Lesson 4
Extrusions

The swept extrusion will be used and extrusions, swept extrusions and sculptured surfaces will be explained. Lesson 3's Revolutions section should be completed first.

DEFINITION:


Extrusion: a FLAT outline, used to make flat items such as a stop sign

Swept Extrusion: an outline with two surfaces adjustable, used to make items such as a decantaur, or other items where front/back or left/right are flat

Sculptured Surface: An outline with three or more surfaces adjustable, used to make items such as animals where there is no flat surface adjustable

In the picture below the buttons are from left to right, Extrusion, Swept Extrusion, Sculptured Surface. Click the Swept Extrusion button, then click your screen. Expand the Swept_Surface1 window and turn on the working grid. This is like the Revolution gird we used in Lesson 3.

Extrusions buttons

Draw out one half of your design, if the design is symetrical, if not draw out complete design. Press the thumbs up button.

Example 5

Your design is now viewed from the top down. Rotate 90 degrees on the X axis. Set X and Z to 0 and visually or if you have a exact sized node mathmatically center it on Y axis.

Edit Sweep Window

(NOTE: If you are only doing 1/2 of your design at this time you must do both front and back of your design the same.) Turn VIEW to right or left view. Open up properties on the node, click edit spine box. Then Insert Vertebra Before, this is your FRONT surface. Tab over to Scale, set scale to .9. Tab over to Trans set Z to -.25. Click your BACK Vertebra on the screen (the small green boxes at the bottom the back one is on your right), set scale to .9. Tab over to Trans set Z to .25. Tab back to Sweep and remove check from Edit Spine Box.
(Note: This gives the node a "crowned" appearance by adding more vertebra you can achieve a more rounded look.)

Spine Example

If your design was complete and not halved, you may skip the next step.
Copy your design, if the design piece is the right side, rotate so that the rotation box shows 180 rotation angle, 0x .7y and -.7z. If it is the left side, rotate it 180 rotation angel, 0x -.7y and .7z.

Node Example Rotation Screen

Translate node you are working with to 0x, 0z and the same Y cordinates as your other node. Turn your VIEW to either right or left side. To combine the nodes, move one node to 1z. Group both together in your tree window (remember to always 0 translate groups before adding to them). Now it is possible to scale and translate the group as one unit.

Example

Sculptured Surfaces are done in much the same way, except you are able to alter the other surfaces in both the outline and the spines. Since this will obviously take a great deal of practice, I will not be trying to teach by example.