tag_t matrix_tag;

int conic_type;

double rotation_angle;

double start_param;

double end_param;

double center[3];

double k1;

double k2;

} UF_CURVE_conic_t, *UF_CURVE_conic_p_t;

Parameter |
Description |

matrix_tag | tag of matrix defining orientation |

conic_type | subtype of the conic section |

rotation_angle | angle conic is rotated away from standard position in defini tion space |

start_param | starting parameter value |

end_param | ending parameter value |

center[3] | center of conic in orientation space |

k1 | shape parameter 1 |

k2 | shape parameter 2 |

The ellipse is counterclockwise when viewed in the direction opposite the Z axis of the matrix. The parameters meet the same requirements as for an arc. The major axis lies on the U axis, and the minor axis lies on the V axis. Conic_type is UF_conic_ellipse_subtype. k1 is the semimajor axis, and k2 is the semiminor axis. The points

The U axis is the direction of the centerline of a parabola, which opens out along that direction. The start and end parameters may be any real numbers as long as start_param is less than end_param. Conic_type is UF_conic_parabola_subtype. The points

The U axis of the matrix is the direction of the centerline of a hyperbola, which opens out along that direction. Note that the hyperbola is numerically unstable at values close to the endpoints of its interval. Conic_type is UF_conic_hyperbola_subtype. The points

The points from the equations above are transformed as follows to put them in absolute space, which is what you will see in the part:

where

is the point in absolute space

is the matrix defining the orientation space

is the rotation matrix from the rotation angle of the conic

is the center point from the conic structure