Often, the hardest part of modeling is object creation. Understanding how Swivel creates an object will enable you to create fascinating three dimensional images as easily as painting or drawing in standard two dimensional packages. This technical note demonstrates how Swivel's code actually creates an object from the input in the drawing windows.
Once having created a model, Swivel provides great flexibility for use with other software packages, such as Adobe Illustrator, where perspective drawing becomes as easy as setting the desired view and exporting an image form Swivel. In less time than it takes to draw the same object in many different views with any other graphics program for the Macintosh, the same image created in Swivel 3D once can be exported in countless perspectives and even saved to a PICS file for animation.
New Object Tool
To get started in Swivel 3D, l;let's create a simple object that is symmetrical about one axis of rotation (e.g. a light bulb or a wine glass.) In this example, the object that will be modeled is a wine glass.
Note in Figure 1 (from Swivel) that the glass is symmetric about the axis drawn. Here are a few quick and easy steps to help you re-create this object in Swivel.
1. First select the New Object Tool (the "Cube Tool") , seventh down on the Tool Palette
2. Click on the World to place the object. The object will "flash" if it is selected.
3. Choose Redesign Object from the Object Menu. This will bring you into the design interface of Swivel 3D. There are four views. The Object View represents the view of the object as it appears in the World View. The Top Section represents the plane which "slices" though the middle of the object as it is viewed form above, as the Side Section and the Cross Section represent their respective planes (see figure 6.)
4. Select the Free Ply Tool, third down on the Design Object Tools Palette. Click the points into the Top View as shown in the pattern below. Note that for each point added Swivel will add a point mirrored about the axis (left to right.) Also note that for every point added in the Top View, the same points are added in the Side View. This makes it very easy to re-create symmetrical objects in Swivel.
4a. Here's a designing tip for the new 3D user. While drawing an abject, do not restrict yourself to thinking about an object such as a wine glass in the conventional orientations (i.e. that the opening of the glass is toward the sky.) Visualizing the glass on its side makes re-creating the glass in Swivel very easy.
5. After drawing the "lathe" form which the Swivel object is created, click on the N-gon Tool (the Circle Tool") fourth down on the Design Object Tools Palette, and click on the Cross Section. A default circle will snap onto the grid.
6. Click on any of the Section Views and note that the Object View redraws the wireframe image of the object as it appears in the World View. Close the design interface to return to the World.
It becomes even easier to draw objects of greater complexity in Swivel with an understanding of what Swivel does to re-create a three dimensional object form the design drawings. The following example of a bread loaf appears on page 17 of the Swivel 3D User's Guide.
First, imagine the loaf of bread as it exists in the real world. Looking down one end of the loaf to the other end, imaging what the loaf would look like when sliced in half:
This view represents the cross-section of the loaf in Swivel's design window (left.) As you look over the top of the loaf, imagine what the loaf would look like when sliced in half:
This view represents the top section of the loaf in Swivel's design window (left.)
As you look at the loaf from the side, imagine what the loaf would look like when sliced in half:
This view represents the side section of the loaf in Swivel's design window (left.) For the sake of a simple example, the top and side planes are made symmetrically. Asymmetrical objects will be covered in Technical Note #2. In order to create this loaf of bread, Swivel combines the three half loaf views given above.
What Swivel does to create the object is to combine the side plane (or side view in the design window) and the top plane (or top view in the design window) and then to stretch the cross-section through these two views. This creates a series of intersecting lines linking the points specified in the drawing views that define the outline or boundary of the object. Thus, from the drawings (Fig. 6, left), Swivel re-creates the bread loaf (Fig. 6, right.) In the "cube object," the dimensions are controlled by the drawings in the top and the side sections. The cross section conforms to the dimension defined in the other two views.Precision Extrusion Tool
Precision Extrusion Tool
This object creation tool is analogous to a cookie-cutter. As compared the "cube" tool's cross section, the cross section of the "triangle" tool gives the size as well as the shape of the object. The top and side sections regulate the depth of the object and the two sections are equivalent in magnitude
To get started with this tool, let's create the letter "A." The letter "A" also serves as an example of how to put a hole in an object.
