Zip Surfaces

The Draw->Zip Surfaces command in the Model module allows you to "zip" or fit one surface to the shape of another (support) surface by mapping points on the zip surface to points on the support surface. Zip Surfaces does not create a new object.

Both surfaces must be of the same type: patch to patch or NURBS to NURBS. Within each type, variants can be zipped; for example, you can zip a B-Spline patch and a Linear patch or a quadratic NURBS and a cubic NURBS.

Contrast this with Draw->Merge Surfaces, which creates a new (merged) object, and leaves both source objects unchanged.

You can use relational modelling concepts on the zipped object. Always make sure that the Preferences->Create Modelling Relation command is activated first. Relational modelling is discussed in the Modelling User's Guide.

Tips

• For best results, the u and v lines should have the same orientation and relative position on both objects; for example, the v lines are in the same direction and the green highlight marking the beginning of the v line has to be at the top or bottom on both objects.
• Normals on both objects must be in the same direction.

It is best to handle these adjustments before trying to zip.

Procedure

1. Select the two surfaces you want to zip together (use the Multi menu cell or branch/tree select for objects in a hierarchy).
2. Choose the Draw->Zip Surfaces command.
3. Pick a point on the supporting surface using the left or middle mouse button. This point defines the origin of the "zipper" and, along with other points in the same row, is highlighted.
   
   The Zipper Direction dialogue box is displayed, with two options that allow you to set the zipper direction in either the U or V direction.
   
4. Select the desired zipper direction for the supporting surface.
5. Click Ok to continue or Cancel to return to step 3.
6. Pick a point on the surface you want to modify using the left or middle mouse button.
7. Select the desired zipper direction in which the surface is to be modified.
8. Click Ok to continue or Cancel to return to step 6.
   
   The Zip Patches dialogue box is displayed.
   
9. Set the parameters to define the number of points to zip together. The zipper is displayed interactively.

• Rows up and down defines the number of rows zipped (on the zip surface) in the direction opposite to the direction picked on the support surface.
• Number of points up and down defines the zipping in the same direction as the direction picked on the zipped surface.

10. Click Ok when you are satisfied with the zipper, or Cancel to exit the dialogue box.

Parameters

Note:

The Down and Up directions are defined in accordance with the number of points of the surfaces.

Rows Down

The number of rows down from the initially selected point for each surface to be included in the zipper.

Rows Up

The number of rows up from the initially selected point for each surface to be included in the zipper.

Number of Points Down

The number of points down in the specified zipper direction from the initially selected point for each surface to be included in the zipper.

Number of Points Up

The number of points up in the specified zipper direction from the initially selected point for each surface to be included in the zipper.

Last updated 08-apr-1998