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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