🐞 fix: fix the bug of exported STL files being empty.

Author: xiangechen

cpp/src/converter.cpp

@@ -4,6 +4,7 @@
 #include "shared.hpp"
 #include <BRep_Builder.hxx>
 #include <BRepTools.hxx>
+#include <BRepMesh_IncrementalMesh.hxx>
 #include <emscripten/bind.h>
 #include <emscripten/val.h>
 #include <IGESCAFControl_Reader.hxx>
@@ -24,6 +25,7 @@
 #include <StlAPI_Writer.hxx>
 #include <BRepBuilderAPI_MakeSolid.hxx>
 #include <BRepBuilderAPI_Sewing.hxx>
+#include "utils.hpp"
 
 using namespace emscripten;
 
@@ -295,6 +297,15 @@ class Converter
         return sewing.SewedShape();
     }
 
+    static void writeBufferToFile(const std::string &fileName, const Uint8Array &buffer)
+    {
+        std::vector<uint8_t> input = convertJSArrayToNumberVector<uint8_t>(buffer);
+        std::ofstream dummyFile;
+        dummyFile.open(fileName, std::ios::binary);
+        dummyFile.write((char *)input.data(), input.size());
+        dummyFile.close();
+    }
+
 public:
     static std::string convertToBrep(const TopoDS_Shape &input)
     {
@@ -339,12 +350,8 @@ class Converter
 
     static std::optional<ShapeNode> convertFromIges(const Uint8Array &buffer)
     {
-        std::vector<uint8_t> input = convertJSArrayToNumberVector<uint8_t>(buffer);
         std::string dummyFileName = "temp.igs";
-        std::ofstream dummyFile;
-        dummyFile.open(dummyFileName, std::ios::binary);
-        dummyFile.write((char *)input.data(), input.size());
-        dummyFile.close();
+        writeBufferToFile(dummyFileName, buffer);
 
         IGESCAFControl_Reader igesCafReader;
         igesCafReader.SetColorMode(true);
@@ -394,73 +401,44 @@ class Converter
 
     static std::optional<ShapeNode> convertFromStl(const Uint8Array &buffer)
     {
-        std::vector<uint8_t> input = convertJSArrayToNumberVector<uint8_t>(buffer);
         std::string dummyFileName = "temp.stl";
-        std::ofstream dummyFile;
-        dummyFile.open(dummyFileName, std::ios::binary);
-        dummyFile.write((char *)input.data(), input.size());
-        dummyFile.close();
+        writeBufferToFile(dummyFileName, buffer);
 
         StlAPI_Reader stlReader;
         TopoDS_Shape shape;
         if (!stlReader.Read(shape, dummyFileName.c_str()))
         {
-            std::remove(dummyFileName.c_str());
             return std::nullopt;
         }
-        std::remove(dummyFileName.c_str());
-
-        TopoDS_Shape sewedShape = sewShapes({shape});
 
         ShapeNode node = {
-            .shape = sewedShape,
+            .shape = shape,
             .color = std::nullopt,
             .children = {},
-            .name = "STL Shape"
-        };
+            .name = "STL Shape"};
 
         return node;
     }
 
-    static std::string convertToStl(const ShapeArray &input)
+    static std::string convertToStl(const TopoDS_Shape &shapeToExport)
     {
-        auto shapes = vecFromJSArray<TopoDS_Shape>(input);
-        if (shapes.empty())
-        {
-            return std::string();
-        }
-
-        TopoDS_Shape shapeToExport = shapes.size() == 1 ? shapes[0] : sewShapes(shapes);
-
         std::string dummyFileName = "temp_export.stl";
+        auto lineDeflection = boundingBoxRatio(shapeToExport, 0.05);
+        BRepMesh_IncrementalMesh mesh(shapeToExport, lineDeflection, true, 0.2, true);
         StlAPI_Writer stlWriter;
         if (!stlWriter.Write(shapeToExport, dummyFileName.c_str()))
         {
-            std::remove(dummyFileName.c_str());
+            BRepTools::Clean(shapeToExport, true);
             return std::string();
         }
+        BRepTools::Clean(shapeToExport, true);
 
