On Surface

Create a blend curve directly on one or more surfaces.

1. On the ribbon, click the Curves tab.
2. Click the On Surface icon.
   
   
3. Click one or more surfaces to place the blend points.
   You can place points on different objects, as long the objects share an edge or the objects are combined.

   Tip: Avoid creating one curve with lots of points; instead, create multiple curves and combine them. This will improve performance and simplify editing.
4. Right-click and mouse through the check mark to exit, or double-right-click.

Reposition and reshape a blend curve.

1. Double-click the blend curve to enter edit mode.
2. Edit the blend curve.

   To	Do this
   Reposition a point	Drag the point. Click the point, click the chevron, and then enter the x, y, and z coordinates.
   Add a point	Hover midway between two points, or at either end of the curve. Click to add a point. Or drag to add a point in a different position.
   Delete a point	Click the point, and then press Delete.
   Change the curve degree	The curve degree controls the placement of the points to determine the shape of the blend curve. In the guide bar, select one of the following options: Cubic (3) Quintic (5): In general, select this option to produce a smoother curve.
   Change the continuity	The continuity is used to constrain the shape of the curve at a selected point. Click a point, and then select one of the following Continuity options: Positional (G0) (default): The blend curve is merely attached to the curve or surface at the blend point. Tangent (G1): The blend curve is made tangent to the curve or surface at the blend point. Curvature (G2): The blend curve follows the curvature of the attached curve or surface. The curvature is the same on both sides across the blend curve's boundaries. Double curvature (G3): Only available if you selected Quintic (5) for the Degree. The blend curve follows the curvature of the attached curve or surface. The curvature's rate of change is the same on both sides across the blend curve's boundaries.
   Change the tangent direction of a point	Click a point, click the chevron, and then select one of the following Tangent options: Auto (default): Automatically calculate the best tangent direction. Custom UV: You can define the custom tangent direction by clicking the four yellow dots on either side of the point. Free 3D: No tangent direction. You need to enter the 3D tangent direction coordinates. The continuity is automatically set to Positional.
   Change the tangent magnitude of a point	Drag the blue square handles. Click a point, click the chevron, and then enter a Tangent magnitude value.
   Trim at a start or end point	Click the start or end point, click the chevron, and then select Trim here. In the Control Panel, select Trim at start, Trim at end, or both.
   Invert the trim at a start or end point	Click the start or end point, click the chevron, and then select Invert trim side. In the Control Panel, select Invert start or Invert end.
   Change the curve tension	This controls the smoothness of the curve. In the Control Panel, enter a Curve tension value. You need to choose a value from 0.01 to 1. Higher values correspond to smoother curves.

3. Right-click and mouse through the check mark to exit, or double-right-click.