  -- </ul>
+  -- This function should always be used to compute the deflection value for building
+  -- discrete representations of the shape (triangualtion, wireframe) to avoid incosistencies
+  -- between different representations of the shape and undesirable visual artifacts.
 end Prs3d;

src/Prs3d/Prs3d.cxx

@@ -15,17 +15,25 @@
 // commercial license or contractual agreement.
 
 #include <Prs3d.ixx>
+#include <Bnd_Box.hxx>
+#include <BRepBndLib.hxx>
+#include <Prs3d_Drawer.hxx>
+#include <TopoDS_Shape.hxx>
 
+//=======================================================================
+//function : MatchSegment
+//purpose  :
+//=======================================================================
 Standard_Boolean Prs3d::MatchSegment 
                  (const Quantity_Length X,
-		  const Quantity_Length Y,
+                  const Quantity_Length Y,
-		  const Quantity_Length Z,
+                  const Quantity_Length Z,
-		  const Quantity_Length aDistance,
+                  const Quantity_Length aDistance,
-		  const gp_Pnt& P1,
+                  const gp_Pnt& P1,
-		  const gp_Pnt& P2,
+                  const gp_Pnt& P2,
-                  Quantity_Length& dist) {
+                  Quantity_Length& dist)
-
+{
-		   Standard_Real X1,Y1,Z1,X2,Y2,Z2;
+  Standard_Real X1,Y1,Z1,X2,Y2,Z2;
   P1.Coord(X1,Y1,Z1); P2.Coord(X2,Y2,Z2);
   Standard_Real DX = X2-X1; 
   Standard_Real DY = Y2-Y1; 
@@ -36,9 +44,32 @@ Standard_Boolean Prs3d::MatchSegment
   Standard_Real Lambda = ((X-X1)*DX + (Y-Y1)*DY + (Z-Z1)*DZ)/Dist;
   if ( Lambda < 0. || Lambda > 1. ) return Standard_False;
   dist =  Abs(X-X1-Lambda*DX) +
-	  Abs(Y-Y1-Lambda*DY) + 
+          Abs(Y-Y1-Lambda*DY) +
-	  Abs(Z-Z1-Lambda*DZ);
+          Abs(Z-Z1-Lambda*DZ);
   return (dist < aDistance);
-
 }
 
+//=======================================================================
+//function : GetDeflection
+//purpose  :
+//=======================================================================
+Standard_Real Prs3d::GetDeflection (const TopoDS_Shape&         theShape,
+                                    const Handle(Prs3d_Drawer)& theDrawer)
+{
+#define MAX2(X, Y)    (Abs(X) > Abs(Y) ? Abs(X) : Abs(Y))
+#define MAX3(X, Y, Z) (MAX2 (MAX2 (X, Y), Z))
+
+  Standard_Real aDeflection = theDrawer->MaximalChordialDeviation();
+  if (theDrawer->TypeOfDeflection() == Aspect_TOD_RELATIVE)
+  {
+    Bnd_Box aBndBox;
+    BRepBndLib::Add (theShape, aBndBox, Standard_False);
+    if (!aBndBox.IsVoid())
+    {
+      Standard_Real aXmin, aYmin, aZmin, aXmax, aYmax, aZmax;
+      aBndBox.Get (aXmin, aYmin, aZmin, aXmax, aYmax, aZmax);
+      aDeflection = MAX3 (aXmax-aXmin, aYmax-aYmin, aZmax-aZmin) * theDrawer->DeviationCoefficient() * 4.0;
+    }
+  }
+  return aDeflection;
+}

src/Prs3d/Prs3d_WFShape.cxx

@@ -28,6 +28,7 @@
 #include <Poly_Array1OfTriangle.hxx>
 #include <Poly_Polygon3D.hxx>
 #include <Poly_PolygonOnTriangulation.hxx>
+#include <Prs3d.hxx>
 #include <Prs3d_Drawer.hxx>
 #include <Prs3d_IsoAspect.hxx>
 #include <Prs3d_PointAspect.hxx>
@@ -154,20 +155,7 @@ void Prs3d_WFShape::Add (const Handle (Prs3d_Presentation)& thePresentation,
     }
   }
 
