Snap NURBS Surfaces

Functionality

This node can adjust two NURBS surfaces in such a way that their edges would coincide. Optionally, it can adjust their tangents along the seam.

After snapping, it is possible to join surfaces into one Surface object with “Concatenate Surfaces” node.

This node is somewhat similar to “Snap Curves” node.

Inputs

This node has the following inputs:

• Surfaces. Surfaces to be adjusted. This input is only available when the Input mode parameter is set to List of Surfaces. The edges of surfaces which will be adjusted are selected according to the order the surfaces are present in this list.

• Surface1, Surface2. Surfaces to be adjusted. These inputs are only available when the Input mode parameter is set to Two Surfaces.

Parameters

This node has the following parameters:

• Input mode. The available modes are Two surfaces and List of surfaces. The default mode is Two surfaces.

• Direction. Surface parameter direction along which the surfaces are arranged. The available options are U and V. The default option is U.

• Bias. This defines where the seam curve, along which the edges of two surfaces will coincide, will be. The following options are available:

  • Middle line. Both surfaces will be adjusted, and the seam line will be the medium line between edges of two original surfaces. This is the default option.

  • Surface 1. The edge of the first surface will be left in place. The second surface will be adjusted in such a way that it’s edge coincides with the edge of the first surface.

  • Surface 2. The edge of the second surface will be left in place. The first surface will be adjusted in such a way that it’s edge coincides with the edge of the second surface.

• Tangents. This defines what should be done with tangents of the surfaces along the seam line. The available options are:

  • No matter. The surfaces will be adjusted in such a way that total movement of their control points is minimal; the procedure will not consider tangents at all. In some cases the tangents can be changed, in some they will not change. This is the default option.

  • Preserve. The surfaces will be adjusted in such a way that their tangents along the seam are not changed.

  • Medium. Tangents of both surfaces will be adjusted; the resulting tangent vectors will be average between tangent vectors of the first and the second surface.

  • Surface 1. Tangents of the first surface will be left as is. Tangents of the second surface will be adjusted in order to match the tangents of the first surface.

  • Surface 2. Tangents of the second surface will be left as is. Tangents of the first surface will be adjusted in order to match the tangents of the second surface.

• Cyclic. If checked, the node will snap surfaces in cycle, i.e. it will snap the last surface to the first one. Unchecked by default.

Outputs

This node has the following output:

• Surfaces. Adjusted surfaces.

Examples of Usage

Original surfaces:

Snap them with default settings - to middle line, not taking tangents into account:

With “preserve tangents” option (tangent vectors of both original surfaces along V direction are horizontal):

Snap second surface to the first one, not taking tangents into account:

Snap first surface to the second one, not taking tangents into account:

Now match tangents as well:

Four original surfaces:

Snap them in cyclic manner, with “preserve tangents” option:

With “medium tangents” mode: