int _find_next_intercept();

// Advance a ray in quadrant 0.
// note that slope must be nonnegative!
// returns 0 if the advance was in x, 1 if it was in y, 2 if it was
// the diagonal
static int _find_next_intercept(double* accx, double* accy, const double slope)
{
    // handle perpendiculars
    if (double_is_zero(slope))
    {
        *accx += 1.0;
        return 0;
    }
    if (slope > 100.0)
    {
        *accy += 1.0;
        return 1;
    }
    const double xtarget = static_cast<int>(*accx) + 1;
    const double ytarget = static_cast<int>(*accy) + 1;
    const double xdistance = xtarget - *accx;
    const double ydistance = ytarget - *accy;
    double distdiff = xdistance * slope - ydistance;
    // exact corner
    if (double_is_zero(distdiff))
    {
        // move somewhat away from the corner
        if (slope > 1.0)
        {
            *accx = xtarget + EPSILON_VALUE * 2;
            *accy = ytarget + EPSILON_VALUE * 2 * slope;
        }
        else
        {
            *accx = xtarget + EPSILON_VALUE * 2 / slope;
            *accy = ytarget + EPSILON_VALUE * 2;
        }
        return 2;
    }
    // move to the boundary
    double traveldist;
    int rc = -1;
    if (distdiff > 0.0)
    {
        traveldist = ydistance / slope;
        rc = 1;
    }
    else
    {
        traveldist = xdistance;
        rc = 0;
    }
    // and a little into the next cell, taking care
    // not to go too far
    if (distdiff < 0.0)
        distdiff = -distdiff;
    traveldist += std::min(EPSILON_VALUE * 10.0, 0.5 * distdiff / slope);
    *accx += traveldist;
    *accy += traveldist * slope;
    return rc;
}

// Advance a ray in quadrant 0.
// note that slope must be nonnegative!
// returns 0 if the advance was in x, 1 if it was in y, 2 if it was
// the diagonal
int ray_def::_find_next_intercept()
{
    // handle perpendiculars
    if (double_is_zero(slope))
    {
        accx += 1.0;
        return 0;
    }
    if (slope > 100.0)
    {
        accy += 1.0;
        return 1;
    }
    const double xtarget = static_cast<int>(accx) + 1;
    const double ytarget = static_cast<int>(accy) + 1;
    const double xdistance = xtarget - accx;
    const double ydistance = ytarget - accy;
    double distdiff = xdistance * slope - ydistance;
    // exact corner
    if (double_is_zero(distdiff))
    {
        // move somewhat away from the corner
        if (slope > 1.0)
        {
            accx = xtarget + EPSILON_VALUE * 2;
            accy = ytarget + EPSILON_VALUE * 2 * slope;
        }
        else
        {
            accx = xtarget + EPSILON_VALUE * 2 / slope;
            accy = ytarget + EPSILON_VALUE * 2;
        }
        return 2;
    }
    // move to the boundary
    double traveldist;
    int rc = -1;
    if (distdiff > 0.0)
    {
        traveldist = ydistance / slope;
        rc = 1;
    }
    else
    {
        traveldist = xdistance;
        rc = 0;
    }
    // and a little into the next cell, taking care
    // not to go too far
    if (distdiff < 0.0)
        distdiff = -distdiff;
    traveldist += std::min(EPSILON_VALUE * 10.0, 0.5 * distdiff / slope);
    accx += traveldist;
    accy += traveldist * slope;
    return rc;
}

        rc = _find_next_intercept(&accx, &accy, slope);
        return rc;

        rc = _find_next_intercept();
        break;

        rc   = _find_next_intercept(&accx, &accy, slope);

        rc   = _find_next_intercept();

        return rc;

        break;

        rc   = _find_next_intercept(&accx, &accy, slope);

        rc   = _find_next_intercept();

        return rc;

        break;

        rc   = _find_next_intercept(&accx, &accy, slope);

        rc   = _find_next_intercept();

        return rc;

        break;

        return -1;

        rc = -1;

    return rc;

    // copy starting point
    double ax = accx;
    double ay = accy;
    int curx, cury;

    ray_def copy = *this;
    coord_def c;

        _find_next_intercept(&ax, &ay, slope);
        curx = static_cast<int>(ax);
        cury = static_cast<int>(ay);
        if (curx*curx + cury*cury > radius2)

        copy._find_next_intercept();
        c = copy.pos();
        if (c.abs() > radius2)

        cpos[cellnum] = coord_def(curx, cury);

        cpos[cellnum] = c;

            double xstart = ((double)(intercept)) / (2*yangle);

            double xstart = ((double)intercept) / (2*yangle);