Audun Ase
June 8, 2021

While working in the wicked world of Houdini, there are certain tasks we do over and over again. Now, while many of those methods are covered by our friendly neighbor SideFx, it is always useful to make your day easier by automating certain things. Here I'll share with you one of my favorite assets from my toolbox. So what does it do? It deletes stuff…

Kicking particles in the arse with style,

Kickblast - Delete Presets

Kickblast is a digital asset I created to avoid having to manually delete stuff, over and over again. “Kickblast” is essentially a collection of different methods for deleting points primarily. It functions purely as a time saver. I've done a bit of work on it lately to be slightly more useful and more compact. I still use it a ton, so I really want to keep the maintenance on it for you guys to use as well.

If you are sold on the idea and feel like this is the next HDA for you. Jump ahead and grab it at the bottom of the page. If you want to know what it does? Read on!

Last updated 25/01/2021


1# Delete by Color / Cd

Hopefully very self explanatory, delete based on Cd attribute. Drag the Threshold slider to tune your selection.

2# Delete by position / P

This will delete points based on position. The bounding box checkbox will clip based on the 'bbox' of the input. Turn this off to get absolute position value. This method is directional, so you need to select your axis and delete from there.

3# Delete by velocity / v

This will delete points based on velocity. I very often have the need to delete or group based on a points velocity, which is why this has been built into the Kickblast. You could do this using the attribute value as well, but I like having a quick pre-set. This will take the length of v and fit it to 0 - 1, which then is added to the Threshold slider.

3# Delete by percentage / %

Another classic! Delete a percentage of the points, very handy for quickly down sampling a heavy particle sim. Good for lowering point density. I recommend using the id option on simulations to retain the selection over time.

4# The "Point Stamper"

Slightly more advanced, but still very useful. This pre-set will reveal a point once, and never again. This is nice for disintegration type effects, where you have a point cloud where you are progressively revealing / introducing points to a simulation.

This setting has two modes - Pre-placed and Continues. Both designed to do a similar job, for slightly different scenarios.

"Pre placed" just means that all points we want to emit from already exist. "Continues" does the same, but from points that are simulated or introduced over time. Keep in mind that this will require unique id attributes for the solver to keep track of the points.

5# Attribute Density

A newcomer to the Kickblast family. This setting will delete based on a "density" attribute. Kickblast will gradually delete points based on this attribute.

You could think of it as a value from 0 - 1, being the likeliness of a point being deleted.

1 = 100% likely to get deleted.

0 = 0% likely to get deleted.

Summed up

Time and time again, I've had the need for Kickblast. It has replaced a lot of the manual labour that comes from having to re-create different types of filters. I'm excited to keep adding things to this as I learn more, and my needs expand. Writing this post has made me realise how epic this asset could be for creating UI interfaces with great options for creating variation and glitchy effects. Kickblast works well in combination with each other, for example while creating dissolve like effects.

Audun out...

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