Hello,
Currently the UVW channel name for +Texture mod expects a float[3] when I’d like to re-control via ramp, the density(float) or opacityPP, after partitioning millions of particles.
And to be clear, I set this previously on maya particles, but after partioning there is no longer control for this on the PRT’s.
I’d like to be able to control the opacity where the v coord of the ramp is particles age, after partitioning.
Is this possible?
thanks
-Dan Delapena
Hi Dan,
Currently we are working on our Magma node-based channel editor which will allow you to do that very easily.
However, there is a way you can do this with the modifiers. Assuming your particles have a channel named “Density” (opacityPP maps to “Density” for Maya’s particle systems) do this:
a) Add a “Set Float[3] Channel”. Use channel name “TextureCoord”.
b) Add a “Copy Channel”. Use source channel “Density”, and destination channel “TextureCoord”. (This converts the opacity into a float[3])
c) Add an “Apply Texture”. Use UVW channel “TextureCoord”.
Does that work-around work for you?
If you copy a Float channel into a Vector channel, all three components of the Vector will be set to the same value. So it is possible to copy Density into Color and you will get a grayscale color.
Similarly, you can copy a Vector channel into a Float channel by checking the “As Vector Length” option which will calculate the Magnitude of the Vector and copy it into the Float channel.
Thus, you can for example copy Density (Float) to a Mapping1 (Vector), remap that using a Gradient Texture writing to a Mapping2 (Vector), then copy the result of Mapping2 As Vector Length back into Density…
Simply copying Density to a new channel name will make another Float channel, so you have to use the Set Float[3] Channel modifier to create the new Mapping1 Vector channel before copying into it.
Hope this helps.
Awesome, yes Conrad, that works.
Thanks.
I think i’m just realizing that the channel name is a name of my choosing. 
or one that already exists.
I’m getting confused seeing a Name and then a Channel Name. (channel name makes me believe its a channel i should know about within prt attrs).
So Name is the type, channel name is essentially custom channel name. got it!
can’t wait for magmaflow, i’m used to that workflow.
This page explains how Krakatoa handles particle channels:
http://www.thinkboxsoftware.com/kmy-data-channels/
There is a section I just added entitled “Mapping from Maya Particle Systems” that shows the pre-defined mapping from Maya’s particle attributes into Krakatoa channels.
Hope that helps. We had also talked about having this mapping be user-defined for more flexibility. We could still do that if need be.