Spaceship shield (Imagine 2.9 and higher)

(By Charles Blaquiere)

To do a Star Trek-like "shield absorbs energy blast and dissipates it", you need to create a sphere for the shield. You then use Shellturb combined with SwapCRF to _vary the transparency_ of the texture and make the energy blast visible.

Here's an example:

Column One     Two
      ____    ____
       0       0.4          Axis position: 110, 0, 0
      20       0.4          Alignment: 0, -90, 0
      30       0
      20       0
      10       0
       5       0
       4       0
       0.4     0

You'll see an energy blast hit the right side of the image, where the ship inside the shield would presumably be pointing, and travel along the shield, dissipating as it goes along.

How does it work?

The base object is white, and gets a turbulent band of black applied to it using Bandturb. Then, SwapCRF turns this color information into _filter_ values -- black means no filter, white means fully transparent. This makes part of the shield visible. All that's needed is to give the visible parta of shield a color using Solid. Finally, we create two states, START and END, which allow the texture axis to travel from one end of the shield to the other. The END state also has Bandturb's Fade parameter set all the way to 1, so that the texture loses strength as it travels along the shield. Just add a ship inside the shield, and a starfield in the background. The effect is beautiful.

Bug alert:

Imagine 3.1 doesn't remember texture parameters and axis settings very well when you use States. Until that bug is fixed, you will need to create two separate objects, Shield-start and shield-end, and morph from one object to the next. No big deal.

Last Update: July 13, 1995
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