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Aggregation system


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I'm working on an aggregation system at the moment and would really like some feedback and any ideas you have.

The idea is to create a system capable of replicating frost formation on surfaces such as windows etc. Then depending on how things are going it could be adapted to how rust or dirt spreads on metal.

So the basic setup is as follows:

I'm starting with just a basic grid and have a point in the center emitting particles:


These particle can then collide with walls that have been extruded around the edge of this grid and stick:


The aggregation process continues creating patterns of particles as follows:


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I'm trying to make it into a tool so it can work on multiple surfaces, giving the user availible parameters to play with.

Also I thought about feeding the points down to the shader so instead of creating new geometry the aggregation only affects the shader on the grid itself.

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  • 2 weeks later...

Hello, I have made some progesss with it. I listened to what people suggested and have got it colliding with textures instead of geometry.

I'm having some problems regulating the growth, I'd like it so people could choose areas that grow faster or slower. At the moment I'm doing this by giving the particles a probability of aggregating, so in some areas they're much more likely to stick than in others. This again is done with textures, so you can paint on high or low probability regions. However this makes it much slower as many of the particles will now fail, but I can't think of another way of doing it. Any suggestions?

Also as well as making geometry as shown in the previous pictures I'd like to be able to use the points to drive the shaders - i.e. where the particles are present a different texture is used from where there are no particles. I'm very new to shaders in houdini so if anyone could explain how to use particles to drive a shader I would be very grateful. Thanks

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  • 2 weeks later...

A little bit of an update:

I changed my system a little bit and concentrated on only having one growth point rather that it growing from every where.

This gave me points like this:


Which I then joined together:


After some resampling I've tried attaching geometry to it:


This is very early attempts so far, but if anyone has some advice on getting that pointy appearance for the ice/frost as I think I'm struggling to achieve it.


Edited by Michael1
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