Control Hair Density with Vertex Map in Redshift

[MaverickMongoose]

Hi Dr Sassi,

I have a solid object that transitions to cloth (a baked mesh) and I want a few hairs to grow out of the cloth part as it transitions.

Is it possible to Control the Hair Density with a Vertex Map in Redshift?

I've tried piping a vertex map into the hair material but it doesnt seem to do anything.

here's the file: https://we.tl/t-gSz9M9PU08

Thanks again for your help!

[Dr. Sassi]

Hi MaverickMongoose,

Please have a look here:

https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2024_PROJECTS_DRS/20240212_CV4_2024_drs_24_RSvh_12.c4d.zip

I have set the Hair to generate Polygons, in the example "Square", and made that editable. With this, I had access to the vertices, allowing me to use a Vertex map with the Linear field.

Yes, that leaves all "Hair" on the surface, but with a Material. Geometry> Opacity this works.

All the best

[MaverickMongoose]

Good option thanks for that!

Only problem is there doesnt seem to be a way to do it on an animated mesh. I cant bake the hair geometry and have it animated.

[Dr. Sassi]

Thanks for the feedback, MaverickMongoose.
Yes, the Vertex Map is tricky here.

The "baking" it into an Alembic helps to allow for a Vertex/Field combination. If the Hair is not long, then the field will work.

If it is long and dynamic, getting a single hair weighted with the help of a Field (not influencing other hair parts) is not simple.
It requires a static version (Alembic Morph Tag is deleted), and that information is transferred to the other Vertex Tag for simple setups that might work with a Vertex Tag dragged into the receiving Tag. But with Alembic and Hair, I needed to do this via XPresso. See below:
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2024_PROJECTS_DRS/20240212_CV4_2024_drs_24_RSvh_31.zip

Cheers

[MaverickMongoose]

Dang, that seems complicated, shame it's not as easy to do as it sounds!

I'll see if I can get my head around this and give it another try.

Thanks again Dr Sassi!

[Dr. Sassi]

You're very welcome, MaverickMongoose.

Have a great start to your week