ArchiCAD Insights: Designing and Editing in MaxonForm12 Jan, 2006 By: Ian Kenney Cadalyst
MaxonForm's Boolean operations make designing easy.
Many of MaxonForm's editing tools overlap and expand on ArchiCAD's own abilities. The Boolean operations in MaxonForm are essentially the same as the solid operations in ArchiCAD, but they offer more flexibility and provide an easier interface for executing complex operations. As a result, you can do the bulk of your designing in ArchiCAD, using MaxonForm only for the complex details, or you can work in MaxonForm from the beginning; the choice is yours.
Another advantage of MaxonForm is how easy it is to model and alter organic forms. For example, while designing a chair, you can precisely mold and form the contours of a seat or headrest , and see the changes displayed in the 3D real-time environment.
The most frequently used tools in MaxonForm are not difficult to learn; they are a series of basic commands and objects -- splines, geometric objects, object deformers and NURBS (non-uniform rational b-splines) to name a few. While these tools are simple to use, you can achieve stunning results through the conjunction of these elements.
MaxonForm treats all transformations and editors as objects. Therefore rather than simply selecting an object and twisting it, you will create a twist that appears in the Object Manager; then by combining the twist with a target object, the deformation begins.
The advantage to this system is that each action you perform is essentially preserved as an object, so you never have to undo intermediate steps in order to change an earlier action. Rather, you select any step from the Object Manager and change it using the Attribute Manager (figure 1). This method essentially chronicles the entire project history and allows you to revisit, undo or edit at any time.
Figure 1. The Object Manager lets you edit any attribute.
Using splines to establish edges and NURBS to create a skin, objects come to life quickly in the design process so that you can effectively monitor your progress and evaluate your design decisions every step of the way. In this example, the object is first created with two splines and a loft NURBS that draws a 2D skin across them (figure 2).
Figure 2. Two splines and a loft NURBS begin the design.
With the NURBS in place, you can manipulate the splines' points. The skin will project the form and display adjustments in real time.
MaxonForm's toolbox provides a number of timesaving tools that streamline the design process. For example, the Symmetry command allows you to design only half of a symmetrical object, then project the other half across a selected axis (figure 3).
Figure 3. The results of the Symmetry command on the example.
The program will match subsequent changes to the original side of the object on the mirrored side so that the symmetry is preserved even as work continues.
With all of the polygons of the seat selected, an extrusion is executed, and the 2D skin is inflated to a specified thickness. You can change the angles of the new polygons from rounded to angular with a single click.
Now a Boolean operation and a solid operator are created and positioned. The nature of the Boolean operation is determined in the Attribute Manager -- here I created a subtraction, and the object and target are grouped under the Boolean in the Object Manager (figure 4).
Figure 4. The object and target are grouped under the Boolean operation in the Object Manager.
As the modeling process continues, the focus shifts from massing a general form to more subtle details. I used the Loop Selection tool to select the outer edges of the form, then drew a spline along this loop using the Spline to Edge command. This spline is combined with a sweep NURBS to produce 3D edging. Even the most precise detailing operations become largely automated.
Using the spline that traces the edge of the seat, along with a new NURBS object, you can produce a ring of trim along the parameter of the object. Sweep NURBS require two splines as children. The first spline (highest in the subset) establishes a profile line -- the shape for extrusion. The second spline establishes the path for the extrusion. In this case, I'll use the outline of the seat for the path and a new circular spline for the profile. The result is a tubular molding along the edge of the chair. I repeated these steps to create edging around the inner parameter as well (figure 5).
Figure 5. Creating outer and inner edging with splines.
Additionally, when considering this model's scale, you can regulate the polygon count on each element to reduce the file size and rendering time. You can rough less prominent details with fewer polygons, while the most important elements can retain a high polygon count to render more clearly (figure 6).
Figure 6. Reduce file size and rendering time by selecting which details need fewer polygons.
When modeling is complete in MaxonForm, the object is sent back to ArchiCAD. Before it is opened in ArchiCAD, however, the program will save it as a GDL object and apply materials using the Materials browser. All objects assigned the same color in MaxonForm will retain the same material tag in ArchiCAD. In this example, the seat, red handle and wheels of the chair will all have the same material, while the inner and outer edging will share another material (figure 7).
Figure 7. Apply materials to your designs.
The principles that apply to creating something as simple as a single chair also apply to creating building elements.
Autodesk Technical Evangelist Lynn Allen guides you through a different AutoCAD feature in every edition of her popular "Circles and Lines" tutorial series. For even more AutoCAD how-to, check out Lynn's quick tips in the Cadalyst Video Gallery. Subscribe to Cadalyst's free Tips & Tools Weekly e-newsletter and we'll notify you every time a new video tip is published. All exclusively from Cadalyst!