Help visualize the Q-value

R_Mur · January 14, 2026, 7:42am

I’m trying to visualize Q-values using C++.
Currently, I can’t get the intended outline to appear as shown in the file below. Could someone please tell me why?
As it stands, it’s currently a cube.
I want to display a rectangular prism outline.

mwestphal · January 14, 2026, 8:16am

Are you looking for the representation selector ?

R_Mur · January 14, 2026, 9:07am

Touching that icon didn’t seem to have any particular effect.
As far as comparing the two outlines goes, it doesn’t appear to be an issue with the camera or anything like that.

mwestphal · January 14, 2026, 9:38am

please share your data

R_Mur · January 15, 2026, 6:00am

The code is as follows:

IMAX=1700

JMAX=204

KMAX=204

dx=0.002

dy=0.00025

dz=0.002

The grid is cut with x and z at equal intervals and y at non-equal intervals.

The Q value threshold is set to 9.94.

void write_paraview(

double x0\[\],

double y0\[\],

double z0\[\],

double q\[\]\[JMAX + 1\]\[IMAX + 1\],

double uzudo\[\]\[JMAX + 1\]\[IMAX + 1\],

double u0\[\]\[JMAX + 1\]\[IMAX + 1\],

double v0\[\]\[JMAX + 1\]\[IMAX + 1\],

double w0\[\]\[JMAX + 1\]\[IMAX + 1\],

double p0\[\]\[JMAX + 1\]\[IMAX + 1\]) {

ofstream datado;

char str\[32\];

sprintf(str, "paraview.%04d.vtk", n / 250);

//char str2\[20\];

//sprintf(str, "./data2/paraview_output/");

std::string datafile = "./data2/paraview_output/";

//string datafile = str2;

//mkdir(str2, 0777);

datafile.append(str);

datado.open(datafile.c_str(), ios::out | ios::binary);

if (!datado) {

    cout << "Error: cannot open file(" << datafile.c_str() << ")" << endl;

    exit(1);

}

if (n == 0) {

    datado << "# vtk DataFile Version 2.0" << endl;

    datado << "q_uzudo" << endl;

    datado << "ASCII" << endl;

    datado << "DATASET RECTILINEAR_GRID" << endl;

    datado << "DIMENSIONS " << IMAX + 1 << ' ' << JMAX + 1 << ' ' << KMAX + 1 << endl;

    datado << "X_COORDINATES " << IMAX + 1 << " double" << endl;

    for (int i = 0; i < IMAX + 1; i++) {

        datado << x0\[i\] << ' ';

    }

    datado << endl;

    datado << "Y_COORDINATES " << JMAX + 1 << " double" << endl;

    for (int j = 0; j < JMAX + 1; j++) {

        datado << y0\[j\] << ' ';

    }

    datado << endl;

    datado << "Z_COORDINATES " << KMAX + 1 << " double" << endl;

    for (int k = 0; k < KMAX + 1; k++) {

        datado << z0\[k\] << ' ';

    }

    datado << endl;

}

else { //境界内の計算

    int imin = 0, imax = 0, jmin = 0, jmax = 0, kmin = 0, kmax = 0;

    for (int i = 1; i < IMAX; i++) {

        for (int j = 1; j < JMAX; j++) {

            for (int k = 1; k < KMAX; k++) {

                if (q\[k\]\[j\]\[i\] > q_threshold) {

                    imin = i;

                    goto loopend1;

                }

            }

        }

    }

loopend1:

    for (int i = IMAX - 1; i > 0; i--) {

        for (int j = 1; j < JMAX; j++) {

            for (int k = 1; k < KMAX; k++) {

                if (q\[k\]\[j\]\[i\] > q_threshold) {

                    imax = i;

                    goto loopend2;

                }

            }

        }

    }

loopend2:

    for (int j = 1; j < JMAX; j++) {

        for (int i = 1; i < IMAX; i++) {

            for (int k = 1; k < KMAX; k++) {

                if (q\[k\]\[j\]\[i\] > q_threshold) {

                    jmin = j;

                    goto loopend3;

                }

            }

        }

    }

loopend3:

    for (int j = JMAX - 1; j > 0; j--) {

        for (int i = 1; i < IMAX; i++) {

            for (int k = 1; k < KMAX; k++) {

                if (q\[k\]\[j\]\[i\] > q_threshold) {

                    jmax = j;

                    goto loopend4;

                }

            }

        }

    }

loopend4:

    for (int k = 1; k < KMAX; k++) {

        for (int j = 1; j < JMAX; j++) {

            for (int i = 1; i < IMAX; i++) {

                if (q\[k\]\[j\]\[i\] > q_threshold) {

                    kmin = k;

                    goto loopend5;

                }

            }

        }

    }

loopend5:

    for (int k = KMAX - 1; k > 0; k--) {

        for (int j = 1; j < JMAX; j++) {

            for (int i = 1; i < IMAX; i++) {

                if (q\[k\]\[j\]\[i\] > q_threshold) {

                    kmax = k;

                    goto loopend6;

                }

            }

        }

    }

loopend6:






    datado << "# vtk DataFile Version 2.0" << endl;

    datado << "q_uzudo" << endl;

    datado << "ASCII" << endl;

    datado << "DATASET RECTILINEAR_GRID" << endl;

    datado << "DIMENSIONS " << imax - imin + 3 << ' ' << jmax - jmin + 3 << ' ' << kmax - kmin + 3 << endl;

    datado << "X_COORDINATES " << imax - imin + 3 << " double" << endl;

    for (int i = imin - 1; i < imax + 2; i++) {

        datado << x0\[i\] << ' ';

    }

    datado << endl;

    datado << "Y_COORDINATES " << jmax - jmin + 3 << " double" << endl;

    for (int j = jmin - 1; j < jmax + 2; j++) {

        datado << y0\[j\] << ' ';

    }

    datado << endl;

    datado << "Z_COORDINATES " << kmax - kmin + 3 << " double" << endl;

    for (int k = kmin - 1; k < kmax + 2; k++) {

        datado << z0\[k\] << ' ';

    }

    datado << endl;

    datado << "POINT_DATA " << (imax - imin + 3) \* (jmax - jmin + 3) \* (kmax - kmin + 3) << endl;

    datado << "SCALARS q double" << endl;

    datado << "LOOKUP_TABLE default" << endl;

    for (int k = kmin - 1; k < kmax + 2; k++) {

        for (int j = jmin - 1; j < jmax + 2; j++) {

            for (int i = imin - 1; i < imax + 2; i++) {

                datado << q\[k\]\[j\]\[i\] << endl;

            }

        }

    }

    datado << "SCALARS uzudo double" << endl;

    datado << "LOOKUP_TABLE default" << endl;

    for (int k = kmin - 1; k < kmax + 2; k++) {

        for (int j = jmin - 1; j < jmax + 2; j++) {

            for (int i = imin - 1; i < imax + 2; i++) {

                datado << uzudo\[k\]\[j\]\[i\] << endl;

            }

        }

    }

    datado << "VECTORS v double" << endl;

    for (int k = kmin - 1; k < kmax + 2; k++) {

        for (int j = jmin - 1; j < jmax + 2; j++) {

            for (int i = imin - 1; i < imax + 2; i++) {

                datado << u0\[k\]\[j\]\[i\] << ' ' << v0\[k\]\[j\]\[i\] << ' ' << w0\[k\]\[j\]\[i\] << endl;

            }

        }

    }

}

datado.close();

}