"Multiple particle emitters with only one cloud" tutorial
by Marc-André Carbonneau
http://www.vertexvandal.com


multi-emit

This tutorial explains how to setup multiple emitters using only one cloud.
The reason why we have to do that instead of creating two cloud system is because XSI Particles
uses a volume shader that when overlapping, creates artifacts at rendering time.

Launch XSI

1- Go in the Simulate module(hit 4 on your keyboard)

2- Create a polymesh->disc

3- Scale it down a little and move it on your right

4- Do: Create->Particles->From Grid and close the PPG that pops up.

5- Select the cloud icon and do: Modify->Particle->Set Emission and pick
the disc you created at the beginning. Right click to end picking.
DON'T CLOSE THE PPG YET!! Lock it instead.


Creating another Particle Type

6- In the PPG that just popped you can see your new emission property for your disc but you also
see the particle type that was created with the cloud. We want a new one so we can have to particle type of two different
colors.
a) Click the button "New" next to the Particle_Type combo box
b) Now you should have a new particle type called Particle_Type1


Change the properties of the new particle type

7- Change it's name in the lower part of the ppg to ParType_disc
a) change the emission rate to 100
b) Go in the rendering properties tab and change the color to pink


8- Playback and there you go! Now you're particles and can cross.


***Notes***

* If you apply forces to this cloud, all the particle types will be affected unless you put the values to "0"
in the environment tab of the ParticleType you DON'T want affected.


* Another problem that could be yours is if you plan on using the shader's properties instead of the Particle Type's ones.
The shader would then take over the particle types colors, shapes and shadows. Example: using the method we just went through, you realize
you would like selfshadows to be casted only for the pink particles. You go in the cloud's sparks shader and set your light association and draw a render region
but now the yellow ones also have selfshadows. There is no workaround to that problem except for rendering 2 different passes for each particle type
turning shadows "on" when rendering the pink particles and "off" when rendering the yellow particles. Hope I'm clear ;) If not, just send me a mail.

* Good thing is this method is also applicable for Fluid, Blob and Explosion particles. Try mixing paint by using fluid or blob particles..