Continuing with the surface modeling explanation, after some weeks of very intense trips.
Select the LOFT command in the Create panel on the Surface tab, and then you can select curves for lofting. By using Ctrl, you can also select a surface’s edge. As usual, Ctrl enables access to subobject level, and in the case of a surface, to its edges. We need to select the edge, in order to get access to the option for continuity.
If we select a spline coincident with the surface edge, we can create the loft, but it will work as a G0, since the command does not detect the adjacent surface when choosing the spline. Once you finish selecting profiles, you will get several options. Let’s focus on Continuity.
The options for Continuity are G0, G1 and G2.
G0 (position) continuity means that there are no gaps, but there’s a sharp angle.
When you create G1 (tangent) continuity, it means that the surfaces have equal angles in their tangency.
When you create G2 (curvature) continuity, there’s not only equal tangency, but also equal radius in the curvature on both surfaces. These are the surfaces that don’t show any flaws when lights are reflected on them. That’s why Zebra analysis is so important in these cases. When the stripes in the Zebra analysis are continuous, then you have good continuity.
You will also notice that when you click on the loft, you’ll get a couple of new icons. If continuity among surfaces is involved, then you will get at least three of them.
The one depicted below (the one to the right) will define the continuity. This is the one that will only appear if at least one surface edge is selected as start or end profile. Please remember that you can change this setting at any time.
You can decide between a smooth fit and ruled loft (the latter will have G0 continuity between all internal profiles).
You can also define if the loft is normal to any of its sections.
Draft Angle can also be triggered from here, although we’ll see that the last control is basically a Direct Manipulation element for Draft Angle.
The last option is to close the surface or solid, which can also make a periodic surface (more on this later).
The control for Draft Angle can also be accessed via Direct Manipulation. Once you click on the triangle, you will get a handle that will control the magnitude of the draft angle, and reach very interesting results.