Creating Shapes by Extracting Curves and Lofting

January 5, 2003 | Comments

Tutorial provided by Nemetschek North America
January 5, 2004

This VectorWorks tutorial  creates a miniature prototype of a chair.


Setting Up the Modeling Units

This tutorial works in inches.

To set up the units for modeling distances in inches:

1. Select Page > Units.

2. In the Units dialog box, select Inches from the Unit Name list.

All distances entered for designs will now be in inches.

Creating the Chair Shape

1. Select View > Standard Views > Right Isometric.

2. Click the Extruded Rectangle tool extruded_rec[1]  from the 3D Tools palette, and create a box shape. Then switch back to Top/Plan view.



3. Click the Rectangle tool rectangle[1]  from the 2D tools palette and draw a rectangle over the left portion of the box shape.



4. Convert the selected rectangle to a NURBS curve by selecting Model > Convert to NURBS. Switch back to Right Isometric view.

5. Click the Protrusion/Cutout tool  protrusion_cut[1]  from the 3D tools palette and select Extrude Face and Add from the Mode bar. Select the edge of the rectangle to highlight it. Drag the green handle up, and then enter 3″ in the Distance field on the Mode bar. Press the Enter (Windows) or Return (Macintosh) key or click the check mark button on the Mode bar to create the protrusion.


6. Add the protrusion to the box by selecting them both and then clicking Model > Add Solids.


7. Click the Fillet Edge tool fillet_edge[1]  from the 3D Tools palette and select Fillet Edge Preferences from the Mode bar to enter a constant fillet radius of 0.5″. Select the following edges (press the Shift key to select more than one edge). Press the Enter (Windows) or Return (Macintosh) key or click the check mark button on the Mode bar to fillet the edges.



8. Create a fillet of 0.25″ radius for the following selected edges.



9. Using the Flyover tool flyover[1]  from the 3D Tools palette, change the view slightly to better access the edges. Click the Extract tool extract[1] from the 3D Tools palette and select Extract Curve from the Mode bar. Select the following edges; it may be necessary to zoom in (by pressing the Space bar to enter Boomerang mode) to select all the edges.


Press the Enter (Windows) or Return (Macintosh) key or click the check mark button on the Mode bar to create a group of NURBS curves.

10. Delete the rest of the solid by selecting it with the 2D Selection tool 2d_selection[1]  and pressing the Delete key.


Creating the Chair Padding

1. Select the group of NURBS curves and ungroup by clicking Organize > Ungroup. Click Yes to confirm the operation.

2. Compose the four top-left NURBS curves into a single NURBS curve by selecting them and then clicking Tool > Compose. Perform the same operation on the right side of the chair.


3. Click the NURBS Curve tool  nurbs_curve[1] from the 3D Tools palette, and connect the top ends of the chair with a NURBS curve.



4. Switch to Top view. With the new NURBS curve selected, change the Degree to 2 in the Object Info palette. A vertex is placed in the center of the curve.

5. Click the 3D Reshape tool reshape[3]  from the 3D Tools palette and select X-axis Constrain from the Mode bar. Move the middle vertex slightly to the left to introduce a slight curve.



6. Switch back to Right Isometric view. Click the Loft Surface tool loft_surface[1]  from the 3D Tools palette and select Birail Sweep from the Mode bar. Select the two top ends of the chair as the rails. Select the top NURBS curve as the profile curve. In the Loft Creation dialog box, select the Keep Curves checkbox. Click OK to create the group of loft surfaces that form the seat of the chair.



7. Ungroup the surfaces by selecting Organize > Ungroup.

8. Thicken the chair seat to create a cushion by selecting the Shell Solid tool shell_solid[3] from the 3D Tools palette. Select Shell Solid Preferences from the Mode bar and enter an Outside thickness of 0.1″. Select each of the four surfaces in turn and for each, press the Enter (Windows) or Return (Macintosh) key or click the check mark button on the Mode bar.



Creating the Chair Frame

1. Select the four shells and group them together by selecting Organize > Group. With the group selected, select Tool > Move > Move 3D, and enter an X Offsetvalue of 5″ so that the chair frame can be easily accessed.



2. Select the profile curve at the top of the chair and press the Delete key to remove it. Click the Flyover tool from the 3D Tools palette to adjust the drawing to better access the chair frame, and then select each of the NURBS curves that make up the frame and compose them into one curve by selecting Tool > Compose.

3. Click the Ellipse tool  ellipse[1]from the 2D Tools palette and draw a circle with a Radius of 0.1″. Select the circle, and then the chair frame, and select Model > Extrude Along Path. Ensure that the chair frame is the path object, and then clickOK to create a tubular frame.



4. Select the seat and move it back to its original position by selecting Tool > Move > Move 3D and entering an X Offset value of -5″.


5. In the Attributes palette, select a seat cushion fill color. Click the Light tool from the 3D Tools palette to insert a light source, and then select View > Rendering > OpenGL to render the chair. For better results, select View > Rendering > Open GL Options. In the Open GL Render Settings dialog box, selectVery High Detail and the Use NURBS checkbox.




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