Point on Surface

This function defines a point in a surface by giving two co-ordinates (two of x, y and z). Together they define a line that is parallel to one of the co-ordinate axes. The system gets a point by intersection of the line and the surface. In case of multiple intersections an "approximate co-ordinate" can be used to make the system select the intersection point that is closest to that co-ordinate.

The following form is used in this function:

Figure 2:22. Form for creation and modification of point on surface

The Surface field: The surface to use in calculating the position of the point. The contents of this field cannot be changed; it is always set to the name of the default surface.

The Coordinate System field: Set this to one of XY, XZ or YZ, depending on which two co-ordinates of the point are known. The co-ordinates should be given in the order indicated by this selection, for example the Coord1 field should contain the y co-ordinate and the Coord2 field should contain the z co-ordinate if this field is set to YZ.

The Coord1 field: The first co-ordinate of the point.

The Coord2 field: The second co-ordinate of the point.

The Approximate Coord field: The third, approximate co-ordinate of the point as described above.

With the Select Surface button you can change the surface to intersect. This button is only displayed when modifying an existing point.

The Select Type button lets you change the type of the point to any of the point types described in this section. This button is only displayed when modifying an existing point.

The Apply button: Create a point with the given input, but keep the form open. This is practical if several points are to be created at the same time. This button is only displayed when creating a new point.

The Ok button: Accept the input and create a new point or modify an existing one according to the input.

The Cancel button: Exit the function without creating or modifying any point.