-  Standard_Real aDeflection = theDrawer->MaximalChordialDeviation();
+  Standard_Real aDeflection = Prs3d::GetDeflection(theShape, theDrawer);
-  if (theDrawer->TypeOfDeflection() == Aspect_TOD_RELATIVE)
-  {
-    // The arrow calculation is based on the global min max
-    Bnd_Box aBndBox;
-    BRepBndLib::Add (theShape, aBndBox);
-    if (!aBndBox.IsVoid())
-    {
-      Standard_Real aXmin, aYmin, aZmin, aXmax, aYmax, aZmax;
-      aBndBox.Get (aXmin, aYmin, aZmin, aXmax, aYmax, aZmax);
-      aDeflection = Max (aXmax-aXmin, Max (aYmax-aYmin, aZmax-aZmin))
-                       * theDrawer->DeviationCoefficient();
-    }
-  }
 
   Handle(Graphic3d_Group) aGroup = Prs3d_Root::CurrentGroup (thePresentation);
 

src/StdPrs/StdPrs_ShadedShape.cxx

@@ -31,6 +31,7 @@
 #include <gp_Pnt.hxx>
 #include <NCollection_List.hxx>
 #include <Precision.hxx>
+#include <Prs3d.hxx>
 #include <Prs3d_Drawer.hxx>
 #include <Prs3d_LineAspect.hxx>
 #include <Prs3d_Presentation.hxx>
@@ -96,28 +97,6 @@ namespace
     }
   }
 
-  //! Computes absolute deflection, required by drawer
-  static Standard_Real getDeflection (const TopoDS_Shape&         theShape,
-                                      const Handle(Prs3d_Drawer)& theDrawer)
-  {
-    #define MAX2(X, Y)    (Abs(X) > Abs(Y) ? Abs(X) : Abs(Y))
-    #define MAX3(X, Y, Z) (MAX2 (MAX2 (X, Y), Z))
-
-    Standard_Real aDeflection = theDrawer->MaximalChordialDeviation();
-    if (theDrawer->TypeOfDeflection() == Aspect_TOD_RELATIVE)
-    {
-      Bnd_Box aBndBox;
-      BRepBndLib::Add (theShape, aBndBox, Standard_False);
-      if (!aBndBox.IsVoid())
-      {
-        Standard_Real aXmin, aYmin, aZmin, aXmax, aYmax, aZmax;
-        aBndBox.Get (aXmin, aYmin, aZmin, aXmax, aYmax, aZmax);
-        aDeflection = MAX3 (aXmax-aXmin, aYmax-aYmin, aZmax-aZmin) * theDrawer->DeviationCoefficient() * 4.0;
-      }
-    }
-    return aDeflection;
-  }
-
   //! Gets triangulation of every face of shape and fills output array of triangles
   static Handle(Graphic3d_ArrayOfTriangles) fillTriangles (const TopoDS_Shape&    theShape,
                                                            const Standard_Boolean theHasTexels,
@@ -458,7 +437,7 @@ void StdPrs_ShadedShape::Tessellate (const TopoDS_Shape&          theShape,
                                      const Handle (Prs3d_Drawer)& theDrawer)
 {
   // Check if it is possible to avoid unnecessary recomputation of shape triangulation
-  Standard_Real aDeflection = getDeflection (theShape, theDrawer);
+  Standard_Real aDeflection = Prs3d::GetDeflection (theShape, theDrawer);
   if (BRepTools::Triangulation (theShape, aDeflection))
   {
     return;

tests/bugs/moddata_1/bug22039

@@ -17,7 +17,8 @@ vsetdispmode 1
 vdisplay result
 vfit
 
-set x1 101
+###set x1 101
+set x1 102
 set y1 199
 set Color [QAGetPixelColor ${x1} ${y1}]
 

tests/bugs/vis/bug25071

@@ -0,0 +1,31 @@
+puts "============"
+puts "CR25071"
+puts "============"
+puts ""
+#######################################################################
+# Check that the selected wireframe representation uses exactly the same
+# discretization of face boundaries as the face outlines shown in shading mode
+#######################################################################
+
+vinit View1
+
+# Computing wireframe without triangulation, then checking face boundaries and selection
+pcone c 0 5 10
+vdisplay c; vfit
+vsetdispmode c 1
+vshowfaceboundary c 1 64 64 0
+vselect 200 200
+
+vdump $imagedir/${casename}_wf_no_triang.png
+
+vremove c
+vclose View1
+vinit View1
+
+# Computing wireframe after triangulation, then checking face boundaries and selection
+vsetdispmode 1
+vdisplay c; vfit
+vshowfaceboundary c 1 64 64 0
+vselect 200 200
+
+vdump $imagedir/${casename}_wf_with_triang.png