Soft-Body Physics - Learn SpriteBuilder for iOS Game Development - page 351

Figure 10-9 . The first circumference distance joint's properties
Now continue to add seven more distance joints in the same way. Start by connecting the
bottom-right node with the bottom node, and continue to connect the neighboring nodes in
clockwise order. Once you have added eight distance joints that form a circle as shown in
Figure 10-10 , be sure to verify that all of the joint's properties are identical. Tiny vari-
ations in minimum/maximum distance are acceptable.