This command is used to attach a curve to a surface. There are two ways of doing this. One way is to use the Fix Pnt To Surface command for each point on a curve entity. When the last point is attached to the surface, the program replaces all of the Fix Pnt To Surface relationships with one Curve-On-Surface relationship. This means that the program treats the curve as a true “parametric” curve on the surface and not just some curve that is only attached to the surface at its edit points. The other way of attaching a curve to a surface is to create or define a new curve directly on the surface. This is done with either the Curve-Attach Polyline to Surface or the Curve-Attach Curve to Surface command. You need to use the first method if the curve already exists, but use the second method if you want to create and attach the curve at the same time. The following will explain how to create and attach a curve to a surface at the same time.
To create and attach a curve to a surface:
1. Select either the Curve-Attach Polyline to Surface or the Curve-Attach Curve to Surface command.
2. Use the left mouse button (or the ‘c’ or ‘k’ keys – see note 1) to pick the location of each point on the curve. Each point must be picked inside the boundaries of the same surface.
3. Click the right mouse button when you want to terminate the curve input.
4. Repeat steps 2 and 3 as many times as you want. The previously selected command will stay active or current until you select another command.
Note 1: You can override the default polyline ‘k’ or curve ‘c’ input style by using the ‘k’ or ‘c’ key for point input rather than clicking the left mouse button.
Note 2: If there are two or more surfaces in the area where you want to attach the curve, you must first hide the “other” surfaces before using this command. (See the “hide” and “un-hide” toolbar buttons.)
Note 3: Once defined, you can apply all of the standard curve operations to the attached curve.
Note 4: Note that straight line segments of true, attached curves may not be straight lines on the surface. The line will be straight in “parametric (u,v) space”, but the surface will be curved and the parametric space will be curved on the surface.