Hello, I seem to be having an issue rendering hair with mantra.

Unknown command: Density
mantra: Unable to resolve geometry op:/OUT_GROOM.
Please ensure the object is included for rendering.
You can turn off vm_renderable if needed.

This occurs when I use a group for my groom source and setting a skin attribute for density. Eliminating either one of these the hair will render. Is there something I'm missing to make these two work together?

I ran into this exact bug.

Bug: hairgen in mantra fails to find source groom with certain configurations #101315

Use a skin group and density override on the hairgen in mantra generation mode. This causes the descriptive parm to contain a ‘\n’. For some reason the presence of the multi-line descriptive parm causes the procedural to fail to find the source groom. Editing the parm ‘description’ to remove the illegal carriage returns, or editing the python sop to omit this parm returns to normal behavior. The description will only contain ‘\n’ if both a skin group and density override are used.

The work around is to edit the descriptive parm on the node (it's hidden and contains an expression), or to edit the python sop in the groom to omit the decriptive parm from the ifd. (it's not needed to generate the fur).

Thank you, with a little bit of help I got it working.

jonathan.mack
I ran into this exact bug.
The work around is to edit the descriptive parm on the node (it's hidden and contains an expression), or to edit the python sop in the groom to omit the decriptive parm from the ifd. (it's not needed to generate the fur).

gravepact
Thank you, with a little bit of help I got it working.

Hi, i'm having the same bug right now.
I'm totally new to Houdini, so it would be great if you could please attach a screenshot or explain it in more detail on how to solve this problem.

Ruffy2018

jonathan.mack
I ran into this exact bug.
The work around is to edit the descriptive parm on the node (it's hidden and contains an expression), or to edit the python sop in the groom to omit the decriptive parm from the ifd. (it's not needed to generate the fur).

gravepact
Thank you, with a little bit of help I got it working.

Hi, i'm having the same bug right now.
I'm totally new to Houdini, so it would be great if you could please attach a screenshot or explain it in more detail on how to solve this problem.

Ruffy2018 you need to go into the 'skin_GEO_hairgen' node if using the shelf tools to create your fur - under the render tab use SOP geometry instead of Generate Geometry in Mantra