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Part III: Modeling Basics

Note
You can make sections only from intersecting a 3D object. If the cross-sectioning plane doesn’t intersect the 3D
object, then it won’t create a shape. You cannot use the Section primitive on shapes, even if it is a renderable
spline. n
The Parameters rollout includes settings for updating the Section shape. You can update it when the
Section plane moves, when the Section is selected, or Manually (using the Update Section button). You
can also set the Section Extents to Infinite, Section Boundary, or Off. The Infinite setting creates the
cross-section spline as if the cross-sectioning plane were of infinite size, whereas the Section Boundary
limits the plane’s extents to the boundaries of the visible plane. The color swatch determines the color of
the intersecting shape.
To give you an idea of what the Section shape can produce, Figure 12.12 shows the shapes resulting from
sectioning two Cone objects, including a circle, an ellipse, a parabola, and a hyperbola. The shapes have
been moved to the sides to be more visible.

FIGURE 12.12
You can use the Section shape primitive to create the conic sections (circle, ellipse, parabola, hyperbola) from
a set of 3D cones.

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