SECTION 2 - Modeling and Detail Editor

38] Extruding 3D objects, By Steven Blackmon.

Extruding 2D objects into 3D objects has obvious uses. Not so obvious is the purpose of being able to extrude fully 3D objects like tubes and spheres. This tip/trick demonstrates the use of this technique to add solidity to objects that normally appear paper thin.

The basic example assumes little knowledge of Imagine. It does assume that You know how to move from editor to editor, and that You know the basic layout (i.e. what and where the user gadgets are, what a requestor is, etc.). All steps are described in extreme detail that may be mind numbing for more advanced users of Imagine.

The goal of this example is create a tube with thick sides.

Enter Detail Editor. Add a primitive tube to the worlspace. Use the default settings for all tube parameters, make sure the Close Top and Close Bottom buttons are unmarked.
Pick the tube.
Bring up the Extrusion requestor, enter 150 in the Length entry box, make sure You hit the return key to make the change active, leave all other settings as is and Perform. You should now see two tubes joined by faces at the top and bottom.

The key to this step is making sure the extrusion length is large enough so that the new points do not overlap the original object.

Change to Pick Points mode, use either Lasso or Drag Box picker to pick all the points in the second tube (the one near the top of the screen in the Top View). Make sure you DO NOT pick any of the points in the original tube.
Once You have the second tube's points picked, enter the Transformation requestor. Click the Translate button, and the cursor will now appear in the X: entry box. Leave X: set to 0 and change the Y: entry to -150 (don't forget to hit the return key) and then hit the Perform button. The second tube created by the Extrusion in step 3 should be on top of the original tube. Make sure You leave the second tubes points picked. You will then have to repeat step 5.

The key to this step is to set the Y: translation value to the negative of the value You entered for extrusion length.

Now You need to Scale the points in the second tube. Either hit the Scale user gadget, or just hit the 's' key. Once in Scale mode, hit the 'z' key to prevent scaling along the z-axis. Move the mouse to the left with the left button depressed until the Scale Factor in the status bar reads 0.80, hit the spacebar to finish.
As a final cleanup step, enter Pick Edges mode. Use the Drag Box in the front view to pick all the edges along the top and bottom of the tube. Don't forget to hold down the left shift key for multi-pick mode. Make Sharp Edges. Constant update subscribers can choose Edge Filter from the menubar and simply accept the defaults once in Pick Edges mode. This will pick all the edges that should be made sharp. Then choose Make Sharp Edges.

Congratulations, Your tube now has thick walls! Try this technique on other objects. For example, instead of a tube, try using a sphere. Make sure to delete some of the points on the sphere, or the extrusion step will simply make an unattached copy of the sphere. Better yet, choose Latticize accepting the default settings. Once You have a latticized sphere, perform steps 2-7. The only change is in the scaling step. Leave all 3 axes active, set the scale factor to 0.98 or 0.96. This procedure will create a THICK lattice that is much more realistic.

The advanced example assumes a working knowledge of Imagine.

We are going to use a temporary project file, use the Shredder F/X to fracture a heavily subdivided sphere, save a snapshot in the Stage Editor, extrude the fractured sphere in the Detail editor, then recenter and scale the new points.

Enter the Projects Editor. Create a New Project called 'TEMP', or some similar name.
Go to the Detail editor and add a heavily subdivided sphere (Circle and Vertical divisions = 36, Stagger Points: ON) and save it.
In the Action editor, set the Frame Count for the temporary project to 30. Add the the sphere and set Start Frame=1, End Frame=30.

Add the Shredder F/X to the sphere. Change the settings until You have a sphere You like. You will have to jump back and forth between the Stage and Action editors, tweaking the numbers until You get a fracturing You like in one of the animation frames. OR You can try the following Shredder settings, which look good in a 30 frame animation at frame 7:

Start frame:	1	End frame:	30
La Machine:	ON
Maximum triangles in Group:	8
Start / End time (seconds):	0.0, 1.0
Explosion Timing Delay (%):	10
'Hold at' frame number:	0
Bounce:	ON
Flip on Bounce:	ON
Ground Z position (Imagine units):	-100
Use Average bounding sphere:	ON
Elasticity Min/Max (%):	5.0, 15.0
Initial Velocity range Min/Max (m/s):	1.0, 1.0
Triangle Rotations Min/Max (rot/s):	0.0, 0.1
Particle Trajectory Min/Max (degrees):	0.0, 45.0
Final Scaling Factor Range Min/Max:	1.0, 1.0
Imagine Units per meter:	20.0

In the Stage editor save a Snapshot of the fractured sphere from the desired frame. If You're using the settings above, take the snapshot in frame 7.
In the Detail editor, Extrude the fractured sphere 150 units. Pick the newly created points with either the Lasso or Drag Box.
Translate the new points via the Transformations requestor -150 units along the Y axis.
Scale the new points by 0.1 in all three axes.

With a little texturing, You have the basic busted spheres from Steven's Emergence picture.

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