With traditional CAD software like AutoCAD, computers have become an efficient means for the production of construction documents, but despite large advances in computer graphics capabilities, traditional drafting software has failed as a professional tool for creative design work. DesignWorkshop is different.
Over a period of years, our research has looked into the interaction between existing design media, such as pencil and paper sketching, and design processes. This has provided the foundation for a new approach to design-oriented CAD. We believe it is absolutely vital for any real design tool to get out of the way of the creative process-for the tool to leave the designer's attention free and available for creative application. In the hands of an experienced user, pencil and paper certainly meet this criteria.
With a moderate amount of practice, the classic Macintosh 2D drawing interface also gets out of the way, allowing the designer to focus on images and ideas. This is possible because the total interface-including noun-verb selection syntax, direct graphic manipulation of objects, and a minimalist iconic command set-allows the designer to produce graphic results with a small set of fairly general functions.
This power of the Macintosh drawing interface is opposite in approach to traditional CAD software, which tends to use a large set of very specialized commands to produce drawings in a painstaking and linear process. Becoming more expert in the traditional CAD environment can actually make it more difficult to get back to a creative aesthetic or problem-solving mode, as command complexity is accumulated.
DesignWorkshop has been created from the ground up to provide a powerful, natural, broad-spectrum design environment for architects and other building designers. It solves the CAD complexity problem by extrapolating the classic Macintosh drawing approach into three dimensions, building a familiar-seeming though fundamentally new interface.
The interface is familiar because it builds directly on the standard Macintosh way to perform key operations. For instance, to move an object, the user can simply click on it, then drag it to a new location anywhere in the model space. To resize an object, the user selects and then drags on object handles. Advancing these familiar methods from the 2D Macintosh drawing world into 3D provides tremendous modeling flexibility using just a few commands.
The DesignWorkshop interface is also fundamentally different. To allow three-dimensional direct manipulation, the focus of interaction is moved from the inherently two-dimensional window pane of the computer screen into the model space itself, in the form of a three-dimensional crosshair. Together with a suite of interface innovations that provide essential cues for depth and relative position, the 3D crosshair makes it possible to do most modeling work in realistic perspective views.
A simple "chording" with the standard keyboard allows the three dimensions of the DesignWorkshop crosshair to be easily controlled by the standard mouse. Dragging the mouse around on the table top moves the crosshair horizontally, in an x-y plane, while dragging with the option key moves the crosshair up and down vertically. By dragging and pressing and releasing the option key, the crosshair can be moved quickly anywhere in the model space, without interrupting the current function. The 3D crosshair puts the design tool into the model space, instead of a normal cursor floating across the 2D window. This is the foundation for a complete 3D analog of the classic Macintosh drawing environment.
The proof of this approach is that major 3D editing operations-like moving, resizing, and reshaping objects-are accomplished interactively in perspective or axonometric view in the default selection mode, without giving any commands. Poly-lines are extruded into solid objects just by pulling up on them (or sideways, if the lines were drawn in an elevational plane). DesignWorkshop will automatically supply a missing segment if necessary to form a solid when extruding, and extrusions are readily reshaped, interactively, in place, with object-global transformations in default mode, or by local transformations when in the special reshape or faces modes.The 3D crosshair is coupled with an underlying object-oriented geometric structure classified as feature-based solid-modeling. This approach means, for instance, that a complete window object can be put in a solid wall object just by clicking on the opening tool icon, then dragging a rectangle on the face of a selected wall. The crosshair aligns to the wall automatically. After the opening has been drawn, it can be selected by clicking, and moved around the wall, and its size and proportion can adjusted by dragging on a corner handle. It is duplicated by the standard command-D shortcut, or deleted by hitting the delete key, leaving a solid healed wall.
Innovations at other levels of the program support the three-dimensional architectural design environment. For instance, Space-Jump and "projection lines" support accurate working in free 3D space. When the spacebar is tapped, Space-Jump instantly sets the crosshair to the three-dimensional position of an existing object handle (for instance, to draw a roof on top of a wall or building mass) by converting a 2D alignment into a 3D alignment. This eliminates any need to "drive" the crosshair laboriously around the model space, to get from one working area to another.
