HOW DO YOU REPLACE SIMULATED PARTICLES WITH CUSTOM GEOMETRY USING MAYA?

Lee Hart, USA

Maya has an amazing set of tools for particle simulation. Personally, I prefer its nparticles system over any other particle system because of the Nucleus node, which is amazing in the way that it ties together every single simulation you do in your world. Everything you do has the same universal settings such as a ground plane and wind direction. That’s what makes it easier to work with and simply better, in my opinion, than any other simulation module in the industry. nparticles itself has quite a lot of different geometry types built-in, but now, in Maya 2017, which ships with Arnold, it has become a bit of a hassle to deal with the particle types that it ships with, especially since Arnold can’t yet render any of those particle types. One of the most unfortunate victims of this is the Sprite particle, which enables you to do some amazing things with it, including changing colour and size over time and by events. As a result, until this is resolved by the developers, you have to make do with custom geometry, which renders fine but has issues such as not being able to change the colour of each individual instance based on an attribute such as age. A script can still be written to achieve all that, but that’s not what we’re going to talk about in this tutorial.

Dealing with Arnold rendering issues is not the only use of the techniques I’ll go through in this tutorial, though. You can also use it for a number of artistic effects, such as making Lego bricks.

Let me give you a quick summary of the tutorial. In the FX module, under nparticles, you’ll find an Instancer tool. This is used in Maya to replace particles with custom geometry. To use it, you

have to select the replacement geometry first and the nparticle node. Once done, an Instancer node is generated which holds all the information of your settings regarding the instances. You can add as many geometry meshes as you want to the instancing and it’ll manage itself. You can also set the rotate order to decide which axis the object is allowed to rotate on. All these features sound like tiny things, but while working, they make the difference between what people generally call ‘Bad CGI’ and the non-noticeable kind of good CGI. Let’s get started.