Lines

A line may either be defined by a point and an inclination in the local coordinate (uv-) plane of the panel or by two points in the xyz-space of the ship. If the line lies in a plane perpendicular to a coordinate axis in the system, where it is described, then only one coordinate need be given (see the images above). The resulting line in the local uv-system will be directed so that the component of its direction vector which has the greatest absolute value in the system used in input will be positive.

Additionally, the direction of unindexed lines can be reversed by a special keyword, REV[ERSE].

To put it formally:

<angle> is the inclination of the line in degrees, measured from the positive u-axis.

<line_uvt1> equal to <line_uvt> with '1' added to all keywords and U1V replacing UV.

<line_uvt2> equal to <line_uvt> with '2' added to all keywords and U2V replacing UV.

Also in the last alternative, the line will be unrestricted and directed from (X, Y, Z) to (XT, YT, ZT).

Also in the last alternative, the line will be unrestricted and directed from (X1, Y1, Z1) to (X2, Y2, Z2). (However, check unrestricted lines below).

<line>::=  <line_uvt> | <line_xyz>

<line_1>::=  <line_uvt1>

<line_2>::=  <line_uvt2> | <line_xyz2>

A restricted line may be defined by two points in the uv-plane:

<line_two_uv-points>::= U1 = <coord>
          ,V1 = <coord>
          ,U2 = <coord>
          ,V2 = <coord>

A restricted line may also be set, using two points in the xyz-space (currently used only in the BOUNDARY statement).

<line_two_xyz-points>::=

      <point defined by x1, y1 or z1> | X1Y=<point_ref>
      ,<point defined by x2, y2 or z2> | X2Y=<point_ref>

Note: that a <line_two_xyz-points> and <line_xyz2> may look the same. If it is restricted or unrestricted depends on the statement in which it is used.

Remarks:

1. All lines are unrestricted except <line_two_uv-points> and <line_two_xyz_points>

2. The use of the keyword REV is restricted to statement types, where the direction of a line has any significance, that means:

   • CURVE statement, fillet curve

   • SEAM statement

   • STIFFENER statement

   • BRACKET statement

     The effect of the keyword REV is not retained to a SAVE statement.

Below, a number of examples of the definition of lines are given.

Examples:

1. <line>:

(equal to X=P1,Y1=P1,XT=P2,YT=P2 (or any suitable combination of these)).

Note: T must not be used together with X, Y, Z.

2. <line_1>:

3. <line_2>:

(In the last example, the panel must not be parallel to any principal plane.)

4. <line_two_uv-points>: