Sample code for Odd Even Spatial Sorting

bool partial_sort()
{
    bool is_sorted = true;
    int index, next;
    PlanarPosition temp;

    // compare even columns
    for (int i = 0; i < dim_x - 1; i += 2) {
        for (int j = 0; j < dim_y; j++) {
            index = i + j * dim_x;
            next  = index + 1;
            if ((position_matrix[index].x >  position_matrix[next].x) ||
                (position_matrix[index].x == position_matrix[next].x  && position_matrix[index].y > position_matrix[next].y)) {
                temp = position_matrix[index];
                position_matrix[index] = position_matrix[next];
                position_matrix[next]  = temp;
                is_sorted = false;
            }
        }
    }

    // compare odd columns
    for (int i = 1; i < dim_x - 1; i += 2) {
        for (int j = 0; j < dim_y; j++) {
            index = i + j * dim_x;
            next  = index + 1;
            if ((position_matrix[index].x >  position_matrix[next].x) ||
                (position_matrix[index].x == position_matrix[next].x  && position_matrix[index].y > position_matrix[next].y)) {
                temp = position_matrix[index];
                position_matrix[index] = position_matrix[next];
                position_matrix[next]  = temp;
                is_sorted = false;
            }
        }
    }

    // compare even rows
    for (int j = 0; j < dim_y - 1; j += 2) {
        for (int i = 0; i < dim_x; i++) {
            index = i + j * dim_x;
            next  = index + dim_x;
            if ((position_matrix[index].y >  position_matrix[next].y) ||
                (position_matrix[index].y == position_matrix[next].y  && position_matrix[index].x > position_matrix[next].x)) {
                temp = position_matrix[index];
                position_matrix[index] = position_matrix[next];
                position_matrix[next]  = temp;
                is_sorted = false;
            }
        }
    }

    // compare odd rows
    for (int j = 1; j < dim_y - 1; j += 2) {
        for (int i = 0; i < dim_x; i++) {
            int index = i + j * dim_x;
            next  = index + dim_x;
            if ((position_matrix[index].y >  position_matrix[next].y) ||
                (position_matrix[index].y == position_matrix[next].y  && position_matrix[index].x > position_matrix[next].x)) {
                temp = position_matrix[index];
                position_matrix[index] = position_matrix[next];
                position_matrix[next]  = temp;
                is_sorted = false;
            }
        }
    }
    return is_sorted;
}

void full_sort()
{
    while (partial_sort() == false)
        ;
}