Copyright Goodheart-Willcox Co., Inc. Chapter 10 Advanced Surface Modeling 249 surface edges. The Chain option is used to assist in selecting edges to create the surface patch. After selecting the SURFPATCH command, select the Chain option and select one of the edges. The remaining edges are automatically selected. Next, press [Enter]. You can adjust the continuity and bulge magnitude settings or press [Enter] to create the patch surface. See Figure 10-15B. Using the Curves option of the SURFPATCH command is shown in Figure 10-16. In Figure 10-16A, multiple curves have been created to design a sophisticated free- form shape. First, the LOFT command is used to create six loft surfaces defi ning the sides. Refer to the shaded surfaces shown in Figure 10-16B. Then, the Curves option of the SURFPATCH command is used to create three surface patches forming the top of the model. Refer to Figure 10-16C. To use the Curves option, enter it after selecting the SURFPATCH command. Then, select the curves defi ning the patch surface. NOTE NOTE Surfaces created using the SURFPATCH command may differ from those created with the LOFT command. In addition, you may come across design situations where curves used with the LOFT command will not create a surface, but will when used with the SURFPATCH command. PROFESSIONAL TIP PROFESSIONAL TIP The PREVIEWCREATIONTRANSPARENCY system variable controls the transparency of surface previews when using the SURFBLEND, SURFPATCH, and SURFFILLET commands. The default setting is 60. Setting a higher value increases the transparency of the surface preview. Exercise 10-4 www.g-wlearning.com/CAD/ Complete the exercise on the companion website. A B Top surface edges (eight total) selected with the Chain option Figure 10-15. Using the Chain option to select multiple surface edges to define the patch surface. A—The original model is a surface converted from a mesh model. The top opening includes eight surface edges. B—The patch surface created after using the Chain option to select the edges. The continuity is set to G2 and the bulge magnitude is set to 0.7.