1. First select the Precision Extrusion Tool (the "Triangle Tool"0, the eighth down on the Tool Palette.
2. Click on the World to place the object. The object will "flash" if it is selected.
3. Choose Redesign Object form the Object Menu. This will bring you into the design interface of Swivel 3D.
4. Select the Free Poly Tool , third down on the Design Object Tools Palette. Click the points 1 through 13 into the Cross Section as shown in the pattern (Fig. 7.)
4a. Note #1: To create any object that encloses a hole, trace the inside of the hole. Then, to close the hole, draw over the line entering into the hole and continue with the rest of the design (notice the position of points 8 and 9.) This input will instruct Swivel to create an object with a small boundary at the place which is "double-lined," and in the World View the object will appear to have a hole.
4b. Note #2: Alternatively, any font can be created by copying an image of a letter form the Scrapbook and using it as a template. To do this, click on the cross section bar, open the Scrapbook, copy the image form the Scrapbook, close the Scrapbook, and paste the image into the Cross Section view. Then, select the Free Poly Tool and trace the outline of the image (as done in Step 4.)
5. After drawing the "cookie cutter" from which the Swivel object is created, click on the Rectangle Tool, fifth down on the Design Object Tools Palette, and drag the "width" of the object into the Top Section. Remember that the top and side sections of an extruded model are equivalent in magnitude.
6. Close the design window to return to the World.
Exporting a PICS file for Animation
1. This simple example will help familiarize you with Swivel's animation capabilities. First, select New from the File Menu.
2. Select the New object Tool and click on upper left of the World to place the object.
3. Select the Precision Extrusion Tool and click on upper right of the World to place the object.
4. Select Open Tween Panel from the Effects Menu. this will bring out a control panel for Swivel's animation functions.
5. Click the Options... button on this panel to access the tweening options. Write to PICS allows you to create a PICS file which you may import to any animation program. The tween from Object's View function allows you to see the changes form the selected object's viewpoint. As in the Effects... function, more than one option can be selected given time. For this example, check the Write to PICS box only.
6. Click Set Key to set the first keyframe of your animation. The Set Key function is also used to reset keyframes that you wish to adjust (see below in Step 10.)
7. Having set the first keyframe, click back onto the World. Select the cube and drag it to a new position. You may scale or rotate the object in any way. Now select the triangle and drag it to a new position. You may scale or rotate the object in any way. However, Swivel does not allow change in an object's design within a tween sequence.
8. Click Add Key to add the next keyframe. Swivel can accept up to sixteen keyframes, so you may repeat this step as necessary. The number of frames generated between keyframes can be typed in. Keep in mind that the greater the number of frames, the smoother the motion will appear between keyframes when playing the PICS file in an animation program.
9. After setting the keyframes, click Preview to view a wireframe rendering of the motions.
10. To adjust any of the keyframes, click the up or down arrows to get to the frame you wish to change. Adjust the position, attitude or scale of the objects and click Set Key.
11. Click Tween. Name your PICS file and click Save. Swivel will now generate a PICS file. Options which are selected in the Effects... function will be rendered for each frame of the PICS file.
12. More complex motions can be created with these simple function. As example is included with the demonstration diskette.
Conclusion
This simple introduction to Swivel 3D shows the basic tools by which more complicated objects can be constructed by using the linking features. The "cube" and the "triangle" tools are the building blocks, and the key to designing in Swivel is not trying to create a very complex object form a single cube.
The technique of slicing an object in half can easily help visualize the sectional drawing for any object. This tip and a reminder not to restrict yourself to the conventional orientations of the world will enable you to recreate any of the objects shown on the cover.
Call Macromedia at 415-442-0200 if you require any further assistance.
WORLD VIEW TOOLS
XY Arrow moves objects across the plane
of the screen. Click on an object and drag
it to a new XY.
XZ Arrow moves objects in and out of the
Z axis. Drag upward to push object back, downward to pull it forward.
