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..::automatic shield generator::..

A few years ago, we would have quite painstaking operation, manually positioning and keyframing off gradients when particles or geometry intersect with the shield geometry we have set up in the scene. However, with Particle Flow we can key all of this off automatically and, if you want to take it further, even have the shields fail after a period of time or number of impacts so the ship itself is shot to hell… it is simply just a matter of setting up the desired events.

Our shield, for this example, would be a large sphere that has been scaled down a little in the Z-Axis, and should create an impact mark which would fade over time (controlled by a Particle Age map) and a fresnel perpendicular bubble effect around the region of the impact site (created by a Falloff map and nested gradients). To control the impact region generation, we are going to use a Shape Mark operator which, when set to Box Intersection, cuts a chunk out of the reference geometry and planar maps the result – perfect for our needs. Using a combination of Falloff (for the perpendicular effect), radial Gradient Ramp (one to control the impact mark and another to control the strength of the falloff so there isn’t any clipping at the edges of the cut-out geometry) and Particle Age maps we can get the resulting particle geometry to fade over a few frames after the initial impact.

The trick here is the Shape Mark’s Box Intersection parameters – we don’t want a shape that is too small so the effect is not overly visible, but also we don’t want it to be too big else, due to the way the booleaned geometry is mapped, we will have a gradient applied to the opposite side of the shield, so it is a case of playing with the settings until we get something inbetween. All we now need to introduce are a few other effects, such as a single dwelling particle to generate a glow effect at the point of impact, plus any other debris, spark effects or, if you’re any good at scripting, lighting to illuminate the hull.

Enlarge Screenshot We are using Shape Mark to Boolean out enough geometry to create a decent sized impact “plate” for our material gradient.
Enlarge Screenshot Here I’ve replaced the teapot with your average UFO, and re-linked and scaled the shield template to fit accordingly before rendering out via Video Post with additional glow elements.
Download the max file! Zip file to accompany.

..::quick tip::..

Instead of working with a bubble for the shields, try using a “Push”’d low polygon version of the spaceship hull with all polygons detached for a Dune-style shield effect!

Initially published: 3D World magazine, Issue 72, Xmas 2005.

Copyright Pete Draper, November 2005. Reproduction without permission prohibited.