Manufacturing

form•Z Basics

1 Aug, 2002 By: John E. Wilson


form•Z is a versatile, moderately priced 3D modeler from auto-des-sys, Inc. used in designing a wide range of items from children's toys to skyscrapers. It runs on computers using either Macintosh or Windows operating systems. Last month's 3D column gave you an overall look at form•Z. This one will focus on form•Z's tools for creating and working with basic geometric shapes.

Toolbars and Palettes
Before you begin creating form•Z objects, you are likely to use the buttons in the Window toolbar to establish the conditions for drawing and viewing objects. With this toolbar, which by default is located on the lower-left edge of the graphics window, you can set object snaps, perform zooms and pans, set 3D viewing directions in real-time, and establish the location and orientation of the drawing plane (or the reference plane, as form•Z calls it). The toolbar also has a button for turning mouse movement snap-to-grid on and off, and by double-clicking this button you can set the spacing of the grid. The Perpendicular button enables you to move and copy objects in the z-axis direction.

The Modeling toolbar is for creating objects and working with and modifying them. By default it is positioned on the left side of the graphics window. With the exception of the Delete button, you can expand each to display a palette of additional tools and tear off these palettes to keep them displayed and positioned in convenient locations.

form•Z uses the term palette for small floating windows that display information, establish parameters and options, and issue command-line prompts, as well as for groups of toolbar buttons. Applicable palettes also appear as you perform an operation. For example, when you select the Cone tool from the Modeling toolbar, the Tool Options palette will display the options available for creating cones, and the Prompts palette will ask you to specify the location and size parameters for creating the cone in accordance with those options.

form•Z Primitives
The tools for directly creating basic 3D shapes-cubes, cylinders, cones, spheres, and tori--are in the Primitives palette, accessible from the top-left button of the Modeling toolbar. You specify the location of these objects with your pointing device or by entering point coordinates in the Prompts pallet. Despite their name, cube objects do not have to have their six faces be the same size. You can specify their width, depth, and height values by using your pointing device, entering length values in the Options palette, or putting point coordinates in the Prompts palette.

Cone primitives can either taper to a point or be truncated. Cylinder, cone, sphere, and torus primitives can be based on an ellipse, rather than a circle and can have sections cut from them. For example, you can create a sphere, cone, or cylinder that has a pie-shaped cut section. You can also specify that the flat faces on these primitives be left open to create a surface object, rather than a solid object. Figure 1 shows examples of form•Z primitives.


Figure 1. form•Z's five primitive objects can assume a wide variety of forms to create both solid and surface objects. The primitives in this figure are in form•Z's Quick Paint display mode, which gives rounded surfaces a faceted look. The surfaces, though, are smooth.

Spherical Objects
The Spherical Objects tool is one of two tools in the Ball palette, located to the right of the Primitives palette. It does more than create round objects. With it, you can create objects having four, six, eight, 12, or 20 faces, as well as a soccer ball that has 24 faces. These 3D objects can be based on either a circle or an ellipse See Figure 2 for examples of spherical objects. As with the primitives, you can specify the size of spherical objects with your pointing device, or by entering values in the Prompts palette or in the Tool Options palette.


Figure 2. The Spherical Objects tool creates a variety of objects that have flat faces. Despite its name, it can create objects having as few as four sides. The spheres shown in this figure are displayed in form•Z's hidden-line viewing mode.

The Revolved sphere and Geodesic sphere options of this tool create 3D objects similar to the ones made by the sphere primitive, but their surfaces are faceted rather than being a smooth mesh. The revolved sphere facets that touch the poles have three sides, while all of its other facets have four. The surface of Geodesic spheres, on the other hand, is composed entirely of triangular facets. Edit boxes in the Tool Options pallet give you control over the facet size of both sphere types.

The other tool in the Ball palette creates metaballs. Metaballs are easy to make, but their purpose is not obvious, so we will save our coverage of them for a future column.

Editing Primitives
form•Z offers a variety of methods for editing primitives. One method is to use the Edit Controls tool, which is located in the Pick palette. You will be prompted to select an object, then two sets of arrows will appear on the object you select. One set is for size control and the other for angle control. For example, when you select a center-cut truncated cone, as shown in Figure 3, size control arrows will point away from the circumference and away from the center of the top and bottom faces. You can click-and-drag those arrows to change the radius and the length of the cone. In addition, angle control arrows, which have a 90-degree bend, will be on the bottom surface of the cone, and you can use them to rotate the cone and change the size of the slice.


Figure 3. The Edit Controls tool is for modifying form•Z's primitive objects. It displays size-control arrows you can drag to change parameters such as radius and height; plus angle-control arrows for rotating objects and changing the angle of sliced sections.

The Edit Surface tool, which is also on the Pick palette, is for changing the size of a primitive object. You will be prompted to pick one object, and an arrow will appear on the object at the point you pick. Then, the object changes size as you drag your pointing device. For instance, if you pick a point on the side of a cone, you can increase or decrease the radius of the cone's base by dragging the arrow. The height of the cone stays the same, with its taper changing to match the radius of its base. You can, though, hold down the Ctrl key on a Macintosh, or Ctrl+Alt on a PC, to maintain the taper angle of the cone as it is enlarged. This creates a truncated cone.

These two editing tools on the Pick palette are handy for modifying objects with your pointing device, but they do not permit you to change sizes numerically, or to change an object's parameters. Furthermore, you cannot use them to modify objects made with the Spherical Objects tool. Both of these limitations are overcome, however, with the Query tool, which uses a question mark as a button icon.

The Query tool prompts you to select an object, and then displays a dialog box containing information about the object. This dialog box has a button labeled "Edit" that opens a second dialog box having fields that are appropriate for the object. For example, when you select a spherical object, the coordinates of the object's centerpoint are displayed, along with all of its other parameters, such as its size and shape. You can modify any of the displayed settings and values, including the shape of a spherical object from that of a cube to that of a geodesic sphere.


About the Author: John E. Wilson


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