Yaw Arrow pivots an object around the
Y axis. Drag the object to a new attitude.
Pitch Arrow pivots an object around the
X axis.
Roll Arrow pivots an object around the
Z axis.
Scale Tool makes an object larger or smaller. Drag the object downward to enlarge, upward to make it smaller.
New Object Tool creates a new object. Select this tool and click where you want to put a new object. The object will always be a default cube.
Extruded Object Tool creates a new object whose scale is determined in the Cross Section View. The object will be created as
a flat triangular solid.
DESIGN OBJECT TOOLS
Double Arrow edits the upper and lower contours of any of the section views. Double click to choose whether to edit on two Sections at a time.
Single Arrow edits a single contour in any one of the section views at a time.
Free Poly Tool creates a new contour with a series of clicks in any of the section. Works in the Top and Side sections simultaneously.
KEYBOARD EQUIVALENTS
Keyboard Equivalents for Adding/Deleting Points
To add a point, hold down the Command key and click on a place along a line. A new point will appear in the last spot where the mouse was clicked.
To delete a point hold down the option key and click the mouse on an existing point.
Keyboard Equivalents for Zooming
To Zoom in on a Object View and Side, Top and Cross Section, hold down the Option key and click on the view's sidebar.
To Zoom out, hold down the Command key and click on the view's sidebar.
Keyboard Equivalents for Moving and Scaling Objects
Select either the Shift, Option, or Command Key then choose the object by clicking and holding the mouse button down. Next drag the mouse to see effect. You can use these tools one after another by continually holding the mouse button down.
To select: Hold down:
Yaw and Roll Option
Yaw and Pitch
Scale Object Shift
Retain same tool as long as Caps Lock
Caps Lock Key is down
COMMAND KEYS
File Menu
-N New: Creates a new document.
-O Open: Presents a file dialog from which to open a Swivel document.
-S Save: Saves the file you are currently working on.
-U Export File...: Asks for a file name, then creates a file of the type selected.
-P Print...: Prints the current document in the format selected in the Output Style dialog box (Edit Menu.)
-Q Quit: Quits the application.
Edit Menu
-Z Undo: Cancels the last action.
-X Cut: Cuts an object and its links and places it on the clipboard.
-C Copy: Copies an object and its links and places it on the clipboard.
-V Paste: Pastes an object form the clipboard into a document or it an object is selected, will replace the selected object in its position, orientation and scale.
-D Duplicate: Duplicates the current object and all objects linked to it.
-L Duplicate Link: Duplicates the current object inheriting constraints, position, attitude and scale.
-7 Paste Command: Pastes a Command File Language command from the clipboard.
-8 Paste Background: Pastes a PICT image from the clipboard onto the background of the current world.
-9 Clear Background: Deletes the PICT image on the background.
-F Find...: Opens a dialog in which objects can be searched and named.
-6 Info...: Opens a dialog where by objects can have TEXT associated with them (Output Style dialog box.)
-I Inherit...: Opens a dialog offering six inheritable options which can be passed from parent object to aqualities down through all objects linked to it.
Object Menu
-R Redesign Object/Return to World...: Opens the selected object to the Design Object View and toggles back to the World View.
-W Object Position...: Opens a dialog for editing the current position of the object and its allowable range of motion.
-E Object Attitude...: Opens a dialog for editing the orientation or Yaw, Pitch and Roll of an object.
Effects Menu
-G Effects...: Opens a dialog box with six special rendering options and will render when Effect Render is selected or during a Tween.
-H Effects Render: Renders the World with all selected Effects.
-J Select Color: Opens the Intermediate Palette for color selction.
-1 Set Key: makes the current World View the current KeyFrame.
-2 Add Key: Inserts a new KeyFrame after the current KeyFrame.
-3 Clear Key: Deletes the current KeyFrame.
-4 Next Key: Displays the next KeyFrame in the Tween sequence.
-5 Last Key: Displays the previous KeyFrame in the Tween sequence.
-T Tween: Starts the Tween with all options selected.
-Y Preview: Allows a fast Tween of a model as simple wireframe cubes.