-        // Read the generated file content
-        std::ifstream file(dummyFileName, std::ios::binary | std::ios::ate);
-        if (!file.is_open())
-        {
-            std::remove(dummyFileName.c_str());
-            return std::string();
-        }
-        
-        std::streamsize size = file.tellg();
-        file.seekg(0, std::ios::beg);
-        
-        std::string content(size, '\0');
-        if (!file.read(content.data(), size))
-        {
-            std::remove(dummyFileName.c_str());
-            return std::string();
-        }
-        
-        file.close();
-        std::remove(dummyFileName.c_str());
-        return content;
+        std::ifstream in(dummyFileName);
+        std::istreambuf_iterator<char> beg(in), end;
+        std::string str(beg, end);
+        in.close();
+
+        return str;
     }
 };
 

cpp/src/mesher.cpp

@@ -24,32 +24,13 @@
 #include <TopoDS_Shape.hxx>
 #include <TopoDS.hxx>
 #include <UnitsMethods.hxx>
+#include "utils.hpp"
 
 using namespace emscripten;
 using namespace std;
 
 const double ANGLE_DEFLECTION = 0.2;
 
-double boundingBoxRatio(const TopoDS_Shape &shape, double linearDeflection)
-{
-    Bnd_Box boundingBox;
-    BRepBndLib::Add(shape, boundingBox, false);
-    if (boundingBox.IsVoid())
-    {
-        return linearDeflection;
-    }
-    Standard_Real xMin, yMin, zMin, xMax, yMax, zMax;
-    boundingBox.Get(xMin, yMin, zMin, xMax, yMax, zMax);
-
-    Standard_Real avgSize = ((xMax - xMin) + (yMax - yMin) + (zMax - zMin)) / 3.0;
-    double linDeflection = avgSize * linearDeflection;
-    if (linDeflection < Precision::Confusion())
-    {
-        linDeflection = 1.0;
-    }
-    return linDeflection;
-}
-
 void addPointToPosition(const gp_Pnt &pnt, std::optional<gp_Pnt> &prePnt, std::vector<float> &position)
 {
     if (prePnt.has_value())

cpp/src/utils.cpp

@@ -1,6 +1,8 @@
 // Part of the Chili3d Project, under the AGPL-3.0 License.
 // See LICENSE file in the project root for full license information.
 
+#include <Bnd_Box.hxx>
+#include <BRepBndLib.hxx>
 #include <GeomAPI_ProjectPointOnCurve.hxx>
 #include <GeomAPI_ExtremaCurveCurve.hxx>
 #include "utils.hpp"
@@ -76,4 +78,24 @@ ProjectPointResult projectOrNearestCP(const Geom_Curve* curve, const gp_Pnt& pnt
     }
 
     return nearestEnd(curve, pnt);
+}
+
+double boundingBoxRatio(const TopoDS_Shape &shape, double linearDeflection)
+{
+    Bnd_Box boundingBox;
+    BRepBndLib::Add(shape, boundingBox, false);
+    if (boundingBox.IsVoid())
+    {
+        return linearDeflection;
+    }
+    Standard_Real xMin, yMin, zMin, xMax, yMax, zMax;
+    boundingBox.Get(xMin, yMin, zMin, xMax, yMax, zMax);
+
+    Standard_Real avgSize = ((xMax - xMin) + (yMax - yMin) + (zMax - zMin)) / 3.0;
+    double linDeflection = avgSize * linearDeflection;
+    if (linDeflection < Precision::Confusion())
+    {
+        linDeflection = 1.0;
+    }
+    return linDeflection;
 }

cpp/src/utils.hpp

@@ -6,11 +6,14 @@
 #include <Geom_Curve.hxx>
 #include <gp_Pnt.hxx>
 #include "shared.hpp"
+#include <TopoDS_Shape.hxx>
 
 std::vector<ExtremaCCResult> extremaCCs(const Geom_Curve* curve1, const Geom_Curve* curve2, double maxDistance);
 
 std::optional<ProjectPointResult> projectToCurve(const Geom_Curve* curve, gp_Pnt pnt);
 
 ProjectPointResult nearestEnd(const Geom_Curve* curve, gp_Pnt pnt);
 
