Fem: Constraint symbol scaling based on shape size - fixes FreeCAD#7030

marioalexis84 · marioalexis84 · commit 863cb80fe2fc · 2024-04-22T00:10:06.000-03:00
diff --git a/src/Mod/Fem/App/FemConstraint.cpp b/src/Mod/Fem/App/FemConstraint.cpp
@@ -28,6 +28,7 @@
 #include <BRepAdaptor_CompCurve.hxx>
 #include <BRepAdaptor_Curve.hxx>
 #include <BRepAdaptor_Surface.hxx>
+#include <BRepBndLib.hxx>
 #include <BRepClass_FaceClassifier.hxx>
 #include <BRepGProp.hxx>
 #include <BRepGProp_Face.hxx>
@@ -131,22 +132,14 @@ App::DocumentObjectExecReturn* Constraint::execute()
     }
 }
 
-// OvG: Provide the ability to determine how big to draw constraint arrows etc.
-unsigned int Constraint::calcSizeFactor(double lparam) const
+// Provide the ability to determine how big to draw constraint arrows etc.
+// Try to get symbol size equal to 1/5 of the characteristic length of
+// the object. Typical symbol size is 5, so use 1/25 of the characteristic length.
+double Constraint::calcSizeFactor(double characLen) const
 {
-    return (static_cast<int>(round(log(lparam) * log(lparam) * log(lparam) / 10)) > 1)
-        ? (static_cast<int>(round(log(lparam) * log(lparam) * log(lparam) / 10)))
-        : 1;
-}
-
-unsigned int Constraint::calcSizeFactor(double lvparam, double luparam) const
-{
-    return calcSizeFactor((lvparam + luparam) / 2.0);
-}
-
-unsigned int Constraint::calcSizeFactor() const
-{
-    return 1;
+    double l = characLen / 25.0;
+    l = ((round(l)) > 1) ? round(l) : l;
+    return (l > Precision::Confusion() ? l : 1);
 }
 
 float Constraint::getScaleFactor() const
@@ -272,7 +265,7 @@ void Constraint::handleChangedPropertyType(Base::XMLReader& reader,
 
 bool Constraint::getPoints(std::vector<Base::Vector3d>& points,
                            std::vector<Base::Vector3d>& normals,
-                           int* scale) const
+                           double* scale) const
 {
     std::vector<App::DocumentObject*> Objects = References.getValues();
     std::vector<std::string> SubElements = References.getSubValues();
@@ -294,42 +287,35 @@ bool Constraint::getPoints(std::vector<Base::Vector3d>& points,
         }
 
         setSubShapeLocation(feat, sh);
+        // Scale by bounding box of the object
+        Bnd_Box box;
+        BRepBndLib::Add(toposhape.getShape(), box);
+        double l = sqrt(box.SquareExtent() / 3.0);
+        *scale = this->calcSizeFactor(l);
 
         if (sh.ShapeType() == TopAbs_VERTEX) {
             const TopoDS_Vertex& vertex = TopoDS::Vertex(sh);
             gp_Pnt p = BRep_Tool::Pnt(vertex);
             points.emplace_back(p.X(), p.Y(), p.Z());
             normals.push_back(NormalDirection.getValue());
-            // OvG: Scale by whole object mass in case of a vertex
-            GProp_GProps props;
-            BRepGProp::VolumeProperties(toposhape.getShape(), props);
-            double lx = props.Mass();
-            // OvG: setup draw scale for constraint
-            *scale = this->calcSizeFactor(sqrt(lx) * 0.5);
         }
         else if (sh.ShapeType() == TopAbs_EDGE) {
             BRepAdaptor_Curve curve(TopoDS::Edge(sh));
             double fp = curve.FirstParameter();
             double lp = curve.LastParameter();
-            GProp_GProps props;
-            BRepGProp::LinearProperties(TopoDS::Edge(sh), props);
-            double l = props.Mass();
             // Create points with 10 units distance, but at least one at the beginning and end of
             // the edge
             int steps;
             // OvG: Increase 10 units distance proportionately to l for larger objects.
             if (l >= 30) {
-                *scale = this->calcSizeFactor(l);  // OvG: setup draw scale for constraint
                 steps = static_cast<int>(round(l / (10 * (*scale))));
                 steps = steps < 3 ? 3 : steps;
             }
             else if (l >= 20) {
                 steps = static_cast<int>(round(l / 10));
-                *scale = this->calcSizeFactor();  // OvG: setup draw scale for constraint
             }
             else {
                 steps = 1;
-                *scale = this->calcSizeFactor();  // OvG: setup draw scale for constraint
             }
 
