Provide the top and the rim the hat
| 384 |
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To draw a disk, you specify both an inner radius and an outer radius. If the inner radius is 0, you get a solid disk like the one shown in Figure 10.7. A nonzero radius gives you a disk with a hole in it, as shown in Figure 10.8. The disk is drawn in the xy plane.
FIGURE 10.7 A quadric disk showing loops and slices.
| FIGURE 10.8 | Built-in Surfaces | 385 |
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A cylinder is used for the body of a black top hat, and two disks, one closed and one open, provide the top and the rim of the hat. The output from SNOWMAN is shown in Figure 10.9. Listing 10.1 shows the rendering code that draws the snowman by simply transforming the various quadric surfaces into their respective positions.
