How to implement the xyz to mesh generation to another code for fluid simulation?

[uljad]

I am running a fluidics simulation in a robotics platform and I am currently pausing the simulation every few steps to mesh the fluid particles. Is there a way I could use the xyz to obj capabilities of fluid engine dev so I will not have to run the partciles2obj examples each timestep?

Currently, I use system to run the examples from the terminal. Can I do it without this extra I/O? It would be amazing if there was a way.

[doyubkim]

Hi @uljadberdica1000,

If you want to adapt particles2obj in your code, you can copy and modify the functions from particles2obj as shown below:

void triangulateAndSave(const ScalarGrid3& sdf,
                        const std::string& objFilename) {
    TriangleMesh3 mesh;
    marchingCubes(sdf.constDataAccessor(), sdf.gridSpacing(), sdf.dataOrigin(),
                  &mesh, 0.0, kDirectionAll);

    std::ofstream file(objFilename.c_str());
    if (file) {
        printf("Writing %s...\n", objFilename.c_str());
        mesh.writeObj(&file);
        file.close();
    } else {
        printf("Cannot write file %s.\n", objFilename.c_str());
        exit(EXIT_FAILURE);
    }
}

void particlesToObj(const Array1<Vector3D>& positions, const Size3& resolution,
                    const Vector3D& gridSpacing, const Vector3D& origin,
                    double kernelRadius, const std::string& method,
                    const std::string& objFilename) {
    PointsToImplicit3Ptr converter;
    if (method == kSpherical) {
        converter =
            std::make_shared<SphericalPointsToImplicit3>(kernelRadius, false);
    } else if (method == kSph) {
        converter = std::make_shared<SphPointsToImplicit3>(
            kernelRadius, sSphCutOffDensity, false);
    } else if (method == kZhuBridson) {
        converter = std::make_shared<ZhuBridsonPointsToImplicit3>(
            kernelRadius, sZhuBridsonCutOffThreshold, false);
    } else {
        converter = std::make_shared<AnisotropicPointsToImplicit3>(
            kernelRadius, sAnisoCutOffDensity, sAnisoPositionSmoothingFactor,
            sAnisoMinNumNeighbors, false);
    }

    VertexCenteredScalarGrid3 sdf(resolution, gridSpacing, origin);
    printInfo(resolution, sdf.boundingBox(), gridSpacing, positions.size(),
              method);

    converter->convert(positions, &sdf);

    triangulateAndSave(sdf, objFilename);
}

You can call particlesToObj function after every time-step.

Hope this helps!