# Sweep1 ## Sweep1 The Sweep1 command fits a surface through a series of profile curves that define the surface cross-sections and one curve that defines a surface edge. ### **Steps** 1. Select a single rail curve. 2. Select cross-section curves in the order that the surface will pass through them.\ When multiple closed cross-section curves are selected, there will be an extra step for adjusting curve seams. ### Command-line options **ChainEdges (rails only):** Select connected edge/curve segments based on the continuity between segments. [How to chain selection.](https://docs.mcneel.com/rhino/8/help/en-us/popup_moreinformation/howtochainselectedges.htm) **Point (cross‑sections only):** Creates a surface that begins or ends at a point. ### Adjust seam options (Closed curves only) #### **Flip** Reverses the curve direction. #### **Automatic** Attempts to align the seam points and directions without intervention. #### **Natural** Moves the seam points to the way they were at the beginning of the command. #### **SnapToKnots** 1. **Yes :** The seam points are always at the knots. You can only move them among the knots. 2. **No :** The seam points may leave the knots. You can move them without restriction. ### Sweep 1 Rail Options #### **Frame Style** A frame is a 3-D point and three direction vectors. It can be drawn as something that looks like the Rhino world axes icon. It describes a unique coordinate system in space. Frames are calculated along the rail and are used to orient the cross-section curves at those locations. In a simple case with one cross-section, frames are made at the cross-section curve location and where the calculated cross-section is going to go. The 3-D rotation between those two frames determines the rotation of the cross-section curve at its new location. Freeform is the default Frame style. The selected Frame style will be remembered in the current Rhino for next use. * **Freeform** The cross-section curve rotates to maintain its angle to the rail throughout the sweep. * **Roadlike** Specify an axis for calculating the 3-D rotation of the cross-section. The default Roadlike axis will be different depending on the rail curve. For a planar rail curve, the default axis is perpendicular to the curve plane. For a non-planar rail curve, world-Z axis will be used. **Set axis -** Sets the axis direction for the Roadlike style. * **Align with surface (surface edge as rail only)** If the rail is a surface edge, the cross-section curve will twist with the surface edge. If the shapes are tangent to the surface, the new surface should also be tangent. #### **Sweep options** * **Closed sweep** Creates a closed surface, continuing the surface past the last curve around to the first curve. This option is only available after you select two cross-section curves. * **Global shape blending** The sweep is linearly blended from one end to the other, creating sweeps that taper from one cross-section curve to the other. Otherwise, the sweep stays constant at the ends and changes more rapidly in the middle. * **Untrimmed miters** If the sweep creates a polysurface with kinks, the component surfaces will be untrimmed. #### **Curve options** * **Refit rail -** Refits the rail curve before creating the sweep. * **Align cross sections -** Allows reversing the direction of the cross-section curves. * **Do not change cross sections -** Creates the sweep without altering the cross-section curves. * **Rebuild cross sections with \_\_\_ control points -** before creating the sweep. * **Refit cross sections within \_\_\_ -** Refits the cross-section curves before creating the sweep. For more information, please refer to the [Rhino documentation](https://docs.mcneel.com/rhino/8/help/en-us/commands/sweep1.htm).