             // OvG: Place upper limit on number of steps
@@ -407,37 +393,31 @@ bool Constraint::getPoints(std::vector<Base::Vector3d>& points,
             // OvG: Increase 10 units distance proportionately to lv for larger objects.
             int stepsv;
             if (lv >= 30) {
-                *scale = this->calcSizeFactor(lv, lu);  // OvG: setup draw scale for constraint
                 stepsv = static_cast<int>(round(lv / (10 * (*scale))));
                 stepsv = stepsv < 3 ? 3 : stepsv;
             }
             else if (lv >= 20.0) {
                 stepsv = static_cast<int>(round(lv / 10));
-                *scale = this->calcSizeFactor();  // OvG: setup draw scale for constraint
             }
             else {
                 // Minimum of three arrows to ensure (as much as possible) that at
                 // least one is displayed
                 stepsv = 2;
-                *scale = this->calcSizeFactor();  // OvG: setup draw scale for constraint
             }
 
             // OvG: Place upper limit on number of steps
             stepsv = stepsv > CONSTRAINTSTEPLIMIT ? CONSTRAINTSTEPLIMIT : stepsv;
             int stepsu;
             // OvG: Increase 10 units distance proportionately to lu for larger objects.
             if (lu >= 30) {
-                *scale = this->calcSizeFactor(lv, lu);  // OvG: setup draw scale for constraint
                 stepsu = static_cast<int>(round(lu / (10 * (*scale))));
                 stepsu = stepsu < 3 ? 3 : stepsu;
             }
             else if (lu >= 20.0) {
                 stepsu = static_cast<int>(round(lu / 10));
-                *scale = this->calcSizeFactor();  // OvG: setup draw scale for constraint
             }
             else {
                 stepsu = 2;
-                *scale = this->calcSizeFactor();  // OvG: setup draw scale for constraint
             }
 
             // OvG: Place upper limit on number of steps
diff --git a/src/Mod/Fem/App/FemConstraint.h b/src/Mod/Fem/App/FemConstraint.h
@@ -123,43 +123,12 @@ class FemExport Constraint: public App::DocumentObject, public App::Suppressible
     App::DocumentObjectExecReturn* execute() override;
 
     /**
-     * @brief Calculates scale factor based on length of edge.
+     * @brief Calculates scale factor based on characteristic length of shape.
      *
      * @details
      *  Used to calculate the scale factor returned by @ref getPoints when the
-     *  scale factor is calculated for a face.
-     *
-     * @note
-     *  This method does a really crazy calculation that I didn't dare to try
-     *  to understand.
-     */
-    unsigned int calcSizeFactor(double lparam) const;
-
-    /**
-     * @brief Calculates scale factor based on size of face.
-     *
-     * @details
-     *  Used to calculate the scale factor returned by @ref getPoints when the
-     *  scale factor is calculated for a edge.
-     *
-     * @note
-     *  This method does a really crazy calculation that I didn't dare to try
-     *  to understand.
-     */
-    unsigned int calcSizeFactor(double lvparam, double luparam) const;
-
-    /**
-     * @brief Returns default scale factor of 1.
-     *
-     * @details
-     *  This is just used to make code more understandable. Other versions
-     *  (overloads) of this function do useful calculations based on faces or
-     *  edges. Used by @ref getPoints if no useful shape information is
-     *  available.
-     *
-     * @return always the integer 1
      */
-    unsigned int calcSizeFactor() const;
+    double calcSizeFactor(double characLen) const;
 
     const char* getViewProviderName() const override
     {
@@ -227,7 +196,7 @@ class FemExport Constraint: public App::DocumentObject, public App::Suppressible
      */
     bool getPoints(std::vector<Base::Vector3d>& points,
                    std::vector<Base::Vector3d>& normals,
-                   int* scale) const;
+                   double* scale) const;
 
     /**
      * @brief Extract properties of cylindrical face.
@@ -263,7 +232,7 @@ class FemExport Constraint: public App::DocumentObject, public App::Suppressible
     /**
      * @brief Symbol size factor determined from the size of the shape.
      */
-    int sizeFactor;
+    double sizeFactor;
 
     void slotChangedObject(const App::DocumentObject& Obj, const App::Property& Prop);
     boost::signals2::connection connDocChangedObject;
diff --git a/src/Mod/Fem/App/FemConstraintTransform.cpp b/src/Mod/Fem/App/FemConstraintTransform.cpp
@@ -110,7 +110,7 @@ void ConstraintTransform::onChanged(const App::Property* prop)
     if (prop == &References) {
         std::vector<Base::Vector3d> points;
         std::vector<Base::Vector3d> normals;
-        int scale = 1;  // OvG: Enforce use of scale
+        double scale = 1;  // OvG: Enforce use of scale
         if (getPoints(points, normals, &scale)) {
             std::string transform_type = TransformType.getValueAsString();
             if (transform_type == "Cylindrical") {