-ProjectPointResult projectOrNearestCP(const Geom_Curve* curve, const gp_Pnt& pnt);
+ProjectPointResult projectOrNearestCP(const Geom_Curve* curve, const gp_Pnt& pnt);
+
+double boundingBoxRatio(const TopoDS_Shape &shape, double linearDeflection);

packages/chili-builder/src/defaultDataExchange.ts

@@ -27,11 +27,21 @@ async function exportBrep(document: IDocument, shapes: IShape[]) {
     if (!comp.isOk) {
         return Result.err(comp.error);
     }
-    return document.application.shapeFactory.converter.convertToBrep(comp.value);
+
+    const result = document.application.shapeFactory.converter.convertToBrep(comp.value);
+    comp.value.dispose();
+    return result;
 }
 
 async function exportStl(document: IDocument, shapes: IShape[]) {
-    return document.application.shapeFactory.converter.convertToSTL(...shapes);
+    const comp = document.application.shapeFactory.combine(shapes);
+    if (!comp.isOk) {
+        return Result.err(comp.error);
+    }
+
+    const result = document.application.shapeFactory.converter.convertToSTL(comp.value);
+    comp.value.dispose();
+    return result;
 }
 
 export class DefaultDataExchange implements IDataExchange {
@@ -113,7 +123,7 @@ export class DefaultDataExchange implements IDataExchange {
     private async convertShapes(type: string, doc: IDocument, shapes: IShape[]) {
         if (type === ".step") return this.handleStepExport(doc, shapes);
         if (type === ".iges") return this.handleIgesExport(doc, shapes);
-        if (type === ".stl") return this.handleStlExport(doc, shapes);
+        if (type === ".stl") return exportStl(doc, shapes);
         return exportBrep(doc, shapes);
     }
 
@@ -125,10 +135,6 @@ export class DefaultDataExchange implements IDataExchange {
         return doc.application.shapeFactory.converter.convertToIGES(...shapes);
     }
 
-    private handleStlExport(doc: IDocument, shapes: IShape[]) {
-        return doc.application.shapeFactory.converter.convertToSTL(...shapes);
-    }
-
     private handleExportResult(result: Result<string> | undefined) {
         if (!result?.isOk) {
             PubSub.default.pub("showToast", "error.default:{0}", result?.error);

packages/chili-core/src/shape/shapeConverter.ts

@@ -13,6 +13,6 @@ export interface IShapeConverter {
     convertFromSTEP(document: IDocument, step: Uint8Array): Result<FolderNode>;
     convertToBrep(shape: IShape): Result<string>;
     convertFromBrep(brep: string): Result<IShape>;
-    convertToSTL(...shapes: IShape[]): Result<string>;
+    convertToSTL(shape: IShape): Result<string>;
     convertFromSTL(document: IDocument, stl: Uint8Array): Result<FolderNode>;
 }

packages/chili-wasm/lib/chili-wasm.d.ts

@@ -577,12 +577,12 @@ interface EmbindModule {
     Converter: {
         convertToBrep(_0: TopoDS_Shape): string;
         convertFromBrep(_0: EmbindString): TopoDS_Shape;
+        convertToStl(_0: TopoDS_Shape): string;
         convertFromStep(_0: Uint8Array): ShapeNode | undefined;
         convertFromIges(_0: Uint8Array): ShapeNode | undefined;
         convertFromStl(_0: Uint8Array): ShapeNode | undefined;
         convertToStep(_0: Array<TopoDS_Shape>): string;
         convertToIges(_0: Array<TopoDS_Shape>): string;
-        convertToStl(_0: Array<TopoDS_Shape>): string;
     };
     ShapeResult: {};
     ShapeFactory: {

packages/chili-wasm/lib/chili-wasm.wasm

@@ -118,14 +118,11 @@ export class OccShapeConverter implements IShapeConverter {
         return Result.ok(OcctHelper.wrapShape(shape));
     }
 
-    convertToSTL(...shapes: IShape[]): Result<string> {
-        let occShapes = shapes.map((shape) => {
-            if (shape instanceof OccShape) {
-                return shape.shape;
-            }
-            throw new Error("Shape is not an OccShape");
-        });
-        return Result.ok(wasm.Converter.convertToStl(occShapes));
+    convertToSTL(shape: IShape): Result<string> {
+        if (shape instanceof OccShape) {
+            return Result.ok(wasm.Converter.convertToStl(shape.shape));
+        }
+        return Result.err("Shape is not an OccShape");
     }
 
     convertFromSTL(document: IDocument, stl: Uint8Array): Result<FolderNode> {