WKT footprint massaging

src/serializers/TtlWktSerializer.cpp

@@ -31,6 +31,10 @@
 #include <TopoDS.hxx>
 #include <Bnd_Box.hxx>
 #include <gp_Pln.hxx>
+#include <TopoDS_Wire.hxx>
+#include <BRepBuilderAPI_MakeFace.hxx>
+#include <GProp_GProps.hxx>
+#include <BRepGProp.hxx>
 
 #endif
 
@@ -396,7 +400,14 @@ void TtlWktSerializer::write(const IfcGeom::BRepElement* brep_obj) {
 
     filename_.stream << ttl_object_id(brep_obj) << " geo:hasMetricLength " << height << " .\n\n";
 
-    gp_Pln pln(gp_Pnt(0, 0, zmin + section_height), gp::DZ());
+    std::map<double, std::string> polygons_by_area;
+
+    double rectangle_area = (x2 - x1) * (y2 - y1);
+    bool emitted_warning = false;
+
+    for (int iter = 0; iter < 10; ++iter) {
+
+        gp_Pln pln(gp_Pnt(0, 0, zmin + section_height + iter * (height - 1.) / 10.), gp::DZ());
 
         Handle(TopTools_HSequenceOfShape) wires = new TopTools_HSequenceOfShape();
 
@@ -417,6 +428,21 @@ void TtlWktSerializer::write(const IfcGeom::BRepElement* brep_obj) {
             ShapeAnalysis_FreeBounds::ConnectEdgesToWires(edges, 1e-4, false, wires);
             for (int i = 1; i <= wires->Length(); ++i) {
                 const TopoDS_Wire& wire = TopoDS::Wire(wires->Value(i));
+                if (!wire.Closed()) {
+                    continue;
+                }
+
+                BRepBuilderAPI_MakeFace mf(wire);
+                if (!mf.IsDone()) {
+                    continue;
+                }
+
+                auto face = mf.Face();
+                // calculate face area
+                GProp_GProps props;
+                BRepGProp::SurfaceProperties(face, props);
+                auto area = props.Mass();
+
                 BRepTools_WireExplorer it(wire);
                 std::vector<double> loop_coords;
                 for (; it.More(); it.Next()) {
@@ -433,19 +459,35 @@ void TtlWktSerializer::write(const IfcGeom::BRepElement* brep_obj) {
 
                 std::string postfix = "_section_geometry_" + std::to_string(N++);
 
-			filename_.stream << ttl_object_id(brep_obj) << " geo:hasGeometry " << ttl_object_id(brep_obj, postfix.c_str()) << " .\n\n";
+                std::ostringstream oss;
-			filename_.stream << ttl_object_id(brep_obj, postfix.c_str()) << " a geo:Geometry ;\n";
+
-			filename_.stream << "    geo:asWKT " << escape_for_turtle(
+                oss << ttl_object_id(brep_obj) << " geo:hasGeometry " << ttl_object_id(brep_obj, postfix.c_str()) << " .\n\n";
-				IfcUtil::convert_utf8(
+                oss << ttl_object_id(brep_obj, postfix.c_str()) << " a geo:Geometry ;\n";
-					capture_output(
+                oss << "    geo:asWKT " << escape_for_turtle(IfcUtil::convert_utf8(capture_output(emit_line_component, loop_coords, loop_idxs, true, POLYGON))) << "^^geo:wktLiteral .\n\n";
-						emit_line_component,
+
-						loop_coords,
+                polygons_by_area[area] = oss.str();
-						loop_idxs,
-						true,
-						POLYGON))
-			) << "^^geo:wktLiteral .\n\n";
             }
         }
+
+        if (polygons_by_area.size() > 0) {
+            if ((polygons_by_area.rbegin()->first > (0.6 * rectangle_area)) || (height < (1. + 1.e-5))) {
+                // Found sufficiently large polygon
+                if (emitted_warning) {
+                    Logger::Warning("Found larger polygon area (" + std::to_string(polygons_by_area.rbegin()->first) + ").");
+                }
+                break;
+            } else if (!emitted_warning) {
+                Logger::Warning("Section polygon area is small compared to bounding box area (" + std::to_string(polygons_by_area.rbegin()->first) + " < " + std::to_string(0.6 * rectangle_area) + "). Trying again with different section height.");
+                emitted_warning = true;
+            }
+        }
+    }
+
+    if (polygons_by_area.size() > 0) {
+        // Emit polygon with largest area
+        auto it = polygons_by_area.rbegin();
+        filename_.stream << it->second;
+    }
 #endif
 }