Birth by Material ID or by Luminance value of a material?

[Swihartc]

Hey all, is there a way to birth fluid from a material ID, much like you can with a poly ID?
I see vertex color and texture mask, but what I have is a 'disintegration' effect from a particle system that I would like the edges that are pure white, to birth fire. I have the material ID's set up for the event, but don't see any way to birth from Mat ID. So then I was wondering, is there a way to birth from object material color luminance, so if the whole object is set to black, and the effect area is set to pure white, then birth from only pure white areas. Are either of those possible? I'm using max 2022, vray5 and phoenix 4.4; so if these options are added in phoenix5, I have to wait a few days while the company is upgrading.

[Joelaff]

You can control the birth with most any Map, and by polygon ID:

https://docs.chaos.com/display/PHX4M...+%7C+PHXSource

BY MatID are you referring to this:


Or this:

because the latter one is the Polygon ID referred to under the Emission section on that help page. The first one would be per Material, and you would have to assign those materials with a polygon ID anyway. So use the polygon ID.

But you can certainly use most any map in the Mask section by clicking Map:


See the General-> Emit Mode section of that help page.

[Swihartc]

Hey Joe, I mean by material ID versus a texture, polyID or vertex coloring. So for example, I'm using Tyflow and I have some particles set to MatID 3, can I set a source and have Phoenix birth based only on where matID 3 material of a multi-subobject is showing? Didn't know if anyone had experienced this situation or a suggestion that I'm being blind to. Its like a bridge needs to happen to where either the particle system can set poly ID's per event or phoenix can detect matID's per event. I may need to make some sort of baked out mesh cache that only displays the geo of matID 3 during the particle simulation and use that as the source. I think I'll try that next.

[Joelaff]

One method is to use a Shape operator in Tyflow, and then a Mesh operator. Set the Shape operator to 2d triangles (or any shape really, but if you want them to act like particles they should be small spheres or polygons, etc.). Set the Mesh Operator to be active all the time (Disable Render Only). Set the shapes to have the material IDs you desire in TyFlow.

Then in the Phoenix Emitter enable the Polygon ID.

Since you have the Mesh operator running all the time Phoenix sees the polygons with the correct Material IDs and emits from them based on the Polygon ID filter built in to the PHX Source.

In the attached when you simulate it only emits from particles with MatID 1.

I am sure there are other methods, likely involving the PhoenixFDParticleTex Map, but I am pretty sure this would be faster to evaluate.

You could also use vertex color instead of MatIDs, and use a VertexColor Map, though I still think this method would be faster.

[Swihartc]

Yup, I think this is the only real work around. Having the particles converted to a mesh based on that matID per the event. The other events I'll leave as a different particle group and only export particle group with MatID 3. Thanks for brainstorming with me.

[georgi.zhekov]

How about sending the particles with the designated Material ID in a specific event, which is exported as a specific particle group and using this for the emission? You can check how to do this using this tutorial here - https://docs.chaos.com/display/PHX4M...me+with+tyFlow

Or I'm totally missing the point