I hesitate to call this a power lookup, for want of a better name.
It’s not power, as in POWAH. It’s power, as in exponent. I’m sure the enkling can help me find a better name.
This 3d texture warp is great for creating a procedural effect for something like a billowing cloud.
These experiments use a 3d cube of xsi ICE particles, with a density function made by looking-up into noise intersected with a soft falloff sphere.
I started playing with this after enkling showed me a wicked puff-ball type noise lookup that maya can do in it’s fluid field system. I want to make a renderman volume shader that replicates this cool 3d texture warp.
To do the noise lookup, i take the particle position (with an animated offset in 3d space), calc the vector length according to a warp center to create a local position, expound it by a power (enk says -1 is nice) then mult by a normalised copy of the local position and then use this to lookup the noise.
To lookup into the “Turbulize Value By Range” node, i had to edit its compound to allow me to plug in a custom vector into its Turbulence node (it originally has a “Get Particle Position” node driving its coordinate lookup). I offset the particleposition by a vector with an animated Y value to get the effect of a billowing cloud.
The power lookup ICE tree:
Here are some Vimeos of the offset power lookup in action:
This last video uses my cell noise ICE node from this post.
Both of these examples use a particle cube of 100×100x100 particles. That’s 1 million particles, for the mental-arithmetically challenged. Because the cell noise version is so heavy, and unoptimised, its ICE tree updated at about 0.5 frames a second.
These videos are also OGL captures straight from the xsi viewport! Using many particles, displayed as camera-aligned rectangles gives a really good impression of a 3d volume.
I’m sure the ray-marched renderman volume shader will be much slower though.
All in all, ICE has turned out to be quite a nice tool for visualising volume density functions. I hope one day we’ll have a specialised volume set viewer in xsi that can be modified in ICE.Tags: 3d, ice, particles, softimage, xsi