I've been using the technique from Ben Watt's Growth Propagation tutorial [vimeo.com].

I'd like to add a leading edge to the effect. So a hot edge which then leaves what is left behind cooler. Probably easier to see what I mean by looking at the attached file.

Currently I'm using the growth propagation and then Time Shifting another version and using that to delete (by colour) the older points.

This works ok but I feel like there probably is a more elegant solution, quite possibly just in the Attribute VOP in the Solver.

Any pointers appreciated.

Thanks

Here's one way…

Thanks again Matt. Much appreciated.

It's a funny thing, it's half way between obvious and head melting.

Heh, here's an alternative way, might be a little less confusing.

This uses the nearpoints() function rather than pclookup, I find it easier to follow. I also use wrangles rather than vops; any time you're doing looping over things, to my eye it just reads more clearly.

The logic is simple, I tag a few points as active, then in a solver, I use nearpoints to get the closest 10 points with 0.1 units.

I then loop through the points, if any of them have an @active value of 1, I add a small amount of @active to myself, clamping it to 1. This has the effect of spreading @active over the points, at a controllable rate.

I do another test, if the current point has @active of 1, I start trackig its age, by adding 1 to its @age attrib each frame.

Outside the solver, I can then use @age to drive a colour ramp.

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