To Align Curves
1. Select a 3D curve or UV-curve that you want to align with another curve or surface.
2. Click
Edit >
Align. The
Align tab opens. A handle appears at one end of the selected curve. This end of the curve is aligned and modified.
3. Select Position, Tangent, Curvature, or Normal on the Align tab. Position is the default.
|  If you selected a UV-curve, only the Position and Tangent constraints are available. |
4. Click the End 1 collector on the Curve Ends tab of the Align tab or right-click and select End 1. Select a vertex of another curve, a location on another curve, a vertex of an edge of a surface, or a location on an edge of a surface as the reference.
While aligning, the 3D curve or UV-curve that you selected modifies itself to align with the selected reference and the selected constraint is applied.
5. If required, to change the constraint, you can right-click and select the required constraint from the shortcut menu.
6. If required, move the vertex of the modified curve along the reference to the required location. The vertex of the modified curve is indicated by a handle.
7. If required, you can also align the other end of the curve. Click End 2 collector on the Curve Ends tab or right-click and select End 2. A handle appears at the other end of the selected curve. This end of the curve is aligned and modified.
8. Select a vertex of another curve, a location on another curve, a vertex of an edge of a surface, or a location on an edge of a surface as the reference.
While aligning, the 3D curve that you selected modifies itself to align with the selected reference and the selected constraint is applied.
9. If required, to change the constraint, you can right-click and select the required constraint from the shortcut menu.
10. If required, move the vertex of the modified curve along the reference to the required location. The vertex of the modified curve is indicated by a handle.
11. If required, change the applied constraint using the Curve Ends tab. Select a new constraint from the list next to the End 1 collector or the list next to the End 2 collector on the Curve Ends tab to apply the constraint to End 1 and End 2 of the 3D or UV-curve, respectively.
12. Click
.