int LineIntersectOperator::SignOfDet2x2()

in aios/storage/indexlib/index/common/field_format/spatial/shape/LineIntersectOperator.cpp [145:376]

• 185 lines of code
• 42 McCabe index (conditional complexity)

int LineIntersectOperator::SignOfDet2x2(double x1, double y1, double x2, double y2)
{
    /**
     * reference to jts::algorithm::RobustDeterminant.signOfDet2x2(...)
     */

    // returns -1 if the determinant is negative,
    // returns  1 if the determinant is positive,
    // retunrs  0 if the determinant is null.
    int sign = 1;
    double swap;
    double k;

    /*
     * testing null entries
     */
    if ((x1 == 0.0) || (y2 == 0.0)) {
        if ((y1 == 0.0) || (x2 == 0.0)) {
            return 0;
        } else if (y1 > 0) {
            if (x2 > 0) {
                return -sign;
            } else {
                return sign;
            }
        } else {
            if (x2 > 0) {
                return sign;
            } else {
                return -sign;
            }
        }
    }
    if ((y1 == 0.0) || (x2 == 0.0)) {
        if (y2 > 0) {
            if (x1 > 0) {
                return sign;
            } else {
                return -sign;
            }
        } else {
            if (x1 > 0) {
                return -sign;
            } else {
                return sign;
            }
        }
    }

    /*
     *  making y coordinates positive and permuting the entries
     *  so that y2 is the biggest one
     */
    if (0.0 < y1) {
        if (0.0 < y2) {
            if (y1 <= y2) {
                ;
            } else {
                sign = -sign;
                swap = x1;
                x1 = x2;
                x2 = swap;
                swap = y1;
                y1 = y2;
                y2 = swap;
            }
        } else {
            if (y1 <= -y2) {
                sign = -sign;
                x2 = -x2;
                y2 = -y2;
            } else {
                swap = x1;
                x1 = -x2;
                x2 = swap;
                swap = y1;
                y1 = -y2;
                y2 = swap;
            }
        }
    } else {
        if (0.0 < y2) {
            if (-y1 <= y2) {
                sign = -sign;
                x1 = -x1;
                y1 = -y1;
            } else {
                swap = -x1;
                x1 = x2;
                x2 = swap;
                swap = -y1;
                y1 = y2;
                y2 = swap;
            }
        } else {
            if (y1 >= y2) {
                x1 = -x1;
                y1 = -y1;
                x2 = -x2;
                y2 = -y2;
            } else {
                sign = -sign;
                swap = -x1;
                x1 = -x2;
                x2 = swap;
                swap = -y1;
                y1 = -y2;
                y2 = swap;
            }
        }
    }

    /*
     * making x coordinates positive
     */
    /*
     * if |x2|<|x1| one can conclude
     */
    if (0.0 < x1) {
        if (0.0 < x2) {
            if (x1 <= x2) {
                ;
            } else {
                return sign;
            }
        } else {
            return sign;
        }
    } else {
        if (0.0 < x2) {
            return -sign;
        } else {
            if (x1 >= x2) {
                sign = -sign;
                x1 = -x1;
                x2 = -x2;
            } else {
                return -sign;
            }
        }
    }

    /*
     * all entries strictly positive   x1 <= x2 and y1 <= y2
     */
    while (true) {
        k = std::floor(x2 / x1);
        x2 = x2 - k * x1;
        y2 = y2 - k * y1;

        /*
         * testing if R (new U2) is in U1 rectangle
         */
        if (y2 < 0.0) {
            return -sign;
        }
        if (y2 > y1) {
            return sign;
        }

        /*
         * finding R'
         */
        if (x1 > x2 + x2) {
            if (y1 < y2 + y2) {
                return sign;
            }
        } else {
            if (y1 > y2 + y2) {
                return -sign;
            } else {
                x2 = x1 - x2;
                y2 = y1 - y2;
                sign = -sign;
            }
        }
        if (y2 == 0.0) {
            if (x2 == 0.0) {
                return 0;
            } else {
                return -sign;
            }
        }
        if (x2 == 0.0) {
            return sign;
        }

        /*
         * exchange 1 and 2 role.
         */
        k = std::floor(x1 / x2);
        x1 = x1 - k * x2;
        y1 = y1 - k * y2;

        /*
         * testing if R (new U1) is in U2 rectangle
         */
        if (y1 < 0.0) {
            return sign;
        }
        if (y1 > y2) {
            return -sign;
        }

        /*
         * finding R'
         */
        if (x2 > x1 + x1) {
            if (y2 < y1 + y1) {
                return -sign;
            }
        } else {
            if (y2 > y1 + y1) {
                return sign;
            } else {
                x1 = x2 - x1;
                y1 = y2 - y1;
                sign = -sign;
            }
        }
        if (y1 == 0.0) {
            if (x1 == 0.0) {
                return 0;
            } else {
                return sign;
            }
        }
        if (x1 == 0.0) {
            return -sign;
        }
    }
}