2d shapes and 3d shapes12/4/2023 Obvious uses are creating wires, rope, and tubing, plant stalks, snakes, orany sort of bent stock used in manufactured items. Open sweeps are created with paths that have two ends, and are idealfor creating a curved extrusion, which the standard Extrude command can'tdo. Although helical could just be considered another open sweep, it is used so often that it deserves special mention.įIGURE 3.21 Sweep types: (a) Open sweep. Sweeps come in three basic flavors, defined by the path: open, closed, and helical (see Figure 3.21). (d) Sweep the cross-section along the path to create a 3D object. (c) Assign the cross-section to the path or vice-versa, adjusting its orientation. (b) Create a path using polylines or splines. Of course, the orientation will affect the final result.Finally, performing the Sweep operation extrudes the cross-section along thepath to create a 3D object.įIGURE 3.20 Sweep process: (a) Define a 2D cross-section. Thecross-section doesn't have to be centered on the path, nor does it need tobe perpendicular. Assign thecross-section to the path or vice-versa, adjusting its orientation. Note that this path can be open or closed. Next, create a path for the cross-section to follow by usingpolylines or splines. To create a swept object, start by defining a 2D cross-section with polylinesor splines. A sweep is a single 2D cross-section that is extruded along a path (see Figure 3.20). For example, 3D Studio refers to these operations as lofts, but many other products refer to them as sweeps, and that's what they'll be called here. SweepingĪlthough common, the next two 2D-to-3D operations have different (and sometimes contradictory) terms applied to them depending on the software being used. Lathes don't have to be a full 360°they could just as easilybe 90°, 180°, or 272°, resulting in a partial lathe.Partial lathes are useful for creating cutaway views of objects, or foreliminating unnecessary portions of the form, such as when part of the lathedobject will be inside of another object.įIGURE 3.19 Lathe types: (a) Closed lathe. If the axis is located in the center of the cross-section, it results in a closed lathe, whereas an open lathe results if the axis is moved away from the center point (see Figure 3.19). Like many 3D tools, lathe offers significantly different results depending on how you set your axis. The result is aradially symmetrical 3D object. Selecting the Lathe command enables you todefine the axis around which the cross-section will be spun. To create a lathed object, define a 2D object or objects with polylines orsplines to use as a cross-section. Along with extrude,it's one of the fundamental operations in 3D graphics. Lathe is ideal for creating any kind of radial object, such as pulleys,reels, pipe flanges, and of course, wine glasses. (bd) The Lathe operation spins the cross-section around the axis, extruding it in small steps. In 3D modeling, a Lathe command spins a 2D shape around an axis, extruding it in small steps as it rotates (see Figure 3.18).įIGURE 3.18 Lathe process: (a) A 2D cross-section is created, and the lathe axis selected. Lathes are used to create intricately carved cylindrical objects such as chair legs and bedposts. In woodworking, a lathe is a device that rotates a block of wood at high speed, enabling you to trim away at the wood with a sharp gouge. The next method of forming a 3D object is lathing. Next, select thedesired shapes and apply an Extrude operation to them, setting the depth of theobject with mouse movement or numerical entry. Note that if you create shapes within shapes, such as the two circlesin the figure, the inner ones will create holes in the object. To create an extruded object, first define the 2D shapes with polylines orsplines. InChapter 5 you'll learn how to modify the Extrude operation to make thisless obvious. (bd) Extrude is applied to the 2D shapes, giving them whatever depth is desired.Įxtrusions are very useful for creating block-like shapes, columns, panels,and the like, but the sharp-edged result definitely has a CG look to it. The result of an extrusion is a 3D object with width, height, and now, depth.įIGURE 3.17 Extrude process: (a) 2D shapes are defined using polylines or splines. An extrusion is simply pushing the 2D shape into the third dimension by giving it a Z-axis depth (see Figure 3.17). The most straightforward way of making a 2D shape into a 3D object is by extruding it. Most 3D programs make heavy use of the mouse for defining andmoving shapes and objects, but most offer numerical entry as well, enabling youto enter precise coordinates, distances, or transformation percentages.
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