void _hex2dToCoordIJK()

in src/h3lib/lib/coordijk.c [53:144]

• 75 lines of code
• 15 McCabe index (conditional complexity)

void _hex2dToCoordIJK(const Vec2d* v, CoordIJK* h) {
    double a1, a2;
    double x1, x2;
    int m1, m2;
    double r1, r2;

    // quantize into the ij system and then normalize
    h->k = 0;

    a1 = fabsl(v->x);
    a2 = fabsl(v->y);

    // first do a reverse conversion
    x2 = a2 / M_SIN60;
    x1 = a1 + x2 / 2.0L;

    // check if we have the center of a hex
    m1 = x1;
    m2 = x2;

    // otherwise round correctly
    r1 = x1 - m1;
    r2 = x2 - m2;

    if (r1 < 0.5L) {
        if (r1 < 1.0L / 3.0L) {
            if (r2 < (1.0L + r1) / 2.0L) {
                h->i = m1;
                h->j = m2;
            } else {
                h->i = m1;
                h->j = m2 + 1;
            }
        } else {
            if (r2 < (1.0L - r1)) {
                h->j = m2;
            } else {
                h->j = m2 + 1;
            }

            if ((1.0L - r1) <= r2 && r2 < (2.0 * r1)) {
                h->i = m1 + 1;
            } else {
                h->i = m1;
            }
        }
    } else {
        if (r1 < 2.0L / 3.0L) {
            if (r2 < (1.0L - r1)) {
                h->j = m2;
            } else {
                h->j = m2 + 1;
            }

            if ((2.0L * r1 - 1.0L) < r2 && r2 < (1.0L - r1)) {
                h->i = m1;
            } else {
                h->i = m1 + 1;
            }
        } else {
            if (r2 < (r1 / 2.0L)) {
                h->i = m1 + 1;
                h->j = m2;
            } else {
                h->i = m1 + 1;
                h->j = m2 + 1;
            }
        }
    }

    // now fold across the axes if necessary

    if (v->x < 0.0L) {
        if ((h->j % 2) == 0)  // even
        {
            long long int axisi = h->j / 2;
            long long int diff = h->i - axisi;
            h->i = h->i - 2.0 * diff;
        } else {
            long long int axisi = (h->j + 1) / 2;
            long long int diff = h->i - axisi;
            h->i = h->i - (2.0 * diff + 1);
        }
    }

    if (v->y < 0.0L) {
        h->i = h->i - (2 * h->j + 1) / 2;
        h->j = -1 * h->j;
    }

    _ijkNormalize(h);
}