Copyright Goodheart-Willcox Co., Inc. 160 AutoCAD and Its Applications—Advanced When the Ruled option is selected in the dialog box, the loft has straight tran- sitions between the cross sections. Sharp edges are created at each cross section. Figure 7-11 shows the same cross sections in Figure 7-8A lofted with the Ruled option on. Compare this to Figure 7-8B. The Smooth Fit option creates a smooth transition between the cross sections. Sharp edges are only created at the fi rst and last cross sections. This is the default setting and the one used to create the loft shown in Figure 7-8B. The Start continuity: and End continuity: settings control the tangency and curvature of the fi rst and last cross sections. The Start bulge magnitude: and End bulge magnitude: settings control the size of the curve at the fi rst and last cross sections. These options only apply if the fi rst and/or last cross sections are regions. See Figure 7-12. The start and end conti- nuity can be set to G0, G1, or G2. The G0 (positional continuity) setting creates a sharp edge. The loft transitions precisely at the location of the profi le. The G1 (tangential continuity) setting is the default. It creates the largest bulge radius. The G2 (curvature or continuous continuity) setting creates a smaller bulge radius. For all three settings, bulge magnitude is initially set to 0.5. Altering the value will make the bulge either larger or smaller but has no effect when continuity is set to G0. When the Normal to: option is selected in the Loft Settings dialog box, you can choose how the normal of the transition is treated at the cross sections. A normal is a vector extending perpendicular to the cross section. When the transition is normal to a cross section, it is perpendicular to the cross section. You can set the transition normal A B C Figure 7-11. The profiles in Figure 7-8A are lofted with the Ruled option selected in the Loft Settings dialog box. Compare this to Figure 7-8B. Figure 7-12. Region profiles are lofted with the Smooth Fit option and different continuity settings selected in the Loft Settings dialog box. Cross sections were selected from bottom to top. Compare these results with Figure 7-8B. A—G0 continuity at the start and end of the loft. Bulge magnitude has no effect at this setting. B—G1 continuity at the start and end of the loft. This is the default setting. C—G2 continuity at the start and end of the loft. Compare the bulge radius to B.