Projection lines are like outline shadows cast vertically from objects down onto the ground plane. These show automatically for selected objects and objects being created, and for other objects as turned on and off with functions in the Arrange menu. The viewer's perceptual system automatically and unconsciously uses the projection lines in building a correct mental model of a 3D scene in wireframe view. For instance, without projection lines you might not be able to see the difference between a small block close to the view point and high above the ground versus a large block in the distance sitting on the ground.
In DesignWorkshop the traditional "working planes" concept is made somewhat obsolete, because the three-dimensional crosshair allows immediate access to all parallel planes. (This family of parallel planes includes all those perpendicular to the current "z" axis.) Instead, we talk about the "working orientation," which can be switched instantly from plan to elevation or to an arbitrary orientation at any location. The arbitrary working orientation can also be matched instantly to the attitude of a selected object or object face, just by double-clicking the arbitrary working orientation tool.
The viewing tools are also based on 3D direct-manipulation, and from the building designer's perspective. On a typical hardware-graphics 3D workstation, dynamic view controls are used to move a part around on screen to see it from different angles. This is subtly incorrect for architectural work, because, unlike mechanical parts, buildings stay still. To see a building from another aspect, the viewer moves, rather than the building. In DesignWorkshop dragging in the scene with the Eye tool moves the viewpoint around the scene in real time, pivoting around the center of interest. Holding down the option key while dragging up or down moves the viewpoint into or out from the scene. The Look tool is used to drag around the center of interest, or "look point", providing the equivalent of standing in one place and looking around. With simple, interactive view adjustment, shifting the view a bit to see the project differently, check a sight line, or inspect an alignment becomes natural, frequent, and nearly unconscious.
Fast 2D zooming functions support getting into detailed views quickly and easily, and 2D panning is controlled by standard Macintosh scrollbars. Multiple windows can be opened simultaneously, showing a model from several views. Multiple models can also be open at the same time, with standard clipboard cut-and-paste of 3D objects between models. Particular views are easily saved, with the view name added to the menu for easy access. These saved views form the starting point for walkthrough capabilities, with list editing and variable interpolation. The goal of making DesignWorkshop a fast and efficient tool for architecture has driven more specific modeling features as well as the fundamental interface. For instance, the Edit menu Wallify function turns multiple selected massing blocks into walls enclosing spaces in one menu pick. Two-dimensional graphics can be pasted onto objects in space, to depict signage and decoration. The Object Info box allows direct inspection and quick numerical editing of object dimensions, specification of object phase and material, etc. Objects carry material information, and, optionally, object names and data. And Paste into Openings, new in DesignWorkshop 1.1, automatically places door and window frames into wall openings (automatically rotating, scaling, and aligning as necessary) as quickly as you can type "Cmd-V".
In DesignWorkshop, three-dimensional objects are handled in a custom format, with all coordinate information in floating point, so there are no worries about scale changes and rounding errors. On the other hand, screen drawing and 2D manipulations are mostly done with standard QuickDraw, so unlike some 3D programs, there are no problems with normal Macintosh functions like printing or 2D cut and paste. In DesignWorkshop pasting a clipboard selection of 3D objects into a 2D graphics program places 2D PICT object graphics according to the view projection at the time of selection.
At any stage an evolving model can be viewed and edited in shaded or hidden-line view for visual completeness, or in wireframe for speed. The shading routines include architectural niceties such as automatic poche of cut faces in section views. Shadow-cast renderings are done in 32-bit color with a ray-tracing algorithm, and sun angles are set by time, date, and latitude. The sun study function renders sequential time-lapse frames in parallel and directly saves QuickTime movies.
DesignWorkshop also has the depth to follow design into development. For example, support for Apple's Publish and Subscribe technology allows 2D views of a 3D building model-plan, section, elevation, perspective, or whatever-to be exported to Subscribe-capable drafting software with live links, permitting a whole drawing set and a multi-person project team to continuously synchronize to the 3D design model. The "subscribers", working in the 2D software of their choice, are updated automatically when changes are saved at the master model.
In actual use, most CAD software draws users into minutiae, sometimes at the expense of common sense and the big picture. In contrast, because it's easy to learn and fast to use, thoroughly visual and interactive, DesignWorkshop encourages creative exploration.
DesignWorkshop is design-oriented CAD from the ground up. It combines a fundamentally new 3D interface with careful fitting of CAD technology to architectural design operations, without losing the generality of a good design tool.
© 1993 Artifice Inc., used by permission
Posted 95.10.25 KMM
Send e-mail: matthews@